Non-Classical Congenital Adrenal Hyperplasia-Causing Alleles in Adolescent Girls with PCOS and in Risk Group for PCOS Development

CYP21A2 Intron 2 Genetic Variants Might Be Associated with the Clinical Characteristics of Women with PCOS

AIMS

Pathogenic variants in the CYP21A2 gene are related to the classic and non-classic forms of congenital adrenal hyperplasia (CAH). However, the role of CAH carrier status in the clinical presentation of polycystic ovarian syndrome (PCOS) is still unclear. Moreover, the possible associations of different CYP21A2 gene polymorphisms with metabolic and reproductive abnormalities in PCOS have not been investigated. Therefore, the present study aims to examine the prevalence of the most common CYP21A2 pathogenic variant IVS2-13A/C>G (c.293-13A/C>G) in Eastern European women with PCOS and to evaluate the associations between common intron 2 genetic polymorphisms and the clinical symptoms of the patients.

METHODS

Sixty consecutively recruited women with PCOS were genotyped for the CYP21A2 intron 2 IVS2-13A/C>G genetic variant. Additionally, CYP21A2 intron 2 polymorphic variants rs6453 (c.293-44G>T), rs6451 (c.293-67C>A/G), rs369651496 (c.293-104del), and rs6474 (c.308G>A/p.R103L) were tested and described. The clinical and hormonal characteristics were compared in women with PCOS and with polymorphic and wild-type genotypes.

RESULTS

The heterozygous CYP21A2 pathogenic variant IVS2-13A/C>G was found in one of the investigated PCOS patients (1.67%) with a non-hyperandrogenic type of PCOS. The presence of the rs6453 (c.293-44G>T) T-allele was associated with increased levels of DHEAS (15.18 vs. 9.14 µmol/L, p = 0.003) compared to the wild-type genotype in the investigated group. The rs6451 (c.293-67C>A/G) minor alleles were associated with an earlier age of menarche in the patients (12.0 vs. 13.0 years, p = 0.007). The polymorphic rs369651496 minor 6G allele was related to a better lipid profile in the women with PCOS, while the rs6474 variant modulated the blood pressure of the patients.

CONCLUSIONS

The presence of CYP21A2 genetic minor alleles of rs6467 (IVS2-13A/C, c.293-13A/C), rs6453 (c.293-44G>T), rs6451 (c.293-67C>A/G), rs369651496 (c.293-104del), and rs6474 (c.308G>A/p.R103L) might modulate the adrenal androgens, age of menarche, and metabolic features in women with PCOS. Further studies on 21-hydroxylase genetic variants (pathogenic and polymorphisms) in different ethnic groups might help reveal the influence of adrenal steroidogenesis on PCOS development, clinical manifestations, and lifelong cardiovascular risks.

Characterization of Mutations Causing CYP21A2 Deficiency in Brazilian and Portuguese Populations

Deficiency of 21-hydroxylase enzyme (CYP21A2) represents 90% of cases in congenital adrenal hyperplasia (CAH), an autosomal recessive disease caused by defects in cortisol biosynthesis. Computational prediction and functional studies are often the only way to classify variants to understand the links to disease-causing effects. Here we investigated the pathogenicity of uncharacterized variants in the CYP21A2 gene reported in Brazilian and Portuguese populations. Physicochemical alterations, residue conservation, and effect on protein structure were accessed by computational analysis. The enzymatic performance was obtained by functional assay with the wild-type and mutant CYP21A2 proteins expressed in HEK293 cells. Computational analysis showed that p.W202R, p.E352V, and p.R484L have severely impaired the protein structure, while p.P35L, p.L199P, and p.P433L have moderate effects. The p.W202R, p.E352V, p.P433L, and p.R484L variants showed residual 21OH activity consistent with the simple virilizing phenotype. The p.P35L and p.L199P variants showed partial 21OH efficiency associated with the non-classical phenotype. Additionally, p.W202R, p.E352V, and p.R484L also modified the protein expression level. We have determined how the selected CYP21A2 gene mutations affect the 21OH activity through structural and activity alteration contributing to the future diagnosis and management of CYP21A2 deficiency.