Introduction: Congenital adrenal hyperplasia(CAH) is due to 21-hidroxilase deficiency(21-OHD) in about 95% of the cases. 21-OH is encoded by CYP21A2 gene, and most frequent mutations occurring in CYP21A2 are due to gene conversions originated from its pseudogene(CYP21A1P). The clinical severity of CAH is associated with the impairment of 21-OH activity, which is directly related with the molecular defect. CAH i...