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

IMPERFORATE ANUS Also known as anal atresia. A birth defect in which the opening of the anus is absent or obstructed. IMPOTENCE The inability to have a penile erection, which can be due to tissue damage resulting from sick- ling within the penis (priapism). IMPRINTING Process 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 UTERO While in the uterus; before birth. IN VITRO FERTILIZATION Process 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 BODY Abnormal 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 SPASMS The 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. INFERTILITY Inability 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 HERNIA A condition in which part of the intestines protrudes through a tear in the muscles of the abdomen. INHERITANCE PATTERN The 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. INSOMNIA An 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. INSULIN A hormone produced by the pancreas that is secreted into the bloodstream and regulates blood sugar levels. INSULIN RECEPTOR GENE The 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 nor- mally to insulin in the bloodstream. 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 re- leased by the liver in response to high levels of growth hormone in the blood. This growth factor is very similar 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 relation- ships of the affected individual may be causing or influ- encing symptoms of depression. INTRACRANIAL HEMORRHAGE Abnormal bleeding within the space of the skull and brain. INTRACRANIAL PRESSURE The pressure of the fluid between the brain and skull. INTRAGENIC Occuring within a single gene. INTRAUTERINE Situated or occurring in the uterus. INTRAUTERINE GROWTH RETARDATION A 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. INTRAVENOUS A 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 PYELOGRAM An x ray assessment of kidney function. INTRON Portion 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 CHANNEL Cell membrane proteins that control the movement of ions into and out of a cell. 1284 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Glossary IONIZING RADIATION High-energy radiation such as that produced by x rays. IQ Abbreviation for Intelligence Quotient. Compares an individual’s mental age to his/her true or chronologi- cal age and multiplies that ratio by 100. IRIS The 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. ISCHOPAGUS Conjoined twins who are attached at the lower half of the body. ISOMERISM Refers 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. ISOMERS Two 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. ISOTOPE Any 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/ISOENZYME A group of enzymes that per- form the same function, but are different from one another in their structure or how they move. I J JAUNDICE Yellowing 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. I K KABUKI Traditional Japanese popular drama per- formed with highly stylized singing and dancing using special makeup and cultural clothing. KALLIKREIN A 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 SYNDROME Another name for autism. KARYOTYPE A standard arrangement of photo- graphic or computer-generated images of chromosome pairs from a cell in ascending numerical order, from largest to smallest. KARYOTYPING A laboratory procedure in which chromosomes are separated from cells, stained, and arranged so that their structure can be studied under the microscope. KERATIN A tough, non-water-soluble protein found in the nails, hair, and the outermost layer of skin. Human hair is made up largely of keratin. KERATINOCYTES Skin cells. KERATOACANTHOMA A firm nodule on the skin typ- ically found in areas of sun exposure. 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 BODIES Products 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. KETOSIS An 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. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 1285 Glossary KIDNEY TUBULES A portion of the kidneys that causes water to be excreted as urine or reabsorbed into the body. KLINEFELTER SYNDROME A syndrome that occurs in XXY males; characterized by sterility and small testes; normal intelligence. KNOCKOUT EXPERIMENT A 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. KYPHOSCOLIOSIS Abnormal 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. I L L-CARNITINE A substance made in the body that car- ries wastes from the body’s cells into the urine. LABIA Lips of the female genitals. LACRIMAL DUCTS Tear ducts. LACTIC ACID The major by-product of anaerobic (without oxygen) metabolism. LACTIC ACIDOSIS A 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. LACTOSE A sugar made up of of glucose and galac- tose. It is the primary sugar in milk. LAPAROSCOPY A 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. LAPAROTOMY An operation in which the abdominal cavity is opened up. LARYNX The 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 MUSCLE The 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 en- largement of the left lower chamber of the heart. LENS The transparent, elastic, curved structure behind the iris (colored part of the eye) that helps focus light on the retina. LENTIGENE A 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 ANGIOMA A swelling of the tis- sue or membrane surrounding the brain and spinal cord, which can enlarge with time. LESION An abnormal or injured section or region of the brain (or other body organ). LEUCOPENIA A decrease in white blood cells. LEUKEMIA Cancer of the blood forming organs that results in an overproduction of white blood cells. LEUKOCYTE A white blood cell. The neutrophils are a type of leukocyte. LEUKOCYTOSIS An increase in the number of leuko- cytes in the blood. LEUKODYSTROPHY A disease that affects the white matter called myelin in the CNS. LEUKOENCEPHALOPATHY Any of various diseases, including leukodystrophies, affecting the brain’s white matter. 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 RISK A risk that exists over a person’s life- time; a lifetime risk to develop disease means that the chance is present until the time of death. LIGAMENT A type of connective tissue that con- nects bones or cartilage and provides support and strength to joints. 1286 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Glossary LIMB DYSTONIA Involuntary cramp or spasm that affects the hands. Also known as writer’s cramp. LIMB GIRDLES Areas 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 SCLERODERMA A 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 ANALYSIS A method of finding mutations based on their proximity to previously identified genetic landmarks. LIPASE A 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. LIPOMA A benign tumor composed of well-differen- tiated fat cells. LIPOPIGMENTS Substances made up of fats and pro- teins found in the body’s tissues. LIPOPROTEIN A 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. LIPOSOME Fat molecule made up of layers of lipids. LISSENCEPHALY A 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 STUDY A type of research project in which the same subjects are interviewed repeatedly at intervals over a period of time. LORICIN One 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 LORDOSIS Abnormal 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 NODE A bean-sized mass of tissue that is part of the immune system and is found in different areas of the body. LYMPHATIC SYSTEM Lymph nodes and lympatic ves- sels that transport infection fighting cells to the body. 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. LYMPHOCYTES Also called white blood cells, lym- phocytes mature in the bone marrow to form B cells, which fight infection. LYMPHOMA A 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). LYSINE A crystalline basic amino acid essential to nutrition. LYSIS Area 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 DISEASE A category of disor- ders that includes mannosidosis. LYSOSOME Membrane-enclosed compartment in cells containing many hydrolytic enzymes; where large molecules and cellular components are broken down. I M MACROCEPHALY A head that is larger than normal. MACROGLOSSIA A large tongue. MACROMOLECULES A large molecule composed of thousands of atoms. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 1287 Glossary MACROPHAGE Specialized white blood cells that play a role in breaking down old or abnormal red blood cells. MACROSOMIA Overall large size due to overgrowth. MACROSTOMIA A mouth that is larger or wider than normal. MACULA A small spot located in the back of the eye that provides central vision and allows people to see col- ors and fine visual details. MACULE A flat, discolored spot or patch on the skin. MADAROSIS The 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 DEFORMITY A forearm bone malfor- mation characterized by a short forearm, arched or bow shaped radius, and dislocation of the ulna. MAFFUCCI DISEASE A 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 DOMINANCE An inheritance pattern in which affected male children die from the char- acteristics of the trait. This death is typically either embryonic, fetal, or neonatal. MALIGNANT A tumor growth that spreads to another part of the body; usually cancerous. MALIGNANT HYPERTHERMIA A condition brought on by anesthesia during surgery. MALROTATION An abnormality that occurs during the normal rotation of an organ or organ system. MAMMOGRAM A 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. MANDIBLE Lower jaw bone. MANDIBULAR HYPOPLASIA Underdevelopment of the lower jaw. MANNOSE A type of sugar that forms long chains in the body. MANOMETRY A balloon study of internal anal sphincter pressure and relaxation. MAO-B INHIBITORS Inhibitors of the enzyme mono- 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. MAORI A native New Zealand ethnic group. MARFANOID Term for body type that is similar to people with Marfan syndrome. Characterized by a tall, lean body with long arms and long fingers. MARFANOID HABITUS An 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. MATERNAL Relating to the mother. MATERNAL SERUM SCREENING A 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. MAXILLA One of the bones of the face. MECONIUM The first waste products to be dis- charged from the body in a newborn infant, usually greenish in color and consisting of mucus, bile, and so forth. 1288 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Glossary MEDIAL RECTUS MUSCLE The 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 ACIDS Fatty acids containing between four and 14 carbon atoms. MEDULLARY CAVITY The 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. MEGACOLON Dilation of the colon. MEIOSIS The process in which a cell in the testes or ovaries undergoes chromosome separation and cell divi- sion to produce sperm or eggs. MELANIN Pigments normally produced by the body that give color to the skin and hair. MELANOCYTES A cell that can produce melanin. MELANOMA Tumor, usually of the skin. MELANOSOMES Granules of pigment within melano- cytes that synthesize melanin. MELATONIN A sleep-inducing hormone secreted by the pineal gland. MEMORY CELLS B-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. MENINGITIS An infection of the covering of the brain. MENOPAUSE Cessation 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 con- necting the elbow to the wrist or forearm. 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 ACIDOSIS High 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 mus- cle diseases whose cause is a metabolic disturbance of some type. METABOLIC PATHWAY A sequence of chemical reac- 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. METABOLISM The total combination of all of the chemical processes that occur within cells and tissues of a living body. METACARPAL A hand bone extending from the wrist to a finger or thumb. METACENTRIC When a chromosome has the cen- tromere in the middle of the chromosome it is called a metacentric chromosome. METACHRONOUS Occurring at separate time intervals. METAFEMALE An out of date term for XXX females; also called triple X syndrome. METAPHYSEAL FLARING A 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. METAPHYSIS An area of softer bone and cartilage in long bones between the diaphysis (shaft) and epiphysis (end). METASTASIS The spreading of cancer from the origi- nal site to other locations in the body. METASTATIC CANCER A cancer that has spread to an organ or tissue from a primary cancer located elsewhere in the body. METATARSAL A foot bone extending from the ankle to a toe. METHYLATION TESTING DNA testing that detects if a gene is active or if it is imprinted. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 1289 Glossary 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 SYNDROME A 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. MICROCEPHALIC Having an abnormally small head. MICROCEPHALIC PRIMORDIAL DWARFISM SYN- DROMES A group of disorders characterized by profound growth delay and small head size. MICROCEPHALY An abnormally small head. MICROCORNEA Abnormal smallness of the cornea. MICRODONTIA Small 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. MICROPHTHALMIA Small or underdeveloped eyes. MICROTIA Small or underdeveloped ears. MIDLINE DEFECTS Disorders involving organs along the center of the body such as the lips, penis, and corpus callosum. MIDLINE ORGANS Organs 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. MISCARRIAGE Spontaneous pregnancy loss. MISMATCH REPAIR Repair of gene alterations due to mismatching. MITOCHONDRIA Organelles within the cell respon- sible for energy production. MITOCHONDRIAL INHERITANCE Inheritance associ- ated with the mitochondrial genome, which is inherited exclusively from the mother. MITOCHONDRIAL MYOPATHIES Diseases of the mus- cle accompanied by abnormal changes in the cell mito- chondria that results in excessive accumulation of lipids. MITOSIS The 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 VALVE The 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 no symptoms. MIXED TYPE HEARING LOSS Hearing loss that in- volves both conductive and sensorineural losses. MONOSOMY Missing an entire copy of a chromo- some or a piece of one copy of a chromosome. MONOZYGOTIC From one zygote, as in identical twins. The zygote is the first cell formed by the union of sperm and egg. MORPHEA The most common form of localized scleroderma. MOSAIC A 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. 1290 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Glossary MOTOR NEURONS Class 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 UNITS Functional connection with a single motor neuron and muscle. MOTTLED RETINA Changes in the retina of the eye causing a loss of visual acuity. MUCOCILIARY ESCALATOR The 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-1 Protein 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. MUCOPOLYSACCHARIDE A 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 MEMBRANE Thin, 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 CANCER Multiple primary can- cers in the same breast. MULTIPLE CARBOXYLASE DEFICIENCY A type of pro- pionic acidemia characterized by an inability to metabo- lize biotin. MULTIPLE SCLEROSIS (MS) A progressive degenera- tion of nerve cells that causes episodes of muscle weak- ness, dizziness, and visual disturbances, followed by periods of remission. MURMUR A noise, heard with the aid of a stetho- scope, made by abnormal patterns of blood flow within the heart or blood vessels. MUSCULAR DYSTROPHY A group of inherited dis- eases characterized by progressive wasting of the muscles. MUTAGEN An environmental influence that causes changes in DNA. MUTANT A change in the genetic material that may alter a trait or characteristic of an individual or manifest as disease. MUTATION A permanent change in the genetic ma- terial that may alter a trait or characteristic of an individ- ual, or manifest as disease, and can be transmitted to offspring. MYELIN A fatty sheath surrounding nerves in the peripheral nervous system, which help them conduct impulses more quickly. MYELODYSPLASIA A bone marrow disorder that can develop into aplastic anemia requiring bone marrow or stem cell transplantation. MYELOMENINGOCELE A sac that protrudes through an abnormal opening in the spinal column. MYOCLONUS Twitching or spasms of a muscle or an interrelated group of muscles. MYOGLOBINURIA The abnormal presence of myo- globin, a product of muscle disintegration, in the urine. Results in dark-colored urine. MYOPATHY Any abnormal condition or disease of the muscle. MYOPIA Nearsightedness. Difficulty seeing objects that are far away. MYOTONIA The inability to normally relax a muscle after contracting or tightening it. MYOTONIC DYSTROPHY A form of muscular dystro- phy, also known as Steinert’s condition, characterized 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. MYXOID Resembling mucus. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 1291 Glossary 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. NALTREXONE A 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. NANISM Short stature. NARCOTICS Strong, 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 CELLS Specialized white blood cells involved in natural immunity. Can kill some viruses and cancer cells. NECROSIS Death of a portion of tissue differentially affected by disease or injury. NECROTIZING ENCEPHALOMYELOPATHY A 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. NEONATAL Neonatal 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. NEPHROPATHY Kidney disease. NEPHROSIS A non-inflammatory disease of the kidneys. NERVE CONDUCTION TESTING Procedure that meas- ures the speed at which impulses move through the nerves. NERVOUS SYSTEM The complete network of nerves, sense organs, and brain in the body. NEUCHAL TRANSLUCENCY A pocket of fluid at the back of an embryo’s neck visible via ultrasound that, when thickened, may indicate the infant will be born with a congenital heart defect. NEURAL Regarding any tissue with nerves, including the brain, the spinal cord, and other nerves. NEURAL CREST CELLS A 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 DEFECT A group of severe birth disor- ders in which the brain and spinal cord are malformed and lack the protective skeletal and soft tissue encasement. 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. NEUROFIBROMA A soft tumor usually located on a nerve. NEUROFIBROMATOSIS Progressive 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. NEUROLEPTIC Another name for the older type of antipsychotic medications given to schizophrenic patients. NEUROLOGIC Relating to the brain and central nerv- ous system. NEUROLOGIST A physician who specializes in disor- ders of the nervous system, including the brain, spine, and nerves. NEUROMETABOLIC DISORDER Any disorder or con- dition that affects both the central nervous system (CNS) and the metabolism of the body. NEUROMUSCULAR Involving both the muscles and the nerves that control them. NEUROMUSCULAR JUNCTION The site at which nerve impulses are transmitted to muscles. NEURON The fundamental nerve cell that conducts impulses across the cell membrane. 1292 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Glossary NEURONAL CEROID LIPOFUSCINOSES A family of four progressive neurological disorders. NEUROPATHY A 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). NEUTROPHIL The primary type of white blood cell involved in inflammation. Neutrophils are a type of gran- ulocyte, also known as a polymorphonuclear leukocyte. NEVI Plural of nevus. NEVUS Any anomaly of the skin present at birth, including moles and various types of birthmarks. NEVUS FLAMMEUS A flat blood vessel tumor present at birth; also known as a “port wine stain.” NEWBORN SCREENING The 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 LOSS Hearing 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 SYNDROME A 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 INHERITANCE Inheritance 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 ACID A type of chemical used as a compo- nent for building DNA. The nucleic acids found in DNA are adenine, thymine, guanine, and cytosine. NUCLEOTIDES Building blocks of genes, which are arranged in specific order and quantity. NUCLEUS The central part of a cell that contains most of its genetic material, including chromosomes and DNA. NYSTAGMUS Involuntary, rhythmic movement of the eye. I O 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 LOBE An 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. OCULAR A broad term that refers to structure and function of the eye. OCULAR ALBINISM A type of albinism that affects the vision. OCULO Related to the eye. OCULO-DIGITAL REFLEX A reflex causing an individ- ual to press on their eyes with their fingers or fists. OCULOCUTANEOUS ALBINISM Inherited loss of pig- ment in the skin, eyes, and hair. 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. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 1293 Glossary [...]... Schinzel-Giedion syndrome, 2: 1 022 Seckel syndrome, 2: 103 9 severe combined immunodeficiency, 2: 10 42 104 3 Sjögren-Larsson syndrome, 2: 106 1 10 62 Smith-Lemli-Opitz syndrome, 2: 106 6 106 8 spinal muscular atrophy, 2: 108 3 Usher syndrome, 2: 1163 Wilson disease, 2: 1199 Wolman disease, 2: 120 8– 121 0 Autosomal recessive retinitis pigmentosa (ArRP), 2: 989–990 GALE ENCYCLOPEDIA OF GENETIC DISORDERS IB B cells, Bruton... syndrome, 2: 120 3 Cartilage chondrosarcoma, 1 :22 7 22 9 osteoarthritis, 2: 853–856 Cat-eye syndrome coloboma, 1 :25 6 Rieger syndrome, 2: 10 02 100 3 Cataplexy, 2: 7 92 793 Cataracts Marfan syndrome, 2: 710, 711 Rothmund-Thomson syndrome, 2: 101 0 101 1 Werner syndrome, 2: 1194 Catatonic schizophrenia, 2: 1 023 Catechol-O-methyltransferase, 2: 886–887 Cathepsin C gene, 1:501–503 Cationic trypsinogen gene, 1:1 92 GALE ENCYCLOPEDIA. .. syndrome, 2: 106 3 Smith-Lemli-Opitz syndrome, 2: 106 7 trisomy 18, 2: 1148 Choroid plexus papillomas, 1:40–41, 41 Choroidal coloboma, 1 :25 5 25 6 Choroideremia, 1 :22 9 23 1 Chromosomal abnormalities, 1 :23 2 23 8 , 23 3, 23 6 23 7 aneuploidy, 1 :23 3 23 5 cell division, 1 :23 2 23 3 deletions, 1 :23 6 23 7, 3 12 315 human chromosome number and structure, 1 :23 2 maternal age and prenatal diagnosis, 1 :23 7 23 8 polyploidy, 1 :23 5 23 6... 1: 620 Cockayne syndrome, 1 :24 7 24 9 Coffin, Grange S., 1 :25 1 Coffin-Lowry syndrome (CLS), 1 :24 9 25 0 , 25 0, 1 :25 2 Coffin-Siris syndrome, 1 :25 0 25 2 Cognitive function, phenylketonuria, 2: 919– 923 COH1 gene, 1 :25 3 Cohen, M M., 1 :25 2 Cohen, Michael, 2: 961 Cohen syndrome, 1 :25 2 25 5 COL2A1 gene Marshall syndrome, 2: 713 osteoarthritis, 2: 855–856 Stickler syndrome, 2: 109 4 COL3A1 gene, 1:378 COL9A1 gene, 2: 855–856... ENCYCLOPEDIA OF GENETIC DISORDERS Charcot-Marie-Tooth disease, 1 :21 9 22 2 Charge Syndrome Foundation, 1 :22 6 CHARGE syndrome, 1 :22 2 22 5, 1 :25 6 25 7 Chediak-Higashi syndrome, 1 :22 6 22 7 albinism with, 1:45 Griscelli syndrome, 1:499–500 Chemotherapy breast cancer, 1:176–177 cancer management, 1:196 liver cancer, 1:680 ovarian cancer, 2: 868 pancreatic cancer, 2: 879–880 prostate cancer, 2: 960 stomach cancer, 2: 11 02 Chest... 1:340 Larsen syndrome, 1:648 Meckel-Gruber syndrome, 2: 728 Wolf-Hirschhorn syndrome, 2: 120 5– 120 7 CMD1 and 2, 1:183–185 CMT (Charcot-Marie-Tooth disease), 1 :21 9 22 2 CMT2 disease, 1 :22 0 CMT3 disease, 1 :22 0 CMT4 disease, 1 :22 0 CMT1B disease, 1 :21 9 22 0 CMTX disease, 1 :22 0 CNS See Central nervous system Coarctation, bicuspid aortic valve, 1:154–156 Cobb angle, 2: 103 6 103 7 Cobblestone dysplasia, 1:674–676... chondrosarcoma, 1 :22 8 22 9 encephalocele, 1:388 liver cancer, 1:679 Moyamoya, 2: 749 pancreatic cancer, 2: 879 Conductive hearing loss, 1:536 otopalatodigital syndrome, 2: 864–865 Rieger syndrome, 2: 10 02 Cone-rod dystrophy (CRD), 1 :26 0 26 1 GALE ENCYCLOPEDIA OF GENETIC DISORDERS Congenital spondyloepiphyseal dysplasia, 2: 108 8 109 1 Congenital stationary night blindness, 2: 100 0 Conjoined twins, 1 :27 2 27 4 , 27 4 Connective... 1 :28 3 28 5 Counseling, genetic See Genetic counseling GALE ENCYCLOPEDIA OF GENETIC DISORDERS Cowden syndrome breast cancer genetics, 1:174 stomach cancer, 2: 109 9 CPT (Carnitine palmitoyltransferase deficiency), 1 :20 1 20 4 CPT1/CPT2 genes, 1 :20 2 CPT-I deficiency, 1 :20 1 20 4 CPT-II deficiency, 1 :20 1 20 4 Crane-Heise syndrome, 1 :28 5 28 6 Cranial nerve defects CHARGE syndrome, 1 :22 4 22 5 Duane retraction syndrome,... syndrome, 1 :20 0 CHARGE syndrome, 1 :22 2, 22 4 Cornelia de Lange syndrome, 1 :27 9 28 1 Costello syndrome, 1 :28 3 28 5 cri du chat syndrome, 1 :29 0 29 1 deletion 22 q11 syndrome, 1:313 Down syndrome, 1:349, 3 52 Ellis-van Creveld syndrome, 1:380–3 82 fetal alcohol syndrome, 1: 423 – 425 frontonasal dysplasia, 1:441–4 42 Holt-Oram syndrome, 1:560–561 Noonan syndrome, 2: 818– 821 Patau syndrome, 2: 8 92 893 Smith-Lemli-Opitz... syndrome, 2: 106 6 106 8 TAR syndrome, 2: 1113–1114 trisomy 18, 2: 1147 Turner syndrome, 2: 1155 VATER association, 2: 1169–11 72 Williams syndrome, 2: 1196–1197 Wolf-Hirschhorn syndrome, 2: 120 7 Congenital hereditary endothelial dystrophy, 1 :27 5 27 7 Congenital hypertrophy of the retinal pigment epithelium, 1:409– 410 Congenital hypoplastic anemia, 1:3–4 Congenital hypothyroid syndrome, 1 :27 0 27 2 , 27 1 27 2 Congenital . calcium. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 1301 Glossary 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. areas of the skin. PUPIL The opening in the iris through which light enters the eye. PUSTULE A pus-filled lesion of the skin that resem- bles the “pimples” of adolescent acne. GALE ENCYCLOPEDIA OF. metabolism in the form of urine and regulating the concentrations of hydrogen, sodium, potassium, phos- phate, and other ions in the body. GALE ENCYCLOPEDIA OF GENETIC DISORDERS 128 5 Glossary KIDNEY