GNRH1 and Kallmann syndrome: Kallmann syndrome (KS) is a type of idiopathic hypogonadotropic hypogonadism (IHH) characterized primarily by a deficiency or dysfunction in the secretion or action of gonadotropin-releasing hormone (GnRH), leading to gonadal insufficiency accompanied by hyposmia or anosmia, as well as other nonreproductive system manifestations.[1] The overall incidence rate of KS is extremely low, with the lowest estimated incidence of 1 in 48,000 (1 in 30,000 for males vs 1 in 125,000 for females).[2] KS is a rare genetic disorder characterized by significant genetic and clinical heterogeneity.