Impact of the Y-chromosome gene on SOX9 stem cell expression in non-obstructive azoospermic cases
Sex differentiation in males is a highly complex phenomenon based on synergistic interactions between genes and their coded proteins. The Sox9 gene plays a critical role in embryonic development, cell lineages, and stem cell maintenance during testicular development. Sox9 gene expression is associated with sex reversal, with a 46, XX karyotype in males and regulating normal functioning of Sertoli cells during spermatogenesis. Clinically diagnosed infertile males (n = 40) with non-obstructive azoospermia (NOA) with respective controls (n = 38) were included in the study. Blood samples were collected and after isolation of genomic DNA, the expression of the Sox9 gene (DNA copy number variations) was measured by fluorescence based quantitative PCR, deletion of AZFc locus determined by STS markers, karyotype analysis and SRY using GTG banding and FISH techniques, respectively. Cytogenetics findings revealed that more that 40% of cases had mosaicism with 46, XY/47, XYY karyotypes and a high frequency of deletion of AZFc (>70%) regions as compared to AZFb (>20%) using STS markers in the cases of NOA. The mean relative fluorescence values of Sox9 gene expression differed significantly between cases (0.32) and controls (0.87) (P < 0.001) with a confidence interval at 95% of 0.0310 - 0.787 in the cases of NOA. SRY + ve cases had higher Rfv of Sox9 gene expression when compared to SRY- ve cases. There was a positive correlation between stem cell Sox9 gene expression, mosaicism and AZFc region affecting a non-disjunction event during spermatogenesis and fertility.