Mis-regulation and defects in these mechanisms such as in mice lacking components of the PIWI/piRNA pathway, including Piwi-like 1(Piwil1), Piwil2, Piwil4, Vasa, Dnmt3l, Hormad1, Prmt5 and others4–10 led to germ cell loss and infertility. This evidence concerns the gene PIWIL1 and Infertility.