ADHD & Autism Shared Risk and Your Genetics

ADHD & Autism Shared Risk is a polygenic trait capturing the degree to which common genetic variants linked to attention-deficit/hyperactivity disorder and autism spectrum disorder overlap in a single genomic profile. These two neurodevelopmental conditions, while clinically distinct, share measurable genetic architecture—including pleiotropic loci that appear to influence brain development pathways relevant to both. [¹] This page explains what that overlap means, which genomic regions carry the strongest evidence, and how to interpret a polygenic score for this trait.

What is ADHD & Autism Shared Risk?

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition characterized by inattention, impulsivity, and hyperactivity. Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by differences in social communication and the presence of restricted, repetitive behaviors. Though their clinical presentations differ substantially, the two conditions frequently co-occur: a substantial share of people who meet criteria for one condition also meet criteria for the other.

This co-occurrence is not coincidence. Genetic studies have established that ADHD and ASD share a portion of their heritable architecture—meaning that some of the same common DNA variants that nudge population-level risk upward for ADHD also nudge risk upward for ASD, and vice versa. The ADHD & Autism Shared Risk trait at ExomeDNA aggregates the signal from these pleiotropic variants into a single polygenic score. A higher score reflects a greater burden of these overlapping variants; it does not indicate that any specific condition is present or will emerge.

Understanding this shared genetic layer matters for several reasons. It helps explain why the two conditions cluster in families, why cognitive and behavioral features sometimes overlap even when only one condition is formally identified, and why research into the neurobiology of one condition often yields insights relevant to the other.

The genetics behind ADHD & Autism Shared Risk

Genome-wide association studies (GWAS) scan millions of common variants across the genome to find positions where one version of a DNA letter is more frequent among people with a given trait than among those without it. When researchers run parallel GWAS for ADHD and ASD and then look for overlap, they find a non-trivial number of genomic regions that reach significance for both—these are the pleiotropic loci that define this trait.

Among the genomic regions with the strongest evidence for this shared signal, the region near the gene KIZ stands out. KIZ encodes a protein that localizes to centrosomes—the cellular structures that anchor the spindle fibers used to pull chromosomes apart during cell division. By strengthening and stabilizing the pericentriolar region prior to spindle formation, the KIZ protein plays a role in the fidelity of cell division. During the rapid neuronal proliferation of early brain development, any disruption to centrosomal function can have downstream effects on cortical architecture and circuit formation—biological processes plausibly relevant to neurodevelopmental susceptibility.

Another authorized gene near this signal, MANBA, encodes a lysosomal enzyme that acts as the final exoglycosidase in the pathway for processing N-linked glycoprotein oligosaccharides. Glycoprotein processing in lysosomes is important for cellular housekeeping in neurons and glia alike; disruptions to this pathway have been linked to lysosomal storage disorders, and emerging evidence suggests that lysosomal function influences synaptic homeostasis.

The full set of authorized genes associated with this trait includes KIZ, MANBA, NIHCOLE, POC1B, RN7SL831P, and SORCS3. Each sits near a genomic signal that has been identified as pleiotropic across the ADHD and ASD landscapes. See our gene page for KIZ for more detail on its biological role.

See our methodology page for how ExomeDNA assesses genetic evidence.

What the research says

Research base: Moderate.

Two peer-reviewed studies anchor the evidence for this trait.

A 2022 study published in Psychiatry Research applied genome-wide genetic correlation analysis and Mendelian randomization to examine the shared architecture between ASD and ADHD. [¹] The researchers found that extraversion—a personality dimension reflecting sociability and outward engagement—showed a positive genetic correlation with ADHD (rg = 0.205) and a negative genetic correlation with ASD (rg = -0.193). This divergence is notable: the same polygenic landscape that elevates ADHD susceptibility appears to be partly distinct from the one elevating ASD susceptibility, even though the two landscapes overlap substantially.

Critically, the same study applied Mendelian randomization to test causal directionality. The analysis identified a bidirectional causal relationship, with the genetic component of ADHD associated with an increased odds of ASD (OR 1.35, 95% CI 1.20–1.52). [¹] Three novel pleiotropic loci were identified in this analysis, including a locus involving the gene KIZ.

OR 1.35 (95% CI 1.20–1.52) — Mendelian randomization estimate for the effect of genetic ADHD liability on ASD susceptibility, based on genome-wide association data.^[¹]

A 2024 study published in Nature Genetics took a different angle, examining how polygenic profiles shape clinical heterogeneity within ADHD itself. [²] Using data from 14,084 people with ADHD drawn from Danish registry and cohort sources, the researchers used polygenic scores to distinguish subgroups: those with ADHD alone versus those with ADHD and co-occurring ASD. The analysis identified one genome-wide significant locus in the ADHD+ASD versus ADHD-only comparison—evidence that the genomic architecture distinguishing the comorbid subgroup is real and detectable at scale.

14,084 people with ADHD examined across Danish registry and cohort data to map how polygenic profiles define clinical subtypes, including the ADHD+ASD subgroup.^[²]

The same study found that autism-predicting polygenic scores in people with ADHD also correlated with cognitive performance in an independent developmental cohort—a finding that points toward shared genetic pathways influencing both neurodevelopmental susceptibility and cognitive variation more broadly. [²]

Taken together, these two studies establish that the overlap between ADHD and ASD has a measurable genetic foundation, that specific pleiotropic loci contribute to that overlap, and that individual variation in the balance of ADHD-type versus ASD-type genetic burden is associated with distinct clinical presentations.

How ADHD & Autism Shared Risk affects you

A polygenic score for ADHD & Autism Shared Risk sits on a continuous spectrum across the population. Most people cluster near the middle; smaller proportions sit at either end. Because the trait aggregates variants that are individually common and of small effect, the score reflects population-level tendencies rather than a binary switch.

For someone with an elevated score, the practical implication is probabilistic: the variants they carry are, in aggregate, more common among people with ADHD, ASD, or both than among the general population. This does not mean those conditions are present, will develop, or that any specific functional challenge is inevitable. Genetic susceptibility is one input among many—developmental environment, early experiences, co-occurring health factors, and individual neurodiversity all shape how any underlying genetic architecture expresses itself over a lifetime.

For someone with a lower score, the converse applies: the relevant variants are less concentrated, which is associated at the population level with lower average susceptibility. Again, this is not a guarantee. A low polygenic score does not preclude neurodevelopmental differences, and the conditions associated with this trait are among the most heterogeneous in psychiatry—they are influenced by many thousands of variants, rare variants not captured by this score, and non-genetic factors.

What the score can usefully inform is self-understanding. People who already know they have ADHD or ASD may find context in understanding that overlapping genetic variants contribute to both conditions. People who notice traits associated with either condition in themselves or family members may find the genetic framing helpful as background context—not as a substitute for professional evaluation, but as one piece of a larger picture.

Working with your ADHD & Autism Shared Risk profile

Polygenic scores for neurodevelopmental traits are most useful when understood in context rather than in isolation. Several principles help frame what to do—and not do—with this score.

Use it for context, not classification. The score does not sort people into those who have ADHD or ASD and those who do not. It describes where someone sits on a continuous genetic spectrum that is correlated with, but not identical to, clinical presentation. The appropriate framework is probabilistic background context, not categorical assignment.

Consider it alongside family history. Because ADHD and ASD are both substantially heritable, a family history of either condition provides additional context that complements the polygenic score. When both sources of information point in the same direction, the overall picture is more informative than either alone.

Discuss it with a qualified professional if clinically relevant. If attention difficulties, social communication differences, or other features associated with ADHD or ASD are already a concern, that is a conversation for a clinician experienced in neurodevelopmental assessment. A polygenic score is not a clinical instrument, and no genetic profile substitutes for structured clinical evaluation.

Recognize what the score does not cover. This polygenic score captures common variant signal from genome-wide association studies. It does not capture rare variants, copy number variants, or other forms of genetic variation that contribute to neurodevelopmental conditions—particularly in more severe or syndromic presentations. The genetic architecture of both ADHD and ASD extends well beyond what any single polygenic score can represent.

Related traits and genes

ADHD & Autism Shared Risk sits within the neurodevelopmental and psychiatric genetics category. Related traits available on ExomeDNA include Schizophrenia Risk, Bipolar Disorder Risk, and Major Depressive Disorder Risk—all conditions that share portions of their genetic architecture with each other and with ADHD and ASD. Cross-category traits with overlapping signal include Cognitive Performance and Educational Attainment, consistent with research showing that polygenic scores for neurodevelopmental conditions correlate with cognitive measures in population samples. [²]

The gene with the strongest evidence near this trait's shared signal is KIZ, a centrosomal stability gene. Its role in ensuring the fidelity of cell division during neurogenesis makes it a plausible candidate for developmental risk pathways. Additional authorized genes—SORCS3, MANBA, NIHCOLE, POC1B, and RN7SL831P—represent further loci at which common variation has been linked to this pleiotropic signal. Visit the KIZ gene page for a deeper look at the biology.

Frequently asked questions

What does it mean to have a higher score on ADHD & Autism Shared Risk? A higher polygenic score on this trait reflects a greater burden of common genetic variants associated with both ADHD and autism spectrum disorder. It does not mean either condition will emerge. Many people with elevated scores never receive either label, while many people with a formal clinical identification carry average or below-average scores. The score captures population-level signal, not individual destiny.

Are ADHD and autism really genetically related? Research confirms a meaningful genetic correlation between the two conditions. Studies using genome-wide association data have identified shared chromosomal regions and overlapping polygenic signals, including pleiotropic loci near genes such as KIZ. The two conditions also share some behavioral and cognitive features, though they remain clinically distinct presentations with different criteria.

Can a genetic test tell me whether I have ADHD or autism? No polygenic score can determine whether someone has any condition. These scores reflect average tendencies across large populations and do not function as clinical tools. A formal evaluation by a qualified clinician—using behavioral observation, history, and validated rating scales—remains the appropriate path for any such question.

What is a pleiotropic locus? A pleiotropic locus is a genomic region where common variants are statistically associated with more than one trait or condition at the same time. For ADHD and autism, researchers have identified loci whose variants appear to influence susceptibility pathways relevant to both conditions simultaneously.

How does personality relate to ADHD and autism genetics? Genome-wide studies have found that the genetic component of extraversion is positively correlated with ADHD genetics (rg = 0.205) and negatively correlated with autism genetics (rg = -0.193). [¹] This suggests that some of the same common variants shaping neurodevelopmental susceptibility also influence personality dimensions, though the full causal picture is still being mapped.

What genes are associated with this shared risk signal? The authorized genes linked to this trait include KIZ, MANBA, NIHCOLE, POC1B, RN7SL831P, and SORCS3. KIZ carries the strongest genomic evidence near this pleiotropic signal and encodes a centrosomal protein involved in stabilizing cell division machinery—a process critical during early brain development.

References

[1] Baranova A et al. Shared genetics between autism spectrum disorder and attention-deficit/hyperactivity disorder and their association with extraversion. Psychiatry Research. 2022;314:114679. PMID: 35717853.

[2] LaBianca S et al. Polygenic profiles define aspects of clinical heterogeneity in attention deficit hyperactivity disorder. Nature Genetics. 2024;56(2):234–244. PMID: 38036780.

Data sources: Genome-wide association summary statistics accessed via curated reference databases. Gene-to-locus mapping based on proximity and functional annotation. See our methodology page for how ExomeDNA assesses genetic evidence.

By the ExomeDNA Research Team