For examples, deficiency in the Wnt signaling, including in Wnt4, Wnt5a, and Wnt7a, will result in severe malformation of the genitals and infertility [30]–[32], whereas hyperactivation of the Wnt/β-catenin pathway can also lead to germ cell apoptosis and male infertility [33], [34]. Here, WNT4 is linked to male infertility.