direct cause of tourettes. Further attempts to replicate the study were done in multiple studies. In a Japanese study, next-gen sequencing was used to screen 92 TS patients and 361 healthy controls, none of TS patients were found to have mutations at either variant or any new mutations in the gene. In a European study it was found that the 2 original variations were not found in any of the 222 trios that were studied. However, tests were also done on SNPs in the groups and 3 were found to have variations. Two of the three variations were found to be associated with the formation of Tourette syndrome. In a different study of 381 Caucasians with some form of OCD with 356 non-OCD control patients, 3 genetic changes were found after genetic screening. Of the 3, 2 were identified only once each and the third was found in 4 OCD patients but also in a non-OCD patient. The non-OCD patient did have compulsive nail biting, but these studies show that a genetic link between SLITRK1 and patients with TS may exist they are more complex in nature than previously understood. Trichotillomania The SLITRK1 gene has also been implicated in a small percentage of cases of trichotillomania, an impulse disorder in which individuals compulsively pull their own hair. In one of the previously mentioned studies the mother of the child who had a de novo translocation on 13q had trichotillomania; this would suggest that there could be a genetic link between SLITRK1 and trichotillomania as well. A study was done in which 44 families with individuals who had trichotillomania had their SLITRK1 gene sequenced. Two new non-synonymous mutations were discovered about 9 base pairs apart from each other, in an area separate from the one where the Tourette mutations were found. These results were compared to a control and none had the mutation, suggesting that these mutations, while rare, were associated with trichotillomania. See also SLITRK2 Protein tyrosine phosphatase References Further reading Tourette syndrome Tourette syndrome