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FOXG1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

FOXG1 gene

The FOXG1 gene encodes a transcription factor essential for early brain development, particularly in the telencephalon, which gives rise to the cerebrum.

Normal Function

The FOXG1 gene provides instructions for making a protein known as forkhead box G1. This protein is a transcription factor, which means it helps regulate the activity of other genes. Specifically, the forkhead box G1 protein acts as a transcriptional repressor, turning off (repressing) the activity of certain genes when they are not needed.

Researchers believe that this protein plays an important role in brain development, particularly in a region of the embryonic brain known as the telencephalon. The telencephalon ultimately develops into several critical structures, including the largest part of the brain (the cerebrum), which controls most voluntary activity, language, sensory perception, learning, and memory.

Health Conditions Related to Genetic Changes

FOXG1 syndrome

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, but it is now usually considered to be distinct.

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, disrupting normal brain development starting before birth.

Lennox-Gastaut syndrome

MedlinePlus Genetics provides information about Lennox-Gastaut syndrome.

Other disorders

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
  • Severe speech impairment

Duplications of the FOXG1 gene have also been identified in several infants diagnosed with West syndrome. Researchers believe that the extra genetic material leads to these developmental problems by altering early brain development.

Other Names for This Gene

  • BF1
  • BF2
  • brain factor 1
  • brain factor 2
  • FHKL3
  • FKH2
  • forkhead box protein G1
  • FOXG1_HUMAN
  • FOXG1A
  • FOXG1B
  • FOXG1C
  • HBF-1
  • HBF-2
  • HBF-3
  • HBF-G2
  • HBF2
  • HFK1
  • HFK2
  • HFK3
  • KHL2
  • oncogene QIN
  • QIN

Frequently Asked Questions

Most FOXG1 mutations arise de novo, meaning they are new in the affected individual and not present in the parents. However, if a parent carries a germline mutation, the risk of recurrence in future pregnancies is about 50%. Genetic counseling and prenatal testing (e.g., chorionic villus sampling or amniocentesis) can determine whether a fetus has the mutation. For families with a known mutation, preimplantation genetic diagnosis (PGD) during in‑vitro fertilization is an option to avoid passing the mutation.
definitive diagnosis of FOXG1 syndrome is made by sequencing the FOXG1 gene to identify point mutations, small insertions or deletions, or by chromosomal microarray analysis to detect deletions that include FOXG1 on chromosome 14q. In some cases, a targeted panel for neurodevelopmental disorders that includes FOXG1 is used. The test results are interpreted by a clinical geneticist who correlates them with the patient’s clinical features.
Parents should watch for delayed or absent head control, poor or absent speech and language development, severe intellectual disability, and abnormal muscle tone (often a mix of hypotonia and hypertonia). Seizures, especially infantile spasms or Lennox‑Gastaut‑type seizures, and distinctive facial features such as a small mouth or micrognathia can also be early clues. Early referral to a pediatric neurologist or developmental specialist is recommended if these signs are present.
Supportive care focuses on maximizing developmental potential and managing seizures. Early intervention programs that include physical, occupational, and speech therapy can improve motor and communication skills. Antiepileptic drugs tailored to the seizure type are used to control seizures; sometimes a combination of medications is needed. Regular monitoring by a neurologist, ophthalmologist, and developmental pediatrician helps address vision, hearing, and feeding issues that often accompany the syndrome. While there is no cure, these therapies can enhance quality of life and functional independence.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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