Mitochondrial dysfunction with myoclonus epilepsy and ragged-red fibers point mutation in nerve, muscle, and adipose tissue of a patient with multiple symmetric lipomatosis

Muscle Nerve. 1997 Jul;20(7):833-9. doi: 10.1002/(sici)1097-4598(199707)20:7<833::aid-mus7>;2-8.


We report a 64-year-old man presenting with multiple symmetric lipomatosis (MSL) and mitochondrial encephalomyoneuropathy. The diagnosis of a mitochondrial cytopathy was based on the typical clinical symptoms and signs, including chronic progressive external ophthalmoplegia, hearing impairment, cerebellar ataxia, proximal myopathy, and polyneuropathy, and on molecular genetic and histological examinations. As a unique finding, the A-->G(8344) myoclonus epilepsy and ragged-red fibers point mutation was found in peripheral nerve, muscle, and adipose tissue. Muscle biopsy revealed multiple ragged-red fibers and other morphological signs of a mitochondrial myopathy. Sural nerve biopsy demonstrated a mixed axonal and demyelinating neuropathy with extensive loss of myelinated fibers and conspicuous onion bulb formations, as well as structural mitochondrial abnormalities on electron microscopy. These findings clearly demonstrate mitochondrial dysfunction in muscle, adipose tissue, and for the first time also in nervous tissue of an MSL patient, and strongly support the concept of mitochondrial cytopathy as one of the possible causes of multiple symmetric lipomatosis.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / physiopathology
  • Atrophy
  • Biopsy
  • Cerebellum / pathology
  • Cerebellum / physiopathology
  • DNA Mutational Analysis
  • Electroencephalography
  • Electron Transport / physiology
  • Epilepsies, Myoclonic / complications*
  • Epilepsies, Myoclonic / diagnosis
  • Evoked Potentials, Motor
  • Humans
  • Lipomatosis, Multiple Symmetrical / complications*
  • Lipomatosis, Multiple Symmetrical / genetics
  • MERRF Syndrome / complications
  • MERRF Syndrome / genetics*
  • Magnetic Resonance Imaging
  • Male
  • Microscopy, Electron
  • Middle Aged
  • Mitochondria / enzymology
  • Muscle, Skeletal / pathology
  • Muscle, Skeletal / physiopathology
  • Muscle, Skeletal / ultrastructure
  • Peripheral Nerves / physiopathology
  • Point Mutation
  • Tomography, X-Ray Computed