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Mutated Gene May Be Key Cause of Dyslexia

October 29, 2005|Alex Raksin | Times Staff Writer

Researchers have identified a single gene alteration that may be a significant cause of dyslexia, a disorder that impairs the ability to comprehend written words.

Dr. Jeffrey R. Gruen, an associate professor of pediatrics at the Yale University School of Medicine, said an analysis of DNA from 153 families showed that a gene known as DCDC2 may be responsible for as much as 20% of dyslexia cases.

Researchers have associated DCDC2 with dyslexia since 1994, but Gruen said his research was the first to assign it such a key role.

Using neural imaging, Gruen's team found that a mutated version of the gene -- with a large deleted sequence -- disrupted the way the dyslexics' brains sent and received impulses from the retina to the visual cortex.

Speaking Friday at a meeting of the American Society of Human Genetics in Salt Lake City, Gruen said he altered the corresponding gene in rats and was able to disrupt the formation of the same brain circuits that impaired reading ability in humans.

Some dyslexia researchers questioned Gruen's conclusion that a single gene could play such a prominent role in a condition as complex as dyslexia, which afflicts as many as 10% of U.S. children.

Gruen acknowledged that many other genes were involved in dyslexia, but his statistical analysis showed strong evidence of DCDC2's central role.

Gruen said the finding could lead to genetic testing that would allow earlier diagnoses of dyslexia, which can be ameliorated through phonics training.

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