While these results suggest a possible mechanism for increased synaptic glutamate and excitotoxicity, we must also acknowledge that only 10–20% of patients with FALS harbor SOD1 mutations [85], and SOD1 ALS represents a major outlier in that the hallmark ALS pathology of TDP-43 aggregates are absent in this form of disease [1]. Here, SOD1 is linked to amyotrophic lateral sclerosis.