SOD1 (superoxide dismutase 1) is the major soluble cytoplasmic enzyme responsible for destroying harmful free superoxide radicals in the body thereby providing defence against oxygen free-radical toxicity. Soluble cytoplasmic SOD1 is a copper- and zinc-containing enzyme and the SOD1 gene maps to chromosome 21q22. Mutations in the SOD1 gene have been implicated to be the cause of familial amyotrophic lateral sclerosis, increased age-related muscle mass loss, early development of cataracts, macular degeneration, thymic involution, hepatocellular carcinoma, and shortned lifespan.