The molecular basis and genotype–phenotype correlations of congenital adrenal hyperplasia (CAH) in Anatolian population

Congenital adrenal hyperplasia (CAH) is an autosomal recessive genetic disorder due to presence of mutations in the genes involved in the metabolism of steroid hormones in adrenal gland. There are two main forms of CAH, classic form and non-classic form. While classic form stands for the severe form, the non-classic form stands for the moderate and more frequent form of CAH. The enzyme deficiencies such as 21-hydroxylase, 11-beta-hydroxylase, 3-beta-hydroxysteroid dehydrogenase, 17-alpha-hydroxylase deficiencies are associated with CAH. In this study, we aimed to investigate CYP21A2 , CYP11B1 , HSD3B2 genes which are associated with 21-hydroxylase, 11-beta-hydroxylase and 3-beta-hydroxysteroid dehydrogenase enzyme deficiencies, respectively, in 365 individuals by using Sanger sequencing method. We emphasized the classification of variants according their disease causing potential, and evaluated variants’ frequencies including newly discovered novel variants. As a result, 32 variants of CYP21A2 including 10 novel variants, 9 variants of CYP11B1 including 3 novel variants and 6 variants of HSD3B2 including 4 novel variants were identified. The conclusions of our study showed that in Anatolia, discovery of novel variants is quite common on account of tremendous ratios of consanguineous marriages which increases the frequency of CAH. These results will contribute to the understanding of molecular pathology of the disease.