The patients with mutations in LRRK2 had a mean duration from the onset of PD to Hoehn and Yahr scale stage 2 (bilateral symptoms, no difficulty walking) of 7·2 years (SD 4·1 years) and a similar duration was seen between LRRK2 Gly2019Ser and LRRK2 non-Gly2019Ser carriers; however, the numbers in the latter group were small and did not include many different mutations. The gene discussed is LRRK2; the disease is Parkinson disease.