MERRF syndrome (Myoclonic Epilepsy with Ragged Red Fibers)
MERRF syndrome (or Myoclonic Epilepsy with Ragged Red Fibers) is a mitochondrial disease. It involves progressive myoclonic epilepsy, clumps of diseased mitochondria accumulated in the subsarcolemmal region of the muscle fiber which appear as “ragged-red fibers” when muscle is stained with modified Gomori trichrome stain, and short stature. MERRF syndrome is caused by a maternally-inherited mutation at position 8344 in the mitochondrial genome. This point mutation disrupts the mitochondrial gene for tRNA-Lys and so disrupts synthesis of proteins essential for oxidative phosphorylation. Many genes are involved, including MT-TK, MT-TL1, MT-TH, MT-TS1, MT-TS2, and MT-TF.