Researchers have identified nine new genes on the X-chromosome that, when mutated, are associated with learning disabilities. "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," explained Professor Michael Stratton, from the Wellcome Trust Sanger Institute. "This is the largest sequencing study of complex disease ever reported." Learning disability is significantly more common in males than in females, and genetic causes have long been sought on the X-chromosome as 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. These new findings are expected to aid the diagnoses of X-linked learning disabilities and to enable more comprehensive genetic counseling. [Press release] [Nature Genetics abstract]Login Or Register To Read Full Story