Question

Mitochondria

•Myoclonic Epilepsy

•Ragged Red-fiber Disease

•Leber’s Optic Neuropathy

All are associated with ATP generation problems and affect organs with high ATP demands (why)?

Answer 1

1. Myoclonic epilepsy refers to a family of epilepsies that present with myoclonus. Myoclonic epilepsy with ragged-red fibers (MERRF) is a disorder that affects many parts of the body, particularly the muscles and nervous system.
2. Mutation in MT-TK (mitochondrially encoded tRNA lysine) gene are the most common cause of myoclonic epilepsy.
3. MT-TK is contained in mitochondrial genome and is involved in oxidative phosphorylation, a process that produces ATP through electron transport chain..
4. Mutations that cause myoclonic epilepsy impair the ability of mitochondria to make proteins, use oxygen, and produce energy. These mutations particularly affect organs and tissues with high energy requirements, such as the brain and muscles.
5. Leber’s hereditary optic neuropathy (LHON) is a severe mitochondrial optic neuropathy disease leading to central vision loss in both eyes. People living with LHON will often find it impossible to read, drive or recognize faces.
6. LHON is usually due to one of three pathogenic mitochondrial DNA (mtDNA) point mutations. Mutations in the MT-ND1, MT-ND4, MT-ND4L, and MT-ND6 genes cause Leber hereditary optic neuropathy.
7. These genes code for the NADH dehydrogenase protein involved in the normal mitochondrial function of oxidative phosphorylation.
8. Thus all these diseases are directly linked with problems in mitochondrial genome which has an important role in cellular respiration and production of energy in the form of ATP.