SOD1 and early-onset autosomal dominant Alzheimer disease: These include protein aggregates formed by hyperphosphorylated tau in Alzheimer’s disease (2), mutant superoxide dismutase 1 (SOD1) (4), and TAR DNA–binding protein 43 (TDP-43) in amyotrophic lateral sclerosis (5), and mutant huntingtin (Htt) in HD (6, 7).