FOXG1 Explained

What is FOXG1 Syndrome?

  • FOXG1 Syndrome is a neurological disorder caused by a mutation in the FOXG1 gene. FOXG1 encodes the Forkhead box G1 protein.
  • FOXG1 was formerly named Brain Factor 1 due to being the first and most fundamental gene formed during human development. 
  • FOXG1 is a transcription factor gene – it transcodes data to tell our brain how to grow cells and contributes to development of the telencephalon (an embryonic structure that gives rise to the cerebrum).
  • Cerebrum is the most important part of the brain – it controls cognition (walking, talking, thinking).
  • The following pathogenic variants have been observed in FOXG1 patients: deletions, duplications, missense, truncation and frameshift variants.

When a child’s FOXG1 Gene is missing, spelled wrong, or duplicated…


…it changes how their FOXG1 Protein works, and that impacts brain development.

FOXG1 Protein tells our brain what to do.

Why FOXG1 is an excellent candidate for biotech investment: 

  1.  FOXG1 Syndrome is caused by just one singular gene - FOXG1.
  2. FOXG1 is a straightforward, single exome gene. It's biological mechanisms are less complex than multi-exome genes.
  3. The size of the FOXG1 gene is ideal for gene therapies. It is reasonable and short enough to be packed into most virovectors used for gene therapy.
  4. We know which cells to target with gene therapies - brain cells. Other CNS disorders are caused by genes that are expressed in many cells in the body, which makes gene therapy more complex.
  5.  FOXG1 is one of the most critical genes in brain development - a cure for FOXG1 mutations can help cure many other disorders. 

These reasons make FOXG1 an easier, less-risky gene for biotechnology companies to test therapies and experiment on. Success can be more easily attained than when working with many other genes. And a fix to FOXG1 could have broad impact on a plethora of other conditions. 

FOXG1 is linked to Major Brain disorders

Research shows FOXG1 plays a role in Autism,  Alzheimer's, Schizophrenia, and Epilepsy.

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This article led by scientist Dr Flora Vaccarino at Yale University showcases FOXG1 plays a critical role in the development of autism spectrum disorders (ASD).

  • ASD affects 1 out of 68 children in the United States alone
  • FOXG1 could be a viable drug target for ASD as lowering FOXG1 expression has shown to reverse ASD symptoms
  • Patients with greater head size, and more severe ASD symptoms, had greater expression of FOXG1

FOXG1 Phenotypes – Human Symptoms


Microcephaly and Structural Brain Abnormalities

  • Small head size with partial or full loss of the corpus callosum (inhibiting communication of left and right brain)

Physical Disability

  • Low muscle tone leads to inability to sit, walk, talk or use hands purposefully
  • Strabismus, poor eye contact, and cortical visual impairment

Associated Conditions & Disorders

  • Autism Spectrum Disorders (ASD)
  • Sensory Processing Disorder (SPD)
  • Movement disorders


  • Infantile spasms and life-threatening seizures resistant to drug and surgical treatments

Feeding Issues

  • Low muscle tone leads to reflux, constipation
  • Most patients require feeding tube placement