Coarctation of the aorta in monozygotic twins.

The aetiology of coarctation of the aorta is still largely unexplained, and investigations on familial occurrence have given confficting results. -3 Only 10 reports of coarctation of the aorta in monozygotic twins have been published. The lesion has shown discordance1 4-9 in all but one'0 of the cases. In only three of these was there a concordant cardiovascular malformation: atrial septal defect,5 hypoplasia of the aortic arch,8 and Marfan's syndrome,9 together with coarctation of the aorta in one of the twins. In this communication we describe coarctation of the aorta in a monozygotic pair of twins: the second reported case with concordance, and the first case where coarctation was found alone in one of the twins and appeared with a vascular ring in the other.