MERRF (Myoclonic Epilepsy with Ragged Red Fibers) syndrome is primarily caused by genetic mutations in mitochondrial DNA (mtDNA).
More specifically:
- Genetic Mutation: The most common cause is the A8344G point mutation in the mitochondrial tRNA-Lys gene. This single nucleotide change disrupts mitochondrial function. This mutation accounts for over three-fourths of MERRF cases.
- Mitochondrial Dysfunction: The mutation affects the mitochondria's ability to produce energy effectively via oxidative phosphorylation.
- Muscle Biopsy: A key diagnostic feature is the presence of "ragged-red fibers" in muscle biopsies. These fibers are muscle cells with abnormal accumulations of mitochondria.
In summary, MERRF syndrome is caused by mutations, most frequently the A8344G mutation in the mitochondrial tRNA-Lys gene, leading to impaired mitochondrial function.
