GNRH1 and hypogonadotropic hypogonadism: Loss‐of‐function mutations in the GnRH1 receptor and deficiency of GnRH I (GNRH1, P01148) are associated with hypogonadotropic hypogonadism although some 'loss of function' mutations may actually prevent trafficking of 'functional' GnRH1 receptors to the cell surface, as evidenced by recovery of function by nonpeptide antagonists [1124].