Previously, we discovered that the generation of succinyl-CoA by the TCA cycle is associated with slower disease progression in ALS.76 Succinyl-CoA is the end-product of the reaction catalyzed by methylmalonyl-CoA mutase and therefore a higher concentration of succinyl-CoA might be expected to shift the reaction equilibrium point and reduce vitamin B12 depletion. The gene discussed is MMUT; the disease is amyotrophic lateral sclerosis.