The INDIVIDUALIST

A Wiki about biochemical individuality

Linguistics

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Description

  • Official Symbol: FOXP2
  • Chromosome: 7; Location: 7q31
  • Name: forkhead box P2
  • Gene type: protein coding
  • Organism: Homo sapiens
  • Gene aliases: SPCH1; CAGH44; TNRC10; DKFZp686H1726

Summary

FOXP2 ("forkhead box P2") is a gene that is implicated in the development of language skills, including grammatical competence. Contents

Phenotype

There are several reasons for believing that the linguistic impairments associated with a mutation of the FOXP2 gene are not simply the result of a fundamental deficit in motor control. For example:

  • the impairments include difficulties in comprehension;
  • brain imaging of affected individuals indicates functional abnormalities in language-related cortical regions, demonstrating that the problems extend beyond the motor system.

The search for the gene

The search for the gene was initially started as a result of the investigations into the KE (or K) family. Certain members of this family suffered from an inherited speech and language disorder and living members stretched back three generations. Closer inspection of the family revealed the disorder to be autosomal dominant.

A scan was performed of the genome of the affected and some of the unaffected family members, this initial scan limited the affected region to a spot on chromosome 7 which the team called SPCH1. Sequencing of this region was done with the aid of bacterial artificial chromosome clones. At this point another individual was located who had a similar disorder but was unrelated to the family, the genome of this individual was mapped and it was discovered that there was a break in chromosome 7.

Further investigation discovered a point mutation in this chromosome, which was sequenced and analysed and is now referred to as the FOXP2 gene.

Evolution

Although FOXP2 exists in many animals, the modern human form of FOXP2 appears to have evolved in Homo sapiens some time in the last 200,000 years. This has provided some support for speculation about a link between the evolution of the modern human form of FOXP2 with the advent of modern human creativity and language.

This gene encodes an evolutionarily conserved transcription factor expressed in fetal and adult brain. This transcription factor is a member of the forkhead/winged-helix (FOX) family of transcription factors, and contains a FOX DNA-binding domain and a large polyglutamine tract. Members of the FOX family of transcription factors are regulators of embryogenesis. The product of this gene is thought to be required for proper development of speech and language regions of the brain during embryogenesis. Although a point mutation in this gene has been associated with the KE pedigree segregating developmental verbal dyspraxia, no association between mutations in this gene and another speech disorder, autism, has been found. Four alternative transcripts encoding three different isoforms have been identified.

Discussion

  • Human FOXP2 contains changes in amino-acid coding and a pattern of nucleotide polymorphism, which strongly suggest that this gene has been the target of selection during recent human evolution. Pubmed
  • FOXP2 codes for a CNS transcriptional repressor, expressed in the basal ganglia, cortex, cerebellum & the thalamus, involved in thalamic-cortical-striatal circuits for motor planning & learning. Its loss causes specific language impairment. Pubmed
  • Genetic factors for regulation of common language impairment appear to reside in the vicinity of FOXP2. Pubmed
  • FOXP2/foxp2 is expressed in several structures in developing human/mouse brain including cortical plate, basal ganglia, thalamus, inferior olives and cerebellum. These data suggest a conserved mammalian role in development of motor-related neural circuits. Pubmed
  • Truncation of FOXP2 is the cause of developmental speech and language deficits. Pubmed

Links

Attribution

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