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Diseases & Conditions

Myths and Facts About Mitochondrial Diseases

MYTH

Mitochondrial disease is a childhood disease.

FACT

Although mitochondrial disorders are commonly seen in infants and children, they can occur at any age.

MYTH

An individual with mitochondrial disease has mental retardation, growth problems, and/or seizures.

FACT

Only some individuals have these developmental problems. Patients’ symptoms can range from extremely mild to severe, involve one or more body systems, and can emerge at any age. The brain, muscles, heart, liver, nerves, eyes, ears and kidneys are the organs and tissues most affected. Most patients’ symptoms fluctuate over the course of their disease -- at times experiencing no or few symptoms while at other times experiencing many and/or severe symptoms. Even family members with the same disorder can experience vastly different symptoms.

MYTH

Mitochondrial diseases are inherited only from your mother.

FACT

Not true. There are several ways mitochondrial diseases can be inherited (passed along from parents to children). Under normal circumstances, a person’s ‘blueprint’ -- the DNA in our genes that makes each of us unique, comes from both our mother and our father. In mitochondrial diseases, these genes have mutated (which means they have changed/become defective; they are not normal.) Instead of receiving pairs of normal genes from each parent, persons with mitochondrial diseases receive mutated genes from each parent or a mutated gene from only one parent.

Another way a mitochondrial disease can be inherited is, in fact, only from the mother. In this type, there is a mutation in the mitochondrial DNA - a special DNA that exists only in the mitochondria. Only mitochondrial disorders caused by mutations in the mitochondrial DNA are exclusively inherited from mothers.

MYTH

If parents don’t have any symptoms of a mitochondrial disease, there’s no chance that their children can have a mitochondrial disease.

FACT

Parents can be ‘genetic carriers’ of a mitochondrial disease. This means that each parent has inherited a defective gene but do not show symptoms of the disease. However, ‘carriers’ are able to pass the defective gene onto their children.

Here’s an example using parents who are both carriers and have four children. One out of the four children would inherit the defective gene and develop a mitochondrial disease and show symptoms. Two out of the four children will be genetic carriers of a mitochondrial disease, just like their parents. The remaining child would be ‘genetically ‘typical.’ Both the genetically ‘typical’ patient and the carriers would not develop mitochondrial disease).

MYTH

Since mitochondrial diseases are incurable, no treatments can be given to these patients.

FACT

Even though these disorders are long term and incurable, treatments are available. Early treatment of symptoms can reduce symptoms or slow the decline in health. Avoiding certain medications and medical stressors that worsen symptoms is also helpful. Certain medications and supplements may improve mitochondrial disease-related symptoms -- just as they do for other incurable diseases -- such as diabetes and emphysema.

MYTH

A muscle biopsy is the "gold standard" for diagnosis of mitochondrial disease.

FACT

Although the muscle biopsy is a powerful diagnostic tool, it should not be considered a “gold standard.” A biopsy examination includes microscopic evaluation, enzyme testing, and genetic testing. Although all U.S. labs that offer muscle biopsy meet strict laboratory guidelines, there is no agreed-upon standard approach for enzyme testing. Furthermore, a muscle biopsy with full analysis costs well over $10,000 and poses both surgical and anesthetic risks. In some patients, the diagnosis can be made based on clinical symptoms and a positive blood test (identifying a genetic mutation) or a combination of clinical findings and other non-invasive testing. In either case, a muscle biopsy is not necessary. Finally, since biopsy results usually do not alter the long-term outcome or treatment considerations, some specialists and patients choose to treat without the need for a muscle biopsy.

MYTH

Immunizations can be harmful to children with mitochondrial diseases.

FACT

There is no clear evidence that immunizations themselves hurt patients with mitochondrial or metabolic disorders.

Medical stress (fever, dehydration, illness, revving up the immune system) may bring out or worsen metabolic disorders. Thus, there have been some patients where the fever after an immunization led to symptom onset or worsening. In these individuals, it was not the immunization itself that caused these problems. It is generally believed that patients should get their immunizations. Still, for individuals whose symptoms emerge or worsen when under medical stress, spacing out immunizations and tight fever-control may help. (This approach is not based in medical science. It’s based solely on reports or observations, which do not provide absolute proof.)

MYTH

All mitochondrial diseases are known by acronym abbreviations (e.g., MELAS, MERRF, NARP, LHON).

FACT

Acronyms were commonly used when these disorders were first described. Today, the naming of mitochondrial disorders is evolving. Mitochondrial disorders are currently named by any of the following methods:

  • By acronym descriptions (still in use although most people with a mitochondrial disorder do not have an "acronymic-named" disorder)
  • By a name based on a person who described the disease
  • By a name based on a specific genetic mutation
  • By a name based on a microscopic description of tissue, or
  • By a name based on the deficient enzyme

It is important to note that the labels given this disorder do not, in and of themselves, predict the long-term outcome or alter treatment.

References

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 7/18/2014...#13143