These results have potential relevance both for genetic studies of TS and related disorders and for clinicians. The high RhoG between TS and OCD suggests that OCD could either be considered as a potentially relevant phenotype in genetic studies of TS, for example including OCD (particularly OCD-affected individuals who also have tics) together with TS in genome-wide association studies, or alternatively, as a constraint on TS genetic studies, limiting such studies to the potentially more genetically homogenous subgroup of individuals with TS+OCD. Another possibility would be to use individuals with one disorder as a replication sample for the other, for example, examining genetic variants associated with TS in a sample of OCD-affected individuals. For clinicians, our findings suggest that TS-affected families may need to be counseled that TS and OCD share genetic susceptibility factors, and thus that offspring of TS families may be at increased risk for either TS or OCD or for the combination of the two.
