Research Notes: Reversible Cytochrome C Oxidase (COX) Deficiency

No To Hattatsu. 1996 Sep.
Benign infantile mitochondrial myopathy caused by reversible cytochrome c oxidase deficiency. [Article in Japanese]
Wada H, Nishio H, Nagaki S, Yanagawa H, Imamura A, Yokoyama S, Sano T, Woo M, Matsuo M, Itoh H, Nakamura H.
Department of Pediatrics, Kobe University School of Medicine.

A 2-month-old girl had generalized weakness, profound muscular hypotonia, hepatomegaly and severe lactic acidosis. She needed ventilatory support. Muscle specimen taken at 2 months showed ragged-red fibers, abnormal mitochondria, and reduced cytochrome c oxidase (CCO) staining. Biochemical analysis showed CCO activity to be reduced to about 16% of the normal mean. She received carnitine and coenzyme Q10 supplementation from the age of 3 months and abnormal blood lactate values declined to near normal values during the first three weeks. Gradually her condition started to improved: she held her head at 9 months, and walked alone at 15 months. The second biopsy specimen at 3 years and 8 months showed almost normal CCO staining and she was free of clinical signs. This case is an example of a rare benign infantile mitochondrial myopathy caused by CCO deficiency. Early diagnosis is crucial to provide intensive treatment until spontaneous clinical improvement appears. We concluded that carnitine and coenzyme Q10 supplementation was a useful treatment for clinical improvement in patients with a benign infantile mitochondrial myopathy caused by CCO deficiency.

J Neurol Sci. 1992 Mar.
Defects of the mitochondrial respiratory chain complexes in three pediatric cases with hypotonia and cardiac involvement.
Figarella-Branger D, Pellissier JF, Scheiner C, Wernert F, Desnuelle C.
Laboratoire d'Anatomie Pathologique, Hôpital de la Timone, Marseille, France.

Three children displaying hypotonia, cardiac involvement and defects of the mitochondrial respiratory chain complexes are reported. The first case showed severe neonatal hypotonia, failure to thrive, hepatomegaly, dilation of the right cardiac cavities, profound lactic acidosis and amino aciduria. The boy died at the age of 7 weeks. In the second case hypotonia, severe cardiomyopathy, cyclic neutropenia, lactic acidosis and 3-methylglutaconic aciduria occurred. The boy died at the age of 27 months. The third case presented at the age of 16 months as an acute hypokinetic hypertrophic cardiomyopathy with transient hypotonia and mild lactic acidosis. Spontaneous clinical remission occurred. In all cases muscle biopsy was performed. Morphological studies failed to show ragged-red fibers but there was lipid storage myopathy and decreased cytochrome c oxidase activity. Biochemical studies confirmed the cytochrome c oxidase deficiency in muscle in all cases. It was associated with complex I III deficiency in case 1 and with severe deficits of all respiratory chain complexes in case 2. Post-mortem studies in case 1 indicated that complex IV was reduced in the liver but not in the heart and quantitative analysis of mtDNA revealed a depletion in muscle. Cases 1 and 2 shared some clinical features with fatal infantile myopathy associated with cytochrome c oxidase deficiency, while case 3 displayed a very unusual clinical presentation. The histochemical enzyme reaction of cytochrome c oxidase is useful for the diagnosis of mitochondrial myopathy because ragged-red fibers may be lacking. Finally, biochemical measurement of the different mitochondrial respiratory chain complexes is required because multiple defects are frequent and occasionally related to mtDNA depletion.

No To Hattatsu. 1989 Nov.
Benign infantile mitochondrial myopathy due to reversible cytochrome c oxidase deficiency: histological and biochemical analysis. [Article in Japanese]
Suzuki M, Sugie H, Tsurui S, Miyamoto R, Sugie Y, Igarashi Y, Kaku H, Fukami S.

We reported a 3-week-old girl with profound generalized weakness, requiring assisted ventilation. There was no consanguinity or family history of any neuromuscular disorders. Serum levels of GOT, GPT and CK were slightly elevated. Although the clinical manifestations mimicked those of Werdning-Hoffmann disease, a lack of the respiratory muscle involvement and the presence of high serum lactate levels suggested an underlying metabolic disorder. During the observation over the months, she gradually improved clinically and assisted ventilation was discontinued at 19 months. Muscle biopsies were performed at 4 and 19 months of age. The first biopsy showed an excessive mitochondrial aggregation and numerous ragged-red fibers. The second biopsy revealed rare ragged-red fibers. However there were definite neurogenic changes including type grouping and angulated fibers. Cytochrome c oxidase (CCO) stain was positive in less than 5% of fibers in the first biopsy but in all fibers in the second biopsy. Biochemical analysis using muscle specimens showed a decreased CCO activity; 18.5% of the control level in the first biopsy and 53.3% in the second biopsy. Immunocytochemistry showed the presence of immunologically reactive enzyme protein in both biopsies. Clinical manifestations of our patient were almost identical to those of two cases reported by DiMauro, et al (1983). The enzyme defect in this case was reversible in contrast to that in the fatal infantile form of CCO deficiency. Histochemical and biochemical bases for these differences were discussed.

Neurology. 1987 Jan.
Benign reversible muscle cytochrome c oxidase deficiency: a second case.
Zeviani M, Peterson P, Servidei S, Bonilla E, DiMauro S.

A 6-week-old boy had generalized weakness, requiring assisted ventilation, and lactic acidosis. At 6 months, the lactic acidosis resolved, and the patient started to improve; assisted ventilation was discontinued at 15 months. Muscle biopsies at 4 and 11 months showed accumulation of mitochondria, lipid, and glycogen; cytochrome c oxidase (COX) activity was 11% of the lowest control in the first biopsy and 57% in the second. Immunocytochemistry and immunotitration showed presence of immunologically reactive enzyme protein in both biopsies. This case confirms a previous report of benign infantile myopathy due to reversible COX deficiency. The severe fibrosis in the second biopsy may explain the slower rate of clinical recovery in this child.

Ann Neurol. 1983 Aug.
Benign infantile mitochondrial myopathy due to reversible cytochrome c oxidase deficiency.
DiMauro S, Nicholson JF, Hays AP, Eastwood AB, Papadimitriou A, Koenigsberger R, DeVivo DC.

A 2-week-old boy had profound generalized weakness, hypotonia, hyporeflexia, macroglossia, and severe lactic acidosis. The infant improved spontaneously: he held his head at 4 1/2 months, rolled over at 7 months, and walked by 16 months. At 33 months of age, he had mild proximal weakness. Macroglossia disappeared by age 4 months. Blood lactic acid declined steadily and was normal by 14 months of age. Histochemical and ultrastructural studies of muscle biopsy specimens obtained at 1 and 7 months of age showed excessive mitochondria, lipid, and glycogen; a third biopsy at age 36 months showed only atrophy of scattered fibers. Cytochrome c oxidase stain was positive in fewer than 5% of fibers in the first biopsy, in approximately 60% of fibers in the second biopsy, and in all fibers in the third biopsy. Biochemical analysis showed an isolated defect of cytochrome c oxidase activity, which was only 8% of the lowest control level in the first biopsy; the activity increased to 47% in the second biopsy and was higher than normal in the third. In contrast to that in the fatal infantile form of cytochrome c oxidase deficiency, the enzyme defect in this condition is reversible. The biochemical basis for this difference remains to be explained.