Given the impact of LRRK2 mutations in Parkinson’s disease, the close functional relationship between macrophages and microglia, and recent genetic insights into the potential importance of microglial LRRK2 in Parkinson’s disease (17, 45), we next differentiated human iPSCs (control, LRRK2 KO, and G2019S) into microglia based on an established protocol (59). Here, LRRK2 is linked to Parkinson disease.