GBA1 and Parkinson disease: Our study had three main goals: (1) Define PD penetrance of the LRRK2/GBA1 variants and whether PRS impacts PD penetrance; (2) Explore phenotypic differences among LRRK2/GBA1 carriers; and (3) Evaluate the role of the APOE E4 allele in the development of dementia/hallucinations.