Congenital hypogonadotropic hypogonadism (CHH) is caused by deficient production, secretion or action of gonadotropin-releasing hormone (GnRH).
CHH is characterized by incomplete or absent puberty and infertility in the setting of isolated hypogonadotropic hypogonadism (that is, otherwise normal anterior pituitary function).
CHH can present solely as congenital GnRH deficiency or be associated with other developmental anomalies such as cleft lip or palate, dental agenesis, ear anomalies, congenital hearing impairment, renal agenesis, bimanual synkinesis or skeletal anomalies.
When associated with anosmia (lack of sense of smell) or hyposmia, CHH is termed Kallmann syndrome. Source