People with obsessive-compulsive disorder are still told to "just stop" checking, washing or counting. A study published in Nature Neuroscience in September 2026 gives that advice its clearest scientific answer yet: in a share of cases, OCD and chronic tic disorders start with rare mutations in genes that build the brain circuits of habit, movement and decision.
The Study
A Rutgers-led consortium of more than 30 research teams sequenced the exome, the protein-coding part of the genome, of 3,964 people with OCD, chronic tic disorders including Tourette syndrome, or both. Senior authors Gary Heiman and Jay Tischfield built the DNA collection over twenty years with volunteer families. The team compared children with their parents to catch de novo mutations, changes present in the child but in neither parent, and compared cases with controls to find rare inherited variants that break a gene.
The result is a list of 36 high-confidence risk genes: 12 specific to OCD, 10 specific to chronic tic disorders, and 34 in the combined analysis. Before this work, only a handful of genes had solid evidence, among them CHD8 and SCUBE1 for OCD and CELSR3 and WWC1 for tic disorders. The new list confirms those and adds dozens more.
What "Large Effect" Means
These are not the tiny common variants of a typical genome-wide study, each nudging risk by a few percent. A damaging mutation in one of the 36 genes multiplies the risk of the disorder roughly 57 times on average. That is the kind of effect seen in autism and developmental-delay genes, and several of the 36 are exactly those genes: the study reports a significant overlap with gene sets for autism, developmental delay, intellectual disability and schizophrenia.
Two honest limits. First, such a mutation was found in only 3 to 8 percent of the people studied. For most people with OCD, the cause remains a mix of many common variants and life experience. Second, this is a research cohort, not a diagnostic test: carrying a variant in one of these genes raises risk, it does not settle a diagnosis.
Why OCD and Tics Share Genes
The most striking number is that 83 percent of the genes showed evidence in both conditions. Clinicians have long noticed that OCD and Tourette run in the same families and often in the same person. The genetics now says why: the genes are active in the cortex and the striatum, the loop that turns intentions into actions and actions into habits. Disrupt that loop and you can get intrusive urges, repetitive movements, or both.
Tischfield put the practical consequence simply: with more than 30 targets acting in networks, treatment research can aim at whole circuits rather than at single molecules.
What a Consumer DNA Test Cannot Tell You
If you have raw data from 23andMe or a similar service, it cannot check any of this. Those kits read a fixed set of common variants; the mutations in this study are rare, often unique to one family, and sit in coding regions that consumer chips do not sequence. We explained the same limit for ADHD in our fact-check of the "ADHD genetics wheel". Only clinical exome or genome sequencing, ordered by a doctor or a geneticist, can find them.
What It Changes For You
Nothing about your treatment today, and a lot about how you can think about it. OCD is a brain-circuit condition with, in some cases, a single identifiable genetic cause. Exposure and response prevention therapy and SSRIs remain the evidence-based first line, and they work on the circuit whatever started it.
If intrusive thoughts, rituals or checking are taking time from your day, our free OCD screening test (OCI-R) gives you a validated score in five minutes and a starting point for a conversation with a professional. It is a screening tool, not a diagnosis.
Sources: Whole-exome sequencing in individuals with obsessive-compulsive disorder and chronic tic disorders identifies 36 large-effect risk genes. Nature Neuroscience (2026); Rutgers University press release (Sept 2026); medRxiv preprint (2025).