Some Practical Aspects of Providing a Diagnostic Service for Respiratory Chain Defects

Ann Clin Biochem. 2003 Jan;40(Pt 1):3-8. doi: 10.1258/000456303321016114.


The oxidative phosphorylation system (OXPHOS) is organized into five multi-protein complexes, comprising four complexes (I-IV) of the respiratory chain and ATP synthase (complex V). OXPHOS has a vital role in cellular energy metabolism and ATP production. Enzyme analysis of individual OXPHOS complexes in a skeletal muscle biopsy remains the mainstay of the diagnostic process for patients suspected of mitochondrial cytopathy. Practical guidelines are presented to provide optimal conditions for performance of laboratory investigations and a reliable diagnosis. A fresh muscle biopsy is preferable to a frozen muscle sample because the overall capacity of the OXPHOS system can be measured in a fresh biopsy. In about 25% of patients referred for muscle biopsy to our centre, reduced substrate oxidation rates and ATP+creatine phosphate production rates were found without any defect in complexes I-V and the pyruvate dehydrogenase complex. Investigation of frozen muscle biopsy alone may lead to false-negative diagnoses in many patients. In some patients, it is necessary to investigate fibroblasts for prospective diagnostic purposes. An exact diagnosis of respiratory chain defects is a prerequisite for rational therapy and genetic counselling. Provided guidelines for specimen collection are followed, there are now reliable methods for identifying respiratory chain defects.

Publication types

  • Review

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Biopsy
  • Fibroblasts / metabolism
  • Humans
  • Mitochondrial Diseases / diagnosis*
  • Mitochondrial Myopathies / diagnosis*
  • Models, Biological
  • Muscle, Skeletal / pathology
  • Oxidative Phosphorylation*
  • Oxygen / metabolism
  • Prenatal Diagnosis


  • Adenosine Triphosphate
  • Oxygen