The Gale Genetic Disorders of encyclopedia vol 2 - part 10 pps

MACROPHAGE Specialized white blood cells thatplay a role in breaking down old or abnormal red blood cells.. In Down syndrome, this may mean that some of the individual’s cells have a nor

IMPERFORATE ANUSAlso known as anal atresia A

birth defect in which the opening of the anus is absent or

obstructed.

IMPOTENCEThe inability to have a penile erection,

which can be due to tissue damage resulting from

sick-ling within the penis (priapism).

IMPRINTINGProcess that silences a gene or group of

genes The genes are silenced depending on if they are

inherited through the egg or the sperm.

IN UTEROWhile in the uterus; before birth.

IN VITRO FERTILIZATIONProcess by which a woman

has her eggs surgically removed and fertilized in the

lab-oratory The developing embryos can then be transferred

to her uterus to hopefully achieve a pregnancy.

INCLUSION BODYAbnormal storage compartment

inside a cell.

INDUCTION Process where one tissue (the

pre-chordal plate, for example) changes another tissue (for

example, changes tissue into neural tissue).

INFANTILE SPASMSThe form of grand mal or focal

seizures experienced by infants prior to the development

of many voluntary muscular controls.

INFECTIVE ENDOCARDITIS An infection of the

endothelium, the tissue lining the walls of the heart.

INFERTILITYInability in a woman to become pregnant.

INFLAMMATION Swelling and reddening of tissue;

usually caused by the immune system’s response to the

body’s contact with an allergen.

INFORMED CONSENT Provision of complete

infor-mation to a competent individual regarding a treatment

or test Part of informed consent is to ensure a patient’s

understanding of the pros and cons of a procedure and to

get their voluntary authorization to perform the procedure.

INGUINAL HERNIAA condition in which part of the

intestines protrudes through a tear in the muscles of the

abdomen.

INHERITANCE PATTERNThe way in which a genetic

disease is passed on in a family.

INHERITED GIANT PLATELET DISORDER (IGPD) A

group of hereditary conditions that cause abnormal blood

clotting and other conditions.

INSOMNIAAn inability to either fall or stay asleep,

particularly at a time of day when sleep is expected A

number of medications are available and may be used for

treatment.

INSULINA hormone produced by the pancreas that

is secreted into the bloodstream and regulates blood

sugar levels.

INSULIN RECEPTOR GENEThe gene responsible for the production of insulin receptor sites on cell surfaces Without properly functioning insulin receptor sites, cells cannot attach insulin from the blood for cellular use.

INSULIN RESISTANCE An inability to respond mally to insulin in the bloodstream.

nor-INSULIN-DEPENDENT DIABETES MELLITUS (IDDM)

Synonymous with type I diabetes, the more serious form

of diabetes that tends to affect people at a younger age.

INSULIN-LIKE GROWTH FACTOR I A hormone leased by the liver in response to high levels of growth hormone in the blood This growth factor is very similar

re-to insulin in chemical composition; and, like insulin, it is able to cause cell growth by causing cells to undergo mitosis (cell division).

INTERPERSONAL THERAPIES Also called “talking therapy,” this type of psychological counseling is focused

on determining how dysfunctional interpersonal ships of the affected individual may be causing or influ- encing symptoms of depression.

relation-INTRACRANIAL HEMORRHAGE Abnormal bleeding within the space of the skull and brain.

INTRACRANIAL PRESSUREThe pressure of the fluid between the brain and skull.

INTRAGENICOccuring within a single gene.

INTRAUTERINESituated or occurring in the uterus.

INTRAUTERINE GROWTH RETARDATIONA form of growth retardation occurring in the womb that is not caused by premature birth or a shortened gestation time Individuals affected with this condition are of lower than normal birth weight and lower than normal length after a complete gestation period.

INTRAVENOUSA route for administration of fluids, nutrients, blood products, or medications A small, flexi- ble plastic tube is inserted into a vein by way of a needle

to establish this route.

INTRAVENOUS PYELOGRAMAn x ray assessment of kidney function.

INTRONPortion of the DNA sequence of a gene that

is not directly involved in the formation of the chemical that the gene codes for.

INTUSSUSCEPTION One piece of bowel inside another, causing obstruction.

INVERSION A type of chromosomal disorder in which a broken segment of a chromosome attaches to the same chromosome, but in reverse position.

ION CHANNELCell membrane proteins that control the movement of ions into and out of a cell.

IONIZING RADIATION High-energy radiation such

as that produced by x rays.

IQAbbreviation for Intelligence Quotient Compares

an individual’s mental age to his/her true or

chronologi-cal age and multiplies that ratio by 100.

IRISThe colored part of the eye, containing pigment

and muscle cells that contract and dilate the pupil.

IRON OVERLOAD A side effect of frequent blood

transfusions in which the body accumulates abnormally

high levels of iron Iron deposits can form in organs,

par-ticularly the heart, and cause life-threatening damage.

ISCHEMIC ATTACK A period of decreased or no

blood flow.

ISCHOPAGUSConjoined twins who are attached at

the lower half of the body.

ISOMERISMRefers to the organs that typically come

in pairs, but where the right organ is structurally different

from the left organ In a condition like asplenia, however,

the organs are identical.

ISOMERSTwo chemicals identical in chemical

com-position (contain the same atoms in the same amounts)

that have differing structures The normal prion protein

and the infectious prion protein are conformational

iso-mers of one another They have the same chemical

struc-tures, but for some reason, assume different shapes.

ISOTOPEAny of two or more species of atoms of a

chemical element with the same atomic number and

nearly identical chemical behavior, but with differing

atomic mass and physical properties.

ISOZYME/ISOENZYMEA group of enzymes that

per-form the same function, but are different from one

another in their structure or how they move.

JAUNDICEYellowing of the skin or eyes due to an

excess of bilirubin in the blood.

JOINT CONTRACTURES Stiffness of the joints that

prevents full extension.

JOINT DISLOCATION The displacement of a bone

from its socket or normal position.

KABUKI Traditional Japanese popular drama

per-formed with highly stylized singing and dancing using

special makeup and cultural clothing.

KALLIKREINA protein necessary for the activation of chemicals that cause dilation of blood vessels to allow increased blood flow to an area that requires more blood than normal It is also capable of cleaving the comple- ment, C5, into C5a, a much more robust and active form

of this complement molecule.

KANNER’S SYNDROMEAnother name for autism.

KARYOTYPE A standard arrangement of graphic or computer-generated images of chromosome pairs from a cell in ascending numerical order, from largest to smallest.

photo-KARYOTYPING A laboratory procedure in which chromosomes are separated from cells, stained, and arranged so that their structure can be studied under the microscope.

KERATINA tough, non-water-soluble protein found

in the nails, hair, and the outermost layer of skin Human hair is made up largely of keratin.

KERATINOCYTESSkin cells.

KERATOACANTHOMAA firm nodule on the skin ically found in areas of sun exposure.

typ-KERATOLYTIC An agent that dissolves or breaks down the outer layer of skin (keratins).

KERATOSIS A raised thickening of the outer horny layer of the skin.

KETOACIDOSIS A condition that results when organic compounds (such as propionic acid, ketones, and fatty acids) build up in the blood and urine.

KETOLACTIC ACIDOSIS The overproduction of ketones and lactic acid.

KETONE BODIESProducts of fatty acid metabolism in the liver that can be used by the brain and muscles as an energy source.

KETONES “Fuel” molecules that can accumulate and cause the potentially life-threatening complication of ketosis.

KETONURIA The presence of excess ketone bodies (organic carbohydrate-related compounds) in the urine.

KETOSISAn abnormal build-up of chemicals called ketones in the blood This condition usually indicates a problem with blood sugar regulation.

KIDNEY Either of two organs in the lumbar region that filter the blood, excreting the end products of the body’s metabolism in the form of urine and regulating the concentrations of hydrogen, sodium, potassium, phos- phate, and other ions in the body.

KIDNEY TUBULESA portion of the kidneys that causes

water to be excreted as urine or reabsorbed into the body.

KLINEFELTER SYNDROMEA syndrome that occurs in

XXY males; characterized by sterility and small testes;

normal intelligence.

KNOCKOUT EXPERIMENTA type of genetic

experi-ment in which researchers are able to deactivate, or

knock out, a gene that may influence a particular trait,

such as vulnerability to alcohol.

KYPHOSCOLIOSISAbnormal front-to-back and

side-to-side curvature of the spine.

KYPHOSIS An abnormal outward curvature of the

spine, with a hump at the upper back.

L-CARNITINEA substance made in the body that

car-ries wastes from the body’s cells into the urine.

LABIALips of the female genitals.

LACRIMAL DUCTSTear ducts.

LACTIC ACID The major by-product of anaerobic

(without oxygen) metabolism.

LACTIC ACIDOSISA condition characterized by the

accumulation of lactic acid in bodily tissues The cells of

the body make lactic acid when they use sugar as energy.

If too much of this acid is produced, the person starts

feeling ill with symptoms such as stomach pain,

vomit-ing, and rapid breathing.

LACTOSEA sugar made up of of glucose and

galac-tose It is the primary sugar in milk.

LAPAROSCOPYA diagnostic procedure in which a

small incision is made in the abdomen and a slender,

hol-low, lighted instrument is passed through it The doctor

can view the ovaries more closely through the

laparo-scope, and if necessary, obtain tissue samples for biopsy.

LAPAROTOMYAn operation in which the abdominal

cavity is opened up.

LARYNXThe voice box, or organ that contains the

vocal cords.

LASER-ASSISTED IN-SITU KERATOMILEUSIS (LASIK)A

procedure that uses a cutting tool and a laser to modify

the cornea and correct moderate to high levels of myopia.

LATERAL RECTUS MUSCLEThe muscle that turns the

eye outward toward the ear (abduction).

LEBERS HEREDITARY OPTIC ATROPHY OR LEBERS

HEREDITARY OPTIC NEUROPATHY (LHON)Discovered in

1871 by Theodore Leber, the painless loss of central

vision in both eyes, usually occurring in the second or third decade of life, caused by a mutation in mitochondr- ial DNA Other neurological problems such as tremors or loss of ankle reflexes may also be present.

LEFT VENTRICULAR ENLARGEMENT Abnormal largement of the left lower chamber of the heart.

en-LENS The transparent, elastic, curved structure behind the iris (colored part of the eye) that helps focus light on the retina.

LENTIGENEA dark colored spot on the skin.

LEPROSY A chronic, contagious skin and nervous system disease that leads, in the more serious form, to numbness, muscle weakness, and paralysis Leprosy is sometimes referred to as Hansen’s disease.

LEPTOMENINGEAL ANGIOMAA swelling of the sue or membrane surrounding the brain and spinal cord, which can enlarge with time.

tis-LESIONAn abnormal or injured section or region of the brain (or other body organ).

LEUCOPENIAA decrease in white blood cells.

LEUKEMIACancer of the blood forming organs that results in an overproduction of white blood cells.

LEUKOCYTEA white blood cell The neutrophils are

LEVOTHYROXINE A form of thyroxine (T4) for replacement of thyroid hormones in hypothryoidism.

LEWY BODIES Areas of injury found on damaged nerve cells in certain parts of the brain associated with dementia.

LI-FRAUMENI SYNDROME Inherited syndrome known to cause increased risk of different cancers, most notably sarcomas.

LIFETIME RISKA risk that exists over a person’s time; a lifetime risk to develop disease means that the chance is present until the time of death.

life-LIGAMENT A type of connective tissue that nects bones or cartilage and provides support and strength to joints.

LIMB DYSTONIA Involuntary cramp or spasm that

affects the hands Also known as writer’s cramp.

LIMB GIRDLESAreas around the shoulders and hips.

LIMB-GIRDLE MUSCULAR DYSTROPHY (LGMD)Form

of muscular dystrophy that begins in late childhood

to early adulthood and affects both men and women,

causing weakness in the muscles around the hips and

shoulders.

LIMITED SCLERODERMAA subtype of systemic

scle-roderma with limited skin involvement It is sometimes

called the CREST form of scleroderma, after the initials

of its five major symptoms.

LINKAGE The association between separate DNA

sequences (genes) located on the same chromosome.

LINKAGE ANALYSISA method of finding mutations

based on their proximity to previously identified genetic

landmarks.

LIPASEA digestive enzyme found in pancreatic fluid

that breaks down fats.

LIPID Large, complex biomolecule, such as a fatty

acid, that will not dissolve in water A major constituent

of membranes.

LIPOMAA benign tumor composed of

well-differen-tiated fat cells.

LIPOPIGMENTSSubstances made up of fats and

pro-teins found in the body’s tissues.

LIPOPROTEINA lipid and protein chemically bound

together, which aids in transfer of the lipid in and out of

cells, across the wall of the intestine, and through the

blood stream.

LIPOSOMEFat molecule made up of layers of lipids.

LISSENCEPHALYA condition in which the brain has a

smooth appearance because the normal convolutions

(gyri) failed to develop.

LOCALIZED SCLERODERMA Thickening of the skin

from overproduction of collagen.

LOCI The physical location of a gene on a

chro-mosome.

LONGITUDINAL STUDYA type of research project

in which the same subjects are interviewed repeatedly at

intervals over a period of time.

LORICINOne of the proteins that give skin cells their

structure.

LOW DENSITY LIPOPROTEINS (LDL) A cholesterol

carrying substance that can remain in the blood stream

for a long period of time.

LUMBAR LORDOSISAbnormal inward curvature of the spine.

LUPUS ERYTHEMATOSUS A chronic inflammatory disease that affects many tissues and parts of the body including the skin.

LUTENIZING HORMONE (LH)A hormone secreted by the pituitary gland that regulates the menstrual cycle and triggers ovulation in females In males it stimulates the testes to produce testosterone.

LYMPH NODEA bean-sized mass of tissue that is part

of the immune system and is found in different areas of the body.

LYMPHATIC SYSTEMLymph nodes and lympatic sels that transport infection fighting cells to the body.

ves-LYMPHEDEMA DISTICHIASIS Autosomal dominant condition with abnormal or absent lymph vessels Common signs include a double row of eyelashes (dis- tichiasis) and edema of the limbs beginning around puberty.

LYMPHOCYTESAlso called white blood cells, phocytes mature in the bone marrow to form B cells, which fight infection.

lym-LYMPHOMAA malignant tumor of the lymph nodes.

LYNCH SYNDROME A genetic syndrome causing increased cancer risks, most notably colon cancer Also called hereditary non-polyposis colon cancer (HNPCC).

LYSINEA crystalline basic amino acid essential to nutrition.

LYSISArea of destruction.

LYSOSOMAL Pertaining to the lysosomes, special parts (organelles) of cells that contain a number of enzymes important in the breakdown of large molecules such as proteins and fats.

LYSOSOMAL STORAGE DISEASEA category of ders that includes mannosidosis.

disor-LYSOSOME Membrane-enclosed compartment in cells containing many hydrolytic enzymes; where large molecules and cellular components are broken down.

MACROCEPHALYA head that is larger than normal.

MACROGLOSSIAA large tongue.

MACROMOLECULESA large molecule composed of thousands of atoms.

MACROPHAGE Specialized white blood cells that

play a role in breaking down old or abnormal red blood

cells.

MACROSOMIAOverall large size due to overgrowth.

MACROSTOMIAA mouth that is larger or wider than

normal.

MACULAA small spot located in the back of the eye

that provides central vision and allows people to see

col-ors and fine visual details.

MACULEA flat, discolored spot or patch on the skin.

MADAROSISThe medical term for loss of hair from

the eyebrows or eyelashes Madarosis may be associated

with a form of alopecia areata called alopecia totalis It

may also result from such diseases as leprosy and

syphilis, or from trauma.

MADELUNG’S DEFORMITYA forearm bone

malfor-mation characterized by a short forearm, arched or bow

shaped radius, and dislocation of the ulna.

MAFFUCCI DISEASEA manifestation of Ollier disease

(multiple enchondromatosis) with hemangiomas, which

present as soft tissue masses.

MAGNETIC RESONANCE IMAGING (MRI)A technique

that employs magnetic fields and radio waves to create

detailed images of internal body structures and organs,

including the brain.

MAJOR DEPRESSION A psychological condition in

which the patient experiences one or more disabling

attacks of depression that lasts two or more weeks.

MAJOR HISTOCOMPATIBILITY COMPLEX (MHC)

Includes HLA, as well as other components of the

immune system Helps the immune system function, in

part by helping it to distinguish ‘self’ from ‘non-self’.

MALAR HYPOLPLASIA Small or underdeveloped

cheekbones.

MALE-LETHAL X-LINKED DOMINANCEAn inheritance

pattern in which affected male children die from the

char-acteristics of the trait This death is typically either

embryonic, fetal, or neonatal.

MALIGNANTA tumor growth that spreads to another

part of the body; usually cancerous.

MALIGNANT HYPERTHERMIAA condition brought on

by anesthesia during surgery.

MALROTATIONAn abnormality that occurs during

the normal rotation of an organ or organ system.

MAMMOGRAMA procedure in which both breasts

are compressed/flattened and exposed to low doses of

x rays, in an attempt to visualize the inner breast tissue.

MAMMOGRAPHY X rays of the breasts; used to screen for breast cancer.

MANDIBLELower jaw bone.

MANDIBULAR HYPOPLASIA Underdevelopment of the lower jaw.

MANNOSEA type of sugar that forms long chains in the body.

MANOMETRY A balloon study of internal anal sphincter pressure and relaxation.

MAO-B INHIBITORSInhibitors of the enzyme amine oxidase B MAO-B helps break down dopamine; inhibiting it prolongs the action of dopamine in the brain Selegiline is an MAO-B inhibitor.

mono-MAORIA native New Zealand ethnic group.

MARFANOIDTerm for body type that is similar to people with Marfan syndrome Characterized by a tall, lean body with long arms and long fingers.

MARFANOID HABITUSAn abnormally low weight to height ratio that is sometimes seen in extremely tall and thin people.

MASCULINIZATION Development of excess body and facial hair, deepening of the voice, and increase in muscle bulk in a female due to a hormone disorder.

MASSETER SPASM Stiffening of the jaw muscles Often one of the first symptoms of malignant hyper- thermia susceptibility that occurs after exposure to a trigger drug.

MATERNALRelating to the mother.

MATERNAL SERUM SCREENINGA blood test offered

to pregnant women usually under the age of 35, which measures analytes in the mother’s blood that are present only during pregnancy, to screen for Down syndrome, tri- somy 18, and neural tube disorders.

MATERNAL UNIPARENTAL DISOMY Chromosome abnormality in which both chromosomes in a pair are inherited from the mother.

MATURITY-ONSET DIABETES OF THE YOUNG (MODY)

A dominantly-inherited subtype of NIDDM with clear genetic inheritance Onset tends to be earlier than in NIDDM.

MAXIALLARY HYPOPLASIA Underdevelopment of the upper jaw.

MAXILLAOne of the bones of the face.

MECONIUM The first waste products to be charged from the body in a newborn infant, usually greenish in color and consisting of mucus, bile, and so forth.

MEDIAL RECTUS MUSCLEThe muscle that turns the

eye inward toward the nose (adduction).

MEDIUM CHAIN ACYL-COA DEHYDROGENASE

Abbreviated MCAD, this is the enzyme responsible for

the breakdown of medium chain fatty acids in humans.

People affected with MCAD deficiency produce a form

of MCAD that is not as efficient as the normal form of

MCAD.

MEDIUM CHAIN FATTY ACIDSFatty acids containing

between four and 14 carbon atoms.

MEDULLARY CAVITYThe marrow-filled cavity inside

of a long bone (such as the femur).

MEDULLOBLASTOMA Tumor of the central nervous

system derived from undifferentiated cells of the

primi-tive medullary tube.

MEGACOLONDilation of the colon.

MEIOSISThe process in which a cell in the testes or

ovaries undergoes chromosome separation and cell

divi-sion to produce sperm or eggs.

MELANINPigments normally produced by the body

that give color to the skin and hair.

MELANOCYTESA cell that can produce melanin.

MELANOMATumor, usually of the skin.

MELANOSOMESGranules of pigment within

melano-cytes that synthesize melanin.

MELATONINA sleep-inducing hormone secreted by

the pineal gland.

MEMORY CELLSB-cells whose antibodies recognized

antigens from a previous infection; able to mount a quick,

efficient response upon a second infection by the same

organism.

MENDEL, GREGOR Austrian monk who discovered

the basic principals of heredity.

MENINGES The two-layered membrane that covers

the brain and spinal cord.

MENINGITISAn infection of the covering of the brain.

MENOPAUSECessation of menstruation in the human

female, usually occurring between the ages of 46 and 50.

MENSTRUATION Discharge of blood and fragments

of the uterine wall from the vagina in a monthly cycle in

the absence of pregnancy.

MENTAL RETARDATION Significant impairment in

intellectual function and adaptation in society Usually

associated with an intelligence quotient (IQ) below 70.

MERMAID SYNDROME Alternate name for

sireno-melia, often used in older references.

MESOMELIA Shortness of the portion of arm necting the elbow to the wrist or forearm.

con-MESOMELIC The anatomical term used to describe the middle of a limb The bones that constitute the mid- dle of the arm are the radius and ulna, and mesomelic bones of the leg are the tibia and fibula.

METABOLIC ACIDOSISHigh acidity (low pH) in the body due to abnormal metabolism, excessive acid intake,

or retention in the kidneys.

METABOLIC DISORDER A disorder that affects the metabolism of the body.

METABOLIC MYOPATHIES A broad group of cle diseases whose cause is a metabolic disturbance of some type.

mus-METABOLIC PATHWAYA sequence of chemical tions that lead from some precursor to a product, where the product of each step in the series is the starting mate- rial for the next step.

reac-METABOLISM The total combination of all of the chemical processes that occur within cells and tissues of

cen-METACHRONOUSOccurring at separate time intervals.

METAFEMALEAn out of date term for XXX females; also called triple X syndrome.

METAPHYSEAL FLARINGA characteristic found only

by x rays If present, it means that the ends of the bone are wider than normal.

METAPHYSES The growth zone of the long bones located between the ends (epiphyses) and the shaft (dia- physis) of the bone.

METAPHYSISAn area of softer bone and cartilage in long bones between the diaphysis (shaft) and epiphysis (end).

METASTASISThe spreading of cancer from the nal site to other locations in the body.

origi-METASTATIC CANCERA cancer that has spread to an organ or tissue from a primary cancer located elsewhere

METHYLMALONIC ACID An intermediate product

formed when certain substances are broken down in

order to create usable energy for the body.

METHYLMALONIC COA MUTASE (MCM)The enzyme

responsible for converting methylmalonic acid to

suc-cinic acid, in the pathway to convert certain substances to

usable energy.

METHYLMALONICACIDEMIA The build-up of high

levels of methylmalonic acid in the bloodstream due to

an inborn abnormality in an enzyme.

METHYLMALONICACIDURIA The buildup of high

levels of methylmalonic acid in the urine due to an inborn

defect in an enzyme.

MICRO-DELETION SYNDROMEA collection of signs

and symptoms caused by a deletion of a gene or genes

that is too small to be seen through the microscope.

MICROARRAY An ordered arrangement of many

different genes on a glass slide or silicon chip

Micro-arrays allow researchers to study large numbers of genes

simultaneously in determining different levels of gene

activity in such complex processes as the body’s response

to alcohol.

MICROCEPHALICHaving an abnormally small head.

MICROCEPHALIC PRIMORDIAL DWARFISM

SYN-DROMESA group of disorders characterized by profound

growth delay and small head size.

MICROCEPHALYAn abnormally small head.

MICROCORNEAAbnormal smallness of the cornea.

MICRODONTIASmall teeth.

MICROGNATHIA A term used to describe small,

underdeveloped lower jaw and chin.

MICROGNATHY Having a very small and

reced-ing jaw.

MICROMELIA The state of having extremely short

limbs.

MICROPHTHALMIASmall or underdeveloped eyes.

MICROTIASmall or underdeveloped ears.

MIDLINE DEFECTSDisorders involving organs along

the center of the body such as the lips, penis, and corpus

callosum.

MIDLINE ORGANSOrgans found along the center of

the body such as the lips, penis, and corpus callosum.

MINIATURIZATION The process of shortening and

thinning of the hair shafts that is found in androgenetic

alopecia It is caused by the effects of DHT on the hair

follicle.

MINOXIDIL A topical medication sold under the trade name Rogaine for the treatment of male pattern hair loss It is applied to the scalp as a 2% or 5% solution.

MISCARRIAGESpontaneous pregnancy loss.

MISMATCH REPAIRRepair of gene alterations due to mismatching.

MITOCHONDRIAOrganelles within the cell sible for energy production.

respon-MITOCHONDRIAL INHERITANCEInheritance ated with the mitochondrial genome, which is inherited exclusively from the mother.

associ-MITOCHONDRIAL MYOPATHIESDiseases of the cle accompanied by abnormal changes in the cell mito- chondria that results in excessive accumulation of lipids.

mus-MITOSISThe process by which a somatic cell—a cell not destined to become a sperm or egg—duplicates its chromosomes and divides to produce two new cells.

MITRAL VALVEThe heart valve that prevents blood from flowing backwards from the left ventricle into the left atrium Also known as bicuspid valve.

MITRAL VALVE PROLAPSE A heart abnormality in which one of the valves of the heart (which normally con- trols blood flow) becomes floppy Mitral valve prolapse may be detected as a heart murmur but there are usually

MORPHEA The most common form of localized scleroderma.

MOSAICA term referring to a genetic situation in which an individual’s cells do not have the exact same composition of chromosomes In Down syndrome, this may mean that some of the individual’s cells have a nor- mal 46 chromosomes, while other cells have an abnormal

47 chromosomes.

MOSAICISM A genetic condition resulting from a mutation, crossing over, or nondisjunction of chromo- somes during cell division, causing a variation in the number of chromosomes in the cells.

MOTOR FUNCTION The ability to produce body movement by complex interaction of the brain, nerves, and muscles.

MOTOR NEURONSClass of neurons that specifically

control and stimulate voluntary muscles.

MOTOR SKILLS DISORDER A disorder that affects

motor coordination or its development, and the control of

particular groups of muscles that perform activities.

MOTOR UNITSFunctional connection with a single

motor neuron and muscle.

MOTTLED RETINA Changes in the retina of the eye

causing a loss of visual acuity.

MUCOCILIARY ESCALATORThe coordinated action of

tiny projections on the surfaces of cells lining the

respi-ratory tract, which moves mucus up and out of the lungs.

MUCOLIPID Lipid that accumulates in cells in

mucolipidosis disorders.

MUCOLIPIN-1Protein in the cell membrane,

proba-bly a calcium ion channel, involved in recycling

mem-brane lipids and is deficient in mucolipidosis IV.

MUCOLYTIC An agent that dissolves or destroys

mucin, the chief component of mucus.

MUCOPOLYSACCHARIDEA complex molecule made

of smaller sugar molecules strung together to form a chain.

Found in mucous secretions and intercellular spaces.

MUCOPOLYSACCHARIDOSIS I H (MPS I H)Another

name for Hurler syndrome.

MUCORMYCOSIS An organism that commonly

in-fects individuals with diabetes following ketosis events.

MUCOUS MEMBRANEThin, mucous covered layer of

tissue that lines organs such as the intestinal tract.

MULLERIAN DUCTS Structures in the embryo that

develop into the fallopian tubes, the uterus, the cervix,

and the upper vagina in females.

MULTI-INFARCT DEMENTIA Dementia caused by

damage to brain tissue resulting from a series of blood

clots or clogs in the blood vessels It is also called

vascu-lar dementia.

MULTIFACTORIAL Describes a disease that is the

product of the interaction of multiple genetic and

envi-ronmental factors.

MULTIFACTORIAL INHERITANCE A type of

inheri-tance pattern where many factors, both genetic and

envi-ronmental, contribute to the cause.

MULTIFOCAL BREAST CANCERMultiple primary

can-cers in the same breast.

MULTIPLE CARBOXYLASE DEFICIENCYA type of

pro-pionic acidemia characterized by an inability to

metabo-lize biotin.

MULTIPLE SCLEROSIS (MS)A progressive tion of nerve cells that causes episodes of muscle weak- ness, dizziness, and visual disturbances, followed by periods of remission.

degenera-MURMURA noise, heard with the aid of a scope, made by abnormal patterns of blood flow within the heart or blood vessels.

stetho-MUSCULAR DYSTROPHY A group of inherited eases characterized by progressive wasting of the muscles.

dis-MUTAGEN An environmental influence that causes changes in DNA.

MUTANTA change in the genetic material that may alter a trait or characteristic of an individual or manifest

as disease.

MUTATIONA permanent change in the genetic terial that may alter a trait or characteristic of an individ- ual, or manifest as disease, and can be transmitted to offspring.

ma-MYELIN A fatty sheath surrounding nerves in the peripheral nervous system, which help them conduct impulses more quickly.

MYELODYSPLASIAA bone marrow disorder that can develop into aplastic anemia requiring bone marrow or stem cell transplantation.

MYELOMENINGOCELEA sac that protrudes through

an abnormal opening in the spinal column.

MYOCLONUSTwitching or spasms of a muscle or an interrelated group of muscles.

MYOGLOBINURIA The abnormal presence of globin, a product of muscle disintegration, in the urine Results in dark-colored urine.

myo-MYOPATHY Any abnormal condition or disease of the muscle.

MYOPIA Nearsightedness Difficulty seeing objects that are far away.

MYOTONIAThe inability to normally relax a muscle after contracting or tightening it.

MYOTONIC DYSTROPHYA form of muscular phy, also known as Steinert’s condition, characterized

dystro-by delay in the ability to relax muscles after forceful contraction, wasting of muscles, as well as other abnor- malities.

MYXEDEMA Swelling of the face, hands, feet, and genitals due to hypothyroidism.

MYXOIDResembling mucus.

I N

N-ACETYLGLUCOSAMINE-1-PHOSPHOTRANSFERASE

(GNPTA)Enzyme that attaches a signal to other enzymes

and directs those enzymes to the lysosome; deficient in

mucolipidoses II and III.

NALTREXONEA medication originally developed to

treat addiction to heroin or morphine that is also used to

treat alcoholism It works by reducing the craving for

alcohol rather than by producing vomiting or other

unpleasant reactions.

NANISMShort stature.

NARCOTICSStrong, prescription medication that can

be effective in treating pain, but has the potential to be

habit-forming if their use is not supervised correctly.

NASOGASTRIC TUBE A long flexible tube inserted

through the nasal passageways, down the throat, and into

the stomach Used to drain the contents of the stomach.

NATURAL IMMUNITY First line immune response

that is non-specific Includes action of phagocytes,

natu-ral killer cells, and complement cells.

NATURAL KILLER CELLSSpecialized white blood cells

involved in natural immunity Can kill some viruses and

cancer cells.

NECROSISDeath of a portion of tissue differentially

affected by disease or injury.

NECROTIZING ENCEPHALOMYELOPATHYA

progres-sive degeneration of the brain and central nervous

sys-tem This condition is fatal in nearly all individuals

affected with type A pyruvate carboxylase deficiency.

NEGATIVE SYMPTOMS Symptoms of schizophrenia

characterized by the absence or elimination of certain

behaviors DSM-IV specifies three negative symptoms:

affective flattening, poverty of speech, and loss of will or

initiative.

NEONATALNeonatal refers to the first 28 days after

birth.

NEONATOLOGIST A physician (pediatrician) who

has special training in the care of newborns (neonates).

NEPHRONS Microscopic-size tubes that filter the

water that flows into the kidneys.

NEPHROPATHYKidney disease.

NEPHROSIS A non-inflammatory disease of the

kidneys.

NERVE CONDUCTION TESTINGProcedure that

meas-ures the speed at which impulses move through the

a congenital heart defect.

NEURALRegarding any tissue with nerves, including the brain, the spinal cord, and other nerves.

NEURAL CREST CELLSA group of cells in the early embryo, located on either side of the area that will even- tually develop into the spinal cord The cells migrate (move) away from the area and give rise to various body structures, including melanocytes (pigment producing cells), certain structures of the face and head, and parts of the nervous system.

NEURAL TUBE DEFECTA group of severe birth ders in which the brain and spinal cord are malformed and lack the protective skeletal and soft tissue encasement.

disor-NEUROCRISTOPATHY A disorder that results from abnormal development and/or migration of the neural crest cells in the embryo.

NEURODEGENERATIVE Relating to degeneration of nerve tissues.

NEUROFIBROMAA soft tumor usually located on a nerve.

NEUROFIBROMATOSISProgressive genetic condition often including multiple café-au-lait spots, multiple raised nodules on the skin known as neurofibromas, developmental delays, slightly larger head sizes, and freckling of the armpits, groin area, and iris.

NEUROLEPTICAnother name for the older type of antipsychotic medications given to schizophrenic patients.

NEUROLOGICRelating to the brain and central ous system.

nerv-NEUROLOGISTA physician who specializes in ders of the nervous system, including the brain, spine, and nerves.

disor-NEUROMETABOLIC DISORDERAny disorder or dition that affects both the central nervous system (CNS) and the metabolism of the body.

con-NEUROMUSCULAR Involving both the muscles and the nerves that control them.

NEUROMUSCULAR JUNCTION The site at which nerve impulses are transmitted to muscles.

NEURONThe fundamental nerve cell that conducts impulses across the cell membrane.

NEURONAL CEROID LIPOFUSCINOSES A family of

four progressive neurological disorders.

NEUROPATHYA condition caused by nerve damage.

Major symptoms include weakness, numbness, paralysis,

or pain in the affected area.

NEUROTRANSMITTER Chemical in the brain that

transmits information from one nerve cell to another.

NEUTROPENIA A condition in which the number

of leukocytes (a type of white or colorless blood cell)

is abnormally low, mainly in neutrophils (a type of

blood cell).

NEUTROPHILThe primary type of white blood cell

involved in inflammation Neutrophils are a type of

gran-ulocyte, also known as a polymorphonuclear leukocyte.

NEVIPlural of nevus.

NEVUS Any anomaly of the skin present at birth,

including moles and various types of birthmarks.

NEVUS FLAMMEUSA flat blood vessel tumor present

at birth; also known as a “port wine stain.”

NEWBORN SCREENINGThe act of testing all infants

for a specific disease shortly after birth for the purpose of

preventing disease progression through prompt medical

treatment.

NITRATES/NITRITES Chemical compounds found in

certain foods and water that, when consumed, may

increase the risk of gastric cancer.

NITROGEN A gaseous element that makes up the

base pairs in DNA.

NON-INSULIN-DEPENDENT DIABETES MELLITUS

(NIDDM)Synonymous with type II diabetes, the most

com-mon form of diabetes that tends to be highly influenced

by lifestyle factors and typically occurs in adulthood.

NON-SYNDROMIC HEARING LOSSHearing loss that

is not accompanied by other symptoms characteristic of

a larger genetic syndrome.

NONDISJUNCTION Non-separation of a

chromo-some pair, during either meiosis or mitosis.

NONSPHEROCYTIC Literally means not

sphere-shaped Refers to the shape of red blood cells in

non-spherocytic hemolytic anemia.

NONVERBAL LEARNING DISABILITY (NLD)A learning

disability syndrome identified in 1989 that may overlap

with some of the symptoms of Asperger syndrome.

NOONAN SYNDROMEA genetic syndrome that

pos-sesses some characteristics similar to

cardiofaciocutan-ous syndrome It is unclear whether the two syndromes

are different or two manifestations of the same disorder.

NUCLEAR INHERITANCEInheritance associated with the nuclear genome (the 23 pairs of chromosomes) This inheritance follows the rules of segregation developed

by Gregor Mendel and is alternately termed Mendelian inheritance.

NUCLEIC ACIDA type of chemical used as a nent for building DNA The nucleic acids found in DNA are adenine, thymine, guanine, and cytosine.

compo-NUCLEOTIDESBuilding blocks of genes, which are arranged in specific order and quantity.

NUCLEUSThe central part of a cell that contains most

of its genetic material, including chromosomes and DNA.

NYSTAGMUS Involuntary, rhythmic movement of the eye.

OBLIGATE CARRIER An individual who, based on pedigree analysis, must carry a genetic mutation for a particular genetic disease Parents of a child with an autosomal recessive disorder are obligate carriers.

OBSESSIVE COMPULSIVE DISORDER (OCD) Disorder characterized by persistent, intrusive, and senseless thoughts (obsessions) or compulsions to perform repeti- tive behaviors that interfere with normal functioning.

OCCIPITAL LOBEAn anatomical subdivision, located

at the back of the brain, that contains the visual cortex.

OCHRONOSIS A condition marked by pigment deposits in cartilage, ligaments, and tendons.

OCULARA broad term that refers to structure and function of the eye.

OCULAR ALBINISM A type of albinism that affects the vision.

OCULORelated to the eye.

OCULO-DIGITAL REFLEXA reflex causing an ual to press on their eyes with their fingers or fists.

individ-OCULOCUTANEOUS ALBINISMInherited loss of ment in the skin, eyes, and hair.

pig-OCULOMOTOR NERVE Cranial nerve III; the nerve that extends from the midbrain to several of the muscles that control eye movement.

OCULOPHARYNGEAL MUSCULAR DYSTROPHY (OPMD)Form of muscular dystrophy affecting adults of both sexes and causing weakness in the eye muscles and throat.

OKIHIRO SYNDROME Inherited disorder

character-ized by abnormalities of the hands and arms and hearing

loss; may be associated with Duane retraction syndrome.

OLIGODACTYLYThe absence of one or more fingers

or toes.

OLIGODONITAThe absence of one or more teeth.

OLIGOHYDRAMNIOS Reduced amount of amniotic

fluid Causes include non-functioning kidneys and

premature rupture of membranes Without amniotic fluid

to breathe, a baby will have underdeveloped and

imma-ture lungs.

OLIGOSACCHARIDESeveral monosaccharide (sugar)

groups joined by glycosidic bonds.

OLLIER DISEASE Also termed multiple

enchondro-matosis Excessive cartilage growth within the bone

extremities that result in benign cartilaginous tumors

arising in the bone cavity.

OMPHALOCELEA birth defect where the bowel and

sometimes the liver, protrudes through an opening in the

baby’s abdomen near the umbilical cord.

OMPHALOPAGUSConjoined twins who are attached

at the abdomen.

ONYCHOGRYPHOSISOvergrowth of the fingernails

and toenails.

OPHTHALMOLOGISTA physician specializing in the

medical and surgical treatment of eye disorders.

OPHTHALMOLOGYThe medical specialty of vision

and the eye.

OPHTHALMOSCOPE An instrument, with special

lighting, designed to view structures in the back of the eye.

OPISTHOTONOSAn arched position of the body in

which only the head and feet touch the floor or bed when

the patient is lying on their back.

OPTIC DISCThe region where the optic nerve joins

the eye, also refered to as the blind spot.

OPTIC NERVEA bundle of nerve fibers that carries

visual messages from the retina in the form of electrical

signals to the brain.

OPTOMETRISTA medical professional who examines

and tests the eyes for disease and treats visual disorders

by prescribing corrective lenses and/or vision therapy In

many states, optometrists are licensed to use diagnostic

and therapeutic drugs to treat certain ocular diseases.

ORAL LOADING TESTA procedure in which cystine is

administered orally to a patient and plasma levels of

cys-tine are measured Under normal circumstances, amino

acids are absorbed by the intestine and result in an increase

in plasma amino acid levels However, in cystinuria, there

is a problem in the absorption process and blood levels of amino acids do not rise or rise slowly after eating.

ORBITAL CYSTS Small fluid-filled sacs that mally develop inside the bony cavity of the skull that holds the eyeball.

abnor-ORGANELLESmall, sub-cellular structures that carry out different functions necessary for cellular survival and proper cellular functioning.

ORGANIC ACIDURIA The condition of having organic acid in the urine.

ORTHODONTISTDentist who specializes in the rection of misaligned teeth.

cor-ORTHOKERATOLOGY A method of reshaping the cornea using a contact lens It is not considered a perma- nent method to reduce myopia.

ORTHOPEDISTA doctor specializing in treatment of the skeletal system and its associated muscles and joints.

ORTHOSTATIC HYPOTENSIONA sudden decrease in blood pressure upon sitting up or standing May be a side effect of several types of drugs.

OSMOLARITYThe concentration of an osmotic tion, especially when measured in osmols or milliosmols per liter of solution.

solu-OSMOTICALLYReferring to the movement of a vent through a semipermeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane.

sol-OSSICLESAny of the three bones of the middle ear, including the malleus, incus, and stapes.

OSSIFICATIONThe process of the formation of bone from its precursor, a cartilage matrix.

OSTEOARTHRITISA degenerative joint disease that causes pain and stiffness.

OSTEOCHONDROMATOSISAnother name for itary multiple exostoses, meaning a growth of bone and cartilage.

hered-OSTEOMAA benign bone tumor.

OSTEOMALACIAThe adult form of rickets, a lack of proper mineralization of bone.

OSTEOPENIAAbnormal bone mineralization, usually resulting from a failure of the rate of bone matrix forma- tion to compensate for the rate of bone decomposition.

OSTEOPENICBone density that is somewhat low, but

not osteoporotic.

OSTEOPOROSIS Loss of bone density that can

increase the risk of fractures.

OTITIS MEDIAInflammation of the middle ear, often

due to fluid accumulation secondary to an infection.

OTOLARYNGOLOGISTPhysician who specializes in

the care of the ear, nose, and throat and their associated

structures.

OTOSCLEROSISThe main type of non-syndromic

pro-gressive conductive hearing loss seen in humans In very

advanced cases, otosclerosis can become of mixed type.

OVAAnother name for the egg cells that are located

in the ovaries.

OVARYThe female reproductive organ that produces

the reproductive cell (ovum) and female hormones.

OVULATIONThe monthly process by which an

ovar-ian follicle or cyst ruptures, releasing a mature egg cell.

OXYGENATED BLOOD Blood carrying oxygen

through the body.

OXYTOCINA hormone that stimulates the uterus to

contract during child birth and the breasts to release milk.

PACHYDERMAAn abnormal skin condition in which

excess skin is produced that appears similar to that of an

elephant (pachyderm).

PACHYGYRIA The presence of a few broad gyri

(folds) and shallow sulci (grooves) in the cerebral cortex.

PALATEThe roof of the mouth.

PALLIATIVE Treatment done for relief of symptoms

rather than a cure.

PALMOPLANTAR KERATODERMA Group of mostly

hereditary disorders characterized by thickening of the

corneous layer of skin (hyperkeratosis) on the palms and

soles as a result of excessive keratin formation (protein in

the skin, hair, and nails).

PALMOPLANTAR KERATOSIS A raised thickening of

the outer horney layer of the skin on the palms of the

hand and the soles of the feet.

PALPEBRAL FISSURESThe opening between the upper

and lower eyelids.

PALPITATIONAn irregular heartbeat.

PALSYUncontrollable tremors.

PANCREAS An organ located in the abdomen that secretes pancreatic juices for digestion and hormones for maintaining blood sugar levels.

PANCREATIC INSUFFICIENCY Reduction or absence

of pancreatic secretions into the digestive system due to scarring and blockage of the pancreatic duct.

PANCREATIC ISLET CELLCells located in the pancreas that serve to make certain types of hormones.

PANCREATITISInflammation of the pancreas.

PANCYTOPENIAAn abnormal reduction in the ber of erythrocytes (red blood cells), leukocytes (a type

num-of white or colorless blood cell), and blood platelets (a type of cell that aids in blood clotting) in the blood.

PANHYPOPITUITARISM Generalized decrease of all

of the anterior pituitary hormones.

PAPILLOMAAny benign localized growth of the skin and the linings of the respiratory and digestive tracts The most common papilloma is the wart.

PAPILLOMATOUS PAPULES Skin-colored, raised bumps (not warts) found on the skin Most of these growths are benign (non-cancerous) and rarely become malignant (cancerous).

PARAPAGUS Conjoined twins who are joined at the side of their lower bodies.

PARAPLEGIALoss of voluntary movement and tion of both lower extremities.

sensa-PARASITIC TWINS Occurs when one smaller, formed twin is dependent on the larger, stronger twin for survival.

mal-PARASYMPATHETIC GANGLION CELL Type of nerve cell normally found in the wall of the colon.

PARATHYROID GLANDSA pair of glands adjacent to the thyroid gland that primarily regulate blood calcium levels.

PARESTHESIA An abnormal sensation resembling burning, pricking, tickling, or tingling.

PARKINSON DISEASEA disease of the nervous system most common in people over 60, characterized by a shuf- fling gait, trembling of the fingers and hands, and muscle stiffness It may be related in some way to Lewy body dementia.

PARKINSONISMA set of symptoms originally ated with Parkinson disease that can occur as side effects

associ-of neuroleptic medications The symptoms include bling of the fingers or hands, a shuffling gait, and tight or rigid muscles.

PATAU SYNDROMEA syndrome caused by trisomy

13; characterized by cleft palate, severe mental

retarda-tion, and many other physical abnormalities; usually

lethal by age one.

PATELLAThe kneecap.

PATERNALRelating to one’s father.

PATHOLOGIST A physician who specializes in the

diagnosis of disease by looking at living tissues with a

microscope.

PECTORALIS MUSCLES Major muscles of the chest

wall.

PECTUS CARINATUMAn abnormality of the chest in

which the sternum (breastbone) is pushed outward It is

sometimes called “pigeon breast.”

PECTUS EXCAVATUMAn abnormality of the chest in

which the sternum (breastbone) sinks inward; sometimes

called “funnel chest.”

PEDIGREE ANALYSIS Analysis of a family tree, or

pedigree, in an attempt to identify the possible

inheri-tance pattern of a trait seen in this family.

PELVIC EXAMINATION Physical examination

per-formed by a physician, often associated with a Pap smear.

The physician inserts his/her finger into a woman’s

vagina, attempting to feel the ovaries directly.

PENDRINA protein encoded by the PDS (Pendred

syndrome) gene located on chromosome 7q31 Pendrin

protein is believed to transport iodide and chloride within

the thyroid and the inner ear.

PENETRANCEThe degree to which individuals

pos-sessing a particular genetic mutation express the trait that

this mutation causes One hundred percent penetrance is

expected to be observed in truly dominant traits.

PEPTIC ULCERA wound in the bowel that can be

caused by stomach acid or a bacterium called

Helico-bacter pylori.

PEPTIDE A molecular compound made of two or

more amino acids.

PERCHLORATE DISCHARGE TESTA test used to check

for Pendred syndrome by measuring the amount of

iodine stored inside the thyroid gland Individuals with

Pendred syndrome usually have more iodine stored than

normal, and thus their thyroid will release a large amount

of iodine into the bloodstream when they are exposed to

a chemical called perchlorate.

PERICARDIAL CAVITYSpace occupied by the heart.

PERICARDITISInflammation of the pericardium, the

membrane surrounding the heart.

PERINATOLOGISTA physician (obstetrician) who has special training in managing difficult pregnancies Some prenatal tests, such as chorionic villus sampling and level

II ultrasound, are performed primarily by perinatologists.

PERIOD OF SUSCEPTIBILITY The time when gens can cause harm to the developing fetus.

terato-PERIODONTITISInflammatory reaction of the tissues surrounding and supporting the teeth that can progress to bone destruction and abscess formation, and eventual tooth loss.

PERIOSTEALRelating to the periosteum, which is the connective tissue that covers all human bones.

PERIPHERAL NERVESNerves throughout the body that carry information to and from the spinal cord.

PERIPHERAL NEUROPATHYAny disease of the nerves outside of the spinal cord, usually resulting in weakness and/or numbness.

PERIPHERAL VISIONThe ability to see objects that are not located directly in front of the eye Peripheral vision allows people to see objects located on the side or edge of their field of vision.

PERITONITIS Inflammation of the peritoneum, the membrane surrounding the abdominal contents.

PERNICIOUS ANEMIA A blood condition with decreased numbers of red blood cells related to poor vitamin B12 absorption.

PEROXISOMEA cellular organelle containing ent enzymes responsible for the breakdown of waste or other products.

differ-PERVASIVE DEVELOPMENTAL DISORDER (PDD) The term used by the American Psychiatric Association for individuals who meet some but not all of the criteria for autism.

PES PLANUSFlat feet.

PEUTZ-JEGHERS SYNDROME Inherited syndrome causing polyps of the digestive tract and spots on the mouth as well as increased risk of cancer.

PHAGOCYTEWhite blood cells capable of engulfing and destroying foreign antigen or organisms in the fluids

PHENYLALANINEAn essential amino acid that must

be obtained from food since the human body cannot

man-ufacture it.

PHENYLKETORNURIA (PKU) An inborn error of

metabolism that causes build-up of the amino acid,

phenylalanine, in the body The first disease to be used

for newborn screening.

PHEOCHROMOCYTOMAA small vascular tumor of

the inner region of the adrenal gland The tumor causes

uncontrolled and irregular secretion of certain hormones.

PHILTRUM The center part of the face between the

nose and lips that is usually depressed.

PHLEBOTOMY The taking of blood from the body

through an incision in the vein, usually in the treatment

of disease.

PHOBIAAn exaggerated fear.

PHOSPHATEA substance composed of the elements

phosphorus and oxygen that contributes to the

hydroxya-patite crystals found in normal bones.

PHOSPHORYLATION The addition of phosphoric

acid to another compound.

PHOTOPHOBIAAn extreme sensitivity to light.

PHOTORECEPTORS Specialized cells lining the

innermost layer of the eye that convert light into

electri-cal messages so that the brain can perceive the

environ-ment There are two types of photoreceptor cells: rod

cells and cone cells The rod cells allow for peripheral

and night vision Cone cells are responsible for

perceiv-ing color and for central vision.

PHOTOREFRACTIVE KERATECTOMY (PRK) A

proce-dure that uses an excimer laser to make modifications to

the cornea and permanently correct myopia As of early

1998, only two lasers have been approved by the FDA for

this purpose.

PHYTANIC ACIDA substance found in various foods

that, if allowed to accumulate, is toxic to various tissues.

It is metabolized in the peroxisome by phytanic acid

hydroxylase.

PHYTANIC ACID HYDROXYLASE A peroxisomal

enzyme responsible for processing phytanic acid It is

abnormal in Refsum disease.

PICK’S DISEASEA rare type of primary dementia that

affects the frontal lobes of the brain It is characterized by

a progressive loss of social skills, language, and memory,

leading to personality changes and sometimes loss of

moral judgment.

PITUITARY GLANDA small gland at the base of the

brain responsible for releasing many hormones,

includ-ing luteinizinclud-ing hormone (LH) and follicle-stimulatinclud-ing hormone (FSH).

PLACENTA The organ responsible for oxygen and nutrition exchange between a pregnant mother and her developing baby.

PLAQUESAbnormally deposited proteins that fere with normal cell growth and functioning and usually progresses to cell death.

inter-PLASMAThe liquid part of the blood and lymphatic fluid that contains antibodies and other proteins.

PLASMA CELLSAntibody-secreting B-cells.

PLASMALOGENS Fat molecules that are important components of cells and of the myelin sheath that pro- tects nerve cells.

PLASMAPHERESIS A procedure in which the fluid component of blood is removed from the bloodstream and sometimes replaced with other fluids or plasma.

PLASMINThe blood protein responsible for ing blood clots.

dissolv-PLATELETS Small disc-shaped structures that late in the bloodstream and participate in blood clotting.

circu-PLEURAL CAVITYArea of the chest occupied by the lungs.

PLEURITISInflammation of the pleura, the membrane surrounding the lungs.

PNEUMONIAAn infection of the lungs.

PODIATRIST A physician who specializes in ders of the feet.

disor-POIKILODERMA A condition characterized by skin atrophy, widening of the small blood vessels (telangiec- tasia), and pigment changes giving a mottled appearance.

POLYDACTYLYThe presence of extra fingers or toes.

POLYGENIC A trait, characteristic, condition, etc that depends on the activity of more than one gene for its emergence or expression.

POLYHYDRAMNIOSA condition in which there is too much fluid around the fetus in the amniotic sac.

POLYMERA very large molecule, formed from many smaller, identical molecules.

POLYMORPHIC Describes a gene for which there exist multiple forms, or alleles.

POLYMORPHISMA change in the base pair sequence

of DNA that may or may not be associated with a disease.

POLYMYOSITISAn inflammation of many muscles.

POLYPA mass of tissue bulging out from the normal

surface of a mucous membrane.

POLYPECTOMYSurgical removal of polyps.

POLYPLOIDY A condition in which a cell receives

more than two complete sets of chromosomes.

POLYPOSISA descriptive term indicating that

hun-dreds to thousands of polyps have developed in an organ.

POLYSACCHARIDE Linear or branched

macromole-cule composed of numerous monosaccharide (sugar)

units linked by glycosidic bonds.

POLYSYNDACTYLY Having both extra digits (toes,

fingers) as well as webbing (syndactyly) between the

digits.

POOR MUSCLE TONE Muscles that are weak and

floppy.

PORPHYRINA large molecule shaped like a four-leaf

clover Combined with an iron atom, it forms a heme

molecule.

PORT-WINE STAINDark-red birthmarks seen on the

skin, named after the color of the dessert wine.

POSITIONAL CLONINGCloning a gene simply on the

basis of its position in the genome, without having any

idea of the function of the gene.

POSITIVE PREDICTIVE VALUE (PPV) The probability

that a person with a positive test result has, or will get,

the disease.

POSITIVE SYMPTOMS Symptoms of schizophrenia

that are characterized by the production or presence of

behaviors that are grossly abnormal or excessive,

includ-ing hallucinations and thought-process disorder

DSM-IV subdivides positive symptoms into psychotic and

disorganized.

POST-AXIAL POLYDACTYLYAn extra finger or toe on

the outside of the hand or foot.

POST-ICTAL STATEA period of lethargy, confusion,

and deep breathing following a grand mal seizure that

may last from a few minutes to several hours.

POSTERIOR FOSSA Area at the base of the skull

attached to the spinal cord.

POVERTY OF SPEECHA negative symptom of

schizo-phrenia, characterized by brief and empty replies to

ques-tions It should not be confused with shyness or

reluctance to talk.

PRADER-WILLI SYNDROMEA syndrome caused by a

deletion in the paternally inherited chromosome 15 or by

uniparental disomy of the maternal chromosome 15.

PRE-AXIAL POLYDACTYLYAn extra finger or toe on the inside of the hand or foot.

PREAURICULAR PITS Small pits in the skin on the outside of the ear.

PRECOCIOUS PUBERTY An abnormal condition in which a person undergoes puberty at a very young age This condition causes the growth spurt associated with puberty to occur before the systems of the body are ready, which causes these individuals to not attain normal adult heights.

PREMUTATION A change in a gene that precedes

a mutation; this change does not alter the function of the gene.

PRENATAL DIAGNOSISThe determination of whether

a fetus possesses a disease or disorder while it is still in the womb.

PRENATAL TESTINGTesting for a disease, such as a genetic condition, in an unborn baby.

PRIMARY ATRIAL SEPTATIONAn improper division of the atria of the heart, or a “hole in the heart,” which results in the formation of a common atrium rather than the normal two-chambered atrium.

PRIMARY CANCER The first or original cancer site, before any metastasis.

PRIMARY CRANIOSYNOSTOSISAbnormal closure of the cranial sutures caused by an abnormality in the sutures themselves.

PRIMARY DYSTONIADystonia that has no connection

to disease or injury Often hereditary.

PRIMARY IMMUNODEFICIENCY DISEASE (PID) A group of approximately 70 conditions that affect the nor- mal functioning of the immune system.

PRIMARY POSITION, PRIMARY GAZEWhen both eyes are looking straight ahead.

PRIMARY TUMOR The organ or tissue where the tumor began.

PRIONA term coined to mean “proteinaceous tious particle.” Prior to the 1982 discovery of prions, it was not believed that proteins could serve as infectious agents.

infec-PROBANDThe person in the family who is affected

by a genetic disorder and who brings the family to the attention of a health care provider.

PROGERIA Genetic abnormality that presents tially as premature aging and failure to thrive in children.

ini-PROGNATHISMA protruding lower jaw.

PROLACTINA hormone that helps the breast prepare for milk production during pregnancy.

PROLIFERATIONThe growth or production of cells.

PROPHYLACTICPreventing disease.

PROPIONIC ACIDAn organic compound that builds

up in the body if the proper enzymes are not present.

PROPIONYL COA CARBOXYLASE An enzyme that

breaks down the amino acids isoleucine, valine,

threo-nine, and methionine.

PROPTOSISBulging eyeballs.

PROSTATECTOMY The surgical removal of the

prostate gland.

PROTANOPIA The inability or difficulty in

distin-guishing blue and yellow colors.

PROTEASEAn enzyme that acts as a catalyst in the

breakdown of peptide bonds.

PROTEIN Important building blocks of the body

composed of amino acids, involved in the formation of

body structures and controlling the basic functions of the

human body.

PROTEINURIAExcess protein in the urine.

PROTEOLIPID PROTEIN GENE (PLP) A gene that

makes a protein that is part of the myelin in the central

nervous system Mutations in this gene cause PMD.

PROTO-ONCOGENEA gene involved in stimulating

the normal growth and division of cells in a controlled

manner.

PROTOPORPHYRINA precursor molecule to the

por-phyrin molecule.

PROXIMALNear the point of origin.

PROXIMAL MUSCLESThe muscles closest to the

cen-ter of the body.

PSEUDOAINHUM Constrictions of the skin seen in

Vohwinkel disease that may lead to damage of the hands

and feet and possible amputation of the affected areas.

PSEUDOCYSTA fluid-filled space that may arise in

the setting of pancreatitis.

PSEUDODEMENTIA A term for a depression with

symptoms resembling those of dementia The term

dementia of depression is now preferred.

PSEUDODOMINANTA recessive trait that appears, in

a pedigree analysis, to be a dominant trait.

PSEUDOTUMOR CEREBRIA syndrome of raised

pres-sure within the skull that may cause vomiting, headache,

and double vision.

PSORIASISA common, chronic, scaly skin disease.

PSYCHODYNAMIC THERAPIESA form of ical counseling that seeks to determine and resolve the internal conflicts that may be causing an individual to be suffering from the symptoms of depression.

psycholog-PSYCHOLOGISTAn individual who specializes in the science of the mind.

PSYCHOMOTOR Movement produced by action of the mind or will.

PSYCHOTHERAPY Psychological counseling that seeks to determine the underlying causes of a patient’s depression The form of this counseling may be cogni- tive/behavioral, interpersonal, or psychodynamic.

PSYCHOTIC DISORDERA mental disorder ized by delusions, hallucinations, or other symptoms of lack of contact with reality The schizophrenias are psy- chotic disorders.

character-PTERYGIUM COLLI Webbing or broadening of the neck, usually found at birth, and usually on both sides of the neck.

PTOSISDrooping of the upper eyelid.

PUBERTY Point in development when the gonads begin to function and secondary sexual characteristics begin to appear.

PULMONARY ARTERY An artery that carries blood from the heart to the lungs.

PULMONARY ATRESIA When there is no valve between the right ventricle and the pulmonary artery (the artery leading from the heart to the lungs) In the absence

of this valve, the blood does not flow into the lungs well.

PULMONARY EDEMAA problem caused when fluid backs up into the veins of the lungs Increased pressure in these veins forces fluid out of the vein and into the air spaces (alveoli) This interferes with the exchange of oxygen and carbon dioxide in the alveoli.

PULMONARY HYPERTENSIONA severe form of high blood pressure caused by diseased arteries in the lung.

PULMONARY STENOSISNarrowing of the pulmonary valve of the heart, between the right ventricle and the pulmonary artery, limiting the amount of blood going to the lungs.

PUMICE STONE A small stone used to wear down thickened areas of the skin.

PUPIL The opening in the iris through which light enters the eye.

PUSTULEA pus-filled lesion of the skin that bles the “pimples” of adolescent acne.

PYELONEPHRITIS Inflammation of the kidney

com-monly caused by bacterial infections.

PYGOPAGUSConjoined twins who are joined back

to back with fused buttocks.

PYLORIC SPHINCTERCircular smooth muscle found

at the outlet of the stomach.

PYLORIC STENOSIS Narrowing of the stomach due

to thickening of the pyloris muscle at the end of the

stomach.

PYOGENICPus forming.

PYREXIAA medical term denoting fevers.

PYRIDOSTIGMINE BROMIDE (MESTINON) An

anti-cholinesterase drug used in treating myasthenia gravis.

PYRUVATE CARBOXYLASE The enzyme responsible

for the first step in the conversion of pyruvate molecules

into glucose molecules Individuals with type A PCD

produce an highly inefficient form of pyruvate

carboxy-lase Individuals with type B PCD either completely lack

the ability to produce this enzyme, or cannot produce it

in sufficient quantities to sustain life.

PYRUVATE DEHYDROGENASE COMPLEXA series of

enzymes and co-factors that allow pyruvate to be

con-verted into a chemical that can enter the TCA cycle.

QT INTERVALThe section on an electrocardiogram

between the start of the QRS complex and the end of the

T wave, representing the firing or depolarization of the

ventricles and the period of recovery prior to

repolariza-tion or recharging for the next contracrepolariza-tion.

QUADRIPLEGIAParalysis of all four limbs.

RACHITIC Pertaining to, or affected by, rickets.

Examples of rachitic deformities include curved long

bones with prominent ends, a prominent middle chest

wall, or bony nodules at the inner ends of the ribs.

RADIAL KERATOTOMY (RK) A surgical procedure

involving the use of a diamond-tipped blade to make

sev-eral spoke-like slits in the periphsev-eral (non-viewing)

por-tion of the cornea to improve the focus of the eye and

correct myopia by flattening the cornea.

RADIATIONHigh energy rays used in cancer

treat-ment to kill or shrink cancer cells.

RADIATION THERAPYTreatment using high-energy radiation from x-ray machines, cobalt, radium, or other sources.

RADICULOPATHYA bulging of disc material often irritating nearby nerve structures resulting in pain and neurologic symptoms A clinical situation where the radicular nerves (nerve roots) are inflamed or com- pressed This compression by the bulging disc is referred

to as a radiculopathy This problem tends to occur most commonly in the neck (cervical spine) and low back (lumbar spine).

RADIOLUCENTTransparent to x ray or radiation The black area on x-ray film.

RANSON CRITERIA A system of measurements, including age and blood testing, used to predict the out- come of a person who has been hospitalized for an episode of pancreatitis.

RAYNAUD PHENOMENON/RAYNAUD DISEASE A condition in which blood flow to the body’s tissues is reduced by a malfunction of the nerves that regulate the constriction of blood vessels When attacks of Raynaud’s occur in the absence of other medical conditions, it is called Raynaud disease When attacks occur as part of

a disease (as in scleroderma), it is called Raynaud nomenon.

phe-RECESSIVEGenetic trait expressed only when present

on both members of a pair of chromosomes, one ited from each parent.

inher-RECESSIVE GENEA type of gene that is not expressed

as a trait unless inherited by both parents.

RECESSIVE TRAITAn inherited trait or characteristic that is outwardly obvious only when two copies of the gene for that trait are present.

RECTUMThe end portion of the intestine that leads to the anus.

RECURRENCE RISK The possibility that the same event will occur again.

RECURRENTTendency to repeat.

RED BLOOD CELLS Hemoglobin-containing blood cells that transport oxygen from the lungs to tissues In the tissues, the red blood cells exchange their oxygen for carbon dioxide, which is brought back to the lungs to be exhaled.

REDUCED PENETRANCEFailing to display a trait or disease despite possessing the dominant gene that deter- mines it.

REFRACTIONThe bending of light rays as they pass from one medium through another Used to describe the

action of the cornea and lens on light rays as they enter

they eye Also used to describe the determination and

measurement of the eye’s focusing system by an

optometrist or ophthalmologist.

REFRACTIVE EYE SURGERYA general term for

surgi-cal procedures that can improve or correct refractive

errors by permanently changing the shape of the cornea.

RENALRelated to the kidneys.

RENAL AGENESISAbsence or failure of one or both

kidneys to develop normally.

RENAL CELL CARCINOMAA cancerous tumor made

from kidney cells.

RENAL COLICA spasmodic pain, moderate to severe

in degree, located in the back, side, and/or groin area.

RENAL HYPOPLASIAAbnormally small kidneys.

RENAL SYSTEMThe organs involved with the

produc-tion and output of urine.

RENINAn enzyme produced by the kidneys.

RENPENNING SYNDROME X-linked mental

retarda-tion with short stature and microcephaly not associated

with the fragile X chromosome and occurring more

frequently in males, although some females may also be

affected.

REPLICATEProduce identical copies of itself.

REPOLARIZATIONPeriod when the heart cells are at

rest, preparing for the next wave of electrical current

(depolarization).

RESPIRATORYHaving to do with breathing.

RETICULOCYTEImmature red blood cells.

RETINAThe light-sensitive layer of tissue in the back

of the eye that receives and transmits visual signals to the

brain through the optic nerve.

RETINAL DYSPLASIA Improper development of the

retina that can lead to detachment of the retina.

RETINAL DYSTROPHY Degeneration of the retina,

causing a decline in visual clarity.

RETINAL LACUNAESmall abnormal cavities or holes

in the retina.

RETINAL PIGMENT EPITHELIUM (RPE)The pigmented

cell layer that nourishes the retinal cells; located just

out-side the retina and attached to the choroid.

RETINITIS PIGMENTOSAProgressive deterioration of

the retina, often leading to vision loss and blindness.

RETINOIDSA derivative of synthetic vitamin A.

RETINOPATHYAny disorder of the retina.

RHABDOMYOLYSIS Breakdown or disintegration of muscle tissue.

RHABDOMYOSARCOMA A malignant tumor of the skeletal muscle.

RHEUMATOID ARTHRITISChronic, autoimmune ease marked by inflammation of the membranes sur- rounding joints.

dis-RHEUMATOID FACTOR Antibodies present in the majority of individuals with rheumatoid arthritis A diag- nostic marker for rheumatoid arthritis that is absent from ankylosing spondylitis and other seronegative spondy- loarthopathies.

RHINITISInfection of the nasal passages.

RHIZOMELIAA term used to describe the physical growth difference of short arms and legs.

RHIZOMELIC Disproportionate shortening of the upper part of a limb compared to the lower part of the limb.

RHO/RAC GUANINE EXCHANGE FACTORMember of

a class of proteins that appear to convey signals important

in the structure and biochemical activity of cells.

RICKETSA childhood disease caused by vitamin D deficiency, resulting in soft and malformed bones.

RING CHROMOSOMEAn abnormal chromosome in which the terminal ends of the short (p) and long (q) arms have been lost and the remaining p and q arms subse- quently join to form a ring.

ROD Photoreceptor that is highly sensitive to low levels of light and transmits images in shades of gray.

RUSSELL SYNDROMEAn alternative term for Silver syndrome Many doctors use this term to mean an individual with Russell-Silver syndrome who does not have body asymmetry.

SACROILIAC JOINTThe joint between the triangular bone below the spine (sacrum) and the hip bone (ilium).

SACROILIITISInflammation of the sacroiliac joint.

SADDLE NOSEA sunken nasal bridge.

SARCOIDOSISA chronic disease characterized by ules forming in the lymph nodes, lungs, bones, and skin.

nod-SARCOPLASMIC RETICULUMA system of tiny tubes located inside muscle cells that allow muscles to contract and relax by alternatively releasing and storing calcium.

SATELLITES OF CHROMOSOMES Small segments of

genetic material at the tips of the short arms of

chromo-somes 13, 14, 15, 21, and 22.

SAVANT SKILLSUnusual talents, usually in art, math,

or music, that some individuals with autism have in

addi-tion to the deficits of autism.

SCAPHOCEPHALYAn abnormally long and narrow

skull.

SCAPULAR WINGINGThe jutting back of the

shoul-der blades that can be caused by muscle weakness.

SCINTIGRAPHY Injection and detection of

radioac-tive substances to create images of body parts.

SCLERAThe tough white membrane that forms the

outer layer of the eyeball.

SCLERODERMAA relatively rare autoimmune disease

affecting blood vessels and connective tissue that makes

skin appear thickened.

SCLEROSISHardening.

SCOLIOMETERA tool for measuring trunk

asymme-try; it includes a bubble level and angle measure.

SCOLIOSISAn abnormal, side-to-side curvature of

the spine.

SCREENINGProcess through which carriers of a trait

may be identified within a population.

SEBACEOUS Related to the glands of the skin that

produce an oily substance.

SECOND-DEGREE RELATIVE Aunts, uncles, nieces,

nephews, grandparents, grandchildren, and half siblings

are second-degree relatives These individuals have one

fourth of their genes in common.

SECONDARY CRANIOSYNOSTOSISAbnormal closure

of the cranial sutures caused by a failure of the brain to

grow and expand.

SECONDARY DYSTONIADystonia that occurs due to

disease, injury, or another non-hereditary factor Also

known as symptomatic dystonia.

SEDATIVEMedication that has a soothing or

tranquil-izing effect.

SEIZUREAny unusual body function or activity that

is under the control of the nervous system.

SEMENA whitish, opaque fluid released at

ejacula-tion that contains sperm.

SEMI-DOMINANTA trait expressed as a severe form

in homozygous individuals and a milder form in

SENSITIZATION Change in immune system so that

it identifies and “remembers” specific properties of an antigen.

SENSORINEURAL HEARING LOSS (SNHL) neural hearing loss occurs when parts of the inner ear, such as the cochlea and/or auditory nerve, do not work correctly It is often defined as mild, moderate, severe, or profound, depending upon how much sound can be heard

Sensori-by the affected individual SNHL can occur Sensori-by itself, or

as part of a genetic condition such as Pendred syndrome.

SENSORY NEURONS Class of neurons that cally regulate and control external stimuli (senses: sight, sound).

specifi-SEPSISAn infection of the bloodstream.

SEPTALRelating to the septum, the thin muscle wall dividing the right and left sides of the heart Holes in the septum are called septal defects.

SEPTUM PELLUCIDUM A membrane between two

of the normal cavities of the brain that prevents cal signals from passing between different portions of the brain.

electri-SERIAL CASTINGA series of casts designed to ally move a limb into a more functional position.

gradu-SEROLOGICALPertaining to serology, the science of testing blood to detect the absence or presence of anti- bodies (an immune response) to a particular antigen (for- eign substance).

SEROSITIS Inflammation of a serosal membrane Polyserositis refers to the inflammation of two or more serosal membranes.

SEROTONIN DOPAMINE ANTAGONIST (SDA) The newer second-generation antipsychotic drugs, also called atypical antipsychotics SDAs include clozapine (Clozaril), risperidone (Risperdal), and olanzapine (Zyprexa).

SEROTYPE One form of a bacteria that has unique surface proteins Each serotype causes a unique antibody response from a person’s immune system.

SERUMThe liquid part of blood, from which all the

cells have been removed.

SERUM CK TEST A blood test that determines the

amount of the enzyme creatine kinase (CK) in the blood

serum An elevated level of CK in the blood indicates that

muscular degeneration has occurred and/or is occurring.

SERUM CREATININEA chemical in the urine of

kid-ney patients used to determine kidkid-ney disease and failure.

Elevated levels of serum creatinine are an early marker

for severe kidney disease or failure.

SEVERE COMBINED IMMUNODEFICIENCY (SCID) A

group of rare, life-threatening diseases present at birth,

that cause a child to have little or no immune system As

a result, the child’s body is unable to fight infections.

SEX CHROMOSOMESThe X and Y chromosomes that

determine the sex of an individual.

SEX-LINKED Related to either the X or the Y

chro-mosome.

SEX-LINKED DISORDERA disorder caused by a gene

located on a sex chromosome, usually the X chromosome.

SHOCK An inability to provide the body with the

oxygen it requires, sometimes due to large amounts of

bleeding or fluid loss.

SHORT RIB POLYDACTYLY SYNDROMESA collection

of genetic disorders characterized by abnormally short

ribs and extra fingers or toes Research is ongoing to

determine if these disorders are the result of mutations in

a common gene.

SHORT STATURE Shorter than normal height, can

include dwarfism.

SHUNTA small tube placed in a ventricle of the brain

to direct cerebrospinal fluid away from the blockage into

another part of the body.

SIALIC ACIDN-acetylneuraminic acid, a sugar that is

often at the end of an oligosaccharide on a glycoprotein.

SICKLE CELLA red blood cell that has assumed an

elongated shape due to the presence of hemoglobin S.

SICKLE CELL ANEMIAA chronic, inherited blood

dis-order characterized by sickle-shaped red blood cells It

occurs primarily in people of African descent, and

pro-duces symptoms including episodic pain in the joints,

fever, leg ulcers, and jaundice.

SIGMOIDOSCOPY The visual examination of the

inside of the rectum and sigmoid colon, using a lighted,

flexible tube connected to an eyepiece or video screen for

viewing.

SILVER SYNDROMEAn alternative term for Silver syndrome Many doctors use this term to mean an individual with Russell-Silver syndrome who also has body asymmetry.

Russell-SJÖGREN SYNDROME A chronic inflammatory ease often associated with rheumatoid arthritis.

dis-SKELETAL DYSPLASIAA group of syndromes ing of abnormal prenatal bone development and growth.

consist-SKELETAL MUSCLEMuscles under voluntary control that attach to bone and control movement.

SKIN ERYTHEMAIrregular red streaks of skin.

SKIN HEMATOMABlood from a broken blood vessel that has accumulated under the skin.

SLEEP APNEATemporary cessation of breathing while sleeping.

SLEEP PARALYSIS An abnormal episode of sleep in which the patient cannot move for a few minutes, usually occurring on falling asleep or waking up Often found in patients with narcolepsy.

SLY DISEASEAutosomal recessive metabolic disorder caused by dysfunction of the lysosomal enzyme beta- glucuronidase.

SMALL INTESTINE The part of the digestive tract between the stomach and the large intestine.

SMALL TESTESRefers to the size of the male ductive glands, located in the cavity of the scrotum.

repro-SOMATIC Relating to the nonreproductive parts of the body.

SOMATIC CELLSAll the cells of the body except for the egg and sperm cells.

SOMATIC GENE THERAPYThe introduction of genes into tissue or cells to treat a genetic related disease in an individual.

SOMATOSTATINA body chemical, known as a cyclic peptide, involved in the release of human growth hor- mone from the pituitary gland.

SOREAn open wound, bruise, or lesion on the skin.

SPASMODIC DYSPHONIA A focal dystonia that causes involuntary “spasms” of the vocal cords—leading

to interruptions of speech and a decrease in voice quality.

SPASTICA condition in which the muscles are rigid, posture may be abnormal, and fine motor control is impaired.

SPASTIC PARAPLEGIAInability to walk, due to lack of proper neural control over the leg muscles.

SPASTICITY Increased muscle tone, or stiffness,

which leads to uncontrolled, awkward movements.

SPECIFICITYThe proportion of people without a

dis-ease who are correctly classified as healthy or not having

the disease (test negative based on diagnostic criteria).

The higher the specificity of a test or diagnostic criteria,

the lower the number of ‘false positives,’ people who do

not have a disease but who ‘test’ positive.

SPEECH THERAPISTPerson who specializes in

teach-ing simple exercises to improve speech.

SPERMATOZOAMature male germ cells that develop

in the seminiferous tubules of the testes.

SPHEROCYTESRed blood cells that are spherical in

shape, as opposed to the normal bi-concave shape.

Spherocytes are more rigid and their membranes are

more fragile than normally-shaped red blood cells.

SPHINGOMYELINA group of sphingolipids

contain-ing phosphorus.

SPHINGOMYELINASE Enzyme required to

break-down sphingomyelin into ceramide.

SPHYGMOMANOMETER An inflatable cuff used to

measure blood pressure.

SPINA BIFIDAAn opening in the spine.

SPINA BIFIDA OCCULTAThe failure of vertebrae to

close into the neural tube without nerves protruding This

is most often asymptomatic.

SPLAYTurned outward or spread apart.

SPLEENOrgan located in the upper abdominal cavity

that filters out old red blood cells and helps fight

bacter-ial infections Responsible for breaking down

sphero-cytes at a rapid rate.

SPLENIC FLEXUREThe area of the large intestine at

which the transverse colon meets the descending colon.

SPLENOMEGALYEnlargement of the spleen.

SPONDYLOARTHRITIS (SPONDYLITIS) Inflammatory

disease of the joints of the spine.

SPONDYLOSISArthritis of the spine.

SPONGIFORM ENCEPHALOPATHY A form of brain

disease characterized by a “sponge-like” appearance of

the brain either on autopsy or via magnetic resonance

imaging (MRI).

SPONTANEOUSOccurring by chance.

SPORADIC Isolated or appearing occasionally with

no apparent pattern.

SPORADIC INHERITANCEA status that occurs when a

gene mutates spontaneously to cause the disorder in a

person with no family history of the disorder.

SPUTUMA mixture of saliva and mucus from the lungs.

STAGEThe extent of a tumor Tests will be done to determine if a tumor is localized to an organ or if it has spread to the lymph nodes and/or other organs Treatment depends upon the stage of the cancer.

STAGING A method of describing the degree and location of cancer.

STATIC ENCEPHALOPATHYA disease of the brain that does not get better or worse.

STELLATEA star-like, lacy white pattern in the iris Most often seen in light-eyed individuals.

STENOSISThe constricting or narrowing of an ing or passageway.

open-STETHOSCOPE An instrument used for listening to sounds within the body, such as those in the heart or lungs.

STILLBIRTH/STILLBORNThe birth of a baby who has died sometime during the pregnancy or delivery.

STOMACHAn organ that holds and begins digestion

of food.

STRABISMUS An improper muscle balance of the ocular muscles resulting in crossed or divergent eyes.

STROKEA sudden neurological condition related to

a block of blood flow in part of the brain, which can lead

to a variety of problems, including paralysis, difficulty speaking, difficulty understanding others, or problems with balance.

STROMA Middle layer of the cornea, representing about 90% of the entire cornea.

SUBARACHNOID SPACE The space between two membranes surrounding the brain, the arachnoid and pia mater.

SUBCORTICAL BAND HETEROTOPIAA mild form of lissencephaly type 1 in which abnormal bands of gray and white matter are present beneath the cortex near the ventricles.

SUBCORTICAL INFARCTSObstruction of nerve ters below the cerebral cortex of the brain.

cen-SUBMETACENTRIC Positioning of the centromere between the center and the top of the chromosome.

SUBSTANTIA NIGRA One of the movement control centers of the brain.

SUDDEN INFANT DEATH SYNDROME (SIDS)The eral term given to “crib deaths” of unknown causes.

gen-SULFATE A chemical compound containing sulfur and oxygen.

SUTURE“Seam” that joins two surfaces together.

SYMPHALANGISMFusion of phalanges at their ends.

SYMPTOMATIC CARRIERA heterozygous person who

carries a semi-dominant trait This person experiences

milder characteristics of this trait than a person who is

homozygous or hemizygous in this trait.

SYNCHRONOUSOccurring simultaneously.

SYNCOPEA brief loss of consciousness caused by

insufficient blood flow to the brain.

SYNDACTYLYWebbing or fusion between the fingers

or toes.

SYNDROMEA group of signs and symptoms that

col-lectively characterize a disease or disorder.

SYNDROMIC HEARING LOSSHearing loss

accompa-nied by other symptoms that characterize a larger genetic

syndrome of which hearing loss is just one of the

charac-teristics.

SYNKINESIAOccurs when part of the body will move

involuntarily when another part of the body moves.

SYNOPHRYSA feature in which the eyebrows join in

the middle Also called blepharophimosis.

SYNOVITIS Inflammation of the synovium, a

mem-brane found inside joints.

SYRINGOMYELIAExcessive fluid in the spinal cord.

SYSTEMIC SCLEROSIS A rare disorder that causes

thickening and scarring of multiple organ systems.

SYSTOLIC BLOOD PRESSURE Blood pressure when

the heart contracts (beats).

TACHYCARDIA An excessively rapid heartbeat; a

heart rate above 100 beats per minute.

TALIPES EQUINOVARUSA type of clubfoot

character-ized by a downward and inward pointing foot.

TAY-SACHS DISEASE An inherited biochemical

dis-ease caused by lack of a specific enzyme in the body In

classical Tay-Sachs disease, previously normal children

become blind and mentally handicapped, develop

seizures, and decline rapidly Death often occurs between

the ages of three to five years Tay-Sachs disease is

com-mon acom-mong individuals of eastern European Jewish

background but has been reported in other ethnic groups.

TCA CYCLEFormerly know as the Kreb’s cycle, this

is the process by which glucose and other chemicals are

broken down into forms that are directly useable as

energy in the cells.

TELANGIECTASIA An abnormal widening of groups

of small blood vessels in the skin.

TELANGIECTASIS Very small arteriovenous mations, or connections between the arteries and veins The result is small red spots on the skin known as “spider veins”.

malfor-TELANGIECTATICA localized collection of distended blood capillary vessels.

TELESCOPINGA term sometimes used to describe the relatively rapid progression of alcoholism in women, even though women usually begin to drink heavily at later ages than men do.

TELOGENThe resting phase of the hair growth cycle.

TENDON A strong connective tissue that connects muscle to bone.

TENOTOMYA surgical procedure that cuts the don of a contracted muscle to allow lengthening.

ten-TENSILON TEST A test for diagnosing myasthenia gravis Tensilon is injected into a vein and, if the person has MG, their muscle strength will improve for about five minutes.

TERATOGENAny drug, chemical, maternal disease,

or exposure that can cause physical or functional malities in an exposed embryo or fetus.

abnor-TERATOGENICAny agent that can cause birth defects

or mental retardation in a developing fetus Common atogens are medications or other chemicals but they also include infections, radiation, maternal medical condition, and other agents.

ter-TERATOGENIC FACTORAny factor that can produce congenital abnormalities.

TERMINAL DELETION The abnormal early tion of a chromosome caused by the deletion of one of its ends.

termina-TESTES The male reproductive organs that produce male reproductive cells (sperm) and male hormones.

TESTICLES Two egg-shaped glands that produce sperm and sex hormones.

TESTOSTERONE Hormone produced in the testicles that is involved in male secondary sex characteristics.

TETRALOGY OF FALLOT A congenital heart defect consisting of four (tetralogy) associated abnormalities: ventricular septal defect (VSD—hole in the wall separat- ing the right and left ventricles); pulmonic stenosis (obstructed blood flow to the lungs); the aorta “over- rides” the ventricular septal defect; and thickening (hypertrophy) of the right ventricle.

TETRAPHOCOMELIAAbsence of all, or a portion of,

all four limbs The hands or feet may be attached directly

THALASSEMIAAn inherited group of anemias

occur-ring primarily among people of Mediterranean descent It

is caused by abnormal formation of part of the

hemoglo-bin molecule.

THALIDOMIDEA mild sedative that is teratogenic,

causing limb, neurologic, and other birth defects in

infants exposed during pregnancy Women used

thalido-mide (early in pregnancy) in Europe and in other

coun-tries between 1957 and 1961 It is still available in many

places, including the United States, for specific medical

uses (leprosy, AIDS, cancer).

THERMOLABILEHeat-sensitive A thermolabile

pro-tein is a propro-tein that easily loses its shape when heated

even only slightly.

THORACIC CAVITYThe chest.

THORACOPAGUS Conjoined twins joined at the

upper body who share a heart.

THROMBOCYTOPENIAA persistent decrease in the

number of blood platelets usually associated with

hemor-rhaging.

THROMBOEMBOLISMA condition in which a blood

vessel is blocked by a free-floating blood clot carried in

the bloodstream.

THYMUS GLANDAn endocrine gland located in the

front of the neck that houses and transports T cells, which

help to fight infection.

THYROID GLANDA gland located in the front of the

neck that is responsible for normal body growth and

metabolism The thyroid traps a nutrient called iodine

and uses it to make thyroid hormones, which allow for

the breakdown of nutrients needed for growth,

develop-ment, and body maintenance.

THYROID STIMULATING HORMONE

(THYRO-TROPIN)A hormone that stimulates the thyroid gland to

produce hormones that regulate metabolism.

THYROXINE (T4) AND TRIIODOTHYRONINE (T3)

Thyroid hormones.

TICBrief and intermittent involuntary movement or

sound.

TISSUEGroup of similar cells that work together to

perform a particular function The four basic types of

tissue include muscle, nerve, epithelial, and connective tissues.

TONEA term used to describe the tension of cles Increased tone is increased tension in the muscles.

mus-TONOMETERA device used to measure fluid sures of the eye.

pres-TORSADE DE POINTESA type of tachycardia of the ventricles that is characteristic of long-QT syndrome and Jervell and Lange Nielsen syndrome.

TORTICOLLISTwisting of the neck to one side that results in abnormal carriage of the head and is usually caused by muscle spasms Also called wryneck.

TORTUOUSHaving many twists or turns.

connec-TRACHEOSTOMYAn opening surgically created in the trachea (windpipe) through the neck to improve breathing.

TRACTION ALOPECIAHair loss caused by pressure or tension on the scalp related to certain types of hair styles

or equipment worn on the head.

TRAITThe set of physically observable tics that results from the expression of a gene.

characteris-TRANS-RECTAL ULTRASOUNDA procedure where a probe is placed in the rectum High-frequency sound waves that cannot be heard by humans are sent out from the probe and reflected by the prostate These sound waves produce a pattern of echoes that are then used by the computer to create sonograms or pictures of areas inside the body.

TRANSCRIPTION The process by which genetic information on a strand of DNA is used to synthesize a strand of complementary RNA.

TRANSCRIPTION FACTOR A protein that works to activate the transcription of other genes.

TRANSFERASES Family of enzymes that transfer a specific chemical group from one molecule to another.

TRANSFUSIONThe injection of a component of the blood from a healthy person into the circulation of a per- son who is lacking or deficient in that same component

of the blood.

TRANSGENIC EXPERIMENTA genetic experiment in

which a gene can be added to a laboratory animal’s

genetic material The behavior of the altered animal can

be compared with the behavior of an unaltered animal to

help pinpoint the role of the gene affecting it.

TRANSLOCATIONThe transfer of one part of a

chro-mosome to another chrochro-mosome during cell division A

balanced translocation occurs when pieces from two

dif-ferent chromosomes exchange places without loss or gain

of any chromosome material An unbalanced

transloca-tion involves the unequal loss or gain of genetic

informa-tion between two chromosomes.

TRANSMEMBRANEAnything that spans the width of

a membrane.

TRANSPLANTATIONThe implanting of an organ from

either a deceased person (cadaver) or from a live donor to

a person whose organ has failed.

TRANSPOSITION OF THE GREAT ARTERIESA reversal

of the two great arteries of the heart, causing blood

containing oxygen to be carried back to the lungs and

blood that is lacking in oxygen to be transported

through-out the body.

TRANSVAGINAL ULTRASOUND A way to view the

ovaries using sound waves A probe is inserted into the

vagina and the ovaries can be seen Color doppler

imag-ing measures the amount of blood flow, as tumors

some-times have high levels of blood flow.

TRANSVERSIONA genetic term referring to a specific

substitution of one base pair for another There are only

four possible tranversions: guanine for cytosine, cytosine

for guanine, adenine for thymine, or thymine for adenine.

TRAUMAInjury.

TRICHOTILLOMANIAA psychiatric disorder

charac-terized by hair loss resulting from compulsive pulling or

tugging on one’s hair.

TRIGGER DRUGS Specific drugs used for muscle

relaxation and anesthesia that can trigger an episode

of malignant hyperthermia in a susceptible person The

trigger drugs include halothane, enflurane, isoflurane,

sevoflurane, desflurane, methoxyflurane, ether, and

suc-cinylcholine.

TRIGLYCERIDES Certain combinations of fatty acids

(types of lipids) and glycerol.

TRIGONOCEPHALYAn abnormal development of the

skull characterized by a triangular shaped forehead.

TRIMESTERA three-month period Human

pregnan-cies are normally divided into three trimesters: first

(con-ception to week 12), second (week 13 to week 24), and third (week 25 until delivery).

TRINUCLEOTIDEA sequence of three nucleotides.

TRINUCLEOTIDE REPEAT EXPANSIONA sequence of three nucleotides that is repeated too many times in a sec- tion of a gene.

TRIOSE PHOSPHATE ISOMERASE Abbreviated TPI, this is the enzyme responsible for the conversion of dihy- droxyacetone phosphate (DHAP) into D-glyceraldehyde- 3-phosphate (GAP) DHAP and GAP are the two major products of a step in the multi-step process that converts glucose into ATP to supply the body with the energy it needs to sustain itself Only GAP can continue in this process, but DHAP is produced in much higher quanti- ties People with TPI deficiency cannot change DHAP into GAP as efficiently as unaffected people, resulting in insufficient amounts of ATP from glucose to maintain normal cell function.

TRIPHALANGEAL THUMB (TPT) A thumb that has three bones rather than two.

TRIPLOIDYA form of polyploidy; three sets of mosomes.

chro-TRISOMY The condition of having three identical chromosomes, instead of the normal two, in a cell.

TRISOMY 18A chromosomal alteration where a child

is born with three copies of chromosome 18 This results

in multiple birth defects and mental retardation.

TRUNCUS ARTERIOSUSHaving only one artery ing from the heart instead of two Often there is a ven- tricular septal defect (VSD) present.

com-TRYPSIN A digestive enzyme found in pancreatic fluid that breaks down proteins This enzyme is abnormal

epithe-TUMORAn abnormal growth of cells Tumors may

be benign (noncancerous) or malignant (cancerous).

TUMOR SUPPRESSOR GENEGenes involved in trolling normal cell growth and preventing cancer.

con-TURNER SYNDROME Chromosome abnormality characterized by short stature and ovarian failure, caused

by an absent X chromosome Occurs only in females.

TYMPANOPLASTYAny of several operations on the eardrum or small bones of the middle ear to restore or improve hearing in patients with conductive hearing loss.

TYPE I INCONTINENTIA PIGMENTISporadic IP This

disorder is caused by mutations in the gene at Xp11.

These mutations are not inherited from the parents, they

are de novo mutations This type of IP probably

repre-sents a different disease than type II IP.

TYPE II INCONTINENTIA PIGMENTI Familial,

male-lethal, type IP This type of IP is the “classic” case of IP.

It is caused by mutations in the NEMO gene located at

Xq28 Inheritance is sex-linked recessive.

TYROSINEAn aromatic amino acid that is made from

phenylalanine.

ULTRASONOGRAM A procedure where

high-fre-quency sound waves that cannot be heard by human ears

are bounced off internal organs and tissues These sound

waves produce a pattern of echoes, which are then used

by the computer to create sonograms or pictures of areas

inside the body.

ULTRASOUNDAn imaging technique that uses sound

waves to help visualize internal structures in the body.

ULTRASOUND EVALUATION A procedure which

examines the tissue and bone structures of an individual

or a developing baby.

ULTRASOUND EXAMINATIONVisualizing the unborn

baby while it is still inside the uterus.

UMBILICAL HERNIA Protrusion of the bowels

through the abdominal wall, underneath the navel.

UNDESCENDED TESTICLES Testicles that failed to

move from the abdomen to the scrotum during the

devel-opment of the fetus.

UNILATERALRefers to one side of the body or only

one organ in a pair.

UNIPARENTAL DISOMYChromosome abnormality in

which both chromosomes in a pair are inherited from the

same parent.

UPSHOOTUpward movement of the eye.

UREAA nitrogen-containing compound that can be

excreted through the kidney.

UREA CYCLEA series of complex biochemical

reac-tions that remove nitrogen from the blood so ammonia

does not accumulate.

UREA CYCLE DISORDERA disease caused by a lack of

the enzyme that removes ammonia from the blood.

UREMIC POISONINGAccumulation of waste

prod-ucts in the body.

URETERSTubes through which urine is transported from the kidneys to the bladder.

URETHRA The tubular portion of the urinary tract connecting the bladder and external meatus through which urine passes In males, seminal fluid and sperm also pass through the urethra.

URETHRITISInflammation of the urethra.

URINARY URGENCY An exaggerated or increased sense of needing to urinate.

URTICARIAAlso known as hives Usually associated with an allergic reaction.

UTERUS A muscular, hollow organ of the female reproductive tract The uterus contains and nourishes the embryo and fetus from the time the fertilized egg is implanted until birth.

UVEITIS Inflammation of all or part of the uvea, which consists of the middle vascular portion of the eye including the iris, ciliary body, and choroid.

VACCINE An injection, usually derived from a microorganism, that can be injected into an individual to provoke an immune response and prevent future occur- rence of an infection by that microorganism.

VACUOLATIONThe formation of multiple vesicles,

or vacuoles, within the cytosol of cells.

VARIABLE EXPRESSIONInstances in which an cal genetic mutation leads to varying traits from affected individual to affected individual This variance may occur between members of two separately affected fami- lies or it may occur between affected members of the same family.

identi-VARIABLE EXPRESSIVITYDifferences in the symptoms

of a disorder between family members with the same genetic disease.

VARIABLE PENETRANCEA term describing the way in which the same mutated gene can cause symptoms of dif- ferent severity and type within the same family.

VASCULARHaving to do with blood vessels.

VASCULAR MALFORMATION Abnormality of the blood vessels that often appears as a red or pink patch on the surface of the skin.

VAS DEFERENSThe long, muscular tube that connects the epididymis to the urethra through which sperm are transported during ejaculation.

VASODILATORA drug that relaxes blood vessel walls.

VECTORSSomething used to transport genetic

infor-mation to a cell.

VELLUS HAIRS The fine lighter-colored hairs that

result from miniaturization.

VELO Derived from the latin word velum, meaning

palate and back of the throat.

VENOUS THROMBOSIS A condition caused by the

presence of a clot in the vein.

VENTILATORMechanical breathing machine.

VENTRAL WALL DEFECTAn opening in the abdomen

(ventral wall) Examples include omphalocele and

gas-troschisis.

VENTRICLEThe fluid filled spaces in the center of the

brain that hold cerebral spinal fluid.

VENTRICULAR SEPTAL DEFECT (VSD) An opening

between the right and left ventricles of the heart.

VENTRICULOPERITONEAL SHUNT A tube equipped

with a low pressure valve, one end is inserted into the

lat-eral ventricles, the other end of which is routed into the

peritoneum, or abdominal cavity.

VERMISThe central portion of the cerebellum, which

divides the two hemispheres It functions to monitor and

control movement of the limbs, trunk, head, and eyes.

VERTEBRA One of the 23 bones that comprise the

spine Vertebrae is the plural form.

VERTEBRALRelated to the vertebrae.

VERY LONG CHAIN FATTY ACIDS (VLCFA)A type of

fat that is normally broken down by the peroxisomes into

other fats that can be used by the body.

VESTIBULAR NERVE The nerve that transmits the

electrical signals collected in the inner ear to the brain.

These signals, and the responses to them, help maintain

balance.

VESTIBULAR SYSTEMA complex organ located inside

the inner ear that sends messages to the brain about

movement and body position Allows people to maintain

their balance when moving by sensing changes in their

direction and speed.

VILLI Tiny, finger-like projections that enable the

small intestine to absorb nutrients from food.

VISUAL ACUITYThe ability to distinguish details and

shapes of objects.

VISUAL CORTEXThe area of the brain responsible for

receiving visual stimuli from the eyes and integrating it

to form a composite picture of an object.

VITAMIN DEFICIENCY Abnormally low levels of a vitamin in the body.

VOLUNTARY MUSCLE A muscle under conscious control, such as arm and leg muscles.

VOLVULUS A twisted loop of bowel, causing obstruction.

VON WILLEBRAND FACTOR (VWF)A protein found

in the blood involved in the process of blood clotting.

WEYERS ACROFACIAL DYSOSTOSIS The condition resulting from a mutation of the same gene that shows mutation in Ellis-van Creveld syndrome As is usually the case when comparing expressions of the same gene mutation, the single dose Weyers acrofacial dysostosis presents milder symptoms than the double dose Ellis-van Creveld syndrome.

WHIPPLE PROCEDURESurgical removal of the creas and surrounding areas including a portion of the small intestine, the duodenum.

pan-WHITE BLOOD CELLA cell in the blood that helps fight infections.

WHITE MATTERA substance found in the brain and nervous system that protects nerves and allows messages

to be sent to and from the brain to various parts of the body.

WILSON DISEASEA rare hereditary disease marked by high levels of copper deposits in the brain and liver It can cause psychiatric symptoms resembling schizophrenia.

WOLFFIAN DUCTS Structures in the embryo that develop into epididymides, vasa deferentia, and seminal vesicles in males.

WORD SALADSpeech that is so disorganized that it makes no linguistic or grammatical sense.

X CHROMOSOMEOne of the two sex chromosomes (the other is Y) containing genetic material that, among other things, determine a person’s gender.

X INACTIVATION Sometimes called “dosage pensation” A normal process in which one X chromo- some in every cell of every female is permanently inactivated.

X RAYAn image of the body made by the passing of

radiation through the body.

X RAYSHigh energy radiation used either to diagnose

or treat disease.

X-LINKED GENEA gene found on the X chromosome.

X-INACTIVATIONA condition in which one of the

X chromosomes of a female is suppressed, or “turned

off,” in favor of the other X chromosome Preferential

X-inactivation is a process in which one X chromosome is

inactivated in all the cells of the body, in preference to the

other X chromosome Females with preferential

X-inac-tivation express X-linked traits as if they are hemizygous

rather than homozygous or heterozygous.

X-LINKEDLocated on the X chromosome, one of the

sex chromosomes X-linked genes follow a characteristic

pattern of inheritance from one generation to the next.

X-LINKED DOMINANT INHERITANCEThe inheritance

of a trait by the presence of a single gene on the X

chro-mosome in a male or female, passed from an affected

female who has the gene on one of her X chromosomes.

X-LINKED MENTAL RETARDATION Subaverage eral intellectual functioning that originates during the developmental period and is associated with impairment

gen-in adaptive behavior Pertagen-ins to genes on the X some.

chromo-X-LINKED MUTATIONAn abnormal gene transmitted

on the X chromosome.

X-LINKED RECESSIVE INHERITANCE The inheritance

of a trait by the presence of a single gene on the X mosome in a male, passed from his mother who has the gene on one of her X chromosomes She is referred to as

I A

A-beta amyloid protein, 1:66, 69

A-T (Ataxia-telangiectasia),

1:124–127, 2: 817–818

A-T mutated gene, 1:125–127

AAMI (Age-associated memory

CHARGE syndrome and, 1:225

Accutane Pregnancy Prevention

ACHOO syndrome, 1:21–23 , 22

Achromatopsia, 1:258 Acid maltase deficiency, 1:23–26 Acidosis, 1:25–26

ACPS See Acrocephalopolysyndactyly

disorders

Acquired immunity, 2:696

Acrocallosal syndrome, 1:26–28 , 28

Acrocephalopolysyndactyly disorders(ACPS)

Carpenter syndrome, 1:205 Pfeiffer syndrome, 2:914–917

Acromegaly, 1:29–32 , 31–32

McCune-Albright syndrome,

2:721–722 osteoporosis, 2:860–863 Acroparesthesias, 1:402 Activated Protein C, 1:404–405

Activin receptor-like kinase 1 gene,

2:851 Acute chest syndrome, 2:1051

Acute intermittent porphyria,

2:940–942 Acute myelogenous leukemia, 1:419

Acyl-CoA dehydrogenase deficiency,

2:843–846 AD3 gene defect, 1:66

Adams-Oliver syndrome (AOS),

Adenomatous polyposis coli (APC)

See Familial adenomatous polyposis

Adenosine deaminase deficiency,

ADHD See Attention-deficit

hyperactivity disorderAdopted children studies

alcoholism genetics, 1:49 schizophrenia, 2:1024

ADP (ALA dehydrogenase deficiency

porphyria), 2:940–941

Adrenal gland abnormalities,

2:1175–1177 Adrenal insufficiency, 1:36–37 Adrenalectomy, 1:265 Adrenocortical carcinoma, 1:665–666

Adrenocorticotropic hormone test,

AFP See Alpha-fetoprotein

African Americans

galactokinase deficiency, 1:448–449

INDEX

References to individual volumes are listed in boldface; numbers following a colon refer to page numbers A boldface page

number indicates the main essay for a topic An italicized page number indicates a photo or illustration.

African Americans (cont’d)

pancreatic cancer, 2:878

prostate cancer, 2:957–959

Age, maternal See Maternal age

Age-associated memory impairment

Alcohol abuse See Alcoholism

Alcohol dependence See Alcoholism

Alcohol Use Disorder Identification

insulin-dependent diabetes mellitus,

1:329, 331 Allen Brown criteria, 2:980

Allergy

ACHOO syndrome, 1:22 asthma, 1:117, 120–123

Alopecia areata, 1:505–506, 1:507

Alpha-1 antitrypsin (ATT), 1:61–64

Alpha-fetoprotein (AFP)

amniocentesis, 1:74, 76 anencephaly, 1:89–90 ataxia-telangiectasia, 1:125

Beckwith-Wiedemann syndrome,

1:149 genetic counseling, 1:469 liver cancer, 1:679 maternal serum test, 1:351, 2:1147 Meckel-Gruber syndrome, 2:728 oligohydramnios sequence, 2:830 omphalocele, 2:831

Alpha-galactosidase A, 1:401

Alpha-L-iduronidase

Hurler syndrome, 1:572–574 MPS I deficiency, 2:754 Alpha-mannosidosis, 2:704–706

Alpha-N-acetylneuraminidase,

2:807–811 Alpha thalassemia, 2:1119–1126

ALS (Amyotrophic lateral sclerosis),

1:79–82, 1:80–81

Alternative therapies, in cancer

management, 1:198 Altmann, Richard, 1:342 Alzheimer, Alois, 1:65

Alzheimer disease, 1:65–69 , 66–68

color blindness, 1:258 dementia, 1:316–318 Down syndrome, 1:350

nephrogenic diabetes insipidus,

2:795 presymptomatic testing, 1:478 stromal dystrophies, 1:276 Werner syndrome, 2:1193

Amastia, ectodermal dysplasia,

1:373–374

AMC (Arthrogryposis multiplex

congenita), 1:104–108, 1: 340 Amelia, 1:70–73

American Optical/Hardy, Rand, and

Ritter Pseudoisochromatic test, 1:259

Amine precursor and uptake

decarboxylase system, 2:763–767 Amino acids, 1:57, 2:843–846

Aminolevulinate dehydratase gene,

2:941 Aminopterin syndrome, 1:285

Ammonia, urea cycle disorders,

Beckwith-Wiedemann syndrome,

1:147–148 biotinidase deficiency, 1:158 Bruton agammaglobulinemia, 1:179 campomelic dysplasia, 1:184–185 Canavan disease, 1:188

Charcot-Marie-Tooth disease, 1:221 chromosomal abnormalities, 1:238 clubfoot, 1:245

congenital adrenal hyperplasia,

1:264 cri du chat syndrome, 1:291 Crouzon syndrome, 1:293 cystic fibrosis, 1:299 cystinosis, 1:303 diastrophic dysplasia, 1:339 Down syndrome, 1:351

Duchenne muscular dystrophy,

1:363

Emery-Dreifuss muscular

dystrophy, 1:386 Fabry disease, 1:403 Friedreich ataxia, 1:440

FSH muscular dystrophy,

1:445–446 genetic counseling, 1:469 GM1-gangliosidosis, 1:490 harlequin fetus, 1:514 hypochondroplasia, 1:586–587 hypophosphatasia, 1:590 Jacobsen syndrome, 1:617 Leigh syndrome, 1:657 neurofibromatosis, 2:813 omphalocele, 2:831 osteogenesis imperfecta, 2:859 preparation and risk, 1:480 sickle cell disease, 2:1052 side effects, 1:74–76 Sjögren-Larsson syndrome, 2:1063

Smith-Lemli-Opitz syndrome,

2:1067

XX male syndrome, 2:1220 XYY syndrome, 2:1223

Amnion

amelia, 1:71

familial Mediterranean fever, 1:416

nephrogenic diabetes insipidus,

Antidepressants, tricyclic See Tricyclic

Antitrypsin protein, alpha-1 antitrypsin,

AOS (Adams-Oliver syndrome),

1:33–34 AP3 molecule, 1:550–551 APA antibodies, 1:214 AP3B1 gene, 1:550–551

APC genefamilial adenomatous polyposis,

Apolipoprotein E gene

Alzheimer disease genetics, 1:66 late-onset Alzheimer disease, 1:316 APP (Amyloid precursor protein), 1:66

APPP (Accutane Pregnancy Prevention

Program), 1:12–13

Aquaporin-2, nephrogenic diabetes

insipidus, 2:794–795

AR gene, Kennedy disease, 1:635

ArCRD (Autosomal recessive cone-rod

dystrophy), 1:260

Ariginase deficiency, 1:101–102 , 102

Arnold-Chiari malformation, 1:102, 1:103–104

Arrhinencephaly See

HoloprosencephalyArrhythmias

holoprosencephaly, 1:558–559

Jervell and Lange-Nielsen

syndrome, 1:618–620 long-QT syndrome, 1:681–686

ArRP (Autosomal recessive retinitis

pigmentosa), 2:989–990 Arterial switch, 1:269 Arteriohepatic dysplasia, 1:41–43 Arteriosclerosis, 2:1111

Artificial reproductive technology,

2:1229

AS See Asperger syndrome

Ashkenazi Jews

Bloom syndrome, 1:165–166 Canavan disease, 1:187–188

early onset idiopathic torsion

dystonia, 1:370 familial dysautonomia, 1:412–413 Fanconi anemia, 1:418–420 Gaucher disease, 1:453–454 Niemann-Pick disease, 2:814–816 Tay-Sachs disease, 2:1115–1116 ASPA gene, 1:186–188

Aspartate transaminase, 1:63 Aspartic acid, 2:972 Aspartoacylase deficiency, 1:185–188 Asperger, Hans, 1:109

Asperger syndrome (AS), 1:109–111 autism and, 1:130

Asthma, 1:115–123 , 119

allergies and, 1:120–121 alpha-1 antitrypsin, 1:62 Astrocytoma, 1:192

Ataxia

abetalipoproteinemia, 1:6 cerebellar, 1:124

ATP See Adenosine triphosphate

ATP-binding cassette transporter,

ATT (Alpha-1 antitrypsin), 1:61–64

Attention-deficit disorder (ADD)

Autonomic nervous system, 1:412–413

Autosomal dominant compelling

heliopthalmic outburst syndrome,

1:21–23 , 22

Autosomal dominant inheritance

acromegaly, 1:32

Adams-Oliver syndrome, 1:33 Alagille syndrome, 1:41 Alzheimer disease, 1:66 amelia, 1:71

amyotrophic lateral sclerosis, 1:80 anemia, sideroblastic X-linked, 1:87

Beare-Stevenson cutis gyrata

syndrome, 1:144 brachydactyly, 1:169 characteristics, 1:606–607 Charcot-Marie-Tooth disease, 1:220 CHARGE syndrome, 1:223 coloboma, 1:256

Costello syndrome, 1:283–285 Ehlers-Danlos syndrome, 1:376

Emery-Dreifuss muscular dystrophy

2, 1:384–385 Engelmann disease, 1:390

familial adenomatous polyposis,

hereditary spherocytosis,

2:1075–1076 hyperlipoproteinemia, 1:583 hypophosphatasia, 1:588

Jackson-Weiss syndrome,

1:613–615 Kallman syndrome, 1:627 Li-Fraumeni syndrome, 1:665–666 long-QT syndrome, 1:682–683 malignant hyperthermia, 2:701–702

multiple endocrine neoplasias,

2:765 myotonic dystrophy, 2:786 oncogenes, 2:836 Opitz syndrome, 2:837–838 osteogenesis imperfecta, 2:856–858 Pallister-Hall syndrome, 2:873 pedigree analysis, 2:897

polycystic kidney disease,

2:931–932 progeria syndrome, 2:953 Rieger syndrome, 2:1001–1003 Robinow syndrome, 2:1007–1009 Saethre-Chotzen syndrome, 2:1019 spinocerebellar ataxia, 2:1085 thanatophoric dysplasia, 2:1131 Treacher Collins syndrome, 2:1140

triose phosphate isomerase

deficiency, 2:1142–1144 Van der Woude syndrome, 2:1167

Autosomal dominant retinitis

carnitine palmitoyltransferase

deficiency, 1:202–203 characteristics, 1:607

Charcot-Marie-Tooth disease,

1:220–221

congenital adrenal hyperplasia,

1:262 Crane-Heise syndrome, 1:285–286 cystinuria, 1:305–307

Dubowitz syndrome, 1:357–359 Ehlers-Danlos syndrome, 1:376

Ellis-van Creveld syndrome,

Kallman syndrome, 1:628 Leigh syndrome, 1:655 Meckel-Gruber syndrome, 2:727 metaphyseal dysplasia, 2:733 mucolipidosis, 2:752 muscular dystrophy, 2:770 Neu-Laxova syndrome, 2:797–798 neuraminidase deficiency, 2:804 organic acidemias, 2:843–844

pancreatic beta cell agenesis,

2:875–876 pedigree analysis, 2:897–898 Pendred syndrome, 2:903–904

polycystic kidney disease,

2:931–932 Robinow syndrome, 2:1008–1009 Schinzel-Giedion syndrome, 2:1022 Seckel syndrome, 2:1039

severe combined immunodeficiency,

Autosomal recessive retinitis

pigmentosa (ArRP), 2:989–990