FOXG1 syndrome is a condition characterized by impaired development and structural brain abnormalities. Affected infants are small at birth, and their heads grow more slowly than normal, leading to an unusually small head size (microcephaly
) by early childhood. The condition is associated with a particular pattern of brain malformations that includes a thin or underdeveloped connection between the right and left halves of the brain (a structure called the corpus callosum
), reduced folds and grooves (gyri) on the surface of the brain, and a smaller than usual amount of brain tissue known as white matter.
FOXG1 syndrome affects most aspects of development, and children with the condition typically have severe intellectual disability. Abnormal or involuntary movements, such as jerking movements of the arms and legs and repeated hand motions, are common, and most affected children do not learn to sit or walk without assistance. Babies and young children with FOXG1 syndrome often have feeding problems, sleep disturbances, seizures, irritability, and excessive crying. Affected individuals may have autism spectrum disorder, which is characterized by limited communication and social interaction, including poor eye contact and a near absence of speech and language skills.
FOXG1 syndrome was previously described as a congenital variant of Rett syndrome, which is a similar disorder of brain development. Both disorders are characterized by impaired development, intellectual disability, and problems with communication and language. However, Rett syndrome is diagnosed almost exclusively in females, while FOXG1 syndrome affects both males and females. Rett syndrome also involves a period of apparently normal early development that does not occur in FOXG1 syndrome. Because of these differences, physicians and researchers now usually consider FOXG1 syndrome to be distinct from Rett syndrome.
Frequency
More than 100 cases of this rare condition have been reported.
Causes
As its name suggests, FOXG1 syndrome is caused by changes involving the FOXG1 gene. This gene provides instructions for making a protein called forkhead box G1. This protein plays an important role in brain development before birth, particularly in a region of the embryonic brain known as the telencephalon. The telencephalon ultimately develops into several critical structures, including the the largest part of the brain (the cerebrum), which controls most voluntary activity, language, sensory perception, learning, and memory.
In some cases, FOXG1 syndrome is caused by mutations within the FOXG1 gene itself. In others, the condition results from a deletion of genetic material from a region of the long (q) arm of chromosome 14 that includes the FOXG1 gene. All of these genetic changes prevent the production of forkhead box G1 or impair the protein's function. A shortage of functional forkhead box G1 disrupts normal brain development starting before birth, which appears to underlie the structural brain abnormalities and severe developmental problems characteristic of FOXG1 syndrome.
Inheritance
FOXG1 syndrome is considered an autosomal dominant condition, which means one copy of the altered gene in each cell is sufficient to cause the disorder. All reported cases have resulted from new mutations or deletions involving the FOXG1 gene and have occurred in people with no history of the disorder in their family. Because the condition is so severe, no one with FOXG1 syndrome has been known to have children.
Other Names for This Condition
- FOXG1-related disorder
Additional Information & Resources
Genetic Testing Information
Genetic and Rare Diseases Information Center
Patient Support and Advocacy Resources
Clinical Trials
Catalog of Genes and Diseases from OMIM
Scientific Articles on PubMed
References
- De Filippis R, Pancrazi L, Bjorgo K, Rosseto A, Kleefstra T, Grillo E, Panighini A, Cardarelli F, Meloni I, Ariani F, Mencarelli MA, Hayek J, Renieri A, Costa M, Mari F. Expanding the phenotype associated with FOXG1 mutations and in vivo FoxG1 chromatin-binding dynamics. Clin Genet. 2012 Oct;82(4):395-403. doi: 10.1111/j.1399-0004.2011.01810.x. Epub 2011 Dec 13. Citation on PubMed
- Florian C, Bahi-Buisson N, Bienvenu T. FOXG1-Related Disorders: From Clinical Description to Molecular Genetics. Mol Syndromol. 2012 Apr;2(3-5):153-163. doi: 10.1159/000327329. Epub 2011 Apr 29. Citation on PubMed or Free article on PubMed Central
- Hou PS, hAilin DO, Vogel T, Hanashima C. Transcription and Beyond: Delineating FOXG1 Function in Cortical Development and Disorders. Front Cell Neurosci. 2020 Feb 25;14:35. doi: 10.3389/fncel.2020.00035. eCollection 2020. Citation on PubMed
- Kortum F, Das S, Flindt M, Morris-Rosendahl DJ, Stefanova I, Goldstein A, Horn D, Klopocki E, Kluger G, Martin P, Rauch A, Roumer A, Saitta S, Walsh LE, Wieczorek D, Uyanik G, Kutsche K, Dobyns WB. The core FOXG1 syndrome phenotype consists of postnatal microcephaly, severe mental retardation, absent language, dyskinesia, and corpus callosum hypogenesis. J Med Genet. 2011 Jun;48(6):396-406. doi: 10.1136/jmg.2010.087528. Epub 2011 Mar 25. Citation on PubMed
- Van der Aa N, Van den Bergh M, Ponomarenko N, Verstraete L, Ceulemans B, Storm K. Analysis of FOXG1 Is Highly Recommended in Male and Female Patients with Rett Syndrome. Mol Syndromol. 2011 Sep;1(6):290-293. doi: 10.1159/000330755. Epub 2011 Aug 9. Citation on PubMed or Free article on PubMed Central
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