In our group, 2.6% (3/113) of 21-OHD patients carried a CYP21A2 gene downstream of TNXA, and three haplotypes were identified, including a well-known haplotype and two novel haplotypes that have never been described. The gene discussed is TNXA; the disease is classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency.