Analysis of the CYP21A2 gene pathogenic variants in CAH patients from Surgut using next-generation sequencing (NGS)

21-hydroxylase deficiency is present in 90–95% of cases of congenital adrenal hyperplasia (CAH). Eleven major pathogenic variants account for 93% of all identified variants in the CYP21A2 gene in various clinical forms of the disease. Each population has its own range of significant pathogenic variants. We aimed to study the frequency of pathogenic variants in the CYP21A2 gene using NGS technology and real-time PCR in Surgut patients with different clinical forms of CAH. NGS was performed on 70 patients with salt-wasting and non-classical clinical forms of 21-hydroxylase deficiency, verified by direct Sanger sequencing and PCR–RFLP analysis. Eleven different pathogenic variants were found in 68.57% (48/70) of patients. Among 92.86% (13/14) of patients with salt-wasting CAH, variants were found to be homozygous, with CYP21A2 gene deletion as the most frequent mutation (46.4% or 13/28 alleles). In the group with non-classical CAH, pathogenic variants were identified only in 60.71% (34/56) of patients. V282L was discovered to be the most common variant in heterozygous carriers (45.45%, 15/33). NGS method identified 2 variants that were not determined by the standard method for major mutations detection: p.C170* and p.W22X, accounting for 3% of all known pathogenic variants. Our data make it possible to clarify the specific spectrum of CYP21A2 gene pathogenic variants in CAH patients from Surgut. The NGS method allows for the identification of rare pathogenic variants (3%) in the CYP21A2 gene that are not included in the conventional PCR–RFLP analysis.