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Gale Encyclopedia of Genetic Disorder / Gale Encyclopedia of Genetic Disorders, Two Volume Set - Volume 2 - M-Z - I

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GLOSSARY

I A

5 VNTR A specific variation outside the insulin gene that is implicated in NIDDM and IDDM susceptibility.

AADC INHIBITORS Drugs that block the amino acid decarboxylase; one type of enzyme that breaks down dopamine. Also called DC inhibitors, they include carbidopa and benserazide.

ABDOMINAL HERNIA Bulging of an organ or tissue through the muscle of the stomach wall.

ABDUCENS NERVE Cranial nerve VI; the nerve that extends from the midbrain to the lateral rectus muscle of the eye and controls movement of the eye toward the ear (abduction).

ABDUCTION Turning away from the body.

ABSCESS A localized collection of pus or infection that is walled off from the rest of the body.

ABSENCE SEIZURE A brief seizure with an accompanying loss of awareness or alertness.

ACAMPROSATE An anti-craving medication used in Europe to reduce the craving for alcohol. It is presently undergoing tests for approval in the United States.

ACANTHOCYTOSIS The presence of acanthocytes in the blood. Acanthocytes are red blood cells that have the appearance of thorns on their outer surface.

ACANTHOSIS NIGRICANS A skin condition characterized by darkly pigmented areas of velvety wart-like growths. Acanthosis nigricans usually affects the skin of the armpits, neck, and groin.

ACCOMMODATION The ability of the lens to change its focus from distant to near objects. It is achieved through the action of the ciliary muscles that change the shape of the lens.

ACETYLCHOLINESTERASE (ACHE) An enzyme found in nerve tissue.

ACHROMATOPSIA The inability to distinguish any colors.

ACID MALTASE The enzyme that regulates the amount of glycogen stored in muscle cells. When too much glycogen is present, acid maltase is released to break it down into waste products.

ACIDOSIS A condition of decreased alkalinity resulting from abnormally high acid levels (low pH) in the blood and tissues. Usually indicated by sickly sweet breath, headaches, nausea, vomiting, and visual impairments.

ACONDROPLASIA An autosomal dominant form of dwarfism caused by a disorder in the formation of cartilage at the ends of long bones. Affected individuals typically have short limbs, a large head with a prominent forehead and flattened profile, and a normal-sized trunk.

ACQUIRED ANGIONEUROTICEDEMA Abbreviated AANE, or AAE, this is a non-hereditary form of angio edema that generally begins to show symptoms in, or after, the fourth decade of life.

ACQUIRED IMMUNITY Also called ‘specific immunity;’ refers to immune reaction mediated by B-cells and/or T-cells. Includes humoral and cellular immunity.

ACROCENTRIC A chromosome with the centromere positioned at the top end.

ACROCEPHALOPOLYSYNDACTYLY SYNDROMES A collection of genetic disorders characterized by cone shaped abnormality of the skull and partial fusing of adjacent fingers or toes.

ACROCEPHALY An abnormal cone shape of the head.

ACROMELIC The anatomical term used to denote the end of a limb (arm or leg). In the context of Robinow syndrome, it refers to bones of the hands and feet.

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ACROOSTEOLYSIS Loss of bone tissue at the ends of the fingers and/or toes.

ACROPARESTHESIAS Painful burning sensation in hands and feet.

ACTION POTENTIAL The wave-like change in the electrical properties of a cell membrane, resulting from the difference in electrical charge between the inside and outside of the membrane.

ACUTE PHASE The initial phase of LHON where visual blurring begins in both eyes and central vision is lost.

ACUTE PHASE REACTANTS Blood proteins whose concentrations increase or decrease in reaction to the inflammation process.

ADDUCTED THUMBS Thumbs clasped across the palm.

ADDUCTION Movement toward the body. In Duane retraction syndrome, turning the eye inward toward the nose.

ADENOCARCINOMA A type of cancer that is in a gland-like form.

ADENOMATOUS Derived from glandular structures.

ADRENAL GLAND A triangle-shaped endocrine gland, located above each kidney, that synthesizes aldosterone, cortisol, and testosterone from cholesterol. The adrenal glands are responsible for salt and water levels in the body, as well as for protein, fat, and carbohydrate metabolism.

ADRENAL INSUFFICIENCY Problems with the adrenal glands that can be life threatening if not treated. Symptoms include sluggishness, weakness, weight loss, vomiting, darkening of the skin and mental changes.

ADRENOCORTICOTROPIN (CORTICOTROPHIN) A hormone that acts on cells of the adrenal cortex, causing them to produce male sex hormones and hormones that control water and mineral balance in the body.

ADVANCED BONE AGE The bones, on x ray, appear to be those of an older individual.

AFFECTIVE FLATTENING A loss or lack of emotional expressiveness. It is sometimes called blunted or restricted affect.

AFLATOXIN A substance produced by molds that grow on rice and peanuts. Exposure to aflatoxin is thought to explain the high rates of primary liver cancer in Africa and parts of Asia.

AGE-ASSOCIATED MEMORY IMPAIRMENT (AAMI) A condition in which an older person experiences some

memory loss and takes longer to learn new information. AAMI is distinguished from dementia in that it is not progressive and does not represent a serious decline from the person’s previous level of functioning.

AGENESIS Failure of an organ, tissue, or cell to develop or grow.

AGENESIS OF THE CORPUS CALLOSUM Failure of the corpus callosum to form and develop. The corpus callosum is the band of nerve fibers located between the two sides, or hemispheres, of the brain.

AGNOSIA Loss of the ability to recognize objects by use of the physical senses.

AGYRI A lack of convolutions (gyri) or normal folds in the brain tissue.

AKATHISIA Agitated or restless movement, usually affecting the legs and accompanied by a sense of discomfort. It is a common side effect of neuroleptic medications.

AKINESIA A loss of the ability to move; freezing in place.

ALKALINE Having a basic pH; not acidic.

ALKALINIZATION The process of making a solution more basic, rather than more acidic, by raising the pH.

ALLELE One of two or more alternate forms of a gene.

ALLELIC Related to the same gene.

ALLELIC VARIANTS A disease is said to have allelic variants when different mutations in the same allele result in identical, or nearly identical, symptoms. An allele is the combined locations of a gene on the two paired chromosomes that contain this gene.

ALLERGEN A substance or organism foreign to the body. Allergens stimulate the immune system to produce antibodies.

ALLERGIC RHINITIS Hay fever.

ALLERGY Condition in which the immune system is hypersensitive to contact with allergens; an abnormal response by the immune system to contact with an allergen. This condition produces symptoms such as inflammation of tissues and production of excess mucus in the respiratory system.

ALOPECIA Loss of hair or baldness.

ALOPECIA AREATA A nonscarring hair loss syndrome characterized by smooth round or oval hairless areas on the scalp.

ALPHA-FETOPROTEIN (AFP) A chemical substance produced by the fetus and found in the fetal circulation.

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AFP is also found in abnormally high concentrations in most patients with primary liver cancer.

ALPHA-L-IDURONIDASE. An enzyme that breaks down dermatan sulfate and heparan sulfate. People with Hurler syndrome do not make enough of this enzyme.

ALPHA-THALASSEMIA Autosomal recessive disorder where no functional hemoglobin is produced. Leads to severe untreatable anemia.

ALTERATION Change or mutation in a gene, specifically in the DNA that codes for the gene.

ALTERNATE COMPLEMENT PATHWAY A cascade of enzymatic reactions that produce antibacterial proteins. This pathway helps to ward off infections.

ALZHEIMER DISEASE A degenerative disease of the central nervous system characterized by premature senility and other mental deterioration.

AMASTIA A birth disorder involving absent breast(s).

AMELOGENESIS IMPERFECTA A hereditary dental abnormality characterized by discoloration of the teeth.

AMINO ACID Organic compounds that form the building blocks of protein. There are 20 amino acids (eight are “essential amino acids” that the body cannot make and must be obtained from food).

AMNIOCENTESIS A procedure performed at 16-18 weeks of pregnancy in which a needle is inserted through a woman’s abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus.

AMNION Thin, tough membrane surrounding the embryo and containing the amniotic fluid.

AMNIOTIC FLUID The fluid surrounding a developing baby during pregnancy.

AMNIOTIC SAC Contains the fetus and its surrounding amniotic fluid.

AMPLIFICATION A process by which something is made larger. In clotting, only a very few chemicals are released by the initial injury; they result in a cascade of chemical reactions which produces increasingly larger quantities of different chemicals, resulting in an appro- priately-sized, strong fibrin clot.

AMPUTATION Surgical removal of any portion of the body.

AMYLASE A digestive enzyme found in saliva or pancreatic fluid that breaks down starch and sugars.

AMYLOID A waxy translucent substance composed mostly of protein, that forms plaques (abnormal deposits) in the brain.

AMYLOIDOSIS Accumulation of amyloid deposits in various organs and tissues in the body such that normal functioning of an organ is compromised.

AMYOPLASIA The mildest form of arthrogryposis muliplex congenita, characterized by sporadic and recurrent contractures of the wrists, elbows, and knees; clubfoot, and an abnormal internal rotation of the shoulders.

ANAGEN The growth phase of the human hair growth cycle.

ANALYTE A chemical substance such as an enzyme, hormone, or protein.

ANDROGENS A group of steroid hormones that stimulate the development of male sex organs and male secondary sexual characteristics.

ANEMIA A blood condition in which the level of hemoglobin or the number of red blood cells falls below normal values. Common symptoms include paleness, fatigue, and shortness of breath.

ANESTHESIA Lack of normal sensation (especially to pain) brought on by medications just prior to surgery or other medical procedures.

ANESTHETIC Drug used to temporarily cause loss of sensation in an area of the body. An anesthetic may either be general, associated with a loss of consciousness, or local, affecting one area only without loss of consciousness. Anesthetics are administered either via inhalation or needle injection.

ANEUPLOIDY An abnormal number of chromosomes in a cell. Trisomy 18 and trisomy 13 are examples of aneuploid conditions.

ANEURYSM Widening of an artery, which could eventually bleed.

ANGELMAN SYNDROME A syndrome caused by a deletion in the maternally inherited chromosome 15 or uniparental disomy of the paternal chromsome 15.

ANGIOGRAPHY Injecting dye into blood vessels so they can be be seen on a radiograph or picture.

ANGIOID STREAKS Gray, orange, or red wavy branching lines in Bruch’s membrane.

ANGIOKERATOMA Skin rash comprised of red bumps. The rash most commonly occurs between the belly button and the knees.

ANGIOMA A benign tumor composed of blood vessels or lymph vessels.

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ANGIONEUROTIC EDEMA Recurrent episodes of swelling of the tissues of the body caused by an overactive immune system. This is also called angioedema.

ANGIOTENSINOGEN A plasma globulin (protein) formed in the liver and directly involved in the regulation of blood pressure.

ANKYLOSIS Immobility of a joint due to the formation of new bone at the site of inflammation.

ANOMALOUS Irregular or different from normal.

ANOMALOUS VENOUS RETURN Normally, the veins that bring blood containing oxygen from the lungs to the heart (called pulmonary veins) are connected to the left atrium. In this situation, the pulmonary veins are connected to the right atrium.

ANOMALY Different from the normal or expected. Unusual or irregular structure.

ANOPTHALMIA A medical condition in which one eye is missing.

ANOTIA Absence of an ear.

ANTERIOR FONTANELLE The soft-spot on the skull of an infant that is located in the center of the head just behind the hairline.

ANTERIOR HORN CELLS Subset of motor neurons within the spinal cord.

ANTI-ANDROGEN DRUGS Drugs that block the activity of the male hormone.

ANTIBIOTICS A group of medications that kill or slow the growth of bacteria.

ANTIBODY A protein produced by the mature B cells of the immune system that attach to invading microorganisms and target them for destruction by other immune system cells.

ANTICIPATION Increasing severity in disease with earlier ages of onset in successive generations; a condition that begins at a younger age and is more severe with each generation.

ANTICOAGULANT Drugs used to prevent blood clots.

ANTIDIURETIC HORMONE (VASOPRESSIN) A hormone that acts on the kidneys to regulate water balance.

ANTIGEN A substance or organism that is foreign to the body and stimulates a response from the immune system.

ANTIGEN PRESENTING CELL Cells that are able to present foreign antigen in conjunction with major histocompatability complex proteins to the immune system.

ANUS The opening at the end of the intestine that carries waste out of the body.

AORTA The main artery located above the heart that pumps oxygenated blood out into the body. Many congenital heart defects affect the aorta.

AORTIC REGURGITATION A condition in which the aortic valve does not close tightly, allowing blood to flow backwards from the aorta into the heart.

AORTIC ROOT The location where the aorta (main heart blood vessel) inserts in the heart. Enlargement of the aortic root can cause it to rupture.

AORTIC STENOSIS A condition in which the aortic valve does not open properly, making it difficult for blood to leave the heart.

APHASIA Loss of previously acquired ability to speak, or to understand written or spoken language.

APLASTIC ANEMIA A form of anemia characterized by a greatly decreased formation of red and white blood cells as a result of abnormal bone marrow.

APNEA An irregular breathing pattern characterized by abnormally long periods of the complete cessation of breathing.

APOENZYME An enzyme that cannot function without assistance from other chemicals called cofactors.

APOPTOSIS The normally programmed cell death process in which cells die in order to be replaced with new cells.

APPENDECTOMY The procedure to surgically remove an appendix.

APPENDICITIS Inflammation of the appendix.

APPENDIX A portion of intestine attached to the cecum.

APRAXIA Impairment of the ability to make purposeful movements, but not paralysis or loss of sensation.

AQUEOUS HUMOR A fluid produced by the ciliary body and contained within the front chamber of the eye.

ARACHNODACTYLY A condition characterized by abnormally long and slender fingers and toes.

ARRHYTHMIA Abnormal heart rhythm. Examples are a slow, fast, or irregular heart rate.

ARTERIOLE The smallest type of artery.

ARTERIOPATHY Damage to blood vessels.

ARTERIOSCLEROSIS Hardening of the arteries that often results in decreased ability of blood to flow smoothly.

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ARTERIOVENOUS MALFORMATION (AVM) Abnormal, direct connection between the arteries and veins (blood vessels). Can range from very small to large in size. Bleeding or an aneurysm may result.

ARTERY A blood vessel that carries blood away from the heart to peripheral tissues.

ARTHROCHALASIA Excessive loosness of the joints.

ARTHROGRYPOSIS Abnormal joint contracture.

ASPERGER SYNDROME A term used to describe highfunctioning individuals with autism. These individuals usually have normal IQ and some language skills.

ASPHYXIA Lack of oxygen. In the case of cerebral palsy, lack of oxygen to the brain.

ASPIRATION Inhalation of food or saliva.

ASPIRATION PNEUMONIA Lung infection due to food or liquids accidentally getting into lungs.

ASPLENIA The absence of the spleen in the body.

ASTIGMATISM A cause of poor eyesight, usually due to an error in the refraction of light within the eye.

ASTROCYTOMA Tumor of the central nervous system derived from astrocytes.

ASYMMETRIC SEPTAL HYPERTROPHY A condition in which the septum (the wall that separates the atria of the heart) is abnormally excessively thickened. In microscopic examination, normal alignment of muscle cells is absent (myocardial disarray).

ASYMPTOMATIC CARRIER A person who carries a recessive trait but does not show any characteristics of the trait.

ATAXIA A deficiency of muscular coordination, especially when voluntary movements are attempted, such as grasping or walking.

ATHEROSCLEROSIS Hardening of the arteries caused by cholesterol and fat deposits. Increases risk of heart disease, stroke, and other complications.

ATHETOSIS A condition marked by slow, writhing, involuntary muscle movements.

ATOPIC A condition or disease that is the result of an allergic reaction.

ATOPIC ASTHMA Asthma caused by an allergic reaction; atopic asthma tends to have a strong inherited component (tends to run in families).

ATOPIC RHINITIS Also referred to as “hay fever;” symptoms of rhinitis caused by an allergic response to the presence of an allergen (such as tree or grass pollen).

ATP Adenosine triphosphate. The chemical used by the cells of the body for energy.

ATRESIA An abnormal condition in which a structure that should be hollow is fused shut.

ATRIA/ATRIUM The upper chamber of the heart. Typically, there are two atrias, one on the right side and one on the left side of the heart.

ATRIAL SEPTAL DEFECT An opening between the right and left atria of the heart.

ATROPHIC DERMATOSIS Wasting away of the skin.

ATROPHIC PHASE The final phase of LHON where cells in the optic disc and optic nerve have atrophied, resulting in legal blindness. Peripheral vision remains.

ATROPHY Wasting away of normal tissue or an organ due to degeneration of the cells.

ATTENTION DEFICIT DISORDER (ADD) Disorder characterized by a short attention span, impulsivity, and in some cases hyperactivity.

ATYPIA Lacking uniformity.

ATYPICAL PERSONALITY DEVELOPMENT Another term for pervasive development disorder (PDD-NOS). Other synonyms for this diagnostic category are atypical autism and atypical PDD.

AUDIOGRAM A graph of hearing level versus frequency. An audiologist plots the hearing loss of a patient on this graph to help determine the type of hearing loss and possible treatments.

AUDITORY NERVE The nerve responsible for transmitting electrical impulses created within the ear in response to sounds to the brain.

AURICULO Related to the ear.

AUTISM A syndrome characterized by a lack of responsiveness to other people or outside stimulus. Often in conjunction with a severe impairment of verbal and non-verbal communication skills.

AUTISTIC PSYCHOPATHY Hans Asperger’s original name for Asperger syndrome. It is still used occasionally as a synonym for the disorder.

AUTISTIC SPECTRUM DISORDERS Another term for the pervasive developmental disorders.

AUTOANTIBODY An antibody that reacts against part of the self.

AUTOIMMUNE Referring to an immune reaction erroneously directed toward ‘self’ tissues.

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AUTOIMMUNE DISEASE Describes a group of diseases characterized by an inflammatory immune reaction erroneously directed toward ‘self’ tissues.

AUTOIMMUNE DISORDER A disorder in which the body’s immune cells mistake the body’s own tissues as foreign invaders; the immune cells then work to destroy tissues in the body.

AUTONOMIC NERVOUS SYSTEM The part of the nervous system that regulates heart muscle, smooth muscle, and glands.

AUTOSOMAL Relating to any chromosome besides the X and Y sex chromosomes. Human cells contain 22 pairs of autosomes and one pair of sex chromosomes.

AUTOSOMAL DISEASE A disease caused by a gene located on an autosomal chromosome.

AUTOSOMAL DOMINANT A pattern of genetic inheritance where only one abnormal gene is needed to display the trait or disease.

AUTOSOMAL DOMINANT MUTATION An abnormal gene on one of the 22 pairs of non-sex chromosomes that will display the disorder when only one copy is inherited.

AUTOSOMAL RECESSIVE A pattern of genetic inheritance where two abnormal genes are needed to display the trait or disease.

AUTOSOMAL RECESSIVE MUTATION A pattern of genetic inheritance where two abnormal genes are needed to display the trait or disease.

AUTOSOME Chromosome not involved in specifying sex.

AXON Skinny, wire-like extension of nerve cells.

I B

B CELL Specialized type of white blood cell that is capable of secreting infection-fighting antibodies.

BALANCED CHROMOSOME TRANSLOCATION A rearrangement of the chromosomes in which two chromosomes have broken and exchanged pieces without the loss of genetic material.

BAND A specific region of a chromosome that is identified by its characteristic staining pattern and location within a chromosome, as seen in a karyotype. A band is either part of the short arm (p arm) or the long arm (q arm) of a chromosome and is further defined by a numeric location, such as chromosome band 11q24.1.

BARIUM A chemical put into a solution and swallowed to help with outlining the gastrointestinal system during an x-ray study.

BARIUM ENEMA X RAY A procedure that involves the administration of barium into the intestines by a tube inserted into the rectum. Barium is a chalky substance that enhances the visualization of the gastrointestinal tract on x ray.

BASAL GANGLIA A section of the brain responsible for smooth muscle movement.

BASE PAIRS Building blocks of DNA, the chemical that genes are made of.

BASEMENT MEMBRANE Part of the epithelium, or outer layer of the cornea.

BECKER MUSCULAR DYSTROPHY (BMD) A type of muscular dystrophy that affects older boys and men, and usually follows a milder course than Duchenne muscular dystrophy.

BECKWITH-WIEDEMANN SYNDROME A collection of health problems present at birth including an omphalocele, large tongue, and large body size.

BENIGN A non-cancerous tumor that does not spread and is not life-threatening.

BENIGN PROSTATIC HYPERPLASIA (BPH) A noncancerous condition of the prostate that causes growth of the prostate tissue, thus enlarging the prostate and blocking urination.

BENIGN TUMOR An abnormal proliferation of cells that does not spread to other sites.

BENZOQUINONE ACETIC ACID Toxic compound that is formed when oxygen reacts with homogentisic acid.

BETA CELLS Specialized cells of the pancreas that make insulin.

BETA-2 MICROGLOBULIN A component protein of class I MHC (major histocompatibility complex).

BETA-ADRENERGIC BLOCKER A drug that works by controlling the nerve impulses along specific nerve pathways.

BILATERAL Relating to or affecting both sides of the body or both of a pair of organs.

BILATERAL BREAST CANCER Cancer of both breasts, caused by two separate cancer processes.

BILE A substance produced by the liver, and concentrated and stored in the gallbladder. Bile contains a number of different substances, including bile salts, cholesterol, and bilirubin.

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BILE ACIDS Steroid acids such as cholic acid that occur in bile, an alkaline fluid secreted by the liver and passed into a part of the small intestine where it aids in absorption of fats.

BILE ALCOHOL A steroid acid with an alcohol group attached.

BILE DUCT A passageway that carries bile (fluid secreted by the liver involved in fat absorption) from the liver to the gallbladder to the small intestine.

BILIRUBIN A yellow pigment that is the end result of hemoglobin breakdown. This pigment is metabolized in the liver and excreted from the body through the bile. Bloodstream levels are normally low; however, extensive red cell destruction leads to excessive bilirubin formation and jaundice.

BIOCHEMICAL TESTING Measuring the amount or activity of a particular enzyme or protein in a sample of blood, urine, or other tissue from the body.

BIOPSY The surgical removal and microscopic examination of living tissue for diagnostic purposes.

BIOPTICS Glasses that have small telescopes fitted in the lens.

BIOSYNTHESIS The manufacture of materials in a biological system.

BIOTIN A growth vitamin of the vitamin B complex found naturally in liver, egg yolks, and yeast.

BIPOLAR DISORDER Formerly called “manic depression,” this psychological disorder is characterized by periods of mania followed by periods of depression.

BITEMPORAL CONSTRICTION Abnormal narrowing of both sides of the forehead.

BLACKFAN-DIAMOND SYNDROME (BDS) A disorder with congenital hypoplastic anemia. Some researchers believe that some or all individuals with Aase syndrome actually have BDS; that Aase syndrome and BDS are not separate disorders.

BLADDER The organ that stores urine after it flows out of the kidneys and through the ureters.

BLEPHAROPHIMOSIS A small eye opening without fusion of the upper eyelid with the lower eyelid at the inner and outer corner of the eye.

BLEPHAROSPASM A focal dystonia marked by excessive blinking and involuntary closing of the eyes.

BLOOD VESSELS General term for arteries, veins, and capillaries that transport blood throughout the body.

BODY ASYMMETRY Abnormal development of the body in which the trunk and/or the limbs are not of equal size from one side of the body to the other.

BONE MARROW A spongy tissue located in the hollow centers of certain bones, such as the skull and hip bones. Bone marrow is the site of blood cell generation.

BONE MARROW TRANSPLANT (BMT) A medical procedure used to treat some diseases that arise from abnormal blood cell formation in the bone marrow. Healthy bone marrow is extracted from a donor to replace the marrow in an ailing individual. Proteins on the surface of bone marrow cells must be identical or very closely matched between a donor and the recipient.

BOWMAN’S LAYER Transparent sheet of tissue directly below the basement membrane.

BOY IN THE BUBBLE A description for SCID since these children need to be isolated from exposure to germs, until they are treated by bone marrow transplantation or other therapy.

BRACHYCEPHALY An abnormal thickening and widening of the skull.

BRACHYDACTYLY Abnormal shortness of the fingers and toes.

BRACHYMELIA A general medical term used to describe short limbs.

BRADYKINESIA Extremely slow movement.

BRAILLE An alphabet represented by patterns of raised dots that can be felt with the fingertips. It is the main method of reading used by the blind today.

BRAIN VENTRICLES A set of four connected cavities that are located deep in the core of the brain. Cerebrospinal fluid is made by cells lining the walls of the first two ventricles, then flows through the third, then fourth ventricle before flowing out of the brain. The fluid-filled cavities provide mechanical cushion for the brain, and the CSF provides nutrients to, and carries metabolic wastes away from, the cells of the brain.

BRANCHED-CHAIN An open chain of atoms having one or more side chains.

BRCA2 Gene, when altered, known to cause increased risks of breast, ovarian, and, possibly pancreatic cancer.

BREAST BIOPSY Small sample of tissue taken from the breast and studied to diagnose and determine the exact type of breast cancer.

BREAST SELF-EXAM (BSE) Examination by an individual of their own breasts.

BREECH DELIVERY Birth of an infant feet or buttocks first.

BROAD LIGAMENT The ligament connecting the ovaries to the uterus.

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BRONCHI Branching tube-like structures that carry air in and out of the lungs. Walls of bronchi contain circular muscles that can constrict (tighten up to make airways narrower) or dilate (relax to make airways wider); bronchi divide into smaller bronchioles within the lung tissue.

BRONCHIECTASIS An abnormal condition of the bronchial tree, characterized by irreversible widening and destruction of the bronchial walls of the lungs.

BRUCH’S MEMBRANE A membrane in the eye between the choroid membrane and the retina.

BRUTON TYROSINE KINASE (BTK) An enzyme vital for the maturation of B cells.

BULBAR MUSCLES Muscles that control chewing, swallowing, and speaking.

BUPHTHALMOS A characteristic enlargement of one or both eyes associated with infantile glaucoma.

I C

C1 INHIBITOR Abbreviated C1-INH, this protein is responsible for preventing the action of the C1 complement molecules in the body. It is this protein that is either deficient or malformed in HANE.

CA-125 (CARBOHYDRATE ANTIGEN 125) A protein that is sometimes high when ovarian cancer is present. A blood sample can determine the level of CA-125 present.

CAFÉ-AU-LAIT SPOTS Birthmarks that may appear anywhere on the skin; named after the French coffee drink because of the light-brown color of the marks.

CALCIFICATION A process in which tissue becomes hardened due to calcium deposits.

CALCITRIOL A substance that assists in bone growth by helping to maintain calcium and phosphate levels in the blood. Vitamin D is converted into this substance by the body.

CALCIUM One of the elements that make up the hydroxyapatite crystals found in bone.

CAMPTODACTYLY An abnormal permanent bending of one or more fingers or toes.

CANAVAN DISEASE A serious genetic disease more common in the Eastern European Jewish population that causes mental retardation and early death. Canavan disease is caused by the lack of an enzyme called aspartoacylase.

CANCER A disease caused by uncontrolled growth of the body’s cells.

CANCER CELLS Have characteristics that distinguish them from normal cells and non-cancerous cells; they are threatening, harmful, and resistant to treatment.

CANDIDATE GENE A gene that encodes proteins believed to be involved in a particular disease process.

CARBOHYDRATE Any of various natural compounds of carbon, hydrogen, and oxygen (as in sugars and starches) that are burned by the body for energy.

CARCINOGEN Any substance capable of causing cancer by mutating the cell’s DNA.

CARCINOMA Any cancer that arises in the epithelium, the tissue that lines the external and internal organs of the body.

CARDIAC CONDUCTION DEFECT Abnormality of the electrical system of the heart, which regulates the heart beat.

CARDIAC MUSCLE The muscle of the heart.

CARDINAL SYMPTOMS A group of symptoms that define a disorder or disease.

CARDIOMYOPATHY A thickening of the heart muscle.

CARNITINE An amino acid necessary for metabolism of the long-chain fatty acid portion of lipids. Also called vitamin B7.

CARNITINE PALMITOYLTRANSFERASE (CPT) An enzyme that transfers a palmitoyl group. CPT is a major regulatory enzyme of lipid metabolism, required for the transport of long-chain fatty acids across the inner mitochondria membrane. This transport depends on carnitine.

CARRIER A person who possesses a gene for an abnormal trait without showing signs of the disorder. The person may pass the abnormal gene on to offspring.

CARRIER TESTING Testing performed to determine if someone possesses one changed copy and one unchanged copy of a particular gene.

CARTILAGE Supportive connective tissue that cushions bone at the joints or that connects muscle to bone.

CASEIN HYDROLYSATE A preparation made from the milk protein casein, which is hydrolyzed to break it down into its constituent amino acids. Amino acids are the building blocks of proteins.

CAT (CT) SCAN Computerized (axial) tomography. A special x ray technique used to examine various tissues, particularly the brain, in great detail.

CATAGEN The breakdown phase of the hair growth cycle.

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CATALYST A substance that changes the rate of a chemical reaction, but is not physically changed by the process.

CATALYZE Facilitate. A catalyst lowers the amount of energy required for a specific chemical reaction to occur. Catalysts are not used up in the chemical reactions they facilitate.

CATAPLEXY A symptom of narcolepsy in which there is a sudden episode of muscle weakness triggered by emotions. The muscle weakness may cause the person’s knees to buckle, or the head to drop. In severe cases, the patient may become paralyzed for a few seconds to minutes.

CATARACT A clouding of the eye lens or its surrounding membrane that obstructs the passage of light resulting in blurry vision. Surgery may be performed to remove the cataract.

CATATONIC BEHAVIOR Behavior characterized by muscular tightness or rigidity and lack of response to the environment. In some patients, rigidity alternates with excited or hyperactive behavior.

CATECHOLAMINES Biologically active compounds involved in the regulation of the nervous and cardiovascular systems, rate of metabolism, body temperature, and smooth muscle.

CATHETER A narrow, flexible tube used to create a pathway for introducing drugs, nutrients, fluids, or blood products into the body and/or for removing fluid or other substances from the body.

CATHETERIZATION The process of inserting a hollow tube into a body cavity or blood vessel.

CATIONIC TRYPSINOGEN GENE Gene known to cause hereditary pancreatitis when significantly altered.

CAUTERIZATION Process of burning tissue either with a laser or electric needle to stop bleeding or destroy damaged tissue.

CDKN2A OR P16 Gene, when altered, known to cause Familial Atypical Multiple Mole Melanoma (FAMMM) syndrome and possibly increased pancreatic cancer risk.

CECUM The first part of the large bowel.

CELL The smallest living units of the body, which group together to form tissues and help the body perform specific functions.

CELL ADHESION MOLECULE Any one of several thousand proteins that together control the cell-to-cell communication that must take place in order for cells to migrate to their proper places, develop into the proper types of cells, and make the appropriate connections with other cells.

CELLULAR IMMUNITY A type of acquired immunity mediated by killer T-cells; important in fighting ‘hidden’ infections, such as those caused by cellular parasites and some viruses.

CENTRAL NERVOUS SYSTEM (CNS) In humans, the central nervous system is composed of the brain, the cranial nerves and the spinal cord. It is responsible for the coordination and control of all body activities.

CENTRAL VISION The ability to see objects located directly in front of the eye. Central vision is necessary for reading and other activities that require people to focus on objects directly in front of them.

CENTROMERE The centromere is the constricted region of a chromosome. It performs certain functions during cell division.

CEREBELLAR ATAXIA Unsteadiness and lack of coordination caused by a progressive degeneration of the part of the brain known as the cerebellum.

CEREBELLUM A portion of the brain consisting of two cerebellar hemispheres connected by a narrow vermis. The cerebellum is involved in control of skeletal muscles and plays an important role in the coordination of voluntary muscle movement. It interrelates with other areas of the brain to facilitate a variety of movements, including maintaining proper posture and balance, walking, running, and fine motor skills, such as writing, dressing, and eating.

CEREBRAL CORTEX The outer surface of the cerebrum made up of gray matter and involved in higher thought processes.

CEREBRAL PALSY Movement disability resulting from nonprogressive brain damage.

CEREBRAL VENTRICLES Spaces in the brain that are located between portions of the brain and filled with cerebrospinal fluid.

CEREBRO Related to the head or brain.

CEREBROSIDES Fatty carbohydrates that occur in the brain and nervous system.

CEREBROSPINAL FLUID Fluid that circulates throughout the cerebral ventricles and around the spinal cord within the spinal canal.

CEREBRUM The largest section of the brain, which is responsible for such higher functions as speech, thought, vision, and memory.

CEROID The by-product of cell membrane breakdown.

CERULOPLASMIN A protein circulating in the bloodstream that binds with copper and transports it.

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CERVICAL DYSTONIA A focal dystonia that causes neck muscles to contract involuntarily—leading to abnormal movements and posture of the head and neck. Also known as spasmodic torticollis.

CERVICITIS Inflammation of the cervix.

CERVICO-MEDULLARY JUNCTION The area where the brain and spine connect.

CFTR Cystic fibrosis transmembrane conductance regulator. The protein responsible for regulating chloride movement across cells in some tissues. When a person has two abnormal copies of the CFTR gene, cystic fibrosis is the result.

CGG OR CGG SEQUENCE Shorthand for the DNA sequence: cytosine-guanine-guanine. Cytosine and guanine are two of the four molecules, otherwise called nucleic acids, that make up DNA.

CHAPERONIN A molecule that captures and refolds misshapen proteins that might interfere with normal cellular functions; also called a protein cage.

CHEMOTHERAPY Treatment of cancer with synthetic drugs that destroy the tumor either by inhibiting the growth of the cancerous cells or by killing the cancer cells.

CHIARI II ANOMALY A structural abnormality of the lower portion of the brain (cerebellum and brain stem) associated with spina bifida. The lower structures of the brain are crowded and may be forced into the foramen magnum, the opening through which the brain and spinal cord are connected.

CHOANAL ATRESIA A bony or membranous blockage of the passageway between the nose and pharynx at birth.

CHOLESTEROL A fatty-like substance that is obtained from the diet and produced by the liver. Cells require cholesterol for their normal daily functions.

CHONDROCYTE A specialized type of cell that secretes the material which surrounds the cells in cartilage.

CHONDROSARCOMA A malignant tumor derived from cartilage cells.

CHOREA Involuntary, rapid, jerky movements.

CHOREOATHETOSIS Involuntary rapid, irregular, jerky movements or slow, writhing movements that flow into one another.

CHORIOCAPILLARIS Capillary layer of the choroid.

CHORION The outer membrane of the amniotic sac. Chorionic villi develop from its outer surface early in pregnancy. The villi establish a physical connection with the wall of the uterus and eventually develop into the placenta.

CHORIONIC VILLI A portion of the placenta that can be sampled at 10-12 weeks of pregnancy for the purposes of diagnosis.

CHORIONIC VILLUS SAMPLING (CVS) A procedure used for prenatal diagnosis at 10-12 weeks gestation. Under ultrasound guidance a needle is inserted either through the mother’s vagina or abdominal wall and a sample of cells is collected from around the fetus. These cells are then tested for chromosome abnormalities or other genetic diseases. Also known as chorionic villus biopsy.

CHOROID A vascular membrane that covers the back of the eye between the retina and the sclera and serves to nourish the retina and absorb scattered light.

CHOROID PLEXUS Specialized cells located in the ventricles of the brain that produce cerebrospinal fluid.

CHROMATID Each of the two strands formed by replication of a chromosome. Chromatids are held together by the centromere until the centromere divides and separates the two chromatids into a single chromosome.

CHROMOSOMAL ANEUPLODIES A condition in which the chromosomal number is either increased or decreased.

CHROMOSOME A microscopic thread-like structure found within each cell of the body and consists of a complex of proteins and DNA. Humans have 46 chromosomes arranged into 23 pairs. Changes in either the total number of chromosomes or their shape and size (structure) may lead to physical or mental abnormalities.

CHROMOSOME DELETION A missing sequence of DNA or part of a chromosome.

CHROMOSOME INVERSION Rearrangement of a chromosome in which a section of a chromosome breaks off and rejoins the chromosome upside down.

CHROMOSOME TRANSLOCATION The exchange of genetic material between chromosomes, which can lead to extra or missing genetic material.

CHRONIC ATROPHIC GASTRITIS Irritation and break down of the stomach wall over a period of time.

CHYLOMICRON A type of lipoprotein made in the small intestine and used for transporting fats to other tissues in the body.

CILIARY BODY A structure within the eye that produces aqueous humor.

CIRCUMCISION The surgical removal of the foreskin of the penis.

CIRRHOSIS A chronic degenerative disease of the liver, in which normal cells are replaced by fibrous tissue.

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