Nail biting (onychophagia) is very common in unselected children, but has also been included in descriptions of complex tics. A report from Taiwan examines prevalence of nail biting in over 2000 children, including 765 with a primary tic disorder, finding that nail biting is very common in TS (56.6%) and provisional tic disorder (27.4%)—much more common than in controls (15.0%)—and begins prior to onset of definite tics \cite{Hsueh2022}.
\cite{Cui_2022a} reported about emotional and behavioral profile of children with GTS in China and compare this profile with sex-matched health controls, ADHD, OCD and depression groups. To assess for behavioral and emotional problems in all groups the Child Behavior Checklist (CBCL) was implemented. No association between the eight factors of the CBCL and motor tics, vocal tics or tic severity assessed by the YGTSS was found. Nevertheless, there was a positive association between the impairment scale of the YGTSS and thought problems as well as rule-breaking behavior as assessed by the YGTSS. Contrary to expected, children with GTS showed similar profile of CBCL to the children with depression, but not ADHD and OCD.