In contrast with our non-significant findings, COMT rs4680 was associated with the occurrence of dyskinesia, motor fluctuations (Watanabe et al., 2003; Bialecka et al., 2008; de Lau et al., 2012; Hao et al., 2014; Wu et al., 2014), and daytime sleepiness (Frauscher et al., 2004) in other studies. The gene discussed is COMT; the disease is drug-induced dyskinesia.