One of the most heritable common conditions there is — and one of the least predictable from a genome. Twin studies put the inherited share around 70-80%, yet the first reliable common variants were only found in 2019, and each one moves the odds by a few percent. This page is about why both of those are true at the same time.
ADHD affects about 5% of children and 2.5% of adults. It runs in families about as strongly as height does. And there is no genetic test for it, nor is one close.
Those three sentences are not in tension once you see the shape of the trait, and that is what this page is for.
Twin and family studies have consistently put the heritability of ADHD at roughly 70-80% — near the top of the range for any common condition. That number describes how much of the variation between people in a population tracks with their genetic similarity. It says the genes matter enormously.
What it does not say is that a small number of genes matter. Decades of candidate-gene work produced almost nothing that replicated. The first genome-wide significant results for ADHD arrived in 2019, from a study of 20,183 diagnosed people and 35,191 controls, and it found 12 independent positions.
Twelve positions, each shifting the odds by a few percent per copy, in a trait that is 70-80% heritable. The inherited component is real and it is spread across thousands of positions, almost all of them too small to see even at that sample size.
Beyond the twelve positions, the paper made three points that matter more than any single rsID.
The signals were enriched in constrained parts of the genome — regions that have changed little across evolution, and genes that do not tolerate being broken. Whatever these variants are doing, they are doing it in parts of the genome that matter.
They were enriched around brain-expressed regulatory marks. Most of them are not in genes at all; they are in the sequence that decides how loudly nearby genes are read, in brain tissue.
And the genetic signal from diagnosed ADHD matched the signal from ADHD symptoms measured across the general population. That is the finding with the most weight outside genetics: it supports the view that a diagnosis is the far end of a continuous trait everybody sits somewhere on, not a separate category of person.
All six come from that 2019 meta-analysis. Two sit in genes with a plausible story — SORCS3, a brain sorting receptor, and PTPRF, involved in building connections between neurons. One, near DUSP6, sits beside a gene tied to dopamine signalling, which is the system ADHD medicines act on. The other three are in sequence with no gene attached — which is what most genome-wide findings look like, and an honest thing to show rather than hide.
A seventh, listed in the catalog against FOXP2, is not resolvable in the current Ensembl release, so it is not here. We would rather have five positions we can check than six we cannot.
It cannot diagnose. ADHD is identified by a clinician from behaviour, observed in more than one setting, over time, with other explanations ruled out. No genotype enters that assessment anywhere.
It cannot predict. The strongest position here changes the odds by about 8% per copy, against a background risk of a few percent. Nothing in that is visible in one person.
It cannot choose a medicine. Stimulant response is not predicted by these positions, and there is no pharmacogenomic guideline for ADHD medicines built on them.
Because "your genes explain most of this, and we still cannot read them" is a real and useful thing to understand — and because the alternative, on the open internet, is a page that promises far more.
It is also the clearest available answer to a bad argument: that a highly heritable condition must be a fixed one. ADHD is as heritable as almost anything in this catalogue, and it is also strongly shaped by sleep, structure, schooling and support. Both of those are true, and the genetics is the reason neither one wins.
Architecture. ADHD heritability from twin studies is approximately 70-80%. The 2019 meta-analysis (20,183 cases, 35,191 controls) identified variants surpassing genome-wide significance at 12 independent loci — the first robust common-variant associations reported for the disorder. Per-allele odds ratios for the loci recorded here are in the range of approximately 1.03 to 1.08. Associations were enriched in evolutionarily constrained genomic regions, in loss-of-function-intolerant genes, and around brain-expressed regulatory marks, consistent with a highly polygenic architecture acting largely through regulation rather than coding change.
Replication and continuity with population traits. Three replication samples were examined: a clinically diagnosed cohort, a self-reported ADHD sample, and a meta-analysis of quantitative measures of ADHD symptoms in the general population. All supported the primary findings, while showing study-specific differences in genetic overlap with educational attainment. The strong concordance between the diagnosed-case GWAS and quantitative population symptom measures supports the interpretation that clinical ADHD represents an extreme expression of continuous heritable traits.
The variants recorded here. rs11591402 (SORCS3, P = 4e-9), rs1592757 (5q21, P = 1e-9), rs4275621 (11p14, P = 3e-9), rs11591402 and rs1427829 (near DUSP6, P = 7e-9), rs3001723 (PTPRF, P = 1e-8) and rs2243517 (RNF219-AS1, P = 4e-8). Positions, alleles and 1000 Genomes frequencies were verified individually against Ensembl GRCh38. The catalog's FOXP2 entry, rs5886709, does not resolve in the current Ensembl release and is excluded.
Clinical boundary. ADHD is a clinical diagnosis based on developmental history and observed impairment across settings, per DSM-5 and ICD-11 criteria. No genotype is diagnostic, contributory or exclusionary. Polygenic scores for ADHD have no established clinical role and are not validated for individual prediction. There is no pharmacogenomic guideline covering stimulant selection or dosing on the basis of these positions; CYP2D6 status is relevant to atomoxetine dosing and is a separate matter from the risk loci described here.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about ADHD (Attention Deficit Hyperactivity Disorder) comes down to these specific, well-studied positions — not a diagnosis.
No, and there is not one on the horizon. ADHD is highly heritable but the inheritance is spread across thousands of positions with tiny individual effects. The first reliable ones were found in 2019, and the strongest of them moves the odds by about 8% per copy. Diagnosis is clinical.
Heritability describes how much of the variation across a population tracks with genetic similarity. It says nothing about how few genes are involved. For ADHD the answer is: thousands, each too small to see. Height works the same way and is far easier to measure.
No — and ADHD is the clearest counter-example in this catalogue. It is about as heritable as anything here, and it also responds to sleep, structure, schooling, support and medication. Heritable and changeable are not opposites.
No. None of these positions predicts stimulant response, and no guideline uses them for prescribing. CYP2D6 status matters for atomoxetine dosing, but that is a separate question from the risk positions on this page.
Because most genome-wide findings are not in genes. They fall in the regulatory sequence between them — DNA that changes how loudly a nearby gene is read. Working out which gene, and in which tissue, is a separate piece of research that has not been done for every one of these.
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