As detailed here, research has identified six toxic proteins (Aβ, Tau, αSyn, FUS, SOD1, TDP-43) that are not only classic biomarkers for AD (Aβ, pTau), ALS (pTau, TDP-43, FUS, SOD1), FTD (pTau, TDP-43, FUS, SOD1), and PD (αSyn) but also contribute to mixed pathologies associated with each of those diseases as detailed above (Figure 4). This evidence concerns the gene SOD1 and Parkinson disease.