is an inherited disorder characterized by delayed puberty and an impaired sense of smell. Other symptoms can include color blindness, cleft lip or palate, hearing loss, failure of the kidneys to develop, abnormal development of secondary sex characteristics (such as breast development or pubic hair), and infertility. This disorder is a form of hypogonadotropic hypogonadism. Affected males are usually born with a small penis and underdeveloped testes. Affected females usually do not begin menstruating at puberty and have little or no breast development. In some people, puberty is incomplete or delayed.
Four types of Kallmann syndrome have been identified, which are designated as types 1 through 4. The most common type is Kallmann syndrome 1, which is inherited in an X-linked recessive fashion. Autosomal recessive and autosomal dominant inheritance has been noted in the other types. Mutations in the KAL1 gene cause Kallmann syndrome 1 and Kallmann syndrome 2 results from mutations in the FGFR1 gene. Mutations in PROKR2 cause Kallmann syndrome 3 and mutations in the PROK2 gene cause Kallmann syndrome 4. Other genes associated with this syndrome include CHD7 and FGF8. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.