Mitochondrial disease refers to a group of conditions that affect how mitochondria work. While there is no cure for mitochondrial disease, supportive care can help prevent life threatening complications.
The mitochondria make energy for almost all cells in the body. When they cannot function, it can affect various body processes, and a person may experience widespread symptoms. However, the severity of the condition can vary greatly.
Several types of mitochondrial diseases exist. Doctors may find mitochondrial diseases challenging to diagnose, and one reason for this could be the vastness of symptoms. In most cases of mitochondrial disease, there is an underlying genetic cause.
Keep reading to learn about mitochondrial diseases, including types, symptoms, diagnosis, treatment, and outlook.
As the name suggests, mitochondrial diseases are conditions that affect the mitochondria in the cells. Most cells in the body contain mitochondria, the main function of which is to provide energy. Mitochondria does this by converting sugar and oxygen into a usable form for the body. The heart, brain, and muscles need a lot of energy to function.
When mitochondria do not work correctly, the cells cannot function as they should. Several types of mitochondrial diseases exist. Some types affect many parts of the body, while other forms only affect one or a few parts.
Experts estimate that mitochondrial diseases occur in about (or more than)
- 23 cases per 100,000 people in northeast England
- 5.7 cases per 100,000 people in Spain
- 2.9 cases per 100,000 people in Japan
Additionally, a study in Canada found a prevalence of
Here are more details about some mitochondrial conditions:
Chronic progressive external ophthalmoplegia (CPEO)
This type mainly affects the muscles in and around the eye. A person with CPEO may not be able to raise their eyelids. Over time, the muscles that manage eye movement become weaker.
The condition can also affect other muscles in the body. Beyond eye muscles, CPEO can weaken muscles in the neck, arms, and legs.
Generally, Pearson syndrome leads to low levels of red and white blood cells and platelets. This may lead to the following:
Leigh syndrome is a severe type of mitochondrial disease. It affects muscles throughout the body and lowers brain function.
Doctors often diagnose it early in a person’s life. The condition can significantly reduce life expectancy.
Neuropathy, ataxia, and retinitis pigmentosa (NARP)
NARP can affect the following functions:
- nerves, leading to numbness or tingling in limbs
- movement, leading to difficulties with coordination and balance
- eyes, leading to damage to the retina and loss of vision
Myoclonus epilepsy with ragged red fibers (MERRF)
One of the first symptoms of MERRF is random and quick muscle twitching. As it progresses, a person may develop the following:
MERRF can also cause problems with heart muscles and an irregular heart rate.
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE)
MNGIE affects the digestive system more than other forms of mitochondrial disease. Symptoms include:
Similar to other forms of mitochondrial disease, it can also involve changes in movement and coordination.
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS)
MELAS causes progressive problems with the muscles and nervous system. It can result in the following:
- muscle weakness
- lack of coordination
- brain damage
A person with MELAS may also have seizures and develop dementia.
Mitochondrial disease can affect nearly all parts of the body, meaning there can be a wide range of symptoms. A person may experience milder or more severe symptoms. The symptoms a person experiences typically depend on the affected cells and whether some mitochondria are still working as they should.
A person may experience symptoms in only one or many parts of the body. Some more general symptoms of mitochondrial disease include:
Errors or mutations in DNA cause mitochondrial disease. DNA is found in all cells, providing instructions to help a cell grow and divide.
Symptoms can develop when the mitochondria cannot make enough energy to meet the cell’s needs. Those cells affected by mitochondrial disease either die or become nonfunctional.
Mitochondrial conditions can run in families. People may inherit this condition if one or both parents carries the mutated gene and it passes to their child. Mitochondria contain their own DNA, called mitochondrial DNA (mtDNA). In certain cases, passing on mutated mtDNA can lead to disease.
Other times, damage to DNA happens randomly, even in a person with no family history of mitochondrial diseases.
Mitochondrial diseases are progressive and can worsen over time. Possible complications of mitochondrial disease include:
- Heart damage: The heart muscles rely on many mitochondria to function. Mitochondrial disease may cause heart muscles to weaken and an irregular heart rate.
- Breathing problems: Mitochondrial disease can damage the muscles involved in breathing. Sometimes, the parts of the brain that regulate breathing do not work correctly.
- Growth and development in children: Childhood is a time of rapid growth and development. Children with mitochondrial disease
oftenexperience developmental delays and difficulty meeting milestones.
Mitochondrial diseases can be difficult to diagnose. One reason for this is that many of the symptoms of mitochondrial diseases are also symptoms of other conditions.
The first step toward getting a diagnosis is a full medical professional evaluation. A doctor will gather a detailed symptom history. If the cluster of symptoms is suggestive of mitochondrial disease, they may recommend more specific types of testing.
Some of the tests that a doctor may use to diagnose mitochondrial disease include:
- exercise testing to monitor strength and exercise tolerance
- cognitive testing
- vision and hearing tests
- muscle biopsies to find out more about the actions of the mitochondria
- blood lactate and pyruvate levels to check mitochondria function
- genetic testing to look for known mutations that could cause mitochondrial disease
Depending on a person’s symptoms, a doctor may order other tests such as imaging or heart scans.
No specific treatment for mitochondrial diseases exist. However, experts are conducting ongoing research into how to manage symptoms and improve the quality of life for people with mitochondrial disease.
Care from a multidisciplinary team is best, as mitochondrial diseases can affect many parts of the body. This might include cardiologists, neurologists, and audiologists. Monitoring heart and respiratory health is an important part of managing mitochondrial disease.
People with mitochondrial disease should also have regular eye exams and hearing tests.
At this point, there is no evidence to suggest that supplements are helpful for everyone.
There are many types of mitochondrial diseases, and each person will experience mitochondrial disease differently.
What is the life expectancy of a person with mitochondrial disease?
Life expectancy will vary. It is impossible to predict exactly how long someone with mitochondrial disease will live. The specific diagnosis and severity of symptoms will likely influence life expectancy.
Mitochondrial diseases are complex, and many types exist. They are conditions that affect the function of the mitochondria, which provide energy for most of the cells in the body. Without the energy they need, cells cannot function as they should.
Because mitochondria exist in nearly all body cells, the range of symptoms a person can experience is widespread. This can make diagnosis challenging.
When doctors suspect mitochondrial disease, they may order a range of exams, including blood, genetic, and cognitive tests, to determine what could be causing symptoms. In most cases, there is a genetic cause.
There is no cure or standard treatment for mitochondrial disease. However, treatment will involve care from a multidisciplinary team. The team can help manage and monitor for any life threatening complications, such as those affecting the heart, respiratory system, or growth.