Alterations in DNA methylation patterns and gene expression in spermatozoa of subfertile males.

This study was designed to evaluate the DNA methylation patterns and gene expression in spermatozoa from subfertile males. Thirty samples were subjected to 450K arrays as a screening study to evaluate the variation in sperm DNA methylation levels between cases and controls groups, and then three CpG sites (cg07227024, cg05813498 and cg23081194) have the highest difference in methylation levels and located within ALS2CR12, GAA and UBE2G2 genes respectively; these were selected for further analysis using deep bisulphite sequencing and qPCR in 136 samples (64 proven fertile males "controls" and 72 subfertile males "cases"). A significant difference in the methylation level was found between cases and controls at two CpGs, six CpGs and three CpGs in ALS2CR12, GAA and UBE2G2 gene-related amplicon respectively. Besides, the qPCR results showed a significant change in the expression levels of GAA, UBE2G2 and ALS2CR12 gene in cases compared to the controls (p ≤ .00001). In conclusion, the methylation levels at CpGs in GAA, UBE2G2 and ALS2CR12 gene amplicons were significantly different in subfertile compared to proven fertile males. In addition, a significantly different was showed in the expression levels of GAA, UBE2G2 and ALS2CR12 genes in subfertile males compared to proven fertile males.