Inactivating mutations of the genes encoding for KP (KISS1) (Topaloglu et al., 2012) or its G-protein-coupled receptor (KISS1R; previously called GPR-54) (De Roux et al., 2003; Seminara et al., 2003) cause hypogonadotropic hypogonadism in humans. Here, KISS1R is linked to hypogonadotropic hypogonadism.