PRKN and Parkinson disease: Two observations contribute to this debate: first, there is solid evidence that not all cases of parkinsonism are characterized by the presence of α-Syn inclusions—several studies have reported that PD patients carrying familial mutations in Parkin gene, and some of those with the LRRK2 G2019S mutation, show neuronal degeneration but do not develop Lewy bodies (Gaig et al., 2009; Johansen et al., 2018) and, second, postmortem analysis reflect that Lewy bodies and Lewy neurites may be present in the absence of clinical PD symptoms (Parkkinen et al., 2005).