Ans: B (CTEV) CONGENITAL ANOMALIES Robbins 7th/470-74# Congenital anomalies are morphologic defects that are present at birth, but some, such as cardiac defects and renal anomalies, may not become clinically apparent until years later.The term congenital does not imply or exclude a genetic basis for the birth defect. It is estimated that about 3% of newborns have a major anomaly, defined as an anomaly having either cosmetic or functional significance.Various kinds of errors in morphogenesis are--mal- formations, disruptions, deformations, sequences, and syndromes.MalformationsIt represents primary errors of morphogenesis, in other words there is an intrinsically abnormal developmental process.They are usually multifactorial rather than the result of a single gene or chromosomal defect.Some, such as congenital heart defects and anencephaiy (absence of brain), involve single body systems, whereas in other cases multiple malformations involving many organs may coexist.DisruptionsIt result from secondary destruction of an organ or body region that was previously normal in development; thus, in contrast to malformations, disruptions arise from an extrinsic disturbance in morphogenesis.Understandably, disruptions are not heritable and hence are not associated with risk of recurrence in subsequent pregnancies.Deformations Robbins 7th/472It like disruptions, also representan extrinsic disturbance of deve/opmentratherthananintrinsicerrorofmorphogenesis.Deformations are common problems, affecting approximately 2% of newborn infants to varying degrees. Fundamental to the pathogenesis of deformations is localized or generalized compression of the growing fetus by abnormal biomechanical forces, leading eventually to a variety of structural abnormalities.The most common underlying factor responsible for deformations is uterine constraint. Between the 35th and 38th weeks of gestation, rapid increase in the size of the fetus outpaces the growth of the uterus, and the relative amount of amniotic fluid (which normally acts as a cushion) also decreases. Thus, even the normal fetus is subjected to some form of uterine constraint.Several factors increase the likelihood of excessive compression of the fetus resulting in deformations. Maternal factors include first pregnancy, small uterus, malformed (bicornuate) uterus, and leiomyomas. Fetal or placental factors include oligohydramnios, multiple fetuses, and abnormal fetal presentation.An example of a deformation is clubfeet (CTEV), often a component of Potter sequenceSequenceIt is a pattern of cascade anomalies. Approximately half the time, congenital anomalies occur singly; in the remaining cases, multiple congenital anomalies are recognized.In some instances, the constellation of anomalies may be explained by a single, localized aberration in organogenesis (malformation, disruption, or deformation) leading to secondary effects in other organs.A good example of a sequence is the oligohydramnios (or Potter) sequenceSyndromeIt is a constellation of congenital anomalies, believed to be pathologically related, that, in contrast to a sequence, cannot be explained on the basis of a single, localized, initiating defect.Syndromes are most often caused by a single etiologic agent, such as a viral infection or specific chromosomal abnormalitv, which simultaneously affects several tissues.Fig. Malformations. Human malformations can range in severity from the incidental to the lethal. Polydactyly (one or more extra digits) and syndactyly (fusion of digits), both of which are illustrated in A, have little functional consequence when they occur in isolation. Similarly, cleft lip (B), with or without associated cleft palate, is compatible with life when it occurs as an isolated anomaly; in the present case, however, this child had an underlying malformation syndrome (trisomy 13) and expired because of severe cardiac defects. The stillbirth illustrated in C represents a severe and essentially lethal malformation, where the midface structures are fused or ill-formed; in a/most all cases, this degree of external dysmorphogenesis is associated with severe internaI anomalies such as maldevelopment of the brain and cardiac defects.