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

Background: 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. Methods: 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. Results: 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. Conclusions: 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. (C) 2010 Published by Elsevier B.V.