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Spontaneous recovery of a childhood onset mitochondrial myopathy caused by a stop mutation in the mitochondrial cytochrome c oxidase III gene
  1. R Horváth1,
  2. H Lochmüller2,
  3. M Hoeltzenbein3,
  4. J Müller-Höcker4,
  5. B G Schoser2,
  6. D Pongratz2,
  7. M Jaksch1
  1. 1Metabolic Disease Center Munich-Schwabing, Institutes of Clinical Chemistry, Molecular Diagnostics and Mitochondrial Genetics; Academic Hospital Schwabing, Munich, Germany
  2. 2Friedrich Baur Institute, Department of Neurology, Ludwig Maximilians University, Munich, Germany
  3. 3Max Planck Institute for Molecular Genetics, Berlin, Germany
  4. 4Institute of Pathology, Ludwig Maximilians University, Munich, Germany
  1. Correspondence to:
 Dr. M Jaksch
 Metabolic Disease Center Munich-Schwabing, Institutes of Clinical Chemistry, Molecular Diagnostics and Mitochondrial Genetics, Academic Hospital Schwabing, Kölner Platz 1, 80804 München, Germany; michaela.jakschlrz.uni-muenchen.de

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In general, the clinical course of patients suffering from different types of mtDNA mediated neurodegenerative disorders progresses with age.1 The clinical progression of muscle weakness has been reported to correlate with an increase in cytochrome c oxidase (COX) negative fibres2 or with an increase of mutant mtDNA in skeletal muscle.3

In a recent issue we reported on a patient with mitochondrial myopathy with ragged red fibres (RRF), lactic acidosis, exercise intolerance, and delayed growth, with a heteroplasmic G9379A nonsense mutation (W58X) in the mtDNA encoded COIII subunit gene.4 A follow up examination of the patient showed significant improvement of the neurological symptoms. Here we present the results of detailed clinical, histological, immunohistological, biochemical, and genetic investigations of a repeated muscle biopsy, which all confirm a spontaneous regression of the disease.

PATIENT AND METHODS

Case report

The early clinical history of the patient has been previously reported in detail4 and is now compared with recent examinations (table 1). In brief, he developed exercise intolerance, generalised muscle weakness with painful muscle cramps, and fatigue at the age of 6 years, and his symptoms were progressing. On examination at 14 years of age, his somatic growth was delayed and he presented generalised mild muscle weakness, muscular hypotonia, and scapular winging. Symptomatic therapy with l-carnitin (2×10 ml), sodium hydrogen carbonate, and regular physiotherapy were initiated.

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Table 1

Summary of the clinical, histological, biochemical and genetic data of the patient at 14 and 20 years of age

From the age of 16 years the patient’s symptoms improved gradually. At 19 years of age rapid growth was noted, but his weight remained low. A detailed neurological examination was carried out at his present age of 20 years. The patient reported an improvement in his muscle strength and the resolution of exercise intolerance. Episodes of myoglobinuria were never …

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Footnotes

  • Conflict of interest: none declared