Mutational spectrum of the gene for 21-hydroxylase in the patients with congenital adrenal hyperplasia from Bashkortostan

Molecular genetic analysis of congenital adrenal hyperplasia (CAH) was carried out in 59 patients from the Republic of Baskortostan, which belonged to two main groups. The first group was represented by 35 patients with salt wasting form of the disease, and the second group was comprised of 24 patients with simple virilizing form. Analysis of the CYP21A2 gene in the patients with congenital adrenal hyperplasia from the Republic of Bashkortostan revealed seven different mutations on 81.58% chromosomes, including deletion/conversion delA2 or LGC gene, R356W, I2splice, I172N, Q318X, V281L, and P30L. The mutations were present on 89.71% of chromosomes from the patients with salt wasting form, and in 69.5% of chromosomes from the patients with simple virilizing form. The most frequent mutation was gene deletion/conversion, delA2 or LGC, which was found with the frequency of 30.83%. In six CAH patients the presence of three different mutation clusters on one chromosome was demonstrated: Q318X + R356W, I172N + Q318X, and delA2 or LGC + V281L. For the mutations leading to partial loss of 21-hydroxylase activity and simple virilizing form, 100% conformity of the phenotype to genotype was established.