KAL1 gene

The KAL1 gene is a human gene which is located on the X chromosome at Xp22.3 and is affected in some individuals with Kallmann syndrome. This gene codes for a protein named anosmin-1, which is responsible for migration of certain nerve cell precursors during embryogenesis. Deletion or mutation of this gene results in loss of the functional protein and affects the proper development of the olfactory system. In addition, neural cells which produce GnRH fail to incorporate into the hypothalamus.

Clinically, mutation results in the X-linked form of Kallmann syndrome. Individuals with Kallmann syndrome experience anosmia (lack of smell) and do not go through puberty (hypothalamic hypogonadotropic hypogonadism).

The KAL1 gene is made of 14 exons and spans 120-200 kilobases. Mutation in the gene is responsible for 14% of the cases of familial Kallmann syndrome and 11% of cases of sporadic cases.