Nine new genes leading to learning disabilities found

A collaboration between more than 70 researchers across the globe has uncovered nine new genes on the X chromosome that, when knocked-out, led to learning disabilities.

The international team studied almost all X chromosome genes in 208 families with learning disabilities - the largest screen of this type ever reported.

Remarkably, the team also found that approximately 1-2 per cent of X chromosome genes, when knocked-out, have no apparent effect on an individual's ability to function in the ordinary world.

The research - a culmination of five years of scientific collaboration - emphasises the power of sequencing approaches to identify novel genes of clinical importance, but also highlights the challenges researchers face when carrying out this kind of study.

Estimates suggest that the prevalence of learning disability is 2-3 per cent. Learning disability is significantly more common in males than in females and genetic causes have long been sought on the X chromosome: males have only one X chromosome and so a gene mutation on the X is more likely to have an effect in males than in females.  

"We sequenced 720 out of the approximately 800 known genes on the X chromosome in more than 200 families affected by X-linked learning disabilities," Professor Mike Stratton, from the Wellcome Trust Sanger Institute said.