Early synaptic dysfunction in PD has been supported by genetic evidence, with recently identified mutations in genes involved in clathrin-dependent synaptic vesicle endocytosis (SVE), such as DNAJC6 (auxilin) and SYNJ-1 (synaptojanin 1), in patients with juvenile and early-onset atypical parkinsonism (Nguyen and Krainc, 2018). The gene discussed is SYNJ1; the disease is Parkinson disease.