A case of mitochondrial encephalomyopathy associated with a muscle coenzyme Q10 deficiency

J Neurol Sci. 1998;156(1):41-6. doi: 10.1016/s0022-510x(98)00006-9.


We report severe coenzyme Q10 deficiency of muscle in a 4-year-old boy presenting with progressive muscle weakness, seizures, cerebellar syndrome, and a raised cerebro-spinal fluid lactate concentration. State-3 respiratory rates of muscle mitochondria with glutamate, pyruvate, palmitoylcarnitine, and succinate as respiratory substrates were markedly reduced, whereas ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine were oxidized normally. The activities of complexes I, II, III and IV of the electron transport chain were normal, but the activities of complexes I+III and II+III, both systems requiring coenzyme Q10 as an electron carrier, were dramatically decreased. These results suggested a defect in the mitochondrial coenzyme Q10 content. This was confirmed by the direct assessment of coenzyme Q10 level by high-performance liquid chromatography in patient's muscle homogenate and isolated mitochondria, revealing levels of 16% and 6% of the control values, respectively. We did not find any impairment of the respiratory chain either in a lymphoblastoid cell line or in skin cultured fibroblasts from the patient, suggesting that the coenzyme Q10 depletion was tissue-specific. This is a new case of a muscle deficiency of mitochondrial coenzyme Q in a patient suffering from an encephalomyopathy.

Publication types

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

MeSH terms

  • Cerebellar Ataxia / complications
  • Child, Preschool
  • Coenzymes
  • Electron Transport
  • Epilepsy / complications
  • Humans
  • Kinetics
  • Lactic Acid / cerebrospinal fluid
  • Male
  • Mitochondria, Muscle / pathology
  • Mitochondrial Encephalomyopathies / cerebrospinal fluid
  • Mitochondrial Encephalomyopathies / complications
  • Mitochondrial Encephalomyopathies / physiopathology*
  • Muscle, Skeletal / physiopathology
  • Polarography
  • Retinal Diseases / complications
  • Ubiquinone / analogs & derivatives*
  • Ubiquinone / physiology


  • Coenzymes
  • Ubiquinone
  • Lactic Acid
  • coenzyme Q10