Mitochondrial diseases, caused by mutation in either a nuclear or mitochondrial gene, usually affect many different parts of the body. In addition, not every person with the same mitochondrial disease has the same symptoms, which may also change over time. For these reasons, mitochondrial diseases are often difficult to diagnose. Some of the more common symptoms of a mitochondrial disease are listed below.
- Loss of motor control (inability to voluntarily move muscles)
- Muscle weakness and pain
- Gastro-intestinal (digestive) disorders
- Swallowing difficulties
- Poor growth
- Cardiac (heart) disease
- Liver disease
- Respiratory (breathing) complications
- Visual and/or hearing problems
- Lactic acidosis (lack of oxygen to the cells that can lead to rapid breathing, vomiting and stomach pain)
- Developmental delays
- Susceptibility to infection
Although mitochondrial diseases are somewhat rare, the function of mitochondria can also be affected in many more common conditions, such as diabetes, Parkinson disease, multiple sclerosis, stroke and heart disease. Mitochondrial dysfunction has even been implicated in causing normal aging. Research to identify new treatments to improve mitochondrial function will thus not only be helpful for patients with traditional mitochondrial diseases, but also for the treatment of individuals with these more common conditions.