Cryptorchidism is evident in about 25% of infants with congenital GnRH or gonadotropin deficiency (either as isolated central hypogonadism, or in the context of combined pituitary hormone deficiencies) as compared to 1–3% of full-term infants in the general population (32). Here, GNRH1 is linked to hypogonadotropic hypogonadism.