Abstract
We report a novel pathogenic mutation of the mitochondrial transfer RNA (tRNA) gene for tryptophan in a patient with isolated myopathy and persistently elevated creatine kinase. Muscle studies revealed ragged red fibres and decreased activity of respiratory chain complex I and cytochrome c oxidase (COX). Sequencing of the 22 mitochondrial tRNA genes revealed a mutation m.5522G>A, which alters a conserved base pairing in the D-stem of the tRNA for tryptophan. The mutation was heteroplasmic with a mutational load between 88 and 99% in COX-negative fibres. This case contributes to the genetic heterogeneity of mitochondrial diseases caused by mutations in mitochondrial tRNA genes.
Publication types
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Case Reports
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Research Support, Non-U.S. Gov't
MeSH terms
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Adolescent
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Base Sequence
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DNA Mutational Analysis
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DNA, Mitochondrial / chemistry
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DNA, Mitochondrial / genetics
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Electron Transport Complex I / metabolism
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Electron Transport Complex IV / metabolism
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Humans
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Immunohistochemistry
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Male
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Microscopy, Electron
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Mitochondrial Myopathies / genetics*
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Mitochondrial Myopathies / metabolism
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Molecular Sequence Data
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Muscle Fibers, Slow-Twitch / metabolism
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Muscle Fibers, Slow-Twitch / pathology
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Muscle Fibers, Slow-Twitch / ultrastructure
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Point Mutation*
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RNA, Transfer, Trp / genetics*
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Sequence Homology, Nucleic Acid
Substances
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DNA, Mitochondrial
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RNA, Transfer, Trp
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Electron Transport Complex IV
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Electron Transport Complex I