The largest genetic study conducted so far provides new perspectives on the causes of dyslexia
Research of the human brain. Photo: Everythingpossible | Dreamstime.com
Dyslexia is a neurological development disorder that affects the ability to read and write correctly and is present in about 5-10% of the world's population, regardless of the level of education or the cultural environment. People with dyslexia have persistent difficulties in the recognition and spelling of words, which can affect their school performance and professional life. A recent study, conducted by researchers at the University of Edinburgh, Max Planck Institute for psycholinguistics and other international research centers, analyzed genetic data of over 1.2 million people, being the largest research of this type so far.
The study, published in the Translational Psychiatry magazine, identified 80 DNA areas associated with dyslexia, of which 36 have not been reported before. Of these, 13 are completely new, without any previous connection with this disorder, writes news.ro.
The research combined two major genetic data sets: one in the Genlang Consortium, which includes detailed reading skills, and another provided by the 23andme company, which included over 50,000 people diagnosed with dyslexia.
By an advanced method called MTAG (simultaneous analysis of several genetic factors), the team managed to identify more genetic variants than it would have been possible by a separate analysis of each data set.
The results have shown that many of the genes associated with dyslexia are active in the brain areas that develop in the first years of life, being involved in the formation of synapses – the connections through which neurons communicate with each other. The researchers also created a polygenic index (genetic score) that estimates the risk of a person to develop reading difficulties.
In an independent group of children, this index explained up to 4.7% of the variation of reading performance, a result considered modest, but important for an eventual identification of the risk of dyslexia.
The study also analyzed ancient DNA, from human remains dated up to 15,000 years ago, to explore how these genes have evolved over time. The results did not show evidence of a recent evolutionary selection, which suggests that the frequency of these genes has remained stable in recent millennia, at least in Northern Europe.
This research makes a significant contribution to understanding the biological bases of dyslexia and opens new directions of study. The team intends to further research whether the genes associated with dyslexia overlap with those involved in disorders such as ADHD, language difficulties or other neurodevelopment conditions. In addition, researchers plan to improve genetic scores, including samples from more diverse populations and environmental factors, such as early education and family reading exposure.
Recent discoveries offer new perspectives on the genetic causes of dyslexia and could contribute, in the long term, to reducing the stigmatization of the affected persons, as well as to the development of personalized support methods for children with difficulty.
