POLG-associated diseases are caused by mutations in a gene needed to maintain DNA inside mitochondria, as shown in the microscope image above. (Image credit: Shutterstock)
Disease name: Polymerase gamma-associated diseases, abbreviated as POLG-associated diseases.
Affected populations: POLG-related disorders are a series of rare and incurable conditions caused by inherited gene mutations. These disease-causing mutations occur in 2% of people of Northern European descent. However, not all mutation carriers ultimately develop a POLG-related disorder.
These diseases are estimated to affect approximately 1 in 10,000 people worldwide.
Causes: POLG-related diseases are caused by several hundred different mutations in the POLG gene. This gene codes for a protein in the mitochondria known as DNA polymerase gamma (pol γ), which is needed to replicate and repair the unique DNA found only inside the mitochondria, not in the cell nucleus.
POLG-associated diseases develop in people who inherit one or two copies of the mutated POLG gene from one or both parents.
Mitochondria are the cellular power plants responsible for breaking down carbohydrates and fatty acids in food to produce molecules known as ATP, which the body uses as an energy source.
In patients with POLG-related diseases, defects in polymerase gamma can lead to either a decrease in the amount of DNA in the mitochondria or to mutations in that DNA. In some cases, both can occur.
Eventually, the cells become depleted, which can lead to organ dysfunction and failure.
POLG mutations are the most common cause of inherited mitochondrial diseases, and about 300 mutations in POLG are known to contribute to disease. Examples of POLG-associated diseases include Alpers-Huttenlocher syndrome, ataxia-neuropathy spectrum disorder, and childhood myocerebrohepatopathy spectrum disorder.
People with POLG-related conditions often experience epileptic seizures caused by electrical instability in the brain.
Symptoms: POLG-related conditions can be difficult to diagnose, in part because they can present with a variety of symptoms that vary in severity. These symptoms can also appear at different times throughout a person’s life, from early childhood to adulthood, depending on the specific condition.
Sourse: www.livescience.com
