Andereggen et al defined hypogonadism as “normal-low levels of gonadotropins in parallel with low estradiol levels,” and Kabootari et al defined central hypogonadism as “amenorrhea for >3 months in women, and sexual dysfunction in men with low levels of gonadal hormones and normal to low levels of LH and FSH” (39). Here, PLOD1 is linked to hypogonadism.