Indeed, impaired membrane trafficking is a hallmark of neurodegenerative diseases, including sporadic amyotrophic lateral sclerosis (ALS), Parkinson's and Alzheimer's disease, and involves Rab GTPase dysfunction, endosomal misrouting and disturbed intracellular transport (Agola et al., 2011; De Vos and Hafezparast, 2017; Kiral et al., 2018; McMillan et al., 2017; Parakh et al., 2018; Schreij et al., 2016; Tan and Gleeson, 2019; Xu et al., 2018). This evidence concerns the gene RAB6A and Parkinson disease.