An analysis on the genetic profile of 1.2 million people has found 13 new DNA regions whose variations are associated with dyslexia.
The wider study so far on the genetics of dyslexia has revealed new details on the biological mechanisms behind this condition. The research of the University of Edinburgh (Scotland) and the Max Planck Institute for Psycholinguistics (Netherlands), recently published in the scientific journal Translational psychiatrystrengthens the idea that dyslexia, rather than a medical condition in its own right, represents the lower tail of an entire spectrum of reading skills, which naturally vary in the population.
Dyslexia: what it is
Dyslexia is part of the specific learning disorders (DSA), a family of different methods of operation of the innate and non -transitional brain, which accompany throughout their lives. It manifests itself with a difficulty in the flowing and accurate reading of a text, which is often reflected in a difficulty of its understanding, and becomes more evident with the beginning of the school path.
Dyslexia has a strong genetic component, and the new study has tried to better understand which genetic variants are connected to its presence, how predictive they are actually predictive of the disorder manifestation and if they are in some way been selected by evolution.
Unpublished regions
Scientists have conducted what in technical terms are called a genome-wide association study (genome-wide association study, or Gwas), an investigation of everyone, or almost all of the genes of different individuals to understand which are associated with a specific condition. They took into consideration the data of two databases – the Genlang Consortium’s Study On Reading Skill and the 23ndme Study on Dyslexia – Until you get to consider 1.2 million people: the largest champion ever considered, which served to point a “magnifying glass” on the genetic bases of dyslexia.
It was thus possible to identify 80 DNA regions linked to dyslexia, of which 36 of new importance and 13 completely unknown to science, that is, without previous associations with dyslexia. Within these new regions there are many genes involved in the initial phase of neural development in the embryonic period.
Some significant variants for dyslexia are also for ADHD, a condition that often accompanies dyslexia. Correlations have also been found between dyslexia and chronic pain (i.e. a pain that persists beyond normal healing times), whose prevalence is higher in those suffering from neurosviluppo disorders, although the reasons are not yet clear.
No apparent evolutionary advantage
From the analysis it does not appear that the genetic factors that influence dyslexia have been subject to recent evolutionary pressures – that is, they would not seem to have been favored by the evolution of recent human history (for example in the transition from the hunter -racketors’ companies to the first European agricultural societies).
Genetics is not all
Finally, the authors tried to understand if the combined effects of the different genetic variants involved could, together, predict the difficulties in reading in groups of individuals. These effects, gathered in a single index, have been able to predict only between 2.3% and 4.7% of the variance in reading skills: it means that in addition to the identified factors, there may be other genetic bases still to be found that influence the difficulties in reading, but also that education, environment and support systems can do a lot.
