Myoclonic epilepsy with red ragged fibers (MERRF)

A.Prof Frank Gaillard and Dr Henry Knipe et al.

Myoclonic epilepsy with red ragged fibers (MERRF) is a rare, multisystem mitochondrial disorder

Patients usually present in late adolescence or early adulthood with 1-3

  • myoclonus
  • epilepsy
  • cerebellar ataxia
  • intellectual disability
  • vision and/or hearing loss
  • cardiomyopathy with Wolff-Parkinson-White syndrome
  • short stature

The diagnosis of MERRF is based on clinical symptoms (myoclonus, epilepsy, ataxia) and ragged-red fibers on muscle biopsy 3.

The mitochondrial gene MT-TK, which encodes tRNALys, is the most commonly affected with an A-to-G transition at nucleotide 8344 (80%) 3.

  • serum and CSF lactic acidosis
  • high CSF protein

Neuroradiological features of MERRF can be seen on CT and/or MRI 1,2:

On imaging consider:

  • MELAS: differentiated by the presence of strokes in MELAS
Inborn errors of metabolism
White matter disorders
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Article information

rID: 39666
Section: Syndromes
Tag: cases
Synonyms or Alternate Spellings:
  • Myoclonic epilepsy with red-ragged fibres (MERRF)

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