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\citet{25158072} 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. 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 were identified: identified (i.e.,  complex vocal tics and obscene behavior, body tics, and head/neck tics. tics) and they accounted for 49% of the variance in tic-related symptoms.  There was no evidence of heritability for the second factor while 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, which range up to 0.65, when comorbid conditions, such as OCD and ADHD are included. These authors conclude that their  results support the argument idea  that OCD and ADHD cannot easily the use of broader tic phenotypes that include comorbidities (e.g., OCD, ADHD), rather than narrower pure tic pheonotypes, may  be separated from tics in people with more successful at identifying the genetic mechanisms underlying  TS. ### Environmental risk factors