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5 Things You Should Know About Mitochondrial Disease

Mitochondria play a major role in all of your organ systems. These energy powerhouses — and part of the inspiration for “the force” in “Star Wars” — help your cells produce hemoglobin, which carries oxygen through your body. They free up the building blocks your body needs to make new cells. They provide the energy your body needs to keep going.

Your mitochondrial DNA predates you by thousands of years. It was passed down to you directly from your mother and has been passed down in this way, from mother to child, since the first humans walked the planet. You have the same mitochondrial DNA as people did 200,000 years ago — in all that time, the mitochondria’s DNA sequence has gone unchanged.

It’s gone mostly unchanged, in any event. At least 1 in 5,000 people is born with a mitochondrial disease, which causes changes in how your mitochondria function. Your mitochondria play a vital role in all of your body’s systems, so when a change happens in the mitochondria’s DNA, or in proteins that interact with the mitochondria, it can have major consequences.

Because mitochondria provide 90% of your body’s energy, the organs most affected by mitochondrial disease are usually the most energy-intensive structures: the brain, muscles, heart and lungs. People who live with the disease may experience a range of symptoms, among them strokes, seizures, blindness, deafness and heart problems. Most of those affected are children.

Mitochondrial disease has no cure, and the process for diagnosing it can be strenuous and lengthy. However, while the condition has ups and downs, many people who have the disease live long lives.

“Unfortunately, if you Google ‘mitochondrial disease’ there’s a lot of doom and gloom out there,” Sumit Parik, M.D., of the Cleveland Clinic told the United Mitochondrial Disease Foundation. “It’s not necessarily as negative as one may think when they first learn about it.”

We’ve put together five facts for people who are interested in mitochondrial disease or think they may be living with it themselves. Read on to learn more.

1. There are hundreds of different mitochondrial diseases.

Mitochondrial disease happens when a change in your mitochondrial DNA impairs the functioning of your mitochondria, or when a protein that interacts with the mitochondria is flawed. Your mitochondria have a hand in the day-to-day functioning of all of your body’s systems, and mitochondrial disease can present very differently depending on which part of the DNA was affected and what organ system is impacted by that change.

There are 3,000 genes involved in making mitochondria, any number of which can undergo a mutation that results in mitochondrial disease. For this reason, researchers believe that there are hundreds of different mitochondrial diseases. For example:

  • Guanidinoacetate methyltransferase deficiency is a mitochondrial disease that typically involves intellectual disability, seizures, and speech problems, caused by a change affecting the GAMT gene
  • Glutaric acidemia type II manifests as a result of a change in the ETFA, ETFB or ETFDH genes and leads to brain and kidney malformations and an enlarged liver

Mitochondrial disease can be inherited from your mother’s mitochondrial DNA or from one of both parent’s DNA. It can also happen spontaneously, in what’s known as a de novo mutation.

 2. It’s impossible to generalize a single experience of mitochondrial disease.

All of your organisms require mitochondria, your body’s energy factories — and all can be affected when the mitochondria fail at their task. Since mitochondrial disease tends to have wide-ranging effects on the body, no two people with mitochondrial disease are the same, even if they have the same gene mutation. Some patients with a gene change that could result in mitochondrial disease never develop the condition at all.

Marni J. Falk, M.D., executive director of the Mitochondrial Medicine Frontier Program in Philadelphia, explained in a video that the disease can manifest in very different ways, even within families. Falk noted that in one survey of people living with mitochondrial disease, patients reported experiencing 16 symptoms on average. While some people experienced as few as one or two symptoms, several patients reported having over 30 symptoms. These symptoms can include ailments as diverse as gastrointestinal problems and heart blocks, blindness and developmental delays, strokes and seizures.

The age of onset can also vary widely among patients. Some people experience symptoms from the time they are born. Most people with mitochondrial disease first experience symptoms as children, though symptoms can appear at any point in a person’s life. Depending on how severe their symptoms are, some children who have mitochondrial disease may not live past their teenage years.

3. Mitochondrial disease is frequently misdiagnosed.

DNA testing is employed whenever possible in the diagnostic process when a doctor suspects mitochondrial disease. These tests can pinpoint the gene change that resulted in mitochondrial disease, putting an end to a family’s “diagnostic odyssey,” as one paper phrased it. However, while DNA testing has become much more sophisticated over the years, it still cannot be used in all cases. If a doctor suspects her patient is living with mitochondrial disease, she may have to resort to more invasive measures.

Among these measures are biochemical testing of a patient’s spinal fluid and a muscle biopsy. The doctor may also request tests of a person’s urine or blood, which can carry several markers of mitochondrial disease. An echocardiogram, electrocardiogram, and ophthalmologic exam may be required, as well as a brain MRI and audiology testing. Patients with developmental disorders may require additional exams.

Mitochondrial disorders are difficult to diagnose, and many people who live with them are misdiagnosed with other conditions, among them atypical cerebral palsy and several seizure disorders.

4. Mitochondrial disease has no cure, but treatment can help.

Researchers have yet to find a cure for mitochondrial disease, but there are several methods by which the disease’s progression can be slowed. There are also treatments available that can address the condition’s symptoms for a higher quality of life with the condition.

Some patients may benefit from adjustments to their diet, since the food you consume also plays a big role in energy management. While the United Mitochondrial Disease Foundation (UMDF) stresses that no dietary regimen works for all people with mitochondrial disease, the organization does provide some suggestions that patients may try out with a physician’s approval.

The UMDF discourages people living with mitochondrial disease from fasting, even if the fasting period is as narrow as 12 hours. In some patients, a hospital visit may be needed to remedy the effects of an unintentional fast caused by illness. Some patients may benefit from taking a small meal at midnight or having a feeding tube put in for nighttime feeding.

People living with mitochondrial disease may do well to avoid foods rich in iron, added the UMDF. The amount of fat that you consume seems to be important as well, though some patients benefit from increasing the amount of fat in their diet while others seem to improve when their fat and total carbohydrate intake is reduced.

People living with mitochondrial diseases are also discouraged from drinking alcohol or smoking cigarettes, as these may hasten the disease’s progression. Products containing MSG should be avoided.

Since some people with mitochondrial disease are unable to regulate their internal temperature, they should take care not to expose themselves to extreme cold or extreme heat. Making sure to get a good night’s rest is helpful too, as ever.

Some patients also benefit from supportive therapies such as physical therapy, respiratory therapy and speech therapy.

5. A new therapy has the potential to prevent passing on mitochondrial disease.

Mitochondrial replacement therapy (MRT) could allow some women with mitochondrial disease to prevent passing the condition on to their children. MRT is an in-vitro fertilization technique that involves replacing damaged mitochondria in a fertilized egg. In the procedure, a donor with healthy mitochondrial DNA supplies normal mitochondria, which takes the place of the damaged mitochondria of the woman hoping to conceive.

However, this therapy can only work in females who developed mitochondrial disease as a result of mutations in their mitochondrial DNA. Women whose mitochondria are damaged due to mutations in the DNA that codes for proteins would not be helped by the therapy.

Mitochondrial replacement therapy is not available in the United States due to legal restrictions, but it is available in the U.K., where the practice is tightly regulated.

 

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Image via Getty/wiroman