Mitochondrial Diseases

What is mitochondrial disease?

Mitochondrial diseases are a group of conditions that affect how mitochondria work in your body. Mitochondria make energy in your cells. When mitochondria aren’t able to produce enough energy that your body needs, it affects how your organs function.

Mitochondrial diseases can affect almost any part of your body, including the cells of your:

• Brain.
• Nerves.
• Muscles.
• Kidneys.
• Heart.
• Liver.
• Eyes.
• Ears.
• Pancreas.

What are mitochondria?

You may hear mitochondria called “the powerhouse of the cell.” Mitochondria are an energy factory. The job of mitochondria is to process oxygen and convert substances from the foods you eat into energy. Mitochondria exist in nearly every cell in the human body. Mitochondria produce 90% of the energy our bodies need to function.

What are the types of mitochondrial disease?

There are many types of mitochondrial diseases. Some of the most common include:

• Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome.
• Leber hereditary optic neuropathy (LHON).
• Leigh syndrome.
• Kearns-Sayre syndrome (KSS).
• Myoclonic epilepsy and ragged-red fiber disease (MERRF).

How common is mitochondrial disease?

An estimated 1 in 5,000 people has a genetic mitochondrial disease. It’s common for mitochondrial diseases to receive a misdiagnosis due to the number and type of symptoms and organ systems involved, so this number may be underestimated.

What are the symptoms of mitochondrial disease?

Symptoms of mitochondrial diseases vary based on the type and location of the affected cells. They can range from mild to severe and could include:

• Poor growth.
• Muscle weakness, muscle pain or a low muscle tone.
• Vision and/or hearing loss.
• Developmental delays or issues with cognitive development.
• Diarrhea or constipation.
• Unexplained vomiting.
• Acid reflux and/or swallowing difficulties.
• Seizures.
• Migraines.
• Respiratory (breathing) problems.
• Fainting.

Symptoms of mitochondrial diseases can be present at birth, but they can also arise at any age. A healthcare provider usually detects symptoms affecting more than one organ or organ system at the same time. Symptoms of the same disease can vary from person to person, even among family members.

What causes mitochondrial disease?

A lack of energy production from mitochondria in your cells causes mitochondrial disease. Mitochondria are responsible for producing energy within your body. When your mitochondria don’t receive the instructions they need from your body’s DNA to make energy, it can damage your cells or cause them to die early. This affects how your organs and organ systems function, which leads to symptoms of the condition.

How does someone get a mitochondrial disease?

Mitochondrial diseases are genetic. You can inherit these conditions from your biological family in an autosomal dominant or autosomal recessive pattern. This means that you can get a changed (mutated) gene that causes this condition from one or both of your biological parents respectfully. Some cases can occur randomly (de novo) without any history of the condition in your biological family.

Certain cases of mitochondrial disease have a mitochondrial inheritance. This occurs when the mitochondria contain their own DNA. Mitochondrial conditions caused by mutations in the mitochondrial DNA are exclusively inherited from the child's mother.

Can other conditions cause mitochondrial diseases?

Yes. Mitochondrial dysfunction occurs when mitochondria don’t work as well as they should due to another disease or condition. Many conditions can lead to secondary mitochondrial dysfunction, including:

• Alzheimer’s disease.
• Muscular dystrophy.
• Type 1 diabetes.
• Multiple sclerosis (MS).
• Cancer.

If you have secondary mitochondrial dysfunction, you don’t have a genetic mitochondrial disease.

What are the risk factors for mitochondrial disease?

You’re more at risk of developing a mitochondrial disease if it runs in your biological family history or if you have a condition that causes secondary mitochondrial dysfunction. Mitochondrial disease affects both adults and children.

What are the complications of mitochondrial disease?

Mitochondrial diseases affect how your organs function. It can cause the following complications:

• Increased risk of infection.
• Strokes.
• Pancreatic failure.
• Parathyroid failure.
• Diabetes.
• Liver failure.
• Cardiomyopathy.
• Kidney disease.
• Dementia.
• Gastrointestinal conditions.
• Drooping eyelid (ptosis).

Complications can be life-threatening.

How is a mitochondrial disease diagnosed?

A healthcare provider will diagnose a mitochondrial disease after a series of examinations and tests that may include:

• A review of your medical and family history.
• A complete physical examination.
• A neurological examination.
• A metabolic examination that includes blood and urine tests and, if needed, a cerebrospinal fluid test (spinal tap).
• DNA testing.

Other tests, depending on your symptoms and the affected areas of your body, might include:

• Magnetic resonance imaging (MRI) or spectroscopy (MRS) for neurological symptoms.
• Retinal exam or electroretinogram (ERG) for vision symptoms.
• Electrocardiogram (EKG) or echocardiogram for symptoms that affect your heart.
• Audiogram for hearing symptoms.
• Electroencephalogram (EEG) for seizures and related brain issues.

More advanced testing could include biochemical testing, which looks for changes in body chemicals involved in energy making. A healthcare provider may perform a biopsy where they take a sample of skin and/or muscle tissue to examine it under a microscope.

Are mitochondrial diseases difficult to diagnose?

Yes. Because mitochondrial diseases affect so many different organs and tissues of your body, and you may have many different symptoms, mitochondrial diseases can be difficult to diagnose. There’s no single laboratory test that can diagnose a mitochondrial disease. This is why a referral to a medical facility with physicians who specialize in these diseases is critical to making the diagnosis.

How is a mitochondrial disease treated?

Treatment for a mitochondrial disease varies based on the type and your symptoms. Treatment could include:

• Taking medications to reduce symptoms, like medications to prevent seizures.
• Taking vitamins or supplements, like riboflavin, coenzyme Q10 and carnitine.
• Changing your diet (nutrition) and exercising.
• Physical therapy, occupational therapy or speech therapy.
• Wearing assistive devices like hearing aids.

There’s no cure for mitochondrial disease. Treatment focuses on preventing life-threatening complications. Treatment that works for one person may differ from what works to treat someone else with the same condition.

Are there side effects of the treatment?

Talk to your healthcare provider about side effects before starting treatment. They’ll discuss the side effects of your treatment specifically and what you should look out for. Each type of treatment comes with its own possible side effects.

Can mitochondrial disease be prevented?

There’s no known way to prevent mitochondrial diseases. If you have a mitochondrial disease, you can avoid situations that can make your symptoms worse like:

• Exposure to extreme cold and/or heat.
• Skipping meals.
• Not getting enough sleep.
• Stress.

A healthcare provider may suggest you conserve (save) your energy to avoid using up all of your body’s energy in a short period of time.

What is the life expectancy for mitochondrial disease?

Your healthcare provider can give you the best advice on your life expectancy after a mitochondrial disease diagnosis. Your outlook depends on your symptoms, affected organs and general health. Some affected children and adults have the same expected lifespan as someone who doesn’t have this condition. Others might experience drastic changes in their health over a very short period of time. Some may have occasional flare-ups of symptoms throughout their lives. Although there’s no cure for mitochondrial diseases, research is ongoing to learn more.

When should I see a healthcare provider?

Visit a healthcare provider if your mitochondrial disease symptoms affect your ability to go about your day normally. If you have severe symptoms like a seizure or you have trouble breathing, call 911 or your local emergency services number immediately.

What questions should I ask my doctor?

Questions you can ask your healthcare provider include:

• What type of mitochondrial disease caused my symptoms?
• What type of treatment do you recommend?
• Are there side effects of the treatment?
• How often should I take vitamins or supplements?
• What type of diet do you recommend?
• How do I conserve my energy?
• Are there support groups for mitochondrial diseases?