The available literature demonstrates that the homeostasis of several tissue-resident macrophage populations, including microglia, is regulated by leucine-rich repeat kinase 2 (LRRK2) [9–11] and that the mutations of LRRK2 are the commonest genetic cause of Parkinson’s disease (PD) [12–14], with G2019S mutation documented in sporadic PD [15]. The gene discussed is LRRK2; the disease is Parkinson disease.