June 14, 2013
Unraveling The Mystery Of Dyslexia Through Genetic Research
April Flowers for redOrbit.com - Your Universe Online
Many students are not diagnosed with dyslexia and other learning disabilities until high school, making treatments less effective. A new study of the genetic origins of these conditions by the Yale School of Medicine could allow for earlier diagnoses and more successful interventions.
The research team, led by Jeffrey R. Gruen, MD, professor of pediatrics, genetics and investigative medicine at Yale, analyzed data from more than 10,000 children born in 1991-1992. The children were part of the Avon Longitudinal Study of Parents and Children (ALSPAC) conducted by investigators at the University of Bristol in the UK.
The ALSPAC data was used to unravel the genetic components of reading and verbal language. During this process, the team identified genetic variants that can predispose children to dyslexia and language impairment. Understanding this predisposition increases the likelihood of earlier diagnosis and more effective treatments.
The development of reading and verbal language skills is difficult with dyslexia and language impairment, which are both common learning disabilities. Both of these disabilities are known to have significant genetic components, but until now determining the root cause had been difficult.
Prior research by Gruen and his team revealed that dopamine-related genes ANKK1 and DRD2 are involved in language processing. Further studies showed prenatal exposure to nicotine has a strong negative effect on both reading and language processing, as well as identifying a gene called DCDC2 that is linked to dyslexia.
The current study looked deeper within the DCDC2 gene, attempting to pinpoint the specific parts of the gene responsible for dyslexia and language impairment. Within the DCDC2 gene, the team found that some variants of a gene regulator called READ1 (regulatory element associated with dyslexia1) are associated with problems in reading performance while other variants are strongly associated with problems in verbal language performance.
According to Gruen, these variants interact with a second dyslexia risk gene called KIAA0319. "When you have risk variants in both READ1 and KIAA0319, it can have a multiplier effect on measures of reading, language, and IQ," he said. "People who have these variants have a substantially increased likelihood of developing dyslexia or language impairment.
"These findings are helping us to identify the pathways for fluent reading, the components of those pathways; and how they interact," said Gruen. "We now hope to be able to offer a pre-symptomatic diagnostic panel, so we can identify children at risk before they get into trouble at school. Almost three-quarters of these children will be reading at grade level if they get early intervention, and we know that intervention can have a positive lasting effect."
The findings of this study were published in the American Journal of Human Genetics.