Mitochondrial myopathy – Symptoms, causes & risk factors

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Mitochondrial myopathy

The mitochondrial myopathy got its name by the specific part of the body which it affects. The mitochondrial diseases are affecting the mitochondria which are tiny energy factories found inside almost all our cells. The mitochondrial disease which is causing prominent muscular problems is known as mitochondrial myopathy. This term comes from two words – myo (which means muscle) and pathos (which means disease).

We know that mitochondria are small structures that are found inside our cells and they are responsible for the energy production. They are like a power generator. They take in the fuel (this is the food which we consume) and they use oxygen to convert it into energy. If this process fails, then the cell is not able to work properly and this can lead to mitochondrial diseases. Mitochondrial diseases can affect different parts of the body, particularly those who need a lot of energy, such as pancreas, liver, heart, nerve, brain and muscle. There are some studies in which are said that the mitochondrial myopathy affects one in every 4,000 people.

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Symptoms

Mitochondrial myopathy

The muscle weakness and atrophy (shrinking) and exercise intolerance are the main symptoms of mitochondrial myopathy. You should know that the mentioned symptoms can vary from one person to another, even in the same family. In some people, the weakness is most prominent in muscles which control movements of the eyes and eyelids. The gradual paralysis of eye movements – PEO and ptosis are the two most common consequences. Also, the mitochondrial myopathy can cause weakness and atrophy in other muscles of the face and neck and this can lead to slurred speech and difficulty with swallowing. There are some cases when people who have mitochondrial myopathy can experience a loss of muscle strength in the arms or legs. Also, the mitochondrial myopathy can cause significant weakness in the muscles which support breathing.

Causes

You should know that mitochondrial diseases are not contagious and they are not caused by anything which a person has done. These diseases are caused by changes in genes or mutations. Those genes which are responsible for building our bodies are passed from parents to children, along with any defects or mutations which they have. This means that the mitochondrial myopathy is an inherited disease but in many cases, this disease affects members of the same family in different ways.

The genes which are involved in the mitochondrial myopathy normally make proteins which work inside the mitochondria. The mitochondrial myopathy is a result of the spontaneous mutations in nDNA or mtDNA. This can lead to altered functions of either proteins or RNA molecules which live within mitochondria compartments of cells. There are some cases when the mitochondrial myopathy can affect only certain tissues during the time of development and growth and they are referred as “tissue – specific isoforms” of the mitochondrial dysfunction.

Doctors do not fully understand why people are affected so differently by mitochondrial problems and what leads to experiencing symptoms with different organs/systems. The mitochondria is making hundreds of different functions in different tissues throughout our bodies which means that the mitochondrial diseases are producing a wide spectrum of problems so the proper diagnosis and treatment is hard for both doctor and patients.

Risk factors

The exact cause for the mitochondrial myopathy is not entirely known. Here are some factors which increase the risk of mitochondrial myopathy:

  • Having high levels of inflammation. It is known that the inflammation is linked to many degenerative diseases, as well as the aging process itself, and the mitochondrial alternations are playing a central role in these processes.
  • If you have a nuclear gene defects which are inherited in an autosomal recessive or autosomal dominant manner. It is known that the mitochondrial myopathy has an approximate recurrence risk of one in 24 within the same family. Those parents who are genetic carriers of the mitochondrial myopathy and who do not show symptoms of their own, are still carriers and they can pass the defective gene to their children.
  • There are some medical conditions which can increase the risk of mitochondrial myopathy, such as cancer, Alzheimer’s disease, stroke, atherosclerotic heart disease, Parkinson’s disease and diabetes type 2.

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