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Reversible infantile respiratory chain deficiency: A clinical and molecular study

Authors

  • Masakazu Mimaki MD, PhD,

    1. Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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  • Hideyuki Hatakeyama PhD,

    1. Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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  • Hirofumi Komaki MD,

    1. Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
    2. Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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  • Mina Yokoyama MD,

    1. Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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  • Hidee Arai MD,

    1. Department of Neurology, Chiba Children's Hospital, Chiba, Japan
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  • Yohei Kirino PhD,

    1. Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
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  • Tsutomu Suzuki PhD,

    1. Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
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  • Ichizo Nishino MD, PhD,

    1. Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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  • Ikuya Nonaka MD, PhD,

    1. Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
    2. Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
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  • Yu-ichi Goto MD, PhD

    Corresponding author
    1. Department of Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
    2. Department of Child Neurology, National Center Hospital of Neurology and Psychiatry, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
    • National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8502, Japan
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  • Potential conflict of interest:

Abstract

Objective

To characterize the clinical features and clarify the pathogenicity of “benign cytochrome c oxidase deficiency myopathy.”

Methods

The study included 8 patients with the phenotype of this disease. Six patients underwent muscle biopsies and all the 8 underwent mitochondrial DNA analyses. To confirm the pathogenicity of the detected mitochondrial DNA mutation, we performed northern blot analysis, using muscle specimens, and blue native polyacrylamide gel electrophoresis and respiratory chain enzyme activity assay of transmitochondrial cell lines (cybrids).

Results

Clinical symptoms were limited to skeletal muscle and improved spontaneously in all cases; however, 2 siblings had basal ganglia lesions. In all patients, we identified a homoplasmic m.14674T>C or m.14674T>G mitochondrial transfer RNA-glutamate mutation. Northern blot analysis revealed decreased levels of mitochondrial transfer RNA-glutamate molecules. Muscle specimens and cybrids derived from patients showed decreased activity of respiratory complexes IV, and/or I, III; however, this was normal in naive myoblasts.

Interpretation

Identification of a novel m.14674T>G mutation in addition to m.14674T>C indicated the importance of this site for disease causation. Analyses of cybrids revealed the pathogenicity of m.14674T>C mutation, which resulted in defects of cytochrome c oxidase and multiple respiratory chain enzymes. Furthermore, patients with basal ganglia lesions provided new insights into this disease, in which only skeletal muscle was thought to be affected. Normal respiratory chain enzyme activities in naive myoblasts suggested the compensatory influence of nuclear factors, which may be a clue to understanding the mechanisms of spontaneous recovery and low penetrance in families carrying the mutation. ANN NEUROL 2010

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