The team from the University of Washington, headed by medical geneticists Dr. Wendy Raskind and Ellen Wijsman and developmental psychologist Virginia Berninger, cautioned that the new findings do not mean that scientists have found "the gene" responsible for dyslexia.
"Just as with heart disease, no single gene will provide the answer to what causes dyslexia," said Raskind. "When you look at something that is inherited there could be multiple genes, perhaps as many as a hundred, that contribute to it. And when you look at any characteristic of a person, you must consider the environmental background. There are other factors besides genes that could modify a behavior."
The study, published in the March issue of the journal Molecular Psychiatry, is noteworthy for two reasons. First, it points to a new location containing genes that contribute to dyslexia. Second, the gene or genes at that location are involved in speed of decoding changing written words into spoken words without clues to their meaning a basic and persistent component of dyslexia.
Building on previous findings by the UW team on familial patterns of accuracy and rates of decoding, the research also provides the first evidence identifying separate genetic influences on these abilities.
"In other published and in-press research we have shown that accuracy of decoding may be a bridge to reading at one stage of learning to read and rate of decoding may be a bridge at a later stage. Effective instructional techniques for each bridge are not necessarily the same and typically require more than teaching as usual," said Berninger, who heads the UW's Learning Disabilities Center.