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Dyslexia is a neurodevelopmental condition that affects the reading and writing ability of one in ten children in the UK, often persisting into adulthood. Although the disorder was already thought to be genetic due to the prevalence of dyslexia being passed down through families, the actual genetic nature of the condition was not previously fully understood.
In October, a paper was published in Nature Genetics outlining the largest genetic study of dyslexia to date, carried out by Dr Michelle Luciano and her colleagues at the University of Edinburgh. The study identified 42 genes associated with the condition.
Developing our understanding of the genetic nature of dyslexia, such as how it passes from parent to child, could potentially be key in future diagnosis and early treatment of the condition.
The genome-wide association study was carried out on 1.1 million adults of European ancestry, consisting of people previously diagnosed with dyslexia as well as non-dyslexic people. Their genomes were scanned, and 42 variations associated with dyslexic traits were identified. Of these variants, 15 had previously been linked to cognitive ability, leaving 27 newly discovered associated variants. The more of these variants identified in one individual, the more likely they were to be dyslexic.
Some of the variants identified had also previously been linked to conditions such as attention deficit hyperactive disorder (ADHD), being ambidextrous, and having a lower pain tolerance. There was also a small overlap identified with lifestyle and psychiatric conditions.
As dyslexia is a complex condition influenced by many genes, the genetic variants involved may alter certain neurodevelopmental processes that could then be responsible for changes in the connections of multiple neurons. It therefore makes sense for there to be overlap between the genetic variants involved in multiple conditions. Studies such as the one carried out by Luciano and her colleagues help scientists not only better understand dyslexia, but a range of other potentially related conditions.
12 of the associated genetic variants found in the study were linked to reading and spelling in English and other European languages, with one even being associated with Chinese language.
This suggests that dyslexia is a common trait for cognitive processes involved in learning to read and although the study was carried out on a European cohort, it could have global relevance for diagnosis and treatment.
Importantly, the study found no genetic correlation between dyslexia and nonverbal performance IQ which backs up previous studies confirming that being dyslexic has no influence over general intelligence. This being said, dyslexia can severely impact a child’s academic performance if undiagnosed and often special learning support systems and techniques are required for a child to reach their full potential.
Early identification is key to ensure children get the required support, but relies on improved diagnostic capabilities.
Although more research is needed, the goal is to eventually identify individuals who may be predisposed to being dyslexic, allowing intervention before symptoms even develop.
