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Multiple mitochondrial DNA deletions in monozygotic twins with OPMD
  1. M M K Muqit1,2,
  2. A J Larner1,3,
  3. M G Sweeney2,
  4. C Sewry4,
  5. V J Stinton2,
  6. M B Davis2,
  7. D G Healy2,
  8. S J Payne5,
  9. K Chotai5,
  10. N W Wood2,
  11. R J M Lane1
  1. 1
    Division of Clinical Neurosciences and Psychological Medicine, Imperial College London, UK
  2. 2
    Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London, UK
  3. 3
    Walton Centre for Neurology and Neurosurgery, Liverpool, UK
  4. 4
    Dubowitz Neuromuscular Unit, Department of Paediatrics, Hammersmith Hospital, London, UK
  5. 5
    Kennedy Galton Centre, Northwick Park and St Mark’s NHS Trust, Harrow, London, UK
  1. Dr R J M Lane, Division of Clinical Neurosciences and Psychological Medicine, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK; r.lane{at}


Background: Oculopharyngeal muscular dystrophy (OPMD) is caused by expansions of the poly (A) binding protein 2 (PABP2) gene. Previous histological analyses have revealed mitochondrial abnormalities in the muscles of OPMD patients but their significance remains uncertain.

Objective: We had the rare opportunity to study monozygotic twins with identical expansions of the PABP2 gene but with markedly different severities of OPMD. Both had histological features of mitochondrial myopathy. We determined whether mitochondrial DNA abnormalities underlay these changes.

Methods: Clinical information was obtained by history and examination. Muscle biopsies were obtained from each subject and genetic analysis was performed using long-range PCR and Southern blotting.

Results: We demonstrate, for the first time, the presence of mitochondrial DNA (mtDNA) deletions by Southern blotting in individuals with OPMD. This correlates with the presence of mitochondrial myopathy in both twins. Moreover, both twins had different mtDNA deletions, which might explain their phenotypic differences.

Conclusion: We hypothesise that mitochondrial dysfunction may occur as a consequence of PABP2 gene mutations, and that this dysfunction may affect the phenotypic manifestations of OPMD.

  • OPMD
  • myopathy
  • mitochondria
  • monozygotic
  • twins

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  • Competing interests: None declared.