TNXB is mapped to the major histocompatibility complex on chromosome 6 (p21.33), with its last exon (exon 44) overlapping the 3’‐UTR of CYP21A2. Defects in CYP21A2 lead to congenital adrenal hyperplasia (CAH) due to 21‐hydroxylase deficiency (CAH, OMIM 201910), an autosomal recessive disorder of steroidogenesis affecting cortisol biosynthesis with a prevalence of 1:15,000 for the classic or severe form and 1:200–1000 for the nonclassic or mild form (Hannah‐Shmouni et al., 2017; Speiser et al., 2018). The gene discussed is CYP21A2; the disease is congenital adrenal hyperplasia.