CRISPR/Cas9-mediated genome editing identifies six testis-expressed genes individually dispensable for overt male fecundity in mice.

The genetic landscape of male infertility is highly complex. It is estimated that at least 1000-2000 genes are involved in human and mouse infertility. Although functional analyses have been performed on hundreds of genes, many others still have unknown functions. Generating gene-editing mice is a powerful tool for exploring whether a given gene is essential for male reproduction in vivo. In the current study, we investigated the function of six genes, Efcab7, Tekt3, Mlf1, Rp1l1, Agbl2, and Tmsb15a, using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Individual disruption of these six genes did not cause overt male sterility in mice under standard breeding conditions. Phenotypic analyses at 8-10 weeks of age generally showed that most reproductive parameters were comparable to those of wild-type controls; however, we observed significant sperm motility alterations in Tekt3-mutant mice (decreased motility) and Rp1l1-mutant mice (increased motility), as well as flagellar abnormalities in Tekt3 mutants. In summary, these findings suggest that complete or near-complete disruption of the tested murine alleles does not cause overt male infertility, providing useful functional evidence for interpretation of candidate variants while not excluding human-specific or allele-specific effects.