FG syndrome is a genetic condition that affects many parts of the body and occurs almost exclusively in males. "FG" represents the surname initials of the first family diagnosed with the disorder.

Researchers have identified changes in five regions of the X chromosome that are linked to FG syndrome in affected families. Mutations in a gene called MED12, which is located in one of these regions, appear to be the most common cause of the disorder. Researchers are investigating genes in other regions of the X chromosome that may also be associated with FG syndrome.

The prevalence of FG syndrome is unknown, although several hundred cases have been reported worldwide. Researchers suspect that FG syndrome may be overdiagnosed because many of its signs and symptoms are also seen with other disorders.

FG syndrome is inherited in an X-linked recessive pattern. The genes likely associated with this disorder, including MED12, are 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 usually must occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of a gene on the X chromosome, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Published Date: December 01, 2012
Published By: National Institutes of Health