PRKN and Parkinson disease: Interestingly, the pre-synaptic functions of parkin resemble the function of synuclein, another key protein involved in PD pathogenesis and a regulator of pre-synapse size and synaptic vesicle pool organization (Anwar et al., 2011; Vargas et al., 2017), additionally, the roles of other PD genes such as DNAJC6, SYNJ1, SH3GL2, LRRK2, and VPS35 in the regulation of synaptic vesicle trafficking SVE are beginning to emerge (Nguyen et al., 2018).