We have previously observed altered metabolic responses in fibroblasts from both SOD1 and sporadic ALS cases (Allen et al., 2014, 2015; Raman et al., 2015), but now, with the adoption of our novel metabolic screening approach, we can conclude with confidence that inherent metabolic flexibility is vital in the CNS and is reduced in ALS patients. Here, SOD1 is linked to amyotrophic lateral sclerosis.