Schematic representation of altered mitochondrial enzymes in NMDs. Mitochondrial metabolic pathways involved in NMDs are shown, and mutated enzymes are highlighted in red. For details, see the text. α-KG, α-ketoglutarate; ACAD, acyl-CoA dehydrogenase; ACO, aconitase; ASP, aspartate; CIT, citrate; CoASH, coenzyme A; ECH, 2-enoyl-CoA hydratase; FUM, fumarate; IDH, isocitrate dehydrogenase; ISO, isocitrate; MAL, malate; MDH, malate dehydrogenase; Mfn1/2, mitofusins 1 and 2; OAA, oxaloacetate; OPA1, optic atrophy 1 protein; SDH, succinate dehydrogenase; SUC, succinate; TCA, tricarboxylic acid cycle.