Loss-of-function mutations in KISS1/Kiss1 or the kisspeptin receptor (GPR54/Gpr54) genes causes infertility due to lack of pubertal development and hypogonadotropic hypogonadism in humans and mice [92, 96, 195, 297, 323]. The gene discussed is KISS1R; the disease is hypogonadotropic hypogonadism.