NR5A1 and cystic fibrosis: The pathogenic genes of male infertility fall into four categories: (1) homozygous mutations in genes that can cause cystic fibrosis and the absence of bilateral fallopian tubes [25, 26]; (2) genes associated with hypogonadism, such as NR5A1 or genes encoding steroidogenic factor [27, 28]; (3) genes encoding motor proteins, such as mutations in NAI1, DNAH5 and DNAH11 leading to dysfunction of sperm forward motor [29–31]; and (4) genes that regulate the endocrine function of auxiliary germ cells.