Fifty percent of patients with non−classic or late onset form of CAH have HLA B14, DR1 in association, since this is coded nearby on the short arm of chromosome 6 and specific mutations in exon 1 or exon 7 CYP21A2 (V281L; P453S) (131). The gene discussed is CYP21A2; the disease is congenital adrenal hyperplasia.