Association between ubiquitin-specific protease USP26 polymorphism and male infertility in Chinese men

Increased sperm ubiquitin was inversely associated with sperm count and motility. Ubiquitin-specific protease 26 (USP26), which is an X-linked gene, has been studied as a potential infertility gene. There are conflicting reports on whether variations in USP26 are associated with spermatogenesis.

In order to assess that USP26 polymorphisms contribute to male infertility, we screened 221 infertile men with azoospermia, oligozoospermia, asthenozoospermia, or oligoasthenozoospermia, and 101 control fertile men using DNA sequencing.

There were six polymorphisms identified, including an unreported variation (508G>A, G170R). Only the allele frequency of 576G>A was significantly higher in fertile men than infertile patients (p<0.001), although this variant does not result in an amino acid change. The major haplotypes in fertile and infertile men were TGATC (76.2% vs 47.5% of the population, p<0.001) and TGGTC (14.9% vs 39.4%, p<0.001). The haplotype TGATC was under-transmitted, whereas the haplotype TGGTC was over-transmitted in infertile men with asthenozoospermia and oligoasthenozoospermia.

Our results indicated the variation of USP26 was not directly associated with human sperm count but suggested it might be a potential role in sperm motility. The 576G>A synonymous single nucleotide polymorphism (SNP) might have a role in improving the sperm motility.