"This discovery proves once and for all that dyslexia is hereditary," said Professor John Stein of the Oxford University Laboratory of Physiology. He now hopes the new findings will convince the Government and local education authorities to provide more resources to help dyslexics. The results, produced by Prof Stein and Professor Tony Monaco of the Wellcome Trust Centre for Human Genetics, Oxford, have been revealed at a time when schools are trying to reach a series of tough targets for improving literacy.
The research was carried out by studying DNA in blood samples from 90 families containing dyslexics. Researchers found the approximate site of genes for dyslexia and made their discovery by using a new technique to mark and track the genes.
The samples were taken from parents and children who both had the condition. Prof Stein, who is the brother of the television chef Rick Stein, found three common genes that were associated with dyslexia in most of these families. The Oxford research confirms an earlier American study which produced similar findings but was unable to establish such a close link. However, the new findings are being treated with scepticism in some medical quarters, where it is argued that dyslexia only exists in the middle-class imagination.
The section of chromosome that the Oxford researchers believe is linked to dyslexic problems is close to the genes that control immunity. This suggests there may be something unusual with the mother or child's immune response and that there is a susceptibility to attacks from antibodies, which could be a cause of dyslexia. Prof Stein hopes the findings will help to lift the stigma faced by dyslexia sufferers. ''A lot of dyslexics are very badly treated, yet we know that with early intervention many of their problems can be prevented,'' he said.
Some 5 to 10 per cent of children show dyslexic problems, and Prof Stein says the condition is a prime cause of childhood depression. He believes strongly that many dyslexics are being neglected. He says some education authorities only recognise the condition when there is a three- year delay in reading - sometimes when children are 10 or 12 - and it is then too late to catch up.
His research also suggests exciting possibilities for establishing an early test for dyslexic problems, focusing on research into a system of nerve cells in the brain called magnocells. These cells react to the slight changes in light that children need to recognise print.
His research into dyslexic's responses to stimuli like light shows their magnocell systems function, less effectively than non-dyslexics. This problem may be caused by the faulty immunity gene as the system of magnocells in the brain is very susceptible to attack or damage.
Jonathan Solity, a lecturer in educational psychology at Warwick University's Institute of Education, was sceptical about the research. Learning to read was determined by many factors to do with teaching as well as inherited characteristics, he said.
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