A case of mitochondrial myopathy, lactic acidosis and complex I deficiency

J Neurol. 1990 Nov;237(7):399-404. doi: 10.1007/BF00314729.


A 34-year-old man affected by exercise intolerance, mild proximal weakness and severe lactic acidosis is described. Muscle biopsy revealed mitochondrial abnormalities and an increase of cytochrome c oxidase histochemical reaction. Biochemical investigations on isolated muscle mitochondria as well as polarographic studies revealed a mitochondrial NADH-CoQ reductase (complex I) deficiency. Mitochondrial dysfunction was confirmed by 31P nuclear magnetic resonance spectroscopy. Immunological investigation showed a generalized reduction of all complex I polypeptides. Genetic analysis did not reveal mitochondrial DNA deletions. The biochemical defect was not present in the patient's muscle tissue culture. Metabolic measurements and functional evaluation showed a reduced mechanical efficiency during exercise.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acidosis, Lactic / etiology*
  • Adenosine Triphosphate / metabolism
  • Adult
  • Cells, Cultured
  • DNA, Mitochondrial / analysis
  • Enzyme-Linked Immunosorbent Assay
  • Exercise / physiology
  • Humans
  • Magnetic Resonance Spectroscopy
  • Male
  • Mitochondria, Muscle* / ultrastructure
  • Muscles / metabolism
  • Muscles / ultrastructure
  • Muscular Diseases / genetics
  • Muscular Diseases / metabolism*
  • Muscular Diseases / pathology
  • NAD(P)H Dehydrogenase (Quinone)
  • Oxygen Consumption / physiology
  • Phosphocreatine / metabolism
  • Quinone Reductases / deficiency*


  • DNA, Mitochondrial
  • Phosphocreatine
  • Adenosine Triphosphate
  • NAD(P)H Dehydrogenase (Quinone)
  • Quinone Reductases