CAH due to 21-hydroxylase deficiency is associated with biallelic mutations in the CYP21A2 gene, at chromosome 6p21.33, a location which is in close proximity to the HLA B and HLA DR loci (3); Jayakrishnan et al showed an association between CYP21A2 (point mutation p.I172N), and the HLA-DQB1*03 allele which was mutated in our case (5). The gene discussed is CYP21A2; the disease is congenital adrenal hyperplasia.