What are Genetic Mitochondrial Diseases?
Genetic mitochondrial diseases are disorders caused by dysfunctional mitochondria, the cellular organelles responsible for producing cellular energy. These disorders can arise from mutations in either the nuclear DNA or the mitochondrial DNA, highlighting the complex interplay between genetic factors and mitochondrial dysfunction. Mitochondrial diseases can present from early childhood to adulthood and include Barth syndrome, Friedreich’s ataxia, Leigh and Leigh-like syndrome, and Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).
These conditions can cause severe symptoms but are often difficult to diagnose. If an experienced physician is involved, a diagnosis can be made through a combination of clinical observation, laboratory evaluation, genetic profiling, imaging studies, and a muscle biopsy. Referral to an appropriate research center is critical.
Common symptoms of genetic mitochondrial diseases can include:
- Liver disease
- Heart disease
- Hyperglycemia
- Chronic fatigue
- Muscle weakness
- Growth retardation
- Visual and hearing issues
- Gastrointestinal symptoms
How are Genetic Mitochondrial Diseases Linked to Mitochondrial Dysfunction?
While the vast majority of the cell’s genes are contained within the nucleus, the mitochondria possess their own genetic material. Individual mitochondrial genes, as well as nuclear genes critical to mitochondrial functioning, can become damaged during gene replication. These mutations can then be passed on to children.
Genetic mitochondrial diseases result from a failure of the mitochondria to function properly. This leads to less cellular energy, progressive cell damage and cell death. The most common organs that may experience damage are the brain, heart, liver, muscles, kidneys and the endocrine system.
Although extensive research is ongoing, treatment options are currently limited. Micronutrient supplements containing substantial dosages of antioxidants are often prescribed. N-acetyl-cysteine (NAC) has been shown to play an important role in improving mitochondrial functioning [1]. Several small pharmaceutical companies are also currently researching treatments for genetic mitochondrial diseases including Stealth BioTherapeutics, Raptor Pharmaceuticals, and Reata Pharmaceuticals.
References: [1] Zhou, J., Terluk, M. R., Orchard, P. J., Cloyd, J. C., & Kartha, R. V. (2021, December 3). N-Acetylcysteine Reverses the Mitochondrial Dysfunction Induced by Very Long-Chain Fatty Acids in Murine Oligodendrocyte Model of Adrenoleukodystrophy. Biomedicines. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8698433/