Tourette Syndrome and Chronic Tic Disorders.

Tourette syndrome (TS) and chronic tic disorder (CTD) are characterized by persistent verbal and motor tics of varying severity. We describe modern genetic studies of TS/CTD focused on common and rare variation, which quantify genetic risk per patient and identify risk genes such as NRXN1 and CELSR3. In general, the burden of TS/CTD genetic risk correlates with tic severity and the likelihood of a case belonging to a multiplex family. These findings do not immediately alter patient treatment, though they may in some cases help better define sources of patient risk.