Kallmann syndrome is a condition characterized by delayed or absent puberty and an impaired sense of smell.

Changes in more than 20 genes have been associated with Kallmann syndrome. Among the most common causes of the condition are mutations in the ANOS1, CHD7, FGF8, FGFR1, PROK2, or PROKR2 gene. In some cases, affected individuals have mutations in more than one of these genes. Additionally, researchers have identified mutations in other genes that may contribute to the development and features of Kallmann syndrome, but are unlikely to cause the disease on their own.

Kallmann syndrome occurs more often in males than in females, with an estimated prevalence of 1 in 30,000 males and 1 in 120,000 females.

When Kallmann syndrome is caused by ANOS1 gene mutations, the condition has an X-linked recessive pattern of inheritance. The ANOS1 gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to be present in both copies of the gene to cause the disorder. No females with two ANOS1 gene mutations have been reported in the medical literature. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Published Date: December 01, 2016
Published By: National Institutes of Health