In the case of most mutations, including common G93A and G37R, the pathology develops in the presence of a fully active enzyme, thus suggesting that ALS-related SOD1 mutations lead to a toxic gain of function by promoting aggregates formation within the cells, but that they also contribute to pathology with a loss-of-function mechanism by reducing the amount of functional enzyme and thus promoting oxidative stress [104,105]. The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.