Kallmann syndrome

Kallmann syndrome is a very rare hereditary disease. It is a disease that results from a deficiency of gonadatropin-releasing hormone (GnRH) from the hypothalamus and that is associated with anosmia (loss of the sense of smell). Without the anosmia, the condition is called idiopathic hypogonadatropic hypogonadism.

The GnRH deficiency stems from a congenital defect in neurons on the hypothalamus that lead to a deficiency of GnRH. These hormones direct sexual development. Men with the condition often have small sex organs; undescended testes, which is a condition called chryptorchidism: and lack of secondary sex characteristics such as facial hair and lower male voice. Women may not have a monthly menstrual period and may have little or no breast development.

This is a rare disorder with an estimated male prevalence varying from 1 in 10, 000 to 1 in 86, 000, according to different studies. Some of the genes involved in the pathogenesis of this syndrome have been identified, the most important one being the KAL 1 gene. When mutant, this gene leads to gonadotropin-releasing hormone deficiency and anosmia due to abnormalities of neuronal migration.
Kallmann syndrome