Forty-nine genetic loci are shared between dyslexia and ADHD, with 40 newly identified, according to a new study.

The research explored the genetic overlap between dyslexia and psychiatric conditions, providing critical insights into the neurodevelopmental basis of dyslexia. Conducted in collaboration with 23andMe, the study utilized genome-wide association studies (GWAS) to examine genetic correlations across dyslexia, ADHD, autism spectrum disorder, and psychiatric conditions such as bipolar disorder and anxiety.

The study analyzed a total sample of 453,408 cases and 2,374,026 controls across neurodevelopmental and psychiatric traits. Published in Molecular Psychiatry, the researchers employed Genomic Structural Equation Modeling to identify five latent genetic factors. Dyslexia and ADHD clustered within the "attention and learning difficulties" factor, which was distinct from other neurodevelopmental traits, such as autism. ADHD showed a stronger genetic association with dyslexia than with autism, reflecting their frequent co-occurrence in clinical populations.

The "attention and learning difficulties" factor showed genetic correlations with internalizing disorders (e.g., anxiety, major depressive disorder) and psychotic disorders (e.g., bipolar disorder, schizophrenia). Specifically, the factor demonstrated strong positive correlations with internalizing disorders (r = 0.40) and moderate correlations with psychotic disorders (r = 0.17) and neurodevelopmental traits like autism (r = 0.25). It also had a negative correlation with compulsive disorders such as obsessive-compulsive disorder and anorexia nervosa (r = -0.16).

Further analysis identified 49 pleiotropic loci associated with both dyslexia and ADHD, with 40 of these loci newly reported. The researchers mapped 174 genes to these loci, of which 121 were newly identified, offering significant insights into the shared genetic architecture of dyslexia and ADHD.

These findings suggest the existence of novel genetic variants contributing to the shared genetic basis of dyslexia and ADHD. The study also indicates that future research into co-occurring learning difficulties, such as dyscalculia and dyspraxia, could further clarify the genetic structure underlying these conditions.

Full disclosures can be found in the published study.