Genetics may explain male learning difficulties

An international team of scientists has identified a set of nine genetic variations that are linked to mental retardation. And they are all in the X chromosome, which could go a long way toward explaining why boys are far more likely than girls to have learning disabilities.

The discovery is based on project in which almost all of the X chromosome genes were sequenced in 208 families with a history of learning disabilities. "This is the largest sequencing study of complex disease ever reported," Professor Mike Stratton said.

But the results come with a cautionary note. The researchers found that they could knock out one to two percent of the genes in the X chromosome without any biological consequences, which would raise serious doubts about the link between some of these mutations and learning difficulties. As the cost of whole genome sequencing drops to the $1,000 mark, researchers expect a flood of new genetic information to help transform medical research.  

- read the report in The Times