Alterations in a gene involved in 'wiring up' the brain may cause up to 20 per cent of dyslexia cases, say US researchers. The team, based at Yale School of Medicine in Connecticut, say that mutations in the DCDC2 gene could cause the common language disorder. The scientists published their findings early online in the Proceedings of the National Academy of Sciences, and also presented the research at the annual meeting of the American Society of Human Genetics (ASHG), held in Salt Lake City last week.
Dyslexia, which affects between 3-10 per cent of the population, is characterised by difficulty in recognising and reading words. Scientists think that a number of different genes and environmental factors combine to cause the disorder.
In the latest study, the researchers looked at 153 families affected by dyslexia. They found that some of those with the condition had inherited an altered version of DCDC2, a gene switched on in the brain's 'reading centres', where it controls the way in which cells are connected up in the developing brain. 'This very architecture of the brain circuitry is necessary for normal reading', said team leader Jeffrey Gruen.
Earlier this year, researchers based at the University of Cardiff linked dyslexia to another gene that could be involved in the movement of brain cells during development, called KIAA0319. And at the ASHG conference, a Swedish group presented evidence that a gene called ROBO1 is involved in the condition. The ROBO1 gene is responsible for forming connections between the two hemispheres of the developing brain. When the gene is less active, there are fewer connections in the area of the brain used for reading, say the researchers. 'You get the right signals going, but they do less well in terms of rapid processing', said team leader Juha Kere. The findings will be published in the journal PLoS Genetics.
The Yale scientists hope that their research will pave the way for better diagnosis and management of dyslexia, rather than a 'cure'. 'People with dyslexia are not less intelligent than others, they just learn in different ways', said Gruen. He called for an end to 'one-size-fits-all schooling', adding 'tailoring programmes to fit the needs of these children will enhance their success in school'.