Overview
- Definition: Disorder characterized by multiple motor and vocal tics.
- Prevalence:
- Overall prevalence of 1% in children aged 5–18 years.
- Prevalence varies from 0.4–3.8% depending on country and diagnostic methodology (Eysturoy et al., 2015).
Aetiology
- Genetic Factors:
- Familial occurrence due to genetic or environmental influences.
- Twin studies: 50–70% concordance in monozygotic twins, 9% in dizygotic twins.
- Suggested complex inheritance involving a major gene and multiple additional factors (Walkup et al., 1996).
- No single locus established (Pascher et al., 2004; Keen-Kim and Freimer, 2006).
- Dopaminergic and serotonergic pathways involvement inconsistent, but DRD2, MAO-A, and DAT1 supported by findings.
- Multiple implicated genes, with SLITRK1 being prominent (Paschou, 2013).
- Deletions of 16p13.11, 22q11, and NRXN1 recorded in some cases (McGrath et al., 2014).