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Glossary Alpha-fetoprotein blood test: A test performed on a pregnant women to identify the presence of a particular protein, which suggests that the fetus has a neural tube defect. Amniocentesis: The sampling of the fluid surrounding the fetus to provide a test for specific conditions such as Down syndrome or spine bifida. Amniotic fluid: The fluid that, contained in the sac of membranes known as the amnion, surrounds the fetus and provides a shock absorber and a secondary vehicle for the exchange of body chemicals with the mother. Anemia: The condition of having fewer than the normal number of red blood cells, or hemoglobin, in the blood, which causes patients to fatigue easily, appear pale, develop palpitations, and become short of breath. There are many causes of anemia, including bleeding, abnormal hemoglobin formation (such as in sickle cell anemia), iron, BE (perni- cious anemia), or folic acid deficiency, rupture of red blood cells (hemolytic anemia), and bone marrow diseases. Anencephaly: Congenital absence of the cranial vault with cerebral hemi- spheres missing or reduced to small masses attached to the base of the skull. Antenatal: Before birth; also called prenatal. Autosomal disorder: If a disorder is autosomal it is found on both the X and Y chromosomes. (Each child receives one chromosome from each parent. The mother has 2 X chromosomes so always gives a X. The father has an X and a Y: when he gives an X, it is a female child, and when he gives a Y. it is a male child). 227
228 REDUCING THE IMPACT OF BIRTH DEFECTS Behavioral change: A change in habits or lifestyle that can be characterized as proceeding through four stages: precontemplation, contemplation, action, and maintenance of a new behavior. Bilirubin: A breakdown product of heme that normally circulates in plasma as a complex with albumin. It is taken up by the liver and conjugated to form bilirubin diglucuronide, which is excreted in bile. Unconjugated bilirubin is not excreted in the urine, which can lead to an excess of bilirubin in the blood (jaundice). Birth defect: Any structural or functional abnormality determined by fac- tors operating largely before conception or during gestation. Birth defects of complex and unknown origin: Birth defects with unknown origins and likely to be due to the additive effects of a few or many genes, which may interact with nongenetic or environmental factors. Birth prevalence: The number of individuals who have an attribute or disease at the time of birth divided by the population at risk of having the attribute or disease the time of birth. Capacity building: Increasing the ability of a local institution to provide high-quality services appropriate to the local setting, which involves performance assessment and targeted strategies to improve staff com- petency, logistics, and other determinants of quality of care. Carrier: One who carries and may transmit a genetic defect or infectious agent in the absence of symptoms. Chorionic villus sampling: A procedure in which a small sample of cells is removed from the placenta where it joins the uterus. The cells are used to test for chromosomal abnormalities in the fetus, such as Down syndrome. Chromosomal disorders: Sporadic nonhereditary losses or rearrangements of genetic material. Chromosomal nondisjunction: An error in cell division that admits three, rather than two, copies of one of the chromosomes into the cells of the affected zygote. Three copies (trisomy) of chromosome 21 cause Down syndrome. Cleft lip and/or palate: A gap in the soft palate and roof of the mouth, sometimes extending through the upper lip. This condition occurs when the various parts of a lip or palate don't grow together to make a single lip or hard palate. It is usually correctable. Eating, speech production, hearing, and tooth formation are all affected by this condition. Clinical trial: A scientifically controlled study carried out in people with a particular disease or class of diseases to test the effectiveness of a treat- ment or a method of prevention, detection, or diagnosis. Community-based rehabilitation (CBR): A strategy in communities for the rehabilitation, equalization of opportunities, and social integration of people with disabilities. The strategy mobilizes local resources and en-
GLOSSARY 229 ables people with disabilities and their communities to create their own solutions and programs for rehabilitation. Congenital abnormality: An anomaly, deformity, malformation, impairment, or dysfunction that is present at birth, but not necessarily inherited. Congenital cytomegalovirus: Fetal infection with cytomegalovirus causes disease only in utero, but this can result in abortion, stillbirth, or vari- ous congenital defects. Persons who have been exposed to the virus will remain cytomegalovirus IgG-positive. Infected cells enlarge and have a characteristic inclusion body (composed of virus particles) in the nucleus. Congenital heart disease: A malformation of the heart or large blood vessels near the heart that is present at birth. This is the most common of the major birth defects and affects 8 per 1,000 live births. Congenital hypothyroidism: Lack of thyroid secretion due to inappropriate development of the thymus gland or inadequate maternal iodine intake during gestation which leads to stunted body growth and mental devel- opment in the first years of life. Congenital rubella syndrome: Fetal infection with rubella virus during the first trimester of pregnancy can cause a series of congenital abnormali- ties including heart disease, deafness, and blindness. Congenital: A condition or disease that is present at birth. It includes con- ditions that are inherited and others caused by a new genetic mutation or an environmental exposure. Consanguineous: Related by blood. Consanguineous marriage usually re- fers to the marriage of first cousins but includes second cousins. Convulsion: A sudden attack usually characterized by loss of consciousness and sustained or rhythmic contractions of some or all voluntary mus- cles. Convulsions are most often a manifestation of a seizure disorder (epilepsy). Cost-effectiveness analysis: A systematic methodology for the comparison of the overall costs and health benefits of public health interventions. Cretinism: Congenital hypothyroidism (underactivity of the thyroid gland at birth) resulting in growth retardation, developmental delay, and other abnormal features. Can be due to deficiency of iodine in the mother's diet during pregnancy or inappropriate development of the thymus gland. Cyanosis: The bluish color of the skin and mucous membranes due to insufficient oxygen in the blood. Cystic fibrosis (CF): A generalized disorder in which there is widespread dysfunction of the exocrine glands, characterized by signs of chronic pulmonary disease (due to excess mucus production in the respiratory tract), pancreatic deficiency, abnormally high levels of electrolytes in the sweat, and occasionally by biliary cirrhosis. There is an ineffective
230 REDUCING THE IMPACT OF BIRTH DEFECTS immunological defense against bacteria in the lungs. Without treat- ment, CF results in death for 95 percent of affected children before age five. With diligent medical care patients with CF can survive beyond middle age. Developing countries: Defined by the World Bank as countries with per capita income below $2996 in 2001. Low-income countries had a per capita income of $755 or less in 2001. Middle-income countries had a per capita income of $756-$2,995 in 2001. Developmental dysplasia of the hip (DDH): DDH is a malformation of the hip joint in which the head of the femur is not correctly positioned in the acetabulum. The cause is unknown, but genetic factors may play a role. Problems range from congenital dislocation of the hip where the head of the femur is completely outside the acetabulum and the hip is very unstable to conditions where the displacement shortens one leg and causes limping, joint and knee problems, and degenerative changes. Diagnosis: Identification of a disease or disorder. Disability-adjusted life years (DALY): An indicator that combines losses from premature death (the difference between the actual age at death and life expectancy in a low-mortality population) and loss of healthy life resulting from disability. Dominant: A mode of inheritance in which the gene from one parent is required for a trait to appear in an offspring. Down syndrome: A common chromosomal disorder in which a person is born with three not two copies of chromosome number 21 (trisomy 211. It causes mental retardation, a characteristic facial appearance, and multiple malformations. It is associated with a major risk for heart malformations, a risk of duodenal atresia in which part of the small intestine is not developed, and a small but significant risk of acute leukemia. Down syndrome can be detected in the first few months of pregnancy by amniocentesis. The risk factors include mothers who become pregnant after age 35 and having a prior child with Down syndrome. This disorder was formerly known as mongolism. Effective treatment: The effect of a treatment as observed in the controlled circumstances of a clinical trial. Efficacious treatment: The effect of a treatment that can be expected in real clinical practice. Encephalocele: A protrusion of the brain or part of the brain through a fissure in the bones of the skull. Environmental birth defect: A defect present in a baby at birth, caused by prenatal events that are not genetic. These include maternal infections, certain medications, some drugs, and ionizing radiation. Evidence-based medicine/health care: In evidence-based health care, the policies and practices used for prevention are based on principles that
GLOSSARY 231 have been proven through appropriate scientific methods. As well as proving the clinical effectiveness of a procedure, this involves evidence of user and provider satisfaction, feasibility, and cost-effectiveness of the procedure in different settings. Fetal alcohol syndrome: A clinical syndrome resulting from the direct toxic effects of alcohol on the developing fetus. Growth retardation, mental retardation, small brain, and heart valve lesions are common. Infants can be identified by close-set eyes, small head, small nasal bridge, re- duction in the vermilion border of the upper lip, eye folds, and small teeth. Genetic birth defect: A defect present in a baby at birth, caused by a genetic factor. Genetic screening test: A test that identifies clinically normal individuals who have genotypes associated with a birth defect or who are at high risk of producing offspring with a birth defect. Genetic screening of large populations aims to identify as many affected individuals as possible, but screening alone does not detect all individuals at high risk. Gestational age: The number of completed weeks since the last menstrual period of the mother. This can be assessed clinically or by obstetric ultrasound. Glucose-6-phosphate debydrogenase (G6PD) deficiency: This enzyme de- fect occurs on the X chromosome. Males with the enzyme deficiency develop anemia due to breakup of their red blood cells when they are exposed to oxidant drugs such as the antimalarial, primaquine, the sulfonamide antibiotics or sulfones, naphthalene mothballs, or fava beans. Fever, viral and bacterial infections, and diabetic acidosis can also precipitate a hemolytic crisis (when the red blood cells break up), resulting in anemia and jaundice. This is the commonest disease-caus- ing enzyme defect in humans, affecting an estimated 400 million people. It occurs with increased frequency in people of sub-Saharan African or Mediterranean origin. The concentration of G6PD deficiency in certain populations is the result of the protective effect it afforded (much like sickle cell trait) against malaria. Goiter: Enlargement of the thyroid gland. Goiter can be associated with levels of thyroid hormone that are normal, too high, or too low. Hemizygote: Nucleus, cell, or organism that has only one of a normally diploid set of genes. In mammals the male is hemizygous for the X chromosome. Hemolysis: The destruction of red blood cells, which leads to the release of hemoglobin into the blood plasma. Hemolytic jaundice: Jaundice (yellowing) caused by destruction of red blood cells. This can be an inborn condition (hereditary spherocytosis) or it
232 REDUCING THE IMPACT OF BIRTH DEFECTS may be caused by a blood transfusion from a different blood group, infection in the blood, or some types of poisoning. Hemophilia A and B: A hemorrhagic diathesis occurring in two main forms, both determined by a mutant gene of the X chromosome. The disease is characterized by subcutaneous and intramuscular hemorrhages; bleed- ing from the mouth, gums, lips, and tongue; hematuria; and hemar- throses. Hemophilia A (classic hemophilia, factor VIII deficiency) is an X-linked disorder due to deficiency of coagulation factor VIII, and hemophilia B (factor IX deficiency, Christmas disease), also X linked, is due to deficiency of coagulation factor IX. Hepatomegaly: Enlargement of the liver. Hereditary: Refers to a disease or condition that is passed from parents to child. Heterozygote: Nucleus, cell, or organism with different alleles of one or more specific genes. A heterozygous organism will produce unlike ga- metes and thus will not breed true. Holoprosencephaly: A disorder characterized by the failure of the embry- onic forebrain to divide to form bilateral cerebral hemispheres (the left and right halves of the brain), causing defects in the development of the face and in brain structure and function. Homozygote: Nucleus, cell, or organism with identical alleles of one or more specific genes; a person who has two identical forms of a particu- lar gene, one inherited from each parent. Hydranencephaly: A condition in which the cerebral hemispheres of the brain are absent and replaced by sacs filled with cerebrospinal fluid. The cerebellum and brainstem are usually formed normally. Hydrocephalus: Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain. Hyperbilirubinemia: An excess of bilirubin in the blood. Hyperthermia: Abnormally high body temperature. Immune: Protected against infection. In utero: Within the womb. Incidence: The number of new cases of a disease among a certain group of people for a certain period of time. Infant mortality rate (IMR): Number of deaths among infants under one year of age per 1,000 live births. Infarction: The formation of an area of tissue death because of a local lack of oxygen. Insulin-dependent diabetes mellitus (IDDM): A chronic condition in which the pancreas makes little or no insulin because the beta cells have been destroyed. Insulin is required for the breakdown of glucose (blood sugar) for energy. IDDM usually occurs abruptly, although the damage
GLOSSARY 233 to the beta cells may begin much earlier. The signs of IDDM are a great thirst, hunger, a need to urinate often, and loss of weight. Treatment of the disease involves insulin injections, a specific diet plan, daily exer- cise, and frequent testing of blood glucose levels. IDDM usually occurs in children and adults under the age of 30. This type of diabetes used to be known as juvenile diabetes, juvenile-onset diabetes, and ketosis- prone diabetes. Intracranial calcification: The process within the skull by which organic tissue becomes hardened by a deposit of calcium salts within its sub- stance. Iodine deficiency disorder: Iodine is a dietary requirement, and inadequate intake causes inadequate production of thyroid hormone (hypothyroid- ism). Ischemia: A low oxygen state usually due to obstruction of the arterial blood supply or inadequate blood flow leading to hypoxia in the tissue. Jaundice: A condition in which high levels of bilirubin in the blood cause a yellow coloration in the skin. Kernicterus: Disorder in a newborn baby caused by high levels of bilirubin in the blood. When bilirubin is deposited in the brain it causes bilirubin encephalopathy. Live birth: A baby born with any signs of life, independently of weight or gestation. Low birth weight (LBW): Birth weight less than 2,500 grams. Macrosomia: Larger-than-normal birth weight, usually more than 9.75 pounds, or 4,500 grams. Management: A process by which one plans, implements, and evaluates an organized response to a health problem. Meningoencephalitis: Inflammation of both the brain and meninges, which are the membranes surrounding the brain and spinal cord. Meta-analysis: The statistical method used to integrate results from more than one study to produce a summary estimate of the treatment effect across studies (typical relative risk). Morbidity: Departure from a state of physiological or psychological well- being. Multiple gestation: More than one fetus developing in the uterus. Mutation: A change in genetic material that occurs by chance. Myelomeningocele: The protrusion of the spinal cord and its membranes. Myxedema: A dry, waxy type of swelling, often with swollen lips and nose, which results from infantile hypothyroidism. Neonate: An infant in the time between birth and 28 completed days of life (the neonatal period). Neural tube defects (NTDs): Major birth defects caused by abnormal devel- opment of the neural tube, the structure present during embryonic life
234 REDUCING THE IMPACT OF BIRTH DEFECTS that gives rise to the central nervous system, brain, and spinal cord. Neural tube defects (NTDs) are among the most common birth defects that cause death and serious disability. The different types of NTDs include anencephaly, spine bifida, and encephalocele. Neural tube: A structure in early fetal life that develops into the brain, spinal cord, spinal nerves, and spine. Non-consanguineous: Not related by blood referring to the parents of an offspring. Nystagmus: An involuntary, rapid, rhythmic movement of the eyeball, which may be horizontal, vertical, rotatory, or mixed. Obstructed labor: Labor in which progress is arrested by mechanical fac- tors. Delivery may require cesarean section. Occiput: The back of the head. Oculocutaneous albinism: An autosomal recessive deficiency of pigment in skin, hair, and eyes; in the tyrosinase-negative type, there is an absence of tyrosinase; in the tyrosinase-positive type, the normal tyrosinase cannot enter pigment cells. There are several types of oculocutaneous albinism. Parity: Number of full-term children previously born by a woman, exclud- ing miscarriages and abortions in early pregnancy, but including still- births. Phenylketonuria: Congenital absence of phenylalanine hydroxylase (the enzyme that converts phenylalanine to tyrosine). Phenylalanine accu- mulates in blood and seriously impairs early neuronal development. Photophobia: Painful oversensitivity to light. Polydactyly: More than the normal number of fingers or toes. Prenatal: The period of time between the conception and birth of an infant. Also called antenatal. Prevalence: The number of instances of a given disease or other condition in a particular population at a specified time. Pulmonary hypertension: High blood pressure in the pulmonary arteries, which can irrevocably damage the lungs. Randomized controlled trials (RCT): Trial experiments in which investiga- tors randomly allocate eligible people or health care units into groups to receive, or not receive, the interventionist being compared. When sample size is adequate, randomization ensures baseline comparability of known and unknown prognostic variables. The outcomes are selected before the experiment to ensure an unbiased assessment of the results. Recessive: A mode of inheritance in which a gene must be present from both parents for the trait to become manifest in an offspring. Reduction deformities of limbs: Congenital absence or attenuation of one or more body parts. Relative risk: The ratio of the risk of death or disease in those exposed to
GLOSSARY 235 the risk compared with the risk in those not exposed. Seizure: A sudden attack of epileptic convulsion in which the patient may experience uncontrollable body movements, unusual smells or tastes, or loss of consciousness. Sickle cell disease: Also known as sickle cell anemia, this is a genetic blood disease that results from the pairing of an abnormal hemoglobin S (Hb S) with another abnormal hemoglobin; the most frequent and severe phenotypes are hemoglobin SS (Hb SS) and hemoglobin SC (Hb SC). The hemoglobin molecules in red blood cells stick to one another and cause the red cells to become crescent- or sickle-shaped. Sickled cells cannot pass easily through tiny blood vessels. Sickle cell disease affects millions of people worldwide but is particularly common among people from sub-Saharan Africa; Spanish-speaking regions; Saudi Arabia; In- dia; and Mediterranean countries. Spina bifida: Incomplete closure of the spinal cord through which the cord and meninges may or may not protrude. Splenomegaly: Enlargement of the spleen. Spontaneous abortion: A pregnancy in which the fetus cannot survive or in which the fetus is born before the 20th week of pregnancy. Also known . . as a miscarriage. Squamous cell carcinoma: Cancer that begins in squamous cells, which are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Stillbirth: The death of a fetus weighing at least 500 g (or when birth weight is unavailable, after 22 completed weeks of gestation or with a crown- hee! length of 25 cm or more), before the complete expulsion or extrac- tion from its mother. Stillborn infant: An infant who shows no evidence of life after birth. Surveillance: The systematic collection and analysis of data in order to make management decisions. Syncope: Partial or complete loss of consciousness with a spontaneous recovery. Talipes, or clubfoot: This is the most common congenital abnormality of the foot. It may occur in several forms. Talipes equinovarus is the most common and in this case the foot turns downward and inward. Treat- ment involves the extended use of orthopedic splints or casts to correct the position of the foot. Talocalcaneonavicular (joint): A ball-and-socket synovial joint, part of which participates in the transverse tarsal joint, formed by the head of the talus articulating with the navicular bone and the anterior part of the calcaneus. Teratogen: Any agent that can disturb the development of an embryo or
236 REDUCING THE IMPACT OF BIRTH DEFECTS fetus, which may halt the pregnancy or cause a birth defect in the chilci. Teratogens inclucle some maternal infections, chemicals, drugs, and . . rac ration. Thalassemias: These are a group of inherited blooci clisorclers in which production of hemoglobin is deficient. There are many different clisor- clers involving defective hemoglobin synthesis and, hence, many types of thalassemia. Oc-Thalassemia, the heterozygous state (with a single gene for alpha- thalassemia) is innocuous or harmless. The homozygous state (with both genes for alpha-thalassemia) can be lethal before birth. p-Thalassemia involves a defect in the production of beta-globin chains, which decreases production of normal aclult hemoglobin (Hb A), the predominant type of hemoglobin from soon after birth until cleath. This is the most common thalassemia. Therapeutic: Pertaining to treatment. Total births: All births, live and stillborn (late fetal cleaths). Toxoplasmosis: An acute or chronic wiclespreaci disease caused by the protozoan Toxoplasma gondii and transmitted by oocysts containing the pathogen in the feces of cats (the definitive host), contaminated soil, direct exposure to infected feces, tissue cysts in infected meat or tachy- zoites (proliferating forms) in blooci. Trisomy 13 syndrome: Children with this syndrome have three, instead of two, copies of chromosome 13. Children born with this syndrome have multiple malformations and mental retardation, inclucling scalp cle- fects, blooci vessel malformations of the face and nape of the neck, cleft lip and palate, malformations of the heart and abdominal organs, and flexeci fingers with extra cligits. The mental retardation is profounci, with an IQ that is too low to accurately test. The majority of trisomy 13 babies clie soon after birth or in infancy. The conclition is also called Patau syndrome. Trisomy 18 syndrome: Children with this syndrome have three, instead of two, copies of chromosome 18. This conclition causes multiple malfor- mations and profounci mental retardation, small head (microcephaly), small jaw (micrognathia), malformations of the heart and kidneys, clenched fists with abnormal finger positioning, malformed feet, and low birth weight. The vast majority (95 percent) of these children clie before their first birthday. The conclition is also called Ec~warcis syn- cirome. Ultrasound: A diagnostic procedure that projects high-frequency sound waves into the bocly and converts the echoes into pictures (sonograms) shown on a monitor. Different types of tissue reflect sound waves clifferently, which makes it possible to finci abnormal growths.
GLOSSARY 237 Ultraviolet radiation: Invisible rays of solar energy. Ultraviolet racliation can burn the skin and cause skin cancer. It is macle up of two types of rays, WA and UVB. WB rays are more likely than WA rays to cause sunburn, but WA rays pass further into the skin. Scientists have long thought that UVB racliation can cause melanoma and other types of skin cancer. WA racliation is now consiclereci to acici skin damage that can leaci to cancer. Sunscreens are recommencleci to block both kinds of . . rac ration. Vital registration: Identifying and recording every birth and cleath of a pregnant woman and newborn. X-linked: A clisorcler founci only on the X chromosome. If a male chilci (XY) has an X-linkeci clisorcler, it was passed on by the mother. If a female chilci (XX) has an X-linkeci clisorcler, the defective gene could have come from either parent. Definitions for this glossary were compiled from the following sources: Birth Disorder Information Directory. Available at http://www.bclici.com/. MeclicineNet, Inc. MedTerms Medical Dictionary. Available at http://www. MeclicineNet.com, 2003. MedlinePlus. The National Library of Medicine (c)ate of last update: 21 November 20021. Available at http://www.nim.nih.gov/mecilineplus/. CancerWEB. The Department of Medical Oncology at the University of Newcastle upon Tyne. Available at http://cancerweb.ncl.ac.uk/omci/ inclex.htmI, 2003.
