How many SNPs have been linked to ADHD? 

The search for ADHD SNPs or single-nucleotide polymorphisms associated with ADHD has come a long way in recent years, because of large-scale genome-wide association studies GWAS. While ADHD is influenced by thousands of common genetic variants, only a smaller number have reached genome-wide significance. 

SNPs, Risk Variants, and Gene Mapping in ADHD 

SNPs, risk variants, and gene mapping reveal genetic factors that increase susceptibility to ADHD by affecting brain function and neurotransmitter regulation. 

Genome-wide significant findings  

The most recent and largest ADHD GWAS meta-analyses have identified around 27–39 independent genome-wide significant loci, depending on the study design and population. Each of these loci can include multiple risk variants (SNPs) that contribute modestly to ADHD risk. 

Thousands of suggestive SNPs 

 Beyond those reaching strict significance thresholds, thousands of additional SNPs that show suggestive associations (e.g. P < 1×10⁻⁵). These variants may become significant with larger samples and are important for polygenic risk scores and gene mapping efforts. 

Heritability and cumulative risk  

Collectively, common SNPs explain about 20–25% of ADHD’s heritability, a figure known as SNP-based heritability. The rest may be due to rare variants, environmental factors, and gene-environment interactions. 

Mapping the associated genes  

Many significant SNPs lie in non-coding regions but influence the expression of nearby or distant genes involved in brain development, dopamine regulation, and synaptic function. Key genes mapped from ADHD SNPs include FOXP2, DUSP6, and SEMA6D, among others. 

The key point is that ADHD has a complex genetic basis. While no single SNP defines the condition, the accumulation of many small-effect variants paints a clearer picture of its biological basis. Visit providers like ADHD Certify for personal consultations informed by your genetic risk profile.

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to Genetic studies and biomarkers.