Mitochondria are the “energy factory” of our body. Several thousand mitochondria are in nearly every cell in the body. Their job is to process oxygen and convert substances from the foods we eat into energy. Mitochondria produce 90 percent of the energy our body needs to function.
Mitochondrial diseases are chronic (long-term), genetic, often inherited disorders that occur when mitochondria fail to produce enough energy for the body to function properly. (Inherited means the disorder was passed on from parents to children.) Mitochondrial diseases can be present at birth, but can also occur at any age.
Mitochondrial diseases can affect almost any part of the body, including the cells of the brain, nerves, muscles, kidneys, heart, liver, eyes, ears or pancreas.
Mitochondrial dysfunction occurs when the mitochondria do not work as well as they should due to another disease or condition. Many conditions can lead to secondary mitochondrial dysfunction and affect other diseases, including Alzheimer’s disease, muscular dystrophy, Lou Gehrig’s disease, diabetes and cancer. Individuals with secondary mitochondrial dysfunction do not have primary genetic mitochondrial disease and do not need to be concerned about the ongoing development or worsening of symptoms.
One in 5,000 individuals has a genetic mitochondrial disease. Each year, about 1,000 to 4,000 children in the United States are born with a mitochondrial disease. With the number and type of symptoms and organ systems involved, mitochondrial diseases are often mistaken for other, more common, diseases.
In most people, primary mitochondrial disease is a genetic condition that can be inherited (passed from parents to their children) in several ways.
To understand inheritance types, it’s helpful to learn more about genes and DNA. Genes are substances that give us our traits, such as brown eyes or blue eyes. Genes contain DNA, which is the “blueprint” that gives each person his or her unique makeup.
Under normal circumstances, a child inherits genes in pairs -- one gene from the mother and one from the father. A child with a mitochondrial disease does NOT receive a normal pair of genes from the parents. The gene has mutated – meaning it has become defective (changed). Learning the way a mitochondrial disease has been inherited helps predict the chance of passing on the disease(s) to future children.
Inheritance types are:
Symptoms of mitochondrial diseases depend on which cells of the body are affected. Patients’ symptoms can range from mild to severe, involve one or more organs, and can occur at any age. Even patients within the same family who have the same mitochondrial disease can have differences in symptoms, severity, and age of onset (start of symptoms).
Symptoms of mitochondrial diseases can include:
Because mitochondrial diseases affect so many different organs and tissues of the body, and patients have so many different symptoms, mitochondrial diseases can be difficult to diagnose. There is no single laboratory or diagnostic test that can confirm the diagnosis of a mitochondrial disease. This is why referral to a medical facility with physicians who specialize in these diseases is critical to making the diagnosis.
Diagnosis starts with a series of examinations and tests that may include:
Other tests, depending on the patient’s symptoms and the areas of the body that are affected, might include:
More advanced testing could include biochemical testing, which looks for changes in body chemicals that are involved in energy making. Biopsies (samples) of skin and muscle tissue may also be performed.
There are no cures for mitochondrial diseases, but treatment can help reduce symptoms or slow the decline in health.
Treatment varies from patient to patient and depends on the specific mitochondrial disease diagnosed and its severity. However, there is no way to predict a patient’s response to treatment or predict how the disease will affect that person in the long run. No two people will respond to the same treatment in the same way, even if they have the same disease.
Treatments for mitochondrial disease may include:
Avoid situations that can make your medical condition worse. These include: exposure to cold and/or heat; starvation; lack of sleep; stressful situations; and use of alcohol, cigarettes and monosodium glutamate (MSG, a flavor enhancer commonly added to Chinese food, canned vegetables, soups, and processed meats).
The outlook for people who have mitochondrial diseases depends on how many organ systems and tissues are affected and the severity of disease. Some affected children and adults live near normal lives. Others might experience drastic changes in their health over a very short period of time. Some patients may have flare-ups of their disease, then return to a more stable state for years. Although there is no cure for mitochondrial diseases at the moment, research is ongoing.
Parents with mitochondrial disease(s) who are considering having other children may want to consult a genetic counselor to discuss their concerns.
© Copyright 1995-2019 The Cleveland Clinic Foundation. All rights reserved.
This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 05/07/2018