Definition - one of a group of muscle diseases that interfere with the processing of carbohydrates

Cause - a defect in the gene for the acid maltase enzyme (also known as acid alpha-glu cosidase) that prevents the breakdown of glycogen (stored sugar)

Onset - infancy to adulthood

Symptoms - slowly progressive weakness of respiratory muscles and muscles of the hips, upper legs, shoulders and upper arms; cardiac involvement common in infantile-onset form

Progression - slowly progressive and less severe in childhood- and adult-onset forms; infantile form usually leads to death within first year of life unless treated early

In April 2006, the U.S. Food and Drug Administration approved Myozyme, an enzyme replacement therapy, for the treatment of acid maltase deficiency. This therapy has significantly improved the prognosis for patients.

Inheritance - autosomal recessive, meaning caused by the contribution of a defective gene from each parent

Facts About Metabolic Diseases of Muscle