The data provide essential new information toward understanding the complex interactions required for normal development and function of the mammalian eye. The results also underscore the importance of confirming neural crest and mesoderm fates in a model mammalian system. The complementary systems used in this study should be useful for studying the respective cell fates in other organ systems.

Amniotic band sequence (ABS) is a well‐described condition involving a variety of congenital anomalies in association with fibrous bands. However, many cases are associated with birth defects that are not readily explained by the mechanism of fibrous strings entangling body parts and causing disruption of the fetal structures. The most common of these is typical cleft lip and palate (CLP). Here we describe such a case, with typical ABS limb defects and constriction bands, along with CLP, supernumerary left nipple, polydactyly, and a skin papilla. This case is nearly identical to a child previously described by Guion‐Almieda and Richieri‐Costa [2000] and may, therefore, represent a previously unrecognized syndrome that overlaps with ABS. Furthermore it may be that cases with ABS‐like anomalies associated with CLP represent a different condition, possibly caused by mutations in the genes Disorganization, p63, or IRF6. © 2005 Wiley‐Liss, Inc.

Purpose: To ascertain the frequency of chromosomal and other anomalies in fetuses with single umbilical artery.Methods: Placentas with single umbilical artery were identified from hospital pathology laboratory records. For each identified case, the next consecutive placenta with two umbilical arteries served as a control. Pathology records, maternal histories, and prenatal ultrasounds when available were reviewed for congenital anomalies, pregnancy complications, and maternal characteristics. When indicated, placental specimens, amniocytes, or neonatal bloods were karyotyped. Results: Single umbilical artery existed in 2.0% (97/4846) of pathological specimens.Fetuses with single umbilical artery had significantly more chromosomal (10.3% vs. 1.0%) and other congenital anomalies (27% vs. 8%). Conclusions: The high incidence of major chromosomal and congenital anomalies justifies detailed fetal ultrasonography, echocardiography, and amniocentesis for karyotype when single umbilical artery is discovered during routine ultrasound. Genet Med 2004:6(1):54 -57. Key Words: single umbilical artery, chromosome anomalies, detailed ultrasound, karyotype, fetal echocardiographyThe umbilical cord forms between 13 and 38 days after conception and normally serves as the conduit for two umbilical arteries and one umbilical vein. 1,2 In some cases only a single umbilical artery (SUA) is present. Some report that this umbilical abnormality can be observed as early as 13 weeks. However, it is typically diagnosed in the third trimester. 1,3 There are three theories to explain how a SUA may form during development. 1,4 The first is that a primary agenesis of one umbilical artery results in a SUA. Another theory attributes the phenomenon to a secondary atrophy or atresia of a previously normal umbilical artery. A third theory describes a persistence of the original allantoic artery of the body stalk as an explanation for SUA. Embryological considerations, as well as the detection of occluded remnants of a second umbilical artery in some SUA fetuses, suggest that the second theory is the most likely explanation. 1,4,5 In a review of eight studies of SUA in the literature, Persutte and Hobbins 1 reported an incidence of SUA in 1.5% in spontaneous abortuses, 7% of pregnancies that were terminated because of a serious malformation, 0.2% to 1.6% of euploid fetuses who underwent prenatal ultrasound examination, 9% to 11% of aneuploid fetuses, and 0.5% to 2.5% of uncomplicated neonates. The reported incidence of SUA varies depending on the method used to identify its occurrence, being highest in abortuses and autopsies and relatively low on ultrasound and in term neonates. 1,6 -8 Although there has been no evidence supporting any genetic etiology or familial tendency of this condition, it is known that SUA occurs more frequently in twin births (4.6%) versus singletons (1%). 4,9 The risk for congenital anomalies in infants with SUA also depends on the method of ascertainment, being highest at autopsy, but cases diagnosed at ultrasound or at t...

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