SOD1 and amyotrophic lateral sclerosis: Consistent with this concept, amyloid protein A (AA; associated with AA amyloidosis), Aβ, α-synuclein, SOD1, tau (associated with taupathies and AD), huntingtin (associated with HD) and TDP-43 [associated with frontotemporal lobar degeneration with ubiqitin-positive inclusions (FTLD-U) and ALS] all have the capacity to seed aggregation of soluble homotypic proteins in vitro and in vivo.