Based on mutational screening-phenotype analysis we hypothesize that USP26 plays a critical role in the regulation of early stages of maturation including mitotic divisions of spermatogonia or migration of primordial germ cells, as mutations in USP26 occur in patients with Sertoli cell only syndrome and early maturation arrest[10], [12]. Here, USP26 is linked to Sertoli Cell-Only Syndrome.