Together, these data add further evidence that LRRK2 G2019S activity is elevated approximately one-and-a-half- to twofold under endogenous conditions in relevant cell types, including CNS cells, and suggest a small (< twofold) increase in phosphorylated Rab10 is sufficient to confer an elevated lifetime risk of Parkinson’s Disease. This evidence concerns the gene RAB10 and Parkinson disease.