DHCR7 genotypes of cousins with Smith-Lemli-Opitz syndrome

Abstract

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder of cholesterol biosynthesis caused by mutations of the 7-dehydrocholesterol reductase gene (DHCR7). We report on three cousins with SLOS, all of whom were found to be compound heterozygotes for the common splice site mutation IVS8-1G-→C and the missense mutation T289I. DNA analysis of one set of parents demonstrated that the father carried the missense mutation and the mother carried the IVS8-1G-→C mutation. By extension, the two unrelated mothers were both heterozygous for IVS8-1G-→C. This finding supports the notion of a high carrier frequency of the IVS8-1G-→C null mutation in Northern European Caucasians. © 2001 Wiley-Liss, Inc.