The difference between cancer cell mitochondria and normal cells includes several functional alterations, such as mutation of mtDNA that lead to OXPHOS (oxidative phosphorylation) inhibition and thus deficient respiration and ATP generation, mutation of mtDNA-encoded mitochondrial enzymes, such as SDH (succinate dehydrogenase), IDH1 (isocitrate dehydrogenase 1), IDH2 (isocitrate dehydrogenase 2) [16], and structural differences, such as higher membrane potential of cancer cell mitochondria and higher basicity inside the mitochondrial lumen. The gene discussed is IDH2; the disease is cancer.