FOXG1

Changes involving the FOXG1 gene cause FOXG1 syndrome, a rare disorder characterized by impaired development and structural brain abnormalities. This condition was previously described as a congenital variant of Rett syndrome, which is a similar disorder of early development. However, doctors and researchers have identified some important differences between the two conditions, so now FOXG1 syndrome is usually considered to be distinct from Rett syndrome.

At least 11 mutations within the FOXG1 gene have been identified in people with FOXG1 syndrome. The condition can also result from a deletion of genetic material from a region of the long (q) arm of chromosome 14 that includes the FOXG1 gene and several neighboring genes. All of these genetic changes prevent the production of forkhead box G1 or impair the protein's function. A shortage of this protein disrupts normal brain development starting before birth, which appears to underlie the brain malformations and severe developmental problems characteristic of FOXG1 syndrome.

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A few people have been found to have an extra copy (duplication) of the part of chromosome 14 that contains the FOXG1 gene. These duplications are associated with recurrent seizures (epilepsy) starting in infancy, intellectual disability, and severe speech impairment. Duplications of the FOXG1 gene have also been identified in several infants diagnosed with West syndrome, a condition characterized by epilepsy that begins in infancy, severe to profound intellectual disability, and related brain abnormalities. Although the mechanism is unclear, researchers believe that the extra genetic material leads to these developmental problems by altering early brain development.