Identification of a common molecular basis for combined 17?-hydroxylase/17,20-lyase deficiency in two Mennonite families

Abstract
During the course of studies to characterize mutations of the CYP17 gene that cause the 17α-hydroxylase-deficient form of congenital adrenal hyperplasia we have discovered two ostensibly unrelated Mennonite families in which affected individuals are homozygous for the same mutation. The defect is a four-base duplication in exon 8 of the CYP17 gene, which alters the reading frame encoding the C-terminal 26 animo acids of cytochrome P45017α.