Novel mutations in ubiquitin-specific protease 26 gene might cause spermatogenesis impairment and male infertility

Aim: To study the incidence of single nucleotide polymorphisms in ubiquitin-specific protease 26 (USP26) gene and its involvement in idiopathic male infertility in China. Methods: Routine semen analysis was performed. Infertility factors such as immunological, infectious and biochemical disorders were examined to select patients with idiopathic infertility. DNA was isolated from peripheral blood of the selected patients and control population, which were examined for mutations using polymerase chain reaction-single strand conformation polymorphism analysis. Furthermore, nucleotide sequences were sequenced in some patients and controls. Results: Of 41 infertile men, 9 (22.0%, P = 0.01) had changes in USP26 gene on the X chromosome. A compound mutation (364insACA; 460G → A) was detected in 8 patients (19.5%, P = 0.01) and a 1044T → A substitution was found in 1 patient (2.4%, P > 0.05). All three variations led to changes in the coding amino acids. Two substitutions predict some changes: 460G → A changes a valine into an isoleucine, and 1044T → A substitutes a leucine for a phenylalanine. Another insertion of three nucleotides ACA causes an insertion of threonine. No other changes were found in the remaining patients and fertile controls. Conclusion: The USP26 gene might be of importance in male reproduction. Mutations in this gene might be associated with male infertility, and might negatively affect testicular function. Further research on this issue is in progress.