CYP21A2 and classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency: Molecular analysis of the CYP21A2 gene in patients with 21OHD, in North American and European populations, has shown that about 25% of these patients present macrodeletions of approximately 30 Kb, which include not only much of the 5′ region of the CYP21A2 gene, but also all of the C4B gene and 3′ region of the CYP21P gene, or CYP21A2 gene macroconversions in a similar way to CYP21P. The remaining 75% have gene microconversions or point mutations (PM) [5, 6].