TACR3 and congenital hypogonadotropic hypogonadism: In the last two years, loss-of-function mutations in TAC3 (MIM 162330) and TACR3 (MIM 162332), the genes encoding neurokinin B (NKB) and its receptor NK3R, respectively, have been described in patients with non syndromic normosmic congenital hypogonadotropic hypogonadism (nCHH) (OMIM #146110), pointing to a fundamental role of this pathway in the physiology of the human gonadotrope axis [1]–[5].