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A novel mitochondrial tRNAPhe mutation causes MERRF syndrome

M Mancuso1, M Filosto, V K Mootha

  • 1Department of Neurology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.

Neurology
|June 9, 2004
PubMed

Insights

A novel mitochondrial DNA mutation (G611A) in the tRNA phenylalanine gene was found in a patient with myoclonic epilepsy with ragged red fibers (MERRF). This finding expands the known genetic causes of MERRF syndrome.

Area of Science:

  • Genetics
  • Neuroscience
  • Mitochondrial Diseases

Background:

  • Myoclonic epilepsy with ragged red fibers (MERRF) is a rare mitochondrial disorder.
  • It is typically associated with mutations in the mitochondrial DNA tRNA lysine gene.
  • The genetic basis for MERRF is not fully understood.

Observation:

  • A patient presented with typical MERRF features.
  • A novel heteroplasmic mutation (G611A) was identified in the mitochondrial DNA tRNA phenylalanine gene.
  • This mutation was present at high levels (91%) in muscle tissue.

Findings:

  • The G611A mutation was heteroplasmic and undetectable in other tissues of the patient and relatives.
  • Higher proportions of the mutation were found in cytochrome c oxidase (COX)-negative ragged red fibers (RRFs) compared to COX-positive fibers.
  • This indicates a strong correlation between the mutation and MERRF pathology.

Implications:

  • This study identifies a new genetic cause for MERRF syndrome.
  • It suggests that MERRF can be caused by mutations in genes other than the tRNA lysine gene.
  • This expands the diagnostic possibilities for MERRF and related mitochondrial disorders.

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