Impaired development and function of GnRH neurons leads to isolated hypogonadotropic hypogonadism (IHH), characterized by delayed/absent puberty and/or infertility. IHH frequently associated with additional phenotypes, such as sensorineural deafness, coloboma, synkinesis, craniofacial abnormalities, and renal agenesis. In this report, we found DUSP6, an inhibitor of FGFR1, mutated in IHH in an autosomal dominant manner. IHH patients with loss-of-function DUSP6 mutations are enriched for additional skeletal phenotypes, cryptorchidism and blue color blindness. We this further added the association of IHH with limb malformation to a new clinical entity for DUSP6. However, one allelic mutation in other two FGFR 1 inhibitors, IL17RD or SPRY4, alone seemed not sufficient to cause IHH. (By Meichao Men, https://jmg.bmj.com/content/early/2020/05/10/jmedgenet-2019-106786 )