The FOXG1 gene encodes a transcription factor known as Forkhead Box G1. As the protein contains the distinct forkhead domain, it is a member of the forked-head transcription factor family and its specific function is to act as a transcriptional repressor. It is believed to play an important role in the development of the embryonic human brain, particularly in the telencephalon region which is responsible for multiple key structures including the cerebrum. This is done by regulating several processes such as neuron differentiation, mitotic cell cycle, neuroblast proliferation, axon midline choice point recognition and dorsal/ventral pattern formation.
Mutations in the FOXG1 gene are associated with Rett Syndrome, Congenital Variant. The disorder, also known as FOXG1 syndrome, is a severe, infantile-onset, neurodevelopmental condition characterized by brain abnormalities and impaired development.
The gene is located on the long arm of chromosome 14. It is just 9 kb long and is an intron-less gene. The protein encoded by this gene is 52 kDa in size and consists of 489 amino acids. The gene is overexpressed in both the fetal and adult brain. At least 11 mutations within the FOXG1 gene have been reported in people with FOXG1 syndrome. Most of these are transitions, transversions or deletions that result in premature truncation of the FOXG1 protein, although some cases are caused by a large deletion in the 14q12 region resulting in the loss of the FOXG1 gene as well as surrounding genes.