Disorders of the mitochondrial respiratory chain: clinical manifestations and diagnostic approach

The clinical identification of patients with defects in the mitochondrial respiratory chain is almost impossible. We describe screening tests that should be performed in order to select those patients in whom a skeletal muscle biopsy should be carried out for more specific biochemical assays. The importance of performing in vivo function tests is stressed. The biochemical diagnosis in disorders of the respiratory chain is presented and the application of immunological methods discussed.Abbreviations ATP adenosine triphosphate - CoA coenzyme A - DCPIP 2,6-dichlorophenol indophenol - KCN potassium cyanide - NAD⁺ nicotinamide adenine dinucleotide (oxidized) - NADH nicotinamide adenine dinucleotide (reduced) - PMS phenazine methosulfate