Male infertility due to multiple morphological abnormalities of the sperm flagella (MMAF) is a genetically heterogeneous disorder. Previous studies revealed several MMAF-associated genes, which account for approximately 60% of human MMAF cases. The pathogenic mechanisms of MMAF remain to be illuminated. In this study, we identified biallelic mutations of the CFAP65 gene in the MMAF cases from different human populations. We also generated a gene knock-out mouse model for Cfap65, and the male mutated mice demonstrated the same phenotypes with human MMAF. Our findings confirm that CFAP65 biallelic mutations induce sperm motility impairment and primary male infertility. (By Prof. Feng Zhang, https://jmg.bmj.com/content/early/2019/09/09/jmedgenet-2019-106344 )