SOD1 and amyotrophic lateral sclerosis: El Oussini et al. (63) found that, in mice with ALS-linked SOD1 mutations, the conditional allele of SOD1 (G37R) caused degeneration of serotonergic neurons, leading to the inactivation of 5-HT2B/C receptors, with clinical manifestations such as increased muscle tone and spasticity disorders.