KATNB 1 in the human testis and its genetic variants in fertile and oligoasthenoteratozoospermic infertile men

Summary Oligoasthenoteratozoospermia ( OAT ) is a phenotype frequently observed in infertile men, and is defined by low spermatozoa number, abnormal spermatozoa morphology and poor motility. We previously showed that a mutation in the Katnb1 gene in mice causes infertility because of OAT . The KATNB 1 gene encodes an accessory subunit of the katanin microtubule‐severing enzyme complex; this accessory subunit is thought to modulate microtubule‐severing location and activity. We hypothesized that KATNB 1 may play a role in human spermatogenesis and that genetic variants in KATNB 1 could be associated with OAT in humans. Using immunostaining, we defined the localization of the KATNB 1 protein in human testes. KATNB 1 was present during spermatid development, and in particular localized to the microtubules of the manchette, a structure required for sperm head shaping. To assess a potential association between genetic variants in the KATNB 1 gene and infertile men with OAT , we performed direct sequencing of genomic DNA samples from 100 OAT infertile and 100 proven fertile men. Thirty‐seven KATNB 1 variants were observed, five of which had not previously been described. Ten variants were present only in OAT men, however, statistical analysis did not reveal a significant association with fertility status. Our results suggest that variants in the KATNB 1 gene are not commonly associated with OAT infertility in Australian men.