There is also substantial evidence implicating oxidative stress as a central mechanism by which motor neuron death occurs, including elevated markers of oxidative damage in ALS patients’ spinal cord and cerebrospinal fluid and mutations in the antioxidant enzyme superoxide dismutase 1 (SOD1), causing approximately 20% of familial ALS cases.7 Furthermore, elevated levels of iron have been found in ALS spinal cord tissue,28 and this may contribute to oxidative damage via the ability of iron to generate reactive oxygen species through the Fenton reaction. The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.