Definition of McArdle syndrome :

McArdle syndrome is the inability to break down glycogen. Glycogen an important source of energy that is stored in muscle tissue.

Causes, incidence, and risk factors:

McArdle syndrome results from a defect in a gene that makes a protein called glycogen phosphorylase. As a result, the body cannot break down glycogen in the muscles. This may lead to weakness, cramps, and muscle pain.

The disease is an autosomal recessive genetic disorder. This means that you get a copy of the defective gene from both parents. A person who gets a defective gene from only one parent usually does not develop this syndrome.

A family history of McArdle syndrome increases the risk.