BACK
TO
TOP
 
E-mail Form
Email Results

 
 
Print-Friendly
Bookmarks
bookmarks-menu

Type V glycogen storage disease

Myophosphorylase deficiency; Muscle glycogen phosphorylase deficiency; PYGM deficiency

Type V (five) glycogen storage disease (GSD V) is a rare inherited condition in which the body is not able to break down glycogen. Glycogen is an important source of energy that is stored in all tissues, especially in the muscles and liver.

GSD V is also called McArdle disease.

Causes

GSD V is caused by a flaw in the gene that makes an enzyme called muscle glycogen phosphorylase. As a result, the body cannot break down glycogen in the muscles.

GSD V is an autosomal recessive genetic disorder. This means to have the disorder, you must receive a copy of the nonworking gene from both parents. A person who receives a nonworking gene from only one parent usually does not develop this syndrome. A family history of GSD V increases the risk.

Symptoms

Symptoms commonly start during early childhood. But, it may be difficult to separate these symptoms from those of normal childhood. Diagnosis may not occur until a person is over 20 or 30 years old.

  • Burgundy-colored urine (myoglobinuria)
  • Fatigue
  • Exercise intolerance, poor stamina
  • Muscle cramps
  • Muscle pain
  • Muscle stiffness
  • Muscle weakness

Exams and Tests

The following tests may be performed:

Treatment

There is no specific treatment.

The health care provider may suggest the following to stay active and healthy and prevent symptoms:

  • Be aware of your physical limitations.
  • Before exercising, warm up gently.
  • Avoid exercising too hard or too long.
  • Eat enough protein.

Ask your provider if it's a good idea to eat some sugar before exercising. This may help prevent muscle symptoms.

If you need to have surgery, ask your provider if it's OK for you to have general anesthesia.

Support Groups

More information and support for people with type V glycogen storage condition and their families can be found at:

Outlook (Prognosis)

People with GSD V can live a normal life by managing their diet and physical activity.

Possible Complications

Exercise may produce muscle pain, or even a breakdown of skeletal muscle (rhabdomyolysis). This condition is associated with burgundy-colored urine and a risk for kidney failure if it is severe.

When to Contact a Medical Professional

Contact your provider if you have repeated episodes of sore or cramped muscles after exercise, especially if you also have burgundy or pink urine.

Consider genetic counseling if you have a family history of GSD V.

References

Brandow AM. Enzymatic defects. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 490.

Weinstein DA. Glycogen storage diseases. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 196.

Williams LM, Mcdonald CM. Myopathic disorders. In: Cifu DX, ed. Braddom's Physical Medicine & Rehabilitation. 6th ed. Philadelphia, PA: Elsevier; 2021:chap 42.

Text only

        A Closer Look

         
         

        Review Date: 11/1/2021

        Reviewed By: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

        The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
        © 1997- adam.com All rights reserved.

         
         
         

         

         

        A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.
        Content is best viewed in IE9 or above, Firefox and Google Chrome browser.