A case of mitochondrial encephalomyopathy associated with a muscle coenzyme Q10 deficiency.
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.
Boitier
E
E
INSERM U75, Faculté de Médecine Necker-Enfants Malades, Paris, France.
Degoul
F
F
Desguerre
I
I
Charpentier
C
C
François
D
D
Ponsot
G
G
Diry
M
M
Rustin
P
P
Marsac
C
C
D002524:Cerebellar Ataxia / Q000150:complications; D002675:Child, Preschool; D003067:Coenzymes; D004579:Electron Transport; D004827:Epilepsy / Q000150:complications; D006801:Humans; D007700:Kinetics; D019344:Lactic Acid / Q000134:cerebrospinal fluid; D008297:Male; D008931:Mitochondria, Muscle / Q000473:pathology; D017237:Mitochondrial Encephalomyopathies / Q000134:cerebrospinal fluid / Q000150:complications / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D011048:Polarography; D012164:Retinal Diseases / Q000150:complications; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000502:physiology
D003067:Coenzymes; D014451:Ubiquinone; D019344:Lactic Acid; C024989:coenzyme Q10