The most common genetic cause of fPD, a mutation in the LRRK2 (Leucine-rich repeat kinase 2) gene (G2019S variant) also promoted α-syn aggregation in a PD-hiPSC-derived neuron model treated with preformed fibrils [164]; the same mutation was associated with defects in the axonal trafficking of lysosomes [170]. Here, LRRK2 is linked to Parkinson disease.