Prenatal Diagnosis: Determination of the nature of a pathological condition or disease in the postimplantation EMBRYO; FETUS; or pregnant female before birth.Fetal Diseases: Pathophysiological conditions of the FETUS in the UTERUS. Some fetal diseases may be treated with FETAL THERAPIES.Ultrasonography, Prenatal: The visualization of tissues during pregnancy through recording of the echoes of ultrasonic waves directed into the body. The procedure may be applied with reference to the mother or the fetus and with reference to organs or the detection of maternal or fetal disease.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Chorionic Villi Sampling: A method for diagnosis of fetal diseases by sampling the cells of the placental chorionic villi for DNA analysis, presence of bacteria, concentration of metabolites, etc. The advantage over amniocentesis is that the procedure can be carried out in the first trimester.Prenatal Exposure Delayed Effects: The consequences of exposing the FETUS in utero to certain factors, such as NUTRITION PHYSIOLOGICAL PHENOMENA; PHYSIOLOGICAL STRESS; DRUGS; RADIATION; and other physical or chemical factors. These consequences are observed later in the offspring after BIRTH.Prenatal Care: Care provided the pregnant woman in order to prevent complications, and decrease the incidence of maternal and prenatal mortality.Amniocentesis: Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions.Abortion, Eugenic: Abortion performed because of possible fetal defects.Heterozygote Detection: Identification of genetic carriers for a given trait.Genetic Counseling: An educational process that provides information and advice to individuals or families about a genetic condition that may affect them. The purpose is to help individuals make informed decisions about marriage, reproduction, and other health management issues based on information about the genetic disease, the available diagnostic tests, and management programs. Psychosocial support is usually offered.Abortion, Therapeutic: Abortion induced to save the life or health of a pregnant woman. (From Dorland, 28th ed)Infant, Newborn: An infant during the first month after birth.Amniotic Fluid: A clear, yellowish liquid that envelopes the FETUS inside the sac of AMNION. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (AMNIOCENTESIS).Gestational Age: The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization.Pregnancy Trimester, Second: The middle third of a human PREGNANCY, from the beginning of the 15th through the 28th completed week (99 to 196 days) of gestation.Abnormalities, MultipleAbortion, Induced: Intentional removal of a fetus from the uterus by any of a number of techniques. (POPLINE, 1978)Fetus: The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.Pregnancy Outcome: Results of conception and ensuing pregnancy, including LIVE BIRTH; STILLBIRTH; SPONTANEOUS ABORTION; INDUCED ABORTION. The outcome may follow natural or artificial insemination or any of the various ASSISTED REPRODUCTIVE TECHNIQUES, such as EMBRYO TRANSFER or FERTILIZATION IN VITRO.Chromosome Disorders: Clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material (either a whole chromosome or a chromosome segment). (from Thompson et al., Genetics in Medicine, 5th ed, p429)Thalassemia: A group of hereditary hemolytic anemias in which there is decreased synthesis of one or more hemoglobin polypeptide chains. There are several genetic types with clinical pictures ranging from barely detectable hematologic abnormality to severe and fatal anemia.Trisomy: The possession of a third chromosome of any one type in an otherwise diploid cell.Cordocentesis: The collecting of fetal blood samples typically via ENDOSCOPIC ULTRASOUND GUIDED FINE NEEDLE ASPIRATION from the umbilical vein.Genetic Testing: Detection of a MUTATION; GENOTYPE; KARYOTYPE; or specific ALLELES associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing.Pregnancy Trimester, First: The beginning third of a human PREGNANCY, from the first day of the last normal menstrual period (MENSTRUATION) through the completion of 14 weeks (98 days) of gestation.Down Syndrome: A chromosome disorder associated either with an extra chromosome 21 or an effective trisomy for chromosome 21. Clinical manifestations include hypotonia, short stature, brachycephaly, upslanting palpebral fissures, epicanthus, Brushfield spots on the iris, protruding tongue, small ears, short, broad hands, fifth finger clinodactyly, Simian crease, and moderate to severe INTELLECTUAL DISABILITY. Cardiac and gastrointestinal malformations, a marked increase in the incidence of LEUKEMIA, and the early onset of ALZHEIMER DISEASE are also associated with this condition. Pathologic features include the development of NEUROFIBRILLARY TANGLES in neurons and the deposition of AMYLOID BETA-PROTEIN, similar to the pathology of ALZHEIMER DISEASE. (Menkes, Textbook of Child Neurology, 5th ed, p213)Hydrops Fetalis: Abnormal accumulation of serous fluid in two or more fetal compartments, such as SKIN; PLEURA; PERICARDIUM; PLACENTA; PERITONEUM; AMNIOTIC FLUID. General fetal EDEMA may be of non-immunologic origin, or of immunologic origin as in the case of ERYTHROBLASTOSIS FETALIS.Karyotyping: Mapping of the KARYOTYPE of a cell.Fetal Death: Death of the developing young in utero. BIRTH of a dead FETUS is STILLBIRTH.Sex Chromosome Disorders: Clinical conditions caused by an abnormal sex chromosome constitution (SEX CHROMOSOME ABERRATIONS), in which there is extra or missing sex chromosome material (either a whole chromosome or a chromosome segment).Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Hemoglobinopathies: A group of inherited disorders characterized by structural alterations within the hemoglobin molecule.Polyhydramnios: A condition of abnormally high AMNIOTIC FLUID volume, such as greater than 2,000 ml in the LAST TRIMESTER and usually diagnosed by ultrasonographic criteria (AMNIOTIC FLUID INDEX). It is associated with maternal DIABETES MELLITUS; MULTIPLE PREGNANCY; CHROMOSOMAL DISORDERS; and congenital abnormalities.Congenital Abnormalities: Malformations of organs or body parts during development in utero.Heart Defects, Congenital: Developmental abnormalities involving structures of the heart. These defects are present at birth but may be discovered later in life.Pedigree: The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.Pregnancy Trimester, Third: The last third of a human PREGNANCY, from the beginning of the 29th through the 42nd completed week (197 to 294 days) of gestation.Preimplantation Diagnosis: Determination of the nature of a pathological condition or disease in the OVUM; ZYGOTE; or BLASTOCYST prior to implantation. CYTOGENETIC ANALYSIS is performed to determine the presence or absence of genetic disease.Ectromelia: Gross hypo- or aplasia of one or more long bones of one or more limbs. The concept includes amelia, hemimelia, phocomelia, and sirenomelia.Ultrasonography, Doppler, Color: Ultrasonography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. This type of ultrasonography is well-suited to identifying the location of high-velocity flow (such as in a stenosis) or of mapping the extent of flow in a certain region.Hernia, Umbilical: A HERNIA due to an imperfect closure or weakness of the umbilical ring. It appears as a skin-covered protrusion at the UMBILICUS during crying, coughing, or straining. The hernia generally consists of OMENTUM or SMALL INTESTINE. The vast majority of umbilical hernias are congenital but can be acquired due to severe abdominal distention.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Pregnant Women: Human females who are pregnant, as cultural, psychological, or sociological entities.beta-Thalassemia: A disorder characterized by reduced synthesis of the beta chains of hemoglobin. There is retardation of hemoglobin A synthesis in the heterozygous form (thalassemia minor), which is asymptomatic, while in the homozygous form (thalassemia major, Cooley's anemia, Mediterranean anemia, erythroblastic anemia), which can result in severe complications and even death, hemoglobin A synthesis is absent.Sex Determination Analysis: Validation of the SEX of an individual by inspection of the GONADS and/or by genetic tests.Fetal Heart: The heart of the fetus of any viviparous animal. It refers to the heart in the postembryonic period and is differentiated from the embryonic heart (HEART/embryology) only on the basis of time.Syndrome: A characteristic symptom complex.Chorionic Villi: The threadlike, vascular projections of the chorion. Chorionic villi may be free or embedded within the DECIDUA forming the site for exchange of substances between fetal and maternal blood (PLACENTA).Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Genetic Diseases, Inborn: Diseases that are caused by genetic mutations present during embryo or fetal development, although they may be observed later in life. The mutations may be inherited from a parent's genome or they may be acquired in utero.Sex Chromosome Aberrations: Abnormal number or structure of the SEX CHROMOSOMES. Some sex chromosome aberrations are associated with SEX CHROMOSOME DISORDERS and SEX CHROMOSOME DISORDERS OF SEX DEVELOPMENT.Twins, ConjoinedAneuploidy: The chromosomal constitution of cells which deviate from the normal by the addition or subtraction of CHROMOSOMES, chromosome pairs, or chromosome fragments. In a normally diploid cell (DIPLOIDY) the loss of a chromosome pair is termed nullisomy (symbol: 2N-2), the loss of a single chromosome is MONOSOMY (symbol: 2N-1), the addition of a chromosome pair is tetrasomy (symbol: 2N+2), the addition of a single chromosome is TRISOMY (symbol: 2N+1).Chromosome Aberrations: Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.Delayed Diagnosis: Non-optimal interval of time between onset of symptoms, identification, and initiation of treatment.Prenatal Injuries: Damages to the EMBRYO, MAMMALIAN or the FETUS before BIRTH. Damages can be caused by any factors including biological, chemical, or physical.Fetoscopy: Endoscopic examination, therapy or surgery of the fetus and amniotic cavity through abdominal or uterine entry.Chromosomes, Human, Pair 18: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.Fatal Outcome: Death resulting from the presence of a disease in an individual, as shown by a single case report or a limited number of patients. This should be differentiated from DEATH, the physiological cessation of life and from MORTALITY, an epidemiological or statistical concept.Hydrocolpos: A fluid-filled VAGINA that is obstructed.Early Diagnosis: Methods to determine in patients the nature of a disease or disorder at its early stage of progression. Generally, early diagnosis improves PROGNOSIS and TREATMENT OUTCOME.Dandy-Walker Syndrome: A congenital abnormality of the central nervous system marked by failure of the midline structures of the cerebellum to develop, dilation of the fourth ventricle, and upward displacement of the transverse sinuses, tentorium, and torcula. Clinical features include occipital bossing, progressive head enlargement, bulging of anterior fontanelle, papilledema, ataxia, gait disturbances, nystagmus, and intellectual compromise. (From Menkes, Textbook of Child Neurology, 5th ed, pp294-5)Musculoskeletal Abnormalities: Congenital structural abnormalities and deformities of the musculoskeletal system.Genetic Linkage: The co-inheritance of two or more non-allelic GENES due to their being located more or less closely on the same CHROMOSOME.Levocardia: Congenital abnormalities in which the HEART is in the normal position (levocardia) in the left side of the chest but some or all of the THORAX or ABDOMEN viscera are transposed laterally (SITUS INVERSUS). It is also known as situs inversus with levocardia, or isolated levocardia. This condition is often associated with severe heart defects and splenic abnormalities such as asplenia or polysplenia.Gastroschisis: A congenital defect with major fissure in the ABDOMINAL WALL lateral to, but not at, the UMBILICUS. This results in the extrusion of VISCERA. Unlike OMPHALOCELE, herniated structures in gastroschisis are not covered by a sac or PERITONEUM.Mosaicism: The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from a single ZYGOTE, as opposed to CHIMERISM in which the different cell populations are derived from more than one zygote.Pulmonary Atresia: A congenital heart defect characterized by the narrowing or complete absence of the opening between the RIGHT VENTRICLE and the PULMONARY ARTERY. Lacking a normal PULMONARY VALVE, unoxygenated blood in the right ventricle can not be effectively pumped into the lung for oxygenation. Clinical features include rapid breathing, CYANOSIS, right ventricle atrophy, and abnormal heart sounds (HEART MURMURS).Chromosomes, Human, Pair 13: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Fetomaternal Transfusion: Transplacental passage of fetal blood into the circulation of the maternal organism. (Dorland, 27th ed)Adrenal Hyperplasia, Congenital: A group of inherited disorders of the ADRENAL GLANDS, caused by enzyme defects in the synthesis of cortisol (HYDROCORTISONE) and/or ALDOSTERONE leading to accumulation of precursors for ANDROGENS. Depending on the hormone imbalance, congenital adrenal hyperplasia can be classified as salt-wasting, hypertensive, virilizing, or feminizing. Defects in STEROID 21-HYDROXYLASE; STEROID 11-BETA-HYDROXYLASE; STEROID 17-ALPHA-HYDROXYLASE; 3-beta-hydroxysteroid dehydrogenase (3-HYDROXYSTEROID DEHYDROGENASES); TESTOSTERONE 5-ALPHA-REDUCTASE; or steroidogenic acute regulatory protein; among others, underlie these disorders.Maternal Age: The age of the mother in PREGNANCY.Genetic Services: Organized services to provide diagnosis, treatment, and prevention of genetic disorders.Anus, Imperforate: A congenital abnormality characterized by the persistence of the anal membrane, resulting in a thin membrane covering the normal ANAL CANAL. Imperforation is not always complete and is treated by surgery in infancy. This defect is often associated with NEURAL TUBE DEFECTS; MENTAL RETARDATION; and DOWN SYNDROME.Echocardiography, Four-Dimensional: Dynamic three-dimensional echocardiography using the added dimension of time to impart the cinematic perception of motion. (Mayo Clin Proc 1993;68:221-40)Genetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.Muscular Dystrophies: A heterogeneous group of inherited MYOPATHIES, characterized by wasting and weakness of the SKELETAL MUSCLE. They are categorized by the sites of MUSCLE WEAKNESS; AGE OF ONSET; and INHERITANCE PATTERNS.DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Hernia, Diaphragmatic: Protrusion of abdominal structures into the THORAX as a result of congenital or traumatic defects in the respiratory DIAPHRAGM.Spinal Muscular Atrophies of Childhood: A group of recessively inherited diseases that feature progressive muscular atrophy and hypotonia. They are classified as type I (Werdnig-Hoffman disease), type II (intermediate form), and type III (Kugelberg-Welander disease). Type I is fatal in infancy, type II has a late infantile onset and is associated with survival into the second or third decade. Type III has its onset in childhood, and is slowly progressive. (J Med Genet 1996 Apr:33(4):281-3)Anencephaly: A malformation of the nervous system caused by failure of the anterior neuropore to close. Infants are born with intact spinal cords, cerebellums, and brainstems, but lack formation of neural structures above this level. The skull is only partially formed but the eyes are usually normal. This condition may be associated with folate deficiency. Affected infants are only capable of primitive (brain stem) reflexes and usually do not survive for more than two weeks. (From Menkes, Textbook of Child Neurology, 5th ed, p247)Oligohydramnios: A condition of abnormally low AMNIOTIC FLUID volume. Principal causes include malformations of fetal URINARY TRACT; FETAL GROWTH RETARDATION; GESTATIONAL HYPERTENSION; nicotine poisoning; and PROLONGED PREGNANCY.Pregnancy, High-Risk: Pregnancy in which the mother and/or FETUS are at greater than normal risk of MORBIDITY or MORTALITY. Causes include inadequate PRENATAL CARE, previous obstetrical history (ABORTION, SPONTANEOUS), pre-existing maternal disease, pregnancy-induced disease (GESTATIONAL HYPERTENSION), and MULTIPLE PREGNANCY, as well as advanced maternal age above 35.Agenesis of Corpus Callosum: Birth defect that results in a partial or complete absence of the CORPUS CALLOSUM. It may be isolated or a part of a syndrome (e.g., AICARDI'S SYNDROME; ACROCALLOSAL SYNDROME; ANDERMANN SYNDROME; and HOLOPROSENCEPHALY). Clinical manifestations include neuromotor skill impairment and INTELLECTUAL DISABILITY of variable severity.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Polymorphism, Restriction Fragment Length: Variation occurring within a species in the presence or length of DNA fragment generated by a specific endonuclease at a specific site in the genome. Such variations are generated by mutations that create or abolish recognition sites for these enzymes or change the length of the fragment.Maternal Exposure: Exposure of the female parent, human or animal, to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals that may affect offspring. It includes pre-conception maternal exposure.Neural Tube Defects: Congenital malformations of the central nervous system and adjacent structures related to defective neural tube closure during the first trimester of pregnancy generally occurring between days 18-29 of gestation. Ectodermal and mesodermal malformations (mainly involving the skull and vertebrae) may occur as a result of defects of neural tube closure. (From Joynt, Clinical Neurology, 1992, Ch55, pp31-41)Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Cystic Adenomatoid Malformation of Lung, Congenital: An abnormality in lung development that is characterized by a multicystic mass resulting from an adenomatous overgrowth of the terminal BRONCHIOLES with a consequent reduction of PULMONARY ALVEOLI. This anomaly is classified into three types by the cyst size.Spinal Dysraphism: Congenital defects of closure of one or more vertebral arches, which may be associated with malformations of the spinal cord, nerve roots, congenital fibrous bands, lipomas, and congenital cysts. These malformations range from mild (e.g., SPINA BIFIDA OCCULTA) to severe, including rachischisis where there is complete failure of neural tube and spinal cord fusion, resulting in exposure of the spinal cord at the surface. Spinal dysraphism includes all forms of spina bifida. The open form is called SPINA BIFIDA CYSTICA and the closed form is SPINA BIFIDA OCCULTA. (From Joynt, Clinical Neurology, 1992, Ch55, p34)Fetal Blood: Blood of the fetus. Exchange of nutrients and waste between the fetal and maternal blood occurs via the PLACENTA. The cord blood is blood contained in the umbilical vessels (UMBILICAL CORD) at the time of delivery.Hypoplastic Left Heart Syndrome: A condition caused by underdevelopment of the whole left half of the heart. It is characterized by hypoplasia of the left cardiac chambers (HEART ATRIUM; HEART VENTRICLE), the AORTA, the AORTIC VALVE, and the MITRAL VALVE. Severe symptoms appear in early infancy when DUCTUS ARTERIOSUS closes.Pregnancy Complications: Conditions or pathological processes associated with pregnancy. They can occur during or after pregnancy, and range from minor discomforts to serious diseases that require medical interventions. They include diseases in pregnant females, and pregnancies in females with diseases.Hydronephrosis: Abnormal enlargement or swelling of a KIDNEY due to dilation of the KIDNEY CALICES and the KIDNEY PELVIS. It is often associated with obstruction of the URETER or chronic kidney diseases that prevents normal drainage of urine into the URINARY BLADDER.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.Maternal-Fetal Exchange: Exchange of substances between the maternal blood and the fetal blood at the PLACENTA via PLACENTAL CIRCULATION. The placental barrier excludes microbial or viral transmission.Diagnosis: The determination of the nature of a disease or condition, or the distinguishing of one disease or condition from another. Assessment may be made through physical examination, laboratory tests, or the likes. Computerized programs may be used to enhance the decision-making process.Micrognathism: Abnormally small jaw.Amniotic Band Syndrome: A disorder present in the newborn infant in which constriction rings or bands, causing soft tissue depressions, encircle digits, extremities, or limbs and sometimes the neck, thorax, or abdomen. They may be associated with intrauterine amputations.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Toxoplasmosis, Congenital: Prenatal protozoal infection with TOXOPLASMA gondii which is associated with injury to the developing fetal nervous system. The severity of this condition is related to the stage of pregnancy during which the infection occurs; first trimester infections are associated with a greater degree of neurologic dysfunction. Clinical features include HYDROCEPHALUS; MICROCEPHALY; deafness; cerebral calcifications; SEIZURES; and psychomotor retardation. Signs of a systemic infection may also be present at birth, including fever, rash, and hepatosplenomegaly. (From Adams et al., Principles of Neurology, 6th ed, p735)Abortion, Legal: Termination of pregnancy under conditions allowed under local laws. (POPLINE Thesaurus, 1991)Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Diagnostic Errors: Incorrect diagnoses after clinical examination or technical diagnostic procedures.Encephalocele: Brain tissue herniation through a congenital or acquired defect in the skull. The majority of congenital encephaloceles occur in the occipital or frontal regions. Clinical features include a protuberant mass that may be pulsatile. The quantity and location of protruding neural tissue determines the type and degree of neurologic deficit. Visual defects, psychomotor developmental delay, and persistent motor deficits frequently occur.Steroid 21-Hydroxylase: An adrenal microsomal cytochrome P450 enzyme that catalyzes the 21-hydroxylation of steroids in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP21 gene, converts progesterones to precursors of adrenal steroid hormones (CORTICOSTERONE; HYDROCORTISONE). Defects in CYP21 cause congenital adrenal hyperplasia (ADRENAL HYPERPLASIA, CONGENITAL).Meningomyelocele: Congenital, or rarely acquired, herniation of meningeal and spinal cord tissue through a bony defect in the vertebral column. The majority of these defects occur in the lumbosacral region. Clinical features include PARAPLEGIA, loss of sensation in the lower body, and incontinence. This condition may be associated with the ARNOLD-CHIARI MALFORMATION and HYDROCEPHALUS. (From Joynt, Clinical Neurology, 1992, Ch55, pp35-6)X Chromosome: The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Imaging, Three-Dimensional: The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.Karyotype: The full set of CHROMOSOMES presented as a systematized array of METAPHASE chromosomes from a photomicrograph of a single CELL NUCLEUS arranged in pairs in descending order of size and according to the position of the CENTROMERE. (From Stedman, 25th ed)Genes, Recessive: Genes that influence the PHENOTYPE only in the homozygous state.Chromosomes, Human, Pair 21: A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.Bone Diseases, DevelopmentalIntestinal Atresia: Congenital obliteration of the lumen of the intestine, with the ILEUM involved in 50% of the cases and the JEJUNUM and DUODENUM following in frequency. It is the most frequent cause of INTESTINAL OBSTRUCTION in NEWBORNS. (From Stedman, 25th ed)Ultrasonography, Doppler, Pulsed: Ultrasonography applying the Doppler effect, with velocity detection combined with range discrimination. Short bursts of ultrasound are transmitted at regular intervals and the echoes are demodulated as they return.In Situ Hybridization, Fluorescence: A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.Consanguinity: The magnitude of INBREEDING in humans.Cloaca: A dilated cavity extended caudally from the hindgut. In adult birds, reptiles, amphibians, and many fishes but few mammals, cloaca is a common chamber into which the digestive, urinary and reproductive tracts discharge their contents. In most mammals, cloaca gives rise to LARGE INTESTINE; URINARY BLADDER; and GENITALIA.Ultrasonography: The visualization of deep structures of the body by recording the reflections or echoes of ultrasonic pulses directed into the tissues. Use of ultrasound for imaging or diagnostic purposes employs frequencies ranging from 1.6 to 10 megahertz.Heart Septal Defects: Abnormalities in any part of the HEART SEPTUM resulting in abnormal communication between the left and the right chambers of the heart. The abnormal blood flow inside the heart may be caused by defects in the ATRIAL SEPTUM, the VENTRICULAR SEPTUM, or both.Umbilical Cord: The flexible rope-like structure that connects a developing FETUS to the PLACENTA in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus.Citrullinemia: A group of diseases related to a deficiency of the enzyme ARGININOSUCCINATE SYNTHASE which causes an elevation of serum levels of CITRULLINE. In neonates, clinical manifestations include lethargy, hypotonia, and SEIZURES. Milder forms also occur. Childhood and adult forms may present with recurrent episodes of intermittent weakness, lethargy, ATAXIA, behavioral changes, and DYSARTHRIA. (From Menkes, Textbook of Child Neurology, 5th ed, p49)Predictive Value of Tests: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.Mothers: Female parents, human or animal.Maternal-Fetal Relations: The bond or lack thereof between a pregnant woman and her FETUS.Respiratory System Abnormalities: Congenital structural abnormalities of the respiratory system.alpha-Thalassemia: A disorder characterized by reduced synthesis of the alpha chains of hemoglobin. The severity of this condition can vary from mild anemia to death, depending on the number of genes deleted.Lymphangioma, Cystic: A cystic growth originating from lymphatic tissue. It is usually found in the neck, axilla, or groin.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Meningocele: A congenital or acquired protrusion of the meninges, unaccompanied by neural tissue, through a bony defect in the skull or vertebral column.Metabolism, Inborn Errors: Errors in metabolic processes resulting from inborn genetic mutations that are inherited or acquired in utero.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Amino Acid Metabolism, Inborn Errors: Disorders affecting amino acid metabolism. The majority of these disorders are inherited and present in the neonatal period with metabolic disturbances (e.g., ACIDOSIS) and neurologic manifestations. They are present at birth, although they may not become symptomatic until later in life.Hemophilia A: The classic hemophilia resulting from a deficiency of factor VIII. It is an inherited disorder of blood coagulation characterized by a permanent tendency to hemorrhage.Ornithine Carbamoyltransferase Deficiency Disease: An inherited urea cycle disorder associated with deficiency of the enzyme ORNITHINE CARBAMOYLTRANSFERASE, transmitted as an X-linked trait and featuring elevations of amino acids and ammonia in the serum. Clinical features, which are more prominent in males, include seizures, behavioral alterations, episodic vomiting, lethargy, and coma. (Menkes, Textbook of Child Neurology, 5th ed, pp49-50)Azygos Vein: A vein which arises from the right ascending lumbar vein or the vena cava, enters the thorax through the aortic orifice in the diaphragm, and terminates in the superior vena cava.Holoprosencephaly: Anterior midline brain, cranial, and facial malformations resulting from the failure of the embryonic prosencephalon to undergo segmentation and cleavage. Alobar prosencephaly is the most severe form and features anophthalmia; cyclopia; severe INTELLECTUAL DISABILITY; CLEFT LIP; CLEFT PALATE; SEIZURES; and microcephaly. Semilobar holoprosencepaly is characterized by hypotelorism, microphthalmia, coloboma, nasal malformations, and variable degrees of INTELLECTUAL DISABILITY. Lobar holoprosencephaly is associated with mild (or absent) facial malformations and intellectual abilities that range from mild INTELLECTUAL DISABILITY to normal. Holoprosencephaly is associated with CHROMOSOME ABNORMALITIES.Rare Diseases: A large group of diseases which are characterized by a low prevalence in the population. They frequently are associated with problems in diagnosis and treatment.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Globins: A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure.Urogenital Abnormalities: Congenital structural abnormalities of the UROGENITAL SYSTEM in either the male or the female.Cystic Fibrosis: An autosomal recessive genetic disease of the EXOCRINE GLANDS. It is caused by mutations in the gene encoding the CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR expressed in several organs including the LUNG, the PANCREAS, the BILIARY SYSTEM, and the SWEAT GLANDS. Cystic fibrosis is characterized by epithelial secretory dysfunction associated with ductal obstruction resulting in AIRWAY OBSTRUCTION; chronic RESPIRATORY INFECTIONS; PANCREATIC INSUFFICIENCY; maldigestion; salt depletion; and HEAT PROSTRATION.Neonatal Screening: The identification of selected parameters in newborn infants by various tests, examinations, or other procedures. Screening may be performed by clinical or laboratory measures. A screening test is designed to sort out healthy neonates (INFANT, NEWBORN) from those not well, but the screening test is not intended as a diagnostic device, rather instead as epidemiologic.Spina Bifida Occulta: A common congenital midline defect of fusion of the vertebral arch without protrusion of the spinal cord or meninges. The lesion is also covered by skin. L5 and S1 are the most common vertebrae involved. The condition may be associated with an overlying area of hyperpigmented skin, a dermal sinus, or an abnormal patch of hair. The majority of individuals with this malformation are asymptomatic although there is an increased incidence of tethered cord syndrome and lumbar SPONDYLOSIS. (From Joynt, Clinical Neurology, 1992, Ch55, p34)Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Hypophosphatasia: A genetic metabolic disorder resulting from serum and bone alkaline phosphatase deficiency leading to hypercalcemia, ethanolamine phosphatemia, and ethanolamine phosphaturia. Clinical manifestations include severe skeletal defects resembling vitamin D-resistant rickets, failure of the calvarium to calcify, dyspnea, cyanosis, vomiting, constipation, renal calcinosis, failure to thrive, disorders of movement, beading of the costochondral junction, and rachitic bone changes. (From Dorland, 27th ed)Nuchal Translucency Measurement: A prenatal ultrasonography measurement of the soft tissue behind the fetal neck. Either the translucent area below the skin in the back of the fetal neck (nuchal translucency) or the distance between occipital bone to the outer skin line (nuchal fold) is measured.XYY Karyotype: Abnormal genetic constitution in males characterized by an extra Y chromosome.Lymphangioma: A benign tumor resulting from a congenital malformation of the lymphatic system. Lymphangioendothelioma is a type of lymphangioma in which endothelial cells are the dominant component.Chromosomes, Human, Pair 22: A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.Perinatology: The branch of medicine dealing with the fetus and infant during the perinatal period. The perinatal period begins with the twenty-eighth week of gestation and ends twenty-eight days after birth. (From Dorland, 27th ed)Prognosis: A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Epidermolysis Bullosa: Group of genetically determined disorders characterized by the blistering of skin and mucosae. There are four major forms: acquired, simple, junctional, and dystrophic. Each of the latter three has several varieties.Postmodernism: A late 20th-century philosophical approach or style of cultural analysis that seeks to reveal the cultural or social construction of concepts conventionally assumed to be natural or universal. (from E.R. DuBose, The Illusion of Trust: Toward a Medical Theological Ethics in the Postmodern Age, Kluwer, 1995)Hydrocephalus: Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, INTRACRANIAL HYPERTENSION; HEADACHE; lethargy; URINARY INCONTINENCE; and ATAXIA.Tricuspid Atresia: Absence of the orifice between the RIGHT ATRIUM and RIGHT VENTRICLE, with the presence of an atrial defect through which all the systemic venous return reaches the left heart. As a result, there is left ventricular hypertrophy (HYPERTROPHY, LEFT VENTRICULAR) because the right ventricle is absent or not functional.Sacrococcygeal Region: The body region between (and flanking) the SACRUM and COCCYX.Cri-du-Chat Syndrome: An infantile syndrome characterized by a cat-like cry, failure to thrive, microcephaly, MENTAL RETARDATION, spastic quadriparesis, micro- and retrognathia, glossoptosis, bilateral epicanthus, hypertelorism, and tiny external genitalia. It is caused by a deletion of the short arm of chromosome 5 (5p-).Echoencephalography: Use of reflected ultrasound in the diagnosis of intracranial pathologic processes.Clubfoot: A deformed foot in which the foot is plantarflexed, inverted and adducted.Klippel-Trenaunay-Weber Syndrome: A congenital disorder that is characterized by a triad of capillary malformations (HEMANGIOMA), venous malformations (ARTERIOVENOUS FISTULA), and soft tissue or bony hypertrophy of the limb. This syndrome is caused by mutations in the VG5Q gene which encodes a strong angiogenesis stimulator.Pregnancy Trimesters: The three approximately equal periods of a normal human PREGNANCY. Each trimester is about three months or 13 to 14 weeks in duration depending on the designation of the first day of gestation.Cesarean Section: Extraction of the FETUS by means of abdominal HYSTEROTOMY.Clinical Enzyme Tests: Analyses for a specific enzyme activity, or of the level of a specific enzyme that is used to assess health and disease risk, for early detection of disease or disease prediction, diagnosis, and change in disease status.Bronchopulmonary Sequestration: A developmental anomaly in which a mass of nonfunctioning lung tissue lacks normal connection with the tracheobroncheal tree and receives an anomalous blood supply originating from the descending thoracic or abdominal aorta. The mass may be extralobar, i.e., completely separated from normally connected lung, or intralobar, i.e., partly surrounded by normal lung.IsraelFoot Deformities, Congenital: Alterations or deviations from normal shape or size which result in a disfigurement of the foot occurring at or before birth.Autopsy: Postmortem examination of the body.Microcephaly: A congenital abnormality in which the CEREBRUM is underdeveloped, the fontanels close prematurely, and, as a result, the head is small. (Desk Reference for Neuroscience, 2nd ed.)Lipidoses: Conditions characterized by abnormal lipid deposition due to disturbance in lipid metabolism, such as hereditary diseases involving lysosomal enzymes required for lipid breakdown. They are classified either by the enzyme defect or by the type of lipid involved.DNA Probes: Species- or subspecies-specific DNA (including COMPLEMENTARY DNA; conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32P and 125I and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections.Arthrogryposis: Persistent flexure or contracture of a joint.Postnatal Care: The care provided to women and their NEWBORNS for the first few months following CHILDBIRTH.46, XY Disorders of Sex Development: Congenital conditions in individuals with a male karyotype, in which the development of the gonadal or anatomical sex is atypical.Chromosomes, Human, X: The human female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in humans.Chondrodysplasia Punctata: A heterogeneous group of bone dysplasias, the common character of which is stippling of the epiphyses in infancy. The group includes a severe autosomal recessive form (CHONDRODYSPLASIA PUNCTATA, RHIZOMELIC), an autosomal dominant form (Conradi-Hunermann syndrome), and a milder X-linked form. Metabolic defects associated with impaired peroxisomes are present only in the rhizomelic form.Aortopulmonary Septal Defect: A developmental abnormality in which the spiral (aortopulmonary) septum failed to completely divide the TRUNCUS ARTERIOSUS into ASCENDING AORTA and PULMONARY ARTERY. This abnormal communication between the two major vessels usually lies above their respective valves (AORTIC VALVE; PULMONARY VALVE).Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Anemia, Sickle Cell: A disease characterized by chronic hemolytic anemia, episodic painful crises, and pathologic involvement of many organs. It is the clinical expression of homozygosity for hemoglobin S.Bladder Exstrophy: A birth defect in which the URINARY BLADDER is malformed and exposed, inside out, and protruded through the ABDOMINAL WALL. It is caused by closure defects involving the top front surface of the bladder, as well as the lower abdominal wall; SKIN; MUSCLES; and the pubic bone.Ichthyosis, Lamellar: A chronic, congenital ichthyosis inherited as an autosomal recessive trait. Infants are usually born encased in a collodion membrane which sheds within a few weeks. Scaling is generalized and marked with grayish-brown quadrilateral scales, adherent at their centers and free at the edges. In some cases, scales are so thick that they resemble armored plate.Homozygote: An individual in which both alleles at a given locus are identical.Thoracic Diseases: Disorders affecting the organs of the thorax.False Positive Reactions: Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)Fetal Alcohol Spectrum Disorders: An umbrella term used to describe a pattern of disabilities and abnormalities that result from fetal exposure to ETHANOL during pregnancy. It encompasses a phenotypic range that can vary greatly between individuals, but reliably includes one or more of the following: characteristic facial dysmorphism, FETAL GROWTH RETARDATION, central nervous system abnormalities, cognitive and/or behavioral dysfunction, BIRTH DEFECTS. The level of maternal alcohol consumption does not necessarily correlate directly with disease severity.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Prune Belly Syndrome: A syndrome characterized by abdominal wall musculature deficiency, cryptorchism, and urinary tract abnormalities. The syndrome derives its name from its characteristic distended abdomen with wrinkled skin.Hemophilia B: A deficiency of blood coagulation factor IX inherited as an X-linked disorder. (Also known as Christmas Disease, after the first patient studied in detail, not the holy day.) Historical and clinical features resemble those in classic hemophilia (HEMOPHILIA A), but patients present with fewer symptoms. Severity of bleeding is usually similar in members of a single family. Many patients are asymptomatic until the hemostatic system is stressed by surgery or trauma. Treatment is similar to that for hemophilia A. (From Cecil Textbook of Medicine, 19th ed, p1008)Neck: The part of a human or animal body connecting the HEAD to the rest of the body.Polydactyly: A congenital anomaly of the hand or foot, marked by the presence of supernumerary digits.Chromosome Deletion: Actual loss of portion of a chromosome.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Aortic Arch Syndromes: Conditions resulting from abnormalities in the arteries branching from the ASCENDING AORTA, the curved portion of the aorta. These syndromes are results of occlusion or abnormal blood flow to the head-neck or arm region leading to neurological defects and weakness in an arm. These syndromes are associated with vascular malformations; ATHEROSCLEROSIS; TRAUMA; and blood clots.Klinefelter Syndrome: A form of male HYPOGONADISM, characterized by the presence of an extra X CHROMOSOME, small TESTES, seminiferous tubule dysgenesis, elevated levels of GONADOTROPINS, low serum TESTOSTERONE, underdeveloped secondary sex characteristics, and male infertility (INFERTILITY, MALE). Patients tend to have long legs and a slim, tall stature. GYNECOMASTIA is present in many of the patients. The classic form has the karyotype 47,XXY. Several karyotype variants include 48,XXYY; 48,XXXY; 49,XXXXY, and mosaic patterns ( 46,XY/47,XXY; 47,XXY/48,XXXY, etc.).Skin Abnormalities: Congenital structural abnormalities of the skin.