LONDON (Reuters) - A gene linked to autism may also play a role in the most common childhood language disorder, researchers said on Wednesday, perhaps explaining why some children develop language difficulties.
"This is the first time anyone has pinpointed a specific gene that is involved in common forms of language impairments," University of Oxford geneticist and Wellcome Trust researcher Simon Fisher, who led the study, said in a telephone interview.
The condition known as specific language impairment affects an estimated 2-7 percent of pre-school children and is as common as dyslexia, Fisher said.
The starting point for the study was a different gene called FOXP2 that regulates other genes and appears to play a role in a severe but rare form of speech and language disorder.
The researchers began identifying genes that are switched on and off by FOXP2, and homed in on one called CNTNAP2 they predicted was the best candidate to help explain the common language disorder.
Tests on children from 184 families showed children who carried certain changes in the gene had reduced language abilities characteristic of the common disorder, Fisher said.
"We tested that gene and showed a significant association," he added in a telephone interview. "What we have found is these variants seem to reduce language ability."
An earlier study had shown that the same gene hinders language ability in autistic children, and the new findings bolster the idea that many genetic factors are at play in autism, Fisher said.
"This supports the emerging view that autism involves the convergence of a number of distinct problems underpinned by different genetic effects," he said.
The British researchers, whose study was published in the New England Journal of Medicine, said they do not know exactly how changes to the gene interfere with language development.
But one possibility may be that changes in CNTNAP2 somehow interferes with production of a type of protein called a neurexin that is important to the fetal development of the nervous system and eventual language ability, he added.
(Reporting by Michael Kahn, Editing by Louise Ireland and Maggie Fox)