Just as some diseases are named for the part of the body they affect (like heart disease), mitochondrial diseases are so named because they affect a specific part of the cells in the body. Specifically, mitochondrial diseases affect the mitochondria — tiny energy factories found inside almost all our cells.
A mitochondrial disease that causes prominent muscular problems is called a mitochondrial myopathy (myo means muscle, and pathos means disease), while a mitochondrial disease that causes both prominent muscular and neurological problems is called a mitochondrial encephalomyopathy (encephalo refers to the brain).
What are the symptoms of mitochondrial myopathies?
Muscular and neurological problems — such as muscle weakness, exercise intolerance, hearing loss, trouble with balance and coordination, seizures and learning deficits — are common features of mitochondrial disease, because muscle cells and nerve cells have especially high energy needs.
Other frequent complications include impaired vision, heart defects, diabetes and stunted growth.
Usually, a person with a mitochondrial disease has two or more of these conditions, some of which occur together so regularly that they’re grouped into syndromes.
The main problems associated with mitochondrial disease — low energy, free radical production and lactic acidosis — can result in a variety of symptoms in many different organs of the body.
The diagram to the right depicts common symptoms of mitochondrial disease. Most affected people have some, but not necessarily all, of these problems.
What causes mitochondrial myopathies?
Mitochondrial myopathies are caused by mutations, or changes, in genes — the cells’ blueprint for making proteins.
They are inheritable, although they can occur with no family history, and they often affect members of the same family in different ways.
What is the progression of mitochondrial myopathies?
The age of onset and progression of mitochondrial myopathy varies greatly from type to type.
What is the status of research on mitochondrial myopathies?
MDA-funded scientists have identified many of the genetic defects that cause mitochondrial diseases, and they’ve used that knowledge to create animal models of many of them.
Understanding the genetic defects that cause mitochondrial myopathies opens up the possibility of developing treatments for these diseases.
Is there any treatment for mitochondrial disease?
Although there is no specific treatment for any of the mitochondrial myopathies, physical therapy may extend the range of movement of muscles and improve dexterity.
Vitamin therapies such as riboflavin, coenzyme Q, and carnitine (a specialized amino acid) may provide subjective improvement in fatigue and energy levels in some patients.
What is the prognosis for mitochondrial disease?
The prognosis for patients with mitochondrial myopathies varies greatly, depending largely on the type of disease and the degree of involvement of various organs.
These disorders cause progressive weakness and can lead to death.