⍺‐synuclein aggregates occur in Parkinson disease, amyloid‐β (Aβ42) and hyperphosphorylated tau in Alzheimer disease, and mislocalisation of nuclear transactive response DNA‐binding protein 43kDa (TDP‐43) in frontotemporal dementia and amyotrophic lateral sclerosis (Figure 1). This evidence concerns the gene SNCA and Parkinson disease.