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A collaborative genetic study \citep{25735483} demonstrated an association of TS with 33 genes related to glycolysis or glutamine metabolism. None of the individual genes would have survived correction for multiple testing and the results were consistent with a combined effect of many genetic variants of small effect. These results suggest a new direction for future genetic, electrophysiological, imaging and pharmacological studies.   Yu et al. reported a genome-wide association study (GWAS) from 1,310 people with OCD, 834 with Tourette syndrome, 579 with both OCD and a chronic tic disorder, and over 5,500 controls matched for ancestry \citet{25158072}. \citep{25158072}.  A significant polygenic component was identified for OCD without tics, but not for the combined patient group or other subgroups. Overall, this study is consistent with previous work but it provided disappointingly few novel results. An international study examined tic symptoms in the United States and the Netherlands \citep{25714449}. Three factors (complex vocal tics and obscene behavior, body tics, and head/neck tics) accounted for 49% of the variance in tic-related symptoms. There was no evidence of heritability for the second factor, but the h2r was approximately 0.2 for the first and third factors when age and sex were included as covariates. Heritability for these narrower tic phenotypes is considerably lower than the heritability estimates (up to 0.65) when comorbid conditions such as OCD and ADHD are included. These authors conclude that broader tic phenotypes, rather than narrower pure tic phenotypes, may be more successful at identifying the genetic mechanisms underlying TS.