CYP21A2 and congenital adrenal hyperplasia: Congenital adrenal hyperplasia (CAH) is a rare (1:10000–1:20000 in severe forms and 1:200–1:1000 in mild forms) [1, 2, 3] recessive genetic disease often requiring lifelong therapy and characterized by impaired cortisol production caused by, in approximately 95% of cases, CYP21A2 mutations leading to defects in the 21‐hydroxylase enzyme [4, 5] (Figure S1).