The Parkinson’s Progression Markers Initiative (PPMI) offers the unique opportunity to address key gaps in knowledge regarding clinical, biomarker, and genetic differences in LRRK2-associated parkinsonism with and without evidence of asyn aggregates, given that the cohort has had in vivo assessment of asyn aggregates in CSF as well as extensive longitudinal phenotyping in a relatively large number of cases. This evidence concerns the gene LRRK2 and Parkinson disease.