Genetics

Kallmann syndrome (KS) is a rare genetic disorder in humans that is defined by a delay/absence of signs of puberty along with an absent/impaired sense of smell. A closely related disorder, normosmic idiopathic hypogonadotropic hypogonadism (nIHH), refers to patients with pubertal failure but with a normal sense of smell.

Both KS and nIHH are due to an isolated deficiency of a key reproductive hormone called gonadotropin-releasing hormone (GnRH). KS and nIHH occurs in both sexes but males are more commonly diagnosed with this condition.