SOD1 and amyotrophic lateral sclerosis: ALS is the most common form of motor neuron disease [2], with about 90% of all ALS cases being sporadic, while the other 10% are familial, and about 15–20% of all familial cases are caused by a mutation in the superoxide dismutase-1 glycine 93 to alanine gene (SOD1 G93A) [3].