Is Dyslexia a Hereditary Genetic Condition?

Check out this answer from Consensus:

Substantial evidence supports the notion that dyslexia is a hereditary genetic condition. Multiple genetic loci and candidate genes have been identified, and heritability estimates indicate a significant genetic contribution. The overlap with other neurodevelopmental disorders further underscores the complex genetic landscape of dyslexia. Continued research in this field is essential for unraveling the full genetic architecture of dyslexia and developing targeted interventions.

Dyslexia, a specific learning disability characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities, affects a significant portion of the population. The question of whether dyslexia is a hereditary genetic condition has been the subject of extensive research. This article aims to explore the genetic underpinnings of dyslexia, examining the evidence that supports its hereditary nature.

Genetic Basis of Dyslexia

Research has consistently shown that dyslexia has a strong genetic component. Studies have identified numerous loci throughout the genome that are likely to harbor candidate dyslexia susceptibility genes. For instance, linkage studies have pinpointed regions such as 1p34–p36, 6p21–p22, 15q21, and 18q11 as significant1 2 7. These regions are believed to contain genes that influence neuronal migration, a process crucial for proper brain development and function.

Candidate Genes

Several candidate genes have been identified in these regions. Notable among them are DYX1C1 on chromosome 15, ROBO1 on chromosome 3, and KIAA0319 and DCDC2 on chromosome 67. These genes are involved in neuronal migration and other brain development processes, which are critical for reading and language skills. Functional studies of these genes have provided insights into the biological mechanisms underlying dyslexia7.

Heritability Estimates

Heritability estimates for dyslexia vary, but they generally indicate a substantial genetic contribution. Studies suggest that inherited factors can account for up to 80% of the variance in dyslexia2. Genome-wide association studies (GWAS) have further supported these findings, identifying specific genetic variants associated with dyslexia and estimating an SNP-based heritability of 20–25%8.

Comorbidity and Genetic Overlap

Dyslexia often co-occurs with other neurodevelopmental disorders such as attention-deficit hyperactivity disorder (ADHD), and there is evidence of shared genetic etiology between these conditions. For example, polygenic risk score (PRS) analyses have revealed significant genetic overlaps between dyslexia and ADHD, as well as other psychiatric conditions like bipolar disorder and schizophrenia6 8.

Historical and Clinical Studies

Historical studies have also contributed to our understanding of the hereditary nature of dyslexia. Early clinical analyses aimed to determine the mode of inheritance and the role of extraneous factors in dyslexia. These studies provided foundational knowledge that has been built upon by modern genetic research4 9.

Is dyslexia a hereditary genetic condition?

Lisa Gabel has answered Near Certain

An expert from Lafayette College in Neuroscience

Dyslexia involves significant impairment of reading accuracy, speed and/or comprehension despite adequate intelligence and educational background. As the most common learning disability, Dyslexia is a global issue that affects 5-17% of the world’s population. Therefore, Dyslexia has far-reaching social and economic consequences. Dyslexia is a complex disorder, involving a number of cognitive and perceptual changes (i.e. short-term memory, phonological processing, visual-spatial abilities, etc.) with a significant genetic component. Dyslexia is associated with an approximate 60% heritability rate, (reported ranges between 40%-80%), with several candidate dyslexia susceptibility genes (CDSGs) identified. The most replicated CDSGs are DCDC2 and KIAA0319, within a region on chromosome 6 referred to as the DYX2 (Dyslexia, region 2) locus. Recently, specific risk variants for RD within the DYX2 locus have been identified and associated with RD severity.

Is dyslexia a hereditary genetic condition?

Dorothy Bishop has answered Near Certain

An expert from Oxford University in Child Development, Neurobiology, Neuropsychology

Developmental dyslexia runs in families, and twin studies have confirmed that there is a substantial genetic contribution to poor reading.

The way in which discoveries in molecular genetics are reported can be misleading, encouraging us to think that there are specific genes that might be used to screen for disorder. However, dyslexia is not a classic Mendelian disorder that is caused by a mutation in a single gene. Rather, like many other common disorders, it appears to involve combined effects of many genes and environmental factors, each of which has a small influence, possibly supplemented by rare variants that have larger effects but apply to only a minority of cases.

Furthermore, to see clearer relationships between genotype and phenotype, we may need to move beyond the clinical category of dyslexia to look at underlying cognitive deficits that may be implicated in other neurodevelopmental disorders.

You can read more about this here on the interplay between genetics and the environment.

Is dyslexia a hereditary genetic condition?

John Stein has answered Near Certain

An expert from Oxford University in Neuroscience

Developmental dyslexia is definitely inherited [1]. (Acquired dyslexia following brain injury is different). c. 60% of the differences between dyslexic and typically developing children’s reading is due to the genes they inherit. But this does not condemn dyslexics to failure; 40% is due to their environment (parental support, teaching etc.) which can compensate. And in any case these genes would not be so common if they did not confer advantages. Many dyslexics are outstandingly talented and successful.

9 gene varients have been associated with dyslexia so far. Many of these help to control the migration of neurones in the brain during early development in the womb, to determine left or right handedness, or to regulate immune responses. But each of them individually contributes to only a tiny proportion of the overall heritability. So there is no ‘gene for dyslexia’. Highly complex interactions of many genes with each other and with their environment are responsible, and it will take a lot more research to understand them.

1. Stein, J. ‘Dyslexia Genetics’. In Dyslexia in Context: Research, Policy and Practice; Reid, G., Fawcett, A. J., Eds.; Whurr Publishers, Ltd.: London, UK, 2008; pp. 76–89 ISBN 9781861564269.

Is dyslexia a hereditary genetic condition?

Johann Bohm has answered Near Certain

An expert from IGBMC in Genetics

Dyslexia can be acquired or have genetic causes. Aquired dyslexia essentially results from brain injury or trauma and has therefore nothing to with the genes. Although the one dyslexia gene has not been found, there are multiple evidences that dyslexia can also have genetic causes:

1) multiple cases of dyslexia within a family (so-called clustering)

2) increased incidence of dyslexia in syndromic disorders as Stormorken syndrome

3) identification of several susceptibility loci. This means that single DNA variants or the combination of two or more DNA variants increase the probability to develop dyslexia.