M1AP and Infertility: Arango et al. (2006) found that this gene is expressed at the beginning of meiosis in female germ cells and at the final stages of spermatogenesis in male germ cells. Therefore, they suggest that the evolutionarily well-conserved M1AP protein may have a role in gametogenesis. Furthermore, Arango et al. (2013) showed that M1AP-deficient male mice have severe oligozoospermia and infertility with many testicular defects. Therefore, they suggest that mutations in M1AP might be reason for nonobstructive oligozoospermia in men.