Remarkably, NDNF mutants were discovered in the genomes of several probands with congenital hypogonadotropic hypogonadism (CHH), a rare genetic disorder that is characterized by absence of puberty, infertility, and anosmia (loss of smell) (Boehm et al., 2015; Lima Amato et al., 2017). Here, NDNF is linked to Kallmann syndrome.