7 out of 13 men had secondary hypogonadism (one was on finasteride and, therefore, was not evaluated), whilst 8 out of 12 women had either secondary hypogonadism or inappropriately low or normal gonadotrophin levels for a post-menopausal state (with LH more commonly involved than FSH). Here, PLOD1 is linked to hypogonadotropic hypogonadism.