hypogonadotropic hypogonadism 3 with or without anosmia
A disorder (OMIM:244200) characterised by absent or incomplete sexual maturation by age 18, low levels of circulating gonadotropins and testosterone and no other hypothalamic-pituitary axis defects, variably accompanied by extragenital/extragonadal defects–e.g., anosmia or hyposmia due to absence/hypoplasia of olfactory bulbs and tracts, cleft palate, and sensorineural hearing loss.
Hypogonadism is due to deficiency in gonadotropin-releasing hormone and probably results from a failure of embryonic migration of gonadotropin-releasing hormone-synthesising neurons. Idiopathic hypogonadotropic hypogonadism accompanied by anosmia is known as Kallmann syndrome; if the patient has a normal sense of smell, the condition is termed normosmic idiopathic hypogonadotropic hypogonadism.
Molecular pathology Defects of PROKR2, which encodes the G protein-coupled receptor for prokineticin 2, a protein that promotes angiogenesis, induces strong gastrointestinal smooth muscle contraction, mobilises calcium, stimulates phosphoinositide turnover and activates p44/p42 mitogen-activated protein kinase, cause hypogonadotropic hypogonadism 3 with or without anosmia.