Hypogonadotropic hypogonadism, also known as secondary hypogonadism, is the most common form of hypogonadism in adult and elderly man [1], related to an absolute or relative defective secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus and/or gonadotropin secretion by the pituitary gland. This evidence concerns the gene GNRH1 and hypogonadotropic hypogonadism.