Saunders-Pullman R, et al. - Experts aspired to determine whether the longitudinal course of Parkinson's disease (PD) in patients with the leucine-rich repeat kinase 2 (LRRK2) mutation differed from the longitudinal course of PD in patients without the mutation. They supported data from a cross-sectional study and showed a slower decline in motor Unified Parkinson’s Disease Rating Scale scores among those with LRRK2 G2019S–associated PD.