Endocytic pathways have been suggested to have a role in differentiation and migration of neuronal cells during development and in adulthood.33 Additionally, a recent study suggested the role of the homotypic fusion and protein sorting complex-mediated endosomal-lysosomal pathways in the dystonia pathogenesis.34 Therefore, it might be speculated that AOPEP could be implicated in the dystonia pathogenesis through being involved in the endosomal-lysosomal pathways (figure 2A). This evidence concerns the gene AOPEP and Dystonia.