SOD1 and amyotrophic lateral sclerosis: In this study, we used human postmortem tissue and human induced pluripotent stem cell (iPSC)-derived motor neurons with familial ALS-causing superoxide dismutase-1 (SOD1) mutations to test the hypothesis that ALS motor neurons accumulate genomic DNA lesions and have aberrant DDR and epigenetic silencing of DNA repair enzyme promoters, thus possibly accounting for DNA damage accumulation.