Abnormalities in the hypothalamic- pituitary- gonadal axis (hypogonadotropic hypogonadism).2 Patients with TM have lower basal FSH and LH secretion, low LH/FSH response to GnRH (gonadotropin releasing hormone) and low sex steroid secretion from the gonads (testosterone). The gene discussed is PLOD1; the disease is hypogonadotropic hypogonadism.