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Mitochondrial Disorders

Medical information you need to know as an adult with mitochondrial disorders

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This overview provides an introduction to mitochondrial disorders, their symptoms, and treatment. You can show it to friends, teachers, school nurses, coaches, new doctors, family members, and anyone else who you feel needs to understand your condition.

What are Mitochondrial Disorders?

In our bodies, mitochondria are the parts of cells that make energy from food and oxygen. With a mitochondrial disorder, something goes wrong with that energy-making process. When a cell is unable to produce enough energy, it may lose some of its ability to function. When enough cells in a certain part of the body are weakened that body part may not work correctly.

Parts of a typical human cell

Parts of a typical human cell

Mitochondria are found in almost all the cells in our bodies. In different people who have a mitochondrial disorder, different sets of cells, different body organs, or different body parts may be affected. Even people from the same family, with the same disorder, can have different health problems.

Depending on which cells are affected, major symptoms might be:

  • Muscle weakness or “heaviness”
  • Vision or hearing problems
  • Liver or kidney disease
  • Diabetes
  • Gastrointestinal problems
  • Brain problems such as seizures

In people with a mitochondrial disorder, symptoms often show up in three or more different systems of the body; for example, in the eyes, muscles, and stomach. The body systems that are affected provide clues for doctors who can then test for a mitochondrial disorder. Many of the tests are typical, such as getting blood drawn. Other tests are more invasive, such as a muscle biopsy. Doctors will schedule the more extensive tests if they feel it’s necessary to learn more about their patient’s condition, and to confirm a diagnosis. Some people with mitochondrial disorders may have trouble with anesthesia, which may limit a doctor’s ability to perform certain tests. So a doctor may decide to give the patient a diagnosis based on his/her observations, on analysis of test results, and on his/her experience treating mitochondrial disease.

Since mitochondria are involved with making energy in the body, a lot of people living with a mitochondrial disorder become very tired, very suddenly. They may become so tired that they can’t pay attention or even stay awake. They may have to stop what they’re doing and find a place to rest and recharge. People sometimes call this “crashing”. It can come on quickly, because the heart, brain, lungs, muscles, and internal organs may be using a lot of energy during a certain activity or under certain circumstances. It’s like an electrical “brownout” — when the lights go dim because everybody in town is using so much electricity that the power-plant can’t keep up.

Two symptoms of mitochondrial disease are the body’s inability to properly regulate temperature, and to stay hydrated. This may cause the person to faint during mild exercise or on warm days. Other symptoms can include: sensitivity to bright lights, muscle spasms, or trouble with digestion and nutrition.

People with mitochondrial disorders have good days and bad days. One day they may wake up feeling alright and have a productive day. Another day they may wake up feeling awful or not have any energy, even though they had a good night’s sleep. Sometimes people may have good and bad parts of days (including “crashing”). Their symptoms may get better or worse over time, or new symptoms may develop. It can sometimes be difficult to predict how new situations and events will affect people with a mitochondrial disorder. They may need to work from home or miss classes, meetings or other events in order to save their energy for completing duties and assignments.

People with mitochondrial disorders may take longer than usual to recover from a common cold. During, and for about two weeks after a typical sickness such as a cold or flu, they may be in danger of getting a more serious infection. So, in addition to extra rest, they may need antibiotics to stop an infection, or intravenous fluids like saline or blood substitutes. It’s important for each person to know his/her own body signs, and to know when to get help from health care providers.

Types of Mitochondrial Disorders

Here are short descriptions of some of the more common mitochondrial disorder syndromes. There are others, and some people are only affected by one or a few symptoms. This list will give you an idea of the challenges that a person with a mitochondrial disorder may be dealing with. The person you know with a mitochondrial disorder may be affected with different combinations of symptoms in different amounts:

Chronic Progressive External Ophthalmoplegia (CPEO)
CPEO is characterized by weakness of the eye muscles which may cause droopy eyelids and reduced ability to move the eyes. CPEO may sometimes be part of another syndrome, or may be one of many symptoms in an individual without a specific mitochondrial disorder syndrome.

Kearns-Sayre Syndrome (KSS)
KSS usually starts before age 20. Common symptoms are: a gradual inability to move the eyes (CPEO), difficulty seeing in the dark, cardiac problems, and uncoordinated muscle movements. Other symptoms may include: hearing problems, kidney disease, diabetes, or short stature.

Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS)
MELAS usually starts in childhood to early adulthood. It can cause migraine-type headaches, vomiting, seizures or stroke-like episodes. Other common symptoms are: inability to move the eyes, hearing loss, diabetes, digestive problems, and muscle weakness.

Myoclonus Epilepsy with Ragged Red Fibers (MERRF)
This disorder usually starts in late childhood or the early teen years. Muscle twitching, weakness, and lack of coordination are common. Other possible symptoms may include: seizures, hearing loss, eye and speech problems, as well as exercise intolerance (muscle cramping, spasms, fatigue), and short stature.

Neuropathy, Ataxia and Retinitis Pigmentosa (NARP)
Primary symptoms of NARP may include: sensory impairment, uncoordinated movement, and gradual loss of vision. It can also cause epileptic seizures.

Not everyone with a mitochondrial disorder will fit neatly into one of these syndromes. Many people are affected by different combinations of these or other symptoms to different degrees.

For more in-depth information about mitochondrial disorders check out the Resources section of this guide. If you’re a patient, you can fill out the Medical Summary section together with your metabolic specialist. Working on it with your doctor can help you learn more about your specific condition. Filling out the Health Readiness Assessment will show you where your knowledge is strong and what you might want to learn more about. The Glossary contains words and definitions you might find useful.

What Next?

Now you can fill out the Medical Health Summary, print it, and save it. This will help you keep important medical information in one place.


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