Benign mitochondrial myopathy with decreased succinate cytochrome C reductase activity.
In most of the cases previously described, the defect on complex II was suggested by low activity of succinate cytochrome C reductase (SCCR). The clinical pattern of the previous 10 cases is heterogeneous and may be limited to one particular tissue or be of a more general nature. We report a 22-year-old-woman, daughter of consanguineous parents, with generalized muscle weakness, easy fatigability and benign course, who showed a decrease of SCCR activity in mitochondria of muscle fibers. Free carnitine (FC) concentration was decreased in muscle as well. The muscle biopsy showed a mild variation in fiber size, with fiber type I predominance, subsarcolemmal oxidative DPNH accumulations, excess of neutral lipids and abnormally large mitochondria with paracrystalline inclusions. A possible inheritance pattern is discussed. Coenzyme Q10 therapy in this patient induced a significant increase of global MRC index score and a decrease of the turns-mean amplitude ratio in the automatic analysis of the EMG.
Servicio de Neurología, Hospital La Paz, Madrid, Spain.
J
J
Arpa
Y
Y
Campos
M
M
Gutiérrez-Molina
A
A
Cruz-Martínez
J
J
Arenas
A B
AB
Caminero
F
F
Palomo
C
C
Morales
P
P
Barreiro
D000328:Adult; D001706:Biopsy; D003241:Consanguinity; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D008854:Microscopy, Electron; D017240:Mitochondrial Myopathies / Q000175:diagnosis / Q000201:enzymology / Q000235:genetics*; D009132:Muscles / Q000473:pathology; D009460:Neurologic Examination; D013384:Succinate Cytochrome c Oxidoreductase / Q000172:deficiency* / Q000235:genetics
D013384:Succinate Cytochrome c Oxidoreductase; D003402:Creatine Kinase