University of Oxford researchers discovered that a gene implicated in autism may also play a role in a common childhood language disorder. Their study appears in Wednesday's online issue of the New England Journal of Medicine.

Specific language impairment, as the disorder is known, affects an estimated 2-7 percent of pre-school children, and is as common as dyslexia, University of Oxford geneticist and Wellcome Trust researcher Simon Fisher, who led the study, said. The disorder consists of unexplained difficulties in producing and understanding language, often revolving around delayed vocabulary and grammar skills in healthy, intelligent children.

Fisher and his colleagues reported that children from 184 families who had variants of the CNTNAP2 gene showed reduced language abilities like those found in specific language impairment, such as repetition and nonsense words.

“This is the first time anyone has pinpointed a specific gene that is involved in common forms of language impairments,” Fisher said.

To identify variants of CNTNAP2 gene, the researchers looked for genes that are switched on and off in the brain by a different gene called FOXP2. Mutations of this gene also appear to play a role in rare cases of severe speech and language disorder.

An earlier study had shown that the same gene (CNTNAP2) hinders language ability in autistic children.

“Autistic children often have deficits in nonsense-word repetition, a finding consistent with a role of CNTNAP2 in nonsense-word repetition. Perhaps CNTNAP2 will be implicated in other clinical populations with disorders involving nonsense-word repetition,” Karin Stromswold, M.D., Ph.D., of Rutgers University in New Brunswick, N.J. said in accompanying study. She added that the findings were a bold step forward in the search for the genetic underpinnings of language impairment.