Dyslexia: New gene identified11/16/2020
Genetic influences play a key role in the development of dyslexia. An international team of scientists has now identified another gene that is involved in this process.
Dyslexia, or reading and spelling disorder, is one of the most common specific learning disorders in childhood and adolescence. Between four and twelve percent of an age group are affected. This means that there are around 3.5 million dyslexics in Germany alone. Despite this large number, very little is still known about dyslexia in many areas of society. Even in schools, affected children are often labelled as stupid or lazy and their actual abilities are not recognised. The fact that dyslexia manifests itself in different ways in different people probably also contributes to this perception. While some pupils struggle with spelling, others may find it more challenging to read.
Lack of knowledge with severe consequences
In fact, dyslexics are not more stupid than other students. The normal distribution of intelligence is the same for both dyslexic and non-dyslexic pupils, meaning that there are less gifted, normally gifted and highly gifted children with dyslexia. They all "only" have the handicap of having major problems in learning the two cultural techniques of reading and writing. However, the lack of knowledge about dyslexia has other drawbacks: Affected children often suffer from exclusion and stigmatisation and about 40 percent of them develop a mental health disorder. Their lifetime prognosis is good if schools compensate for the disorder, dyslexic pupils get support from their school and family or participate in therapeutic interventions.
"Molecular genetic studies have long shown that genetic influences undoubtedly play an important role in the development of dyslexia," says Professor Tiemo Grimm. "If one child in a family suffers from dyslexia, there is a 40 percent likelihood that siblings or one or both parents are affected, too". Grimm is a human geneticist and, until his retirement, did research at the Institute of Human Genetics at the Biocenter of the University of Würzburg (JMU). Even now he continues to research the causes of dyslexia – for an obvious reason: Grimm is dyslexic himself; other members of his family are also affected.
A gene at work in the brain
To date, over 20 different genes or gene loci are known to play a role in the development of dyslexia. Scientists from the JMU and the University Hospital of Würzburg have now added one more entry to this list together with scientists from research institutions in Germany and the USA. They identified a new gene locus on chromosome 4q28A in a well-documented family with dyslexia over four generations. "In the affected members of this family, a specific nucleotide variant was found in a sequence of the SPRY1 gene, a gene that is expressed in the brain," says Grimm. This sequence change could affect the expression of the SPRY1 gene product.
However, this research finding does not have any direct consequences or leads to treatment options for dyslexia. It is "fundamental research," explains the human geneticist. After all, the discovery provides one more piece of the puzzle to get an overall picture of the processes taking place in the brain. "Dyslexia develops in close connection with the biological maturation of the central nervous system. The special features of auditory and visual information processing and probably also of the temporal processes in the central nervous system play a role," says Grimm.
This has a consequence: About 60 to 80 percent of children with dyslexia have a weakness in what is known as "phonological awareness" – which refers to the ability to recognise and use phonetic features of written language, for example the ability to distinguish the sound "u" from the sound "o". On the other hand, a minority of children with dyslexia are affected by difficulties in visual information processing. Usually, they are not able to combine individual letter characters, such as C - a - r to form the word "car" when they try to read it with their eyes only.
“A Novel Locus and Candidate Gene for Familial Developmental Dyslexia on Chromosome 4q”, Tiemo Grimm, Masoud Garshasbi, Lucia Puettmann, Wei Chen, Reinhard Ullmann, Bertram Müller-Myhsok, Eva Klopocki, Lina Herbst, Janina Haug, Lars R. Jensen, Christine Fischer, Markus Nöthen, Kerstin Ludwig, Andreas Warnke, Jürg Ott, Gerd Schulte-Körne, Hans-Hilger Ropers, and Andreas W. Kuss. Zeitschrift für Kinder- und Jugendpsychiatrie und Psychotherapie (2020), 48, pp. 478-489. https://doi.org/10.1024/1422-4917/a000758.
Prof. Dr. Tiemo Grimm, University of Würzburg, firstname.lastname@example.org