PIWIL2 and male infertility: Five of these genes were characterized as male infertility‐related genes, including Polo‐like kinase 4 (PLK4), AGTPBP1, KISS1 receptor, Meiosis Expressed Gene 1 (MEIG1), and Piwi Like RNA‐Mediated Gene Silencing 2 (PIWIL2) (Figure 1).