Overexpression of LRRK2 wild-type and G2019S mutant induces the aggregation of A53T α-syn variant [156], and the LRRK2 G2019S variant enhanced abnormal α-syn aggregation in Lewy’s Bodies in Parkinson’s patients [147], in human-induced pluripotent stem cell-derived (iPSC) neurons, and PD mouse models [157,158,159,160,161,162], confirming the involvement of LRRK2 itself and the importance of kinase activity of the LRRK2 G2019S mutant in phosphorylation and the progression of α-syn pathology. This evidence concerns the gene LRRK2 and Parkinson disease.