MERRF is a maternally inherited neurodegenerative disorder.
Within an affected family, maternal relatives progress through the following stages of the disease:
- neurosensory deafness
- myoclonic epilepsy
- progressive dementia
- cardiac failure
- renal failure
This degenerative neurological disease 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.
The clinical severity correlates with the loss of oxidative phosphorylation complexes in the mitochondria.