McArdle syndrome (glycogen storage disease type V)

Table of Contents

Definition

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


Alternative Names

Glycogen storage disease type V (GSDV); Myophosphorylase deficiency; Muscle glycogen phosphorylase deficiency; PYGM deficiency


Causes, incidence, and risk factors

McArdle syndrome is caused by a defect in a gene that makes an enzyme called glycogen phosphorylase. As a result, the body cannot break down glycogen in the muscles.

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



Review Date: 03/29/2011
Reviewed By: A.D.A.M. Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Chad Haldeman-Englert, MD, Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA. Review provided by VeriMed Healthcare Network (1/21/2010).

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