The diagnosis of CAH is usually performed with a basal and/or dynamic evaluation of 17-OH progesterone (17OHP) in the early follicular phase: 17OHP concentration above 30 nmol/L is consistent with NCAH; however, a CYP21A2 genetic test should be performed to confirm the diagnosis and to exclude other causes of high levels of 17OHP, such as adrenal malignancies [40]. This evidence concerns the gene CYP21A2 and congenital adrenal hyperplasia.