CAGn Polymorphic Locus of Androgen Receptor (AR) Gene in Russian Infertile and Fertile Men

The androgen receptor (AR) is critical for mediating the effects of androgens. The polymorphic CAG<i>n</i> locus in exon 1 of the <i>AR</i> gene is associated with several diseases, including spinal and bulbar muscular atrophy (SBMA), prostate cancer, and male infertility. This study evaluated the CAG<i>n</i> locus in 9000 infertile Russian men and 286 fertile men (control group). The CAG<i>n</i> locus was analyzed using the amplified fragment length polymorphism method. In the infertile cohort, the number of CAG repeats ranged from 6 to 46, with a unimodal distribution. The number of CAG repeats in infertile and fertile men was 22.15 ± 0.93 and 22.02 ± 1.36, respectively. In infertile men, variants with 16 to 29 repeats were present in 97% of the alleles. A complete mutation (≥42 CAG repeats) was found in three patients, while three others had 39-41 repeats. The incidence of SBMA was 1:3000 infertile men. Significant differences (<i>p</i> < 0.05) were observed between infertile and fertile men in alleles with 21, 24 and 25 repeats. This study revealed certain differences in the CAG<i>n</i> polymorphic locus of the <i>AR</i> gene in Russian infertile and fertile men and determined the frequency of SBMA in infertile patients.