GBA1 and Parkinson disease: In other studies, PD patients carrying GBA mutations were reported to be less likely to have tremor at onset but more likely to present bradykinesia at onset (Gan-Or et al., 2010; Lesage et al., 2011; Swan and Saunders-Pullman, 2013), which may suggest the need to expand the sample size and extend the follow-up times.