Although the incidence of dyskinesia was similar in both groups, the time to onset was longer in patients with mutations in LRRK2 than in patients with idiopathic PD (8·4 years [SD 4·6 years] vs 5·6 years [SD 3·7 years], difference 2·8 years, 95% CI 2·3–3·3 years; p<0·0001). This evidence concerns the gene LRRK2 and drug-induced dyskinesia.