Karsch-Neugebauer syndrome in two sibs with unaffected parents.

We report on 2 sisters with Karsch-Neugebauer syndrome comprising split foot and split hand anomalies in association with congenital nystagmus. These sisters share a nearly identical phenotype with the 8 previously reported instances of this disorder. Although genetic heterogeneity can not be formally excluded, most evidence suggests that Karsch-Neugebauer syndrome is an autosomal dominant disorder. If so, then this report of 2 affected sibs born to healthy parents is the second instance of apparent gonadal mosaicism in this disorder. The apparent high frequency of gonadal mosaicism is important to recognize in counseling families with this disorder.