Mitochondrial function is at the root of a wide array of diseases
Because mitochondria are essential energy-converting organelles, dysfunction that affects mitochondrial pathways can have wide-ranging effects throughout the body. Dysfunctional mitochondria are involved in more than 50 diseases which can be broadly classified as primary mitochondrial diseases and secondary mitochondrial diseases.
Primary Mitochondrial Diseases
Primary mitochondrial diseases (PMDs) are a group of rare conditions which affect individuals of all ages. They are genetically inherited and are classified by their causative mutations, which can either occur in mitochondrial DNA or nuclear DNA. Some examples are MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes), NARP (neuropathy, ataxia and retinitis pigmentosa), Leigh syndrome, LHON (Leber hereditary optic neuropathy), MNGIE (mitochondrial neurogastrointestinal encephalopathy), and Alpers. Even within these syndromes, patients’ clinical presentation can vary widely. Therefore an increasing effort is being made to define PMDs more precisely based on the specific genetic mutation a patient presents.
- Prevalence Approx.
1 in 5,000 people
- Age of onset Varies
- Causes Genetic
Secondary Mitochondrial Diseases
Many diseases not typically thought of as mitochondrial diseases nevertheless show signs of mitochondrial involvement, in what is called secondary mitochondrial dysfunction (SMD). SMD can be genetically inherited or it can be acquired, for instance in response to environmental exposures. Diseases involving SMD include neurodegenerative disorders like Alzheimer’s and Parkinson’s diseases, and autoimmune diseases like multiple sclerosis and lupus. Since mutations in mitochondrial DNA accumulate over time, SMD is also one of the most important factors contributing to aging.
- Prevalence Unknown, but likely
much more common
- Age of onset More common with older age
- Causes Genetic or environmental