for National Geographic Today
Researchers in England have identified the first gene to be linked to
language and speech, suggesting that our human urge to babble and chat
is innate, and that our linguistic abilities are at least partially
hardwired.
"It is important to realize that this is a
gene associated with language, not the gene," said Anthony
Monaco of the University of Oxford, England, who led the genetic
aspects of the study.
The gene is required during early embryonic development for formation of brain regions associated with speech and language.
The gene, called FOXP2, was identified through studies of a severe speech and language disorder that affects almost half the members of a large family, identified only as "KE." Individuals with the disorder are unable to select and produce the fine movements with the tongue and lips that are necessary to speak clearly.
"The most obvious feature is that they are unintelligible both to naive listeners and to other KE family members without the disorder," said neurologist Faraneh Vargha-Khadem of London's Institute for Child Health, who studied the family. The members of the family also have dyslexic tendencies, difficulty processing sentences, and poor spelling and grammar.
FOXP2 is responsible for the rare disorder seen in the KE family that is a unique mixture of motor and language impediments, said Monaco.
But, Monaco cautioned, "FOXP2 is unlikely to be the cause of less severe language deficits that affect approximately 4 percent of schoolchildren. FOXP2 will not be the major gene involved in most of these cases."
Their findings are published in the October 4 issue of the journal Nature.
Using data from the KE family, researchers narrowed the location of the FOXP2 gene to a region of chromosome 7 that contained about 70 genes. Analyzing these genes one by one is a task that could easily have taken more than a year. But Monaco's team made a breakthrough when researcher Jane Hurst of Oxford Radcliffe Hospital identified a British boy, unrelated to the KE family, who had an almost identical language deficit.
The boy, known as "CS," had a visible defect in chromosome 7 that specifically affected the FOXP2 gene. "The defect was like a signpost, precisely highlighting the gene responsible for the speech disorder," said Monaco.
The FOXP2 gene produces a protein called a transcription factor, which attaches itself to other regions of DNA and switches genes on and off.
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