Millions of Americans have dyslexia, a language-based learning disability that makes reading and spelling more difficult. Studies have suggested that the condition runs in families, but no research had determined which genes are linked to it.
Now, in the largest genome-wide association study on dyslexia, scientists have pinpointed 42 genetic variants correlated with the disability. They published their findings last week in Nature Genetics.
“We can follow up the significant genes to see what their function is and how it might relate to the cognitive processes involved in reading and spelling,” lead researcher Michelle Luciano, a psychologist at the University of Edinburgh in Scotland, tells the Guardian’s Nicola Davis. “At the moment, there are no direct implications for people with dyslexia, although it helps them understand that the condition has very complex causes.”
The authors analyzed data from 51,800 adults with self-reported dyslexia and from more than one million adults without it. Most participants were of European origin, and all were involved in research with 23andMe, a DNA testing and ancestry service.
Of the genetic variations they found, 15 had previously been linked with thinking skills, academic achivement or other neurodevelopmental conditions such as language delay, per a statement from the Max Planck Institute for Psycholinguistics. But 27 were completely new; they had not been associated with any related cognitive trait.
These genes do not necessarily cause dyslexia, but they might make it more likely to crop up if combined with certain environmental factors, such as learning styles, Luciano tells New Scientist’s Christa Lesté-Lasserre.
“When people think of genetics, the first thing they might think is that it’s something that’s fixed, and we know that that’s simply not the case,” Luciano tells the publication. “Genes operate within environments, so the environment is really important to consider.”
The researchers also found a genetic overlap between self-reported ambidexterity and dyslexia—though not between left-handedness and dyslexia. And they found a “moderate genetic correlation” between dyslexia and ADHD, per the study.
Better understanding genes linked to dyslexia may help with expanding diagnostic tools and identifying people more prone to this and co-occurring disorders, write the authors in the paper. Diagnosing and treating dyslexia early may help kids become skilled readers more quickly and mitigate further learning difficulties.
“We welcome any insight into biological origins of dyslexia,” Helen Ross, a trustee of the British Dyslexia Association, tells the Guardian. “Any insight which will help us to identify people who may have dyslexia will be helpful in providing early intervention to bypass the potential of years of academic challenge and associated difficulties.”