Close genetic linkage between HLA and congenital adrenal hyperplasia (21-hydroxylase deficiency).

Congenital adrenal hyperplasia (C.A.H.) with 21-hydroxylase deficiency is an autosomal recessive disease. HLA genotyping of parents and children in six families in which more than 1 child had C.A.H. established that the gene responsible for 21-hydroxylase deficiency is closely linked to HLA. One patient had inherited a maternal HLA-A/B recombinant haplotype and studies in this family indicated that the abnormal gene is close to the HLA-B locus. The findings provide a method for identification of C.A.H. carriers and for prenatal diagnosis of affected children.