Metabolic Diseases of Muscles
Metabolic diseases of muscle are disorders caused by a different genetic defect that impairs the body’s metabolism.
The metabolic diseases of muscle interfere with chemical reactions involved in drawing energy from food. Normally, fuel molecules derived from food must be broken down further inside each cell before they can be used by the cells’ mitochondria to make the energy molecule ATP.
The mitochondria inside each cell could be called the cell’s “engines.” The metabolic muscle diseases are caused by problems in the way certain fuel molecules are processed before they enter the mitochondria, or by the inability to get fuel molecules into mitochondria.
Muscles require a lot of energy in the form of ATP to work properly. When energy levels become too low, muscle weakness and exercise intolerance with muscle pain or cramps may occur.
Features
Metabolic diseases of muscle can affect all the body’s voluntary muscles, such as those in the arms, legs and trunk. Some can alsoincrease risk of heart or liver diseases, and the effects can damage the kidneys. Metabolic muscle diseases that have their onset in infancy tend to be the most severe, and some forms are fatal. Those that begin in childhood or adulthood tend to be less severe, and changes in diet and lifestyle can help most people with the milder forms.
There are 10 metabolic diseases of muscle (myopathies). Each one gets its name from the substance that’s lacking:
- acid maltase deficiency (Pompe disease)
- carnitine deficiency
- carnitine palmityl transferase deficiency
- debrancher enzyme deficiency (Cori or Forbes disease)
- lactate dehydrogenase deficiency
- myoadenylate deaminase deficiency
- phosphofructokinase deficiency (Tarui disease)
- phosphoglycerate kinase deficiency
- phosphoglycerate mutase deficiency
- phosphorylase deficiency (McArdle disease)
Cause
Metabolic diseases of muscle are caused by defects in the enzymes that control chemical reactions used to break down food. Enzyme defects are caused by flaws in the genes.