Congenital adrenal hyperplasia in paediatric age: molecular analysis of the CYP21A2 gene and implications for genetic counselling

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 is classified as classic salt-wasting(SW) and simple virilising(SV) forms, and nonclassic(NC) form of the disease. SW and SV are usually diagnosed after birth or during the first years of life, respectively, while most cases of NC-CAH are diagnosed during infancy, puberty or until adult age. Here we present the molecular results performed in paediatric patients with CAH.