SOD1 and Parkinson disease: Research in this field has traditionally focussed on individual proteins known to form characteristic pathologies in each disorder, such as α-synuclein in Parkinson’s disease, β-amyloid or tau in Alzheimer’s, TAR DNA-binding protein 43 (TDP-43) or superoxide dismutase 1 (SOD1) in amyotrophic lateral sclerosis.