Abundant literature suggest that LRRK2, as well as several other PD-associated genes, are key mediators of endocytosis and intracellular trafficking.(Pan et al., 2017; Matta et al., 2012; Rivero-Ríos et al., 2019; Schreij et al., 2014; Piccoli et al., 2011; Arranz et al., 2014; Abeliovich and Gitler, 2016) However, it remains unclear if these pathways are causal for PD in humans. The gene discussed is LRRK2; the disease is Parkinson disease.