POLG (DNA polymerase gamma) is an enzyme that plays a crucial role in mitochondrial DNA replication and repair. Mutations in POLGgene can result in a wide spectrum of mitochondrial diseases with various clinical presentations, ranging from infantile-onset fatal disorders to adult-onset neurodegenerative diseases.
Some of the diseases associated with mutations in the POLGgene include:
1. Alpers-Huttenlocher syndrome: It is a severe, progressive disorder that affects infants and children. Symptoms usually start with seizures, followed by liver failure, loss of cognitive and motor skills, and eventual death.
2. Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO): It is a rare disorder that affects the nervous system, resulting in a loss of coordination, muscle weakness, difficulty speaking, and eye muscle weakness.
3. Ataxia-neuropathy syndrome: It is a disorder that affects the nervous system, resulting in a progressive loss of coordination and muscle control. Other symptoms include muscle weakness, vision problems, and hearing loss.
4. Myoclonic epilepsy with ragged red fibers (MERRF): It is a rare disorder that affects the muscles and nervous system. Symptoms usually include myoclonus (sudden, brief muscle spasms), seizures, muscle weakness, and ataxia.
5. Progressive external ophthalmoplegia (PEO): It is a rare disorder that affects the muscles that control eye movements. Symptoms include droopy eyelids, difficulty moving the eyes, and weakness in other muscles.
6. Autosomal dominant progressive external ophthalmoplegia (adPEO): It is a milder form of PEO that typically starts in adulthood. Symptoms include ptosis (droopy eyelids), difficulty moving the eyes, and weakness in other muscles.
The severity and age of onset of these disorders can vary widely, even among individuals with the same mutation in the POLGgene.
POLG