Organ asymmetries as correlates of other anomalies

Fetuses with deviations in the normal left versus right weight relationship s of the paired viscera were examined for correlation with particular malfo rmations, syndromes, or other common factors. Alterations of the normal pat tern were observed among cases with cytogenetic anomalies, diaphragmatic he rnia, renal duplication, dyshydramnios, and single umbilical artery. A reve rsal of the left versus right weight pattern was found in the adrenals of c ases with hepatic situs inversus but not in those with heterotaxic cardiac lesions. Recipient twins in the twin-twin transfusion syndrome had reduced left lung weights, presumably because of inhibition of lung growth by the e nlarged heart. The side of umbilical artery absence did not predict either the nature or complexity of associated malformations. However, it is sugges tive that there is discordance between the side of the missing artery and u nilateral renal abnormality and that there is preferential absence of the r ight or left artery, depending on the karyotype, (C) 2001 Wiley-Liss, Inc.