Accumulation of destructive molecules called free radicals can lead to motor neuron death. Free radicals damage components of the cells' membranes, proteins or genetic material by "oxidizing" them - the same chemical reaction that causes iron to rust. Some patients with familial ALS have mutations in the gene for superoxide dismutase type 1 (SOD1). SOD1 normally breaks down free radicals, but mutant SOD1 is unable to perform this function. These free radicals may be generated when the enzyme superoxide dismutase malfunctions (either because of a genetic mutation or because of the chemical environment of the nerve cells), or they may be generated as a result of glutamate excitotoxicity, or for some other reason. Many ALS patients take over the counter antioxidants such as Coenzyme Z Q10 and Vitamin E in an effort to neutralize free radicals.