However, a recent longitudinal study of a large PD sample measuring progression using the Montreal Cognitive Assessment and Movement Disorders Society—Unified Parkinson Disease Rating Scale–Part III, showed that patients with both the p.G2019S mutation and GBA-PD had a slower rate of decline than those with GBA-PD alone, which was no different from LRRK2-G2019S alone [148]. This evidence concerns the gene GBA1 and Parkinson disease.