Muscle diseases weaken and waste muscles and can be inherited or acquired and affect people of all ages, backgrounds and nationalities.

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The health care provider will also be trying to distinguish common cramping from muscle diseases that can mimic it and be an uncommon side effect of commonly prescribed drugs used to lower cholesterol (such as cholestyramine) or decrease stomach acid (cimetidine or ranitidine).

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It is difficult to diagnose mitochondrial diseases and the only current test is a muscle biopsy.

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The benefits go far beyond the Duchenne muscular dystrophy, a disease that is diagnosed in only 600 American boys a year, to diseases like cancer and AIDS. Such drugs could even have a big effect on the muscle weakening that comes with aging.

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