SHT - Gene gives clue to human language capability

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Gene found to give clue to language

By Rick Weiss the Washington Post, 10/4/2001

Scientists have for the first time identified a gene that plays a crucial role in human language and speech. The finding sheds light on what scientists suspect is one of several inherited elements of language ability that, in combination with key social and environmental cues, have allowed the human species to talk, gab, gossip, and schmooze its way to global dominance.

The new work does not reveal the extent to which linguistic ability is ''hard-wired'' into the brain as opposed to learned. It also does not answer longstanding questions about animals' potential to learn grammar and syntax. Indeed, the study focuses entirely on a rare speech disorder known to affect only 16 people worldwide, 15 of them in a single family.

But scientists said the genetic information gleaned from the new work offers an exciting entree into an area of human behavior that until now has been largely inaccessible to DNA probing. If related genetic studies advance apace, they said, the molecular basis of language may in the next decade or so come largely into focus.

''It's the first gene ever implicated in a speech and language disorder, and it's an entry point for understanding the developmental process that culminates in speech and language,'' said Anthony Monaco, director of the Wellcome Trust Centre for Human Genetics at Oxford University and the lead researcher on the work, described in today's issue of the journal Nature.

Studies of the equivalent gene in animals, ranging from mice to chimpanzees, may someday help clarify why no animal has ever taken language to human heights, Monaco and others said.

Monaco and his colleagues studied a speech disorder that affects a large British family whose identity has been kept secret. The disorder is a kind of ''specific linguistic impairment,'' a catch-all phrase that includes many different conditions, each characterized by its own speech deficits.

Fifteen out of 31 family members spanning three generations inherited the condition, which makes them unable to learn certain rules of grammar and tense, interferes with their ability to break words into sounds, and blocks them from enunciating certain verbal patterns. For example, they can make the sound of the letter ''s'' if it occurs at the beginning of a word, as in ''Sam,'' but they can't make the ''s'' sound at the end of a word, as in ''girls.''

Complicating matters, the condition also has physical components: Affected individuals have abnormal motor control regions in their brains and have trouble coordinating muscles in their mouths and tongues. But the syndrome appears to be a true language processing defect, not a motor problem, since the speech deficits - such as the trouble with the letter ''s'' - are context-specific.

Monaco and his colleagues had found that the condition was linked to a stretch of chromosome 7, one of 46 chromosomes found in human cells. The new work - boosted by genetic studies on a newly identified, unrelated British boy who has the same syndrome - identified the precise gene on chromosome 7 that, when disrupted, causes the problem.

Of the approximately 2,500 molecular ''letters'' that together ''spell out'' that gene's code, the scientists found the one letter that is consistently written wrong in affected family members. They also showed that the gene, FOXP2, is spelled correctly in every healthy family member and in more than 150 unrelated volunteers.

-- Anonymous, October 04, 2001


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