SOD1 and amyotrophic lateral sclerosis: The identification of non‐genetic factors underlying region‐specific SOD1 misfolding and deposition in SOD1‐linked familial ALS, which may also contribute to wild‐type SOD1 misfolding in sporadic ALS, idiopathic Parkinson's disease and potentially Alzheimer's disease will significantly improve our understanding of the biology of this protein.