Ubiquitin-Specific Protease 26 (USP26), which belongs to the ubiquitination-specific processing protease family, is a deubiquitinating enzyme with histidine (His) and cysteine (Cys) structural domains. the USP26 gene is specifically expressed in testicular tissue as well as in the blood-testis barrier, and premeiotic spermatogonia during spermatogenesis The gene is expressed in the spermatogonia before meiosis during spermatogenesis, including primitive A-, Ap- and B-type spermatogonia. The main diseases associated with USP26 are male infertility, including weak teratozoospermia, non-obstructive azoospermia (NOA), Sertoli cell-only syndrome (SCOS), and Klinefelter syndrome (KS). Homozygous Usp26 KO mice are viable.