New Insights Into Molecular Basis Of Language Development Through Genetic Study

Scientists have identified the first gene that is associated with a common childhood language disorder, known as specific language impairment (SLI). The gene – CNTNAP2 – has also been recently implicated in autism, and could represent a crucial genetic link between the two disorders.

"It has long been suspected that inherited factors play an important role in childhood language disorders," says Dr Simon Fisher, a Royal Society Research Fellow at the Wellcome Trust Centre, who led the research. "But this is the first time that we have been able to implicate variants of a specific gene in common forms of language impairment."

The trail to this new finding began with studies of another language-related gene, called FOXP2, previously found to be mutated in rare cases of a severe speech and language disorder. Versions of FOXP2 are found in many animals, including primates, birds, bats and mice. In birds, for example, it has been linked to song, in mice to learning of sequences of movement, and in bats it may relate to echo-location.

FOXP2 acts to regulate other genes in the brain, switching them on and off. Dr Fisher and colleagues began analysing human neurons grown in the laboratory in order to search for these target genes. They identified CNTNAP2 as a key part of the network.

Recent studies have also implicated CNTNAP2 in autism, a syndrome characterised by communication deficits, impaired social interaction, and repetitive behaviours. In particular, one investigation uncovered an association between variants of CNTNAP2 and delayed language development in children with autism.

"Our findings suggest that similar changes in the regulation or function of this gene could be involved in language deficits in both SLI and autism," says Dr Fisher. "This supports the emerging view that autism involves the convergence of a number of distinct problems underpinned by different genetic effects."