A previous report showed that disruption of the H3K4 methyltransferase gene Prdm9 (also known as Meisetz) in mice results in infertility in both sexes due to severe impairment of the double-strand break (DSB) repair pathway12, suggesting that maintenance of appropriate H3K4 methylation levels is important for genome integrity in germ cells. This evidence concerns the gene PRDM9 and Infertility.