One of the most heritable conditions in psychiatry, and its first genome-wide study found nothing that met the threshold. The variant on this page is that study’s top signal — published because a near miss in a small sample is information too.
Tourette syndrome is defined by tics: sudden, repeated movements and sounds that a person can suppress for a while and not indefinitely. It begins in childhood, it usually peaks in early adolescence, and it often improves in adult life. It frequently occurs alongside obsessive-compulsive symptoms and ADHD.
It also has one of the highest familial recurrence rates of any neuropsychiatric condition with complex inheritance. Run it in families and inheritance is obvious. Look for the genes and, for a long time, nothing.
A 2013 study assembled 1,285 cases and 4,964 ancestry-matched controls of European ancestry — including two population isolates chosen because isolates simplify the search: Ashkenazi Jews from North America and Israel, and French Canadians from Quebec.
No marker reached genome-wide significance. Not one passed P < 5 × 10⁻⁸.
The top signal was rs7868992, on chromosome 9q32, at P = 1.85 × 10⁻⁶. A secondary analysis added 211 cases and 285 controls from Latin American isolates in Costa Rica and Colombia.
A variant at P = 1.85 × 10⁻⁶ is, by the convention genetics uses, not a finding. That threshold exists for a good reason — our lesson on p-values is entirely about why it is 0.00000005 and not 0.05 — and a result that misses it should not be described as a discovery.
But it is also not nothing, and pretending otherwise is its own distortion. What it most likely means is that 1,285 cases is too few. A highly heritable condition with no genome-wide hits in a sample of that size is telling you about the sample, not about the biology.
So the honest description of this page is: here is the best signal a well-conducted study could produce, here is why it does not count as a finding, and here is why the number of cases is the thing to fix.
The paper places rs7868992 within COL27A1, a collagen gene. Our catalogue records it against KIF12, a neighbouring gene, because that is the annotation the source database carried.
We are stating both rather than silently choosing. For a signal that did not reach significance, the nearest-gene label carries very little weight either way, and pretending to know which gene is involved would be a larger error than the disagreement.
It does not predict, diagnose or explain anything about a person. Tourette syndrome is diagnosed clinically from the pattern and duration of tics, and no genetic test is part of that.
What helps is not genetic either: understanding what tics are and are not, behavioural therapy aimed at the urge that precedes them, and medication where tics are disabling. Most people improve as they get older, and that is worth knowing at the point where it is least believable.
Source. Scharf et al. (Mol Psychiatry 2013) reported the first genome-wide association study of Tourette syndrome, in 1,285 cases and 4,964 ancestry-matched controls of European ancestry including two European-derived population isolates — Ashkenazi Jews from North America and Israel, and French Canadians from Quebec. In the primary meta-analysis no marker achieved the genome-wide significance threshold of P < 5 × 10⁻⁸; the top signal was rs7868992 on chromosome 9q32 within COL27A1 (P = 1.85 × 10⁻⁶). A secondary analysis added 211 cases and 285 controls from two closely related Latin American population isolates. The authors note that Tourette syndrome has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance.
Position listed here. rs7868992. The source places it within COL27A1; our catalogue carries the annotation KIF12, a neighbouring gene. Both are recorded on this page. For a sub-threshold signal the nearest-gene assignment is weakly informative regardless.
Interpretation. A null genome-wide result in a highly familial condition constrains the sample rather than the architecture: 1,285 cases has limited power for common variants of the effect sizes typical in psychiatric genetics. This result should not be cited as evidence against a common-variant contribution.
Clinical use. None. Diagnosis is clinical, requiring multiple motor tics and at least one vocal tic persisting more than a year with onset before age 18. Management is behavioural — comprehensive behavioural intervention for tics, habit reversal — with pharmacotherapy reserved for disabling symptoms. No genotype is used.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Tourette Syndrome comes down to these specific, well-studied positions — not a diagnosis.
Because saying so is more useful than leaving a gap. It was the best signal a carefully conducted study could produce, it does not meet the threshold, and the most likely reason is that 1,285 cases is too few for this kind of search. A reader who finds the variant elsewhere should meet that context here rather than a claim.
Familial clustering tells you inheritance matters; it does not tell you the contribution is made of common variants that a study of this size can see. The mismatch points at sample size, at rarer variants of larger effect, or at both — and it is why the field has spent the years since collecting more cases.
In most people the severity peaks in early adolescence and declines through adult life. That is worth knowing at the age when it is hardest to believe. Diagnosis and management are clinical and no genotype is involved in either.
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