ACE2 and Parkinson disease: Since the pathological burden of α-synuclein in the olfactory bulb is thought to play a cardinal role in α-synucleinopathies, such as PD [84], and olfactory epithelial cells express the angiotensin-converting enzyme 2 (ACE2), the receptor assumed to mediate the entry of the COVID-19 virus into the cell [85], a significant amount of discussion has taken place considering the role of COVID-19 in the pathogenesis of PD [86,87].