Glycogen Storage Disease Type VII

Glycogen Storage Disease Type VII

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Glycogen Storage Disease Type VII is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • Tarui Disease
  • GSD VII
  • PFKM Deficiency
  • Muscle Phosphofructokinase Deficiency

Disorder Subdivisions

  • None

General Discussion

Glycogen storage diseases are a group of disorders in which stored glycogen cannot be metabolized into glucose to supply energy for the body. Glycogen storage disease type VII (GSD VII) is characterized by weakness, pain and stiffness during exercise. GSD VII is caused by abnormalities in the muscle phosphofructokinase gene that results in a deficiency of the phosphofructokinase enzyme. This enzyme deficiency leads to a reduced amount of energy available to muscles during exercise. GSD VII is inherited as an autosomal recessive genetic disorder.

Symptoms

GSD type VII usually begins in childhood and is characterized by weakness, pain and stiffness during exercise, sometimes associated with nausea and vomiting and dark, burgundy-colored urine due to the presence of myoglobin (myoglobinuria). Destruction of muscle tissue (rhabdomyolysis) can also occur. A rare form of GSD type VII has been reported in infants that is associated with progressive loss of muscle tone (hypotonia), muscle weakness and death. A late-onset form has been reported in adults who experience only muscle weakness.

Causes

Glycogen storage disease type VII is caused by abnormalities (mutations) in the muscle phosphofructokinase gene that results in a deficiency of the phosphofructokinase enzyme. This enzyme normally converts fructose-6-phosphate to fructose-1,6-diphosphate. This is the controlling step in the breakdown of glucose into available energy and if the enzyme is deficient, energy is not available to muscles during heavy exercise. Consequently, pain and cramps occur in the muscle.



Glycogen storage disease type VII is inherited as an autosomal recessive genetic disorder. Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.



All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Affected Populations

Glycogen storage disease type VII is a rare disorder that occurs more often in individuals of Japanese and Ashkenazi Jewish descent. GSD type VII affects males and females in equal numbers.

Standard Therapies

Diagnosis

GSD type VII is diagnosed by a muscle biopsy for measurement of the phosphofructokinase enzyme level or measurement of the phosphofructokinase enzyme level in red blood cells. Molecular genetic testing for the phosphofructokinase gene mutations prevalent in the Ashkenazi Jewish population are available on a research basis.



Treatment

Strenuous exercise should be avoided to prevent muscle pain and cramps. Consumption of carbohydrates should be avoided because this can exacerbate exercise intolerance.



Genetic counseling is recommended for affected individuals and their families.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.



For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:



Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov



For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

References

TEXTBOOK

Weinstein DA, Koeberl DD and Wolfsdorf JI . Type VII Glycogen Storage Disease. In: The NORD Guide to Rare Disorders, Philadelphia: Lippincott, Williams and Wilkins, 2003:456-7.



Chen Y-T. Glycogen storage diseases. In: Scriver CR, Beaudet AL, Sly WS, et al., eds. The metabolic and molecular basis of inherited diseases. New York: McGraw-Hill, 2001:1521-1551.



JOURNAL ARTICLE

DiMauro S, Bruno C. Glycogen storage diseases of muscle. Curr Opin Neurol 1998:11:477-484.



FROM THE INTERNET

McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). Baltimore, MD: The Johns Hopkins University; Entry No. 232800; Last Update: 5/31/05.

Resources

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building

176 Nantwich Road

Crewe, CW2 6BG

United Kingdom

Tel: 4408452412173

Fax: 4408452412174

Email: enquiries@climb.org.uk

Internet: http://www.CLIMB.org.uk



Association for Glycogen Storage Disease

P.O. Box 896

Durant, IA 52747

USA

Tel: (563)514-4022

Fax: (563)514-4022

Email: info@agsdus.org

Internet: http://www.agsdus.org



Vaincre Les Maladies Lysosomales

2 Ter Avenue

Massy, 91300

France

Tel: 0169754030

Fax: 0160111583

Email: accueil@vml-asso.org

Internet: http://www.vml-asso.org



Muscular Dystrophy Association

3300 East Sunrise Drive

Tucson, AZ 85718-3208

USA

Tel: (520)529-2000

Fax: (520)529-5300

Tel: (800)572-1717

Email: mda@mdausa.org

Internet: http://www.mda.org/



NIH/National Institute of Diabetes, Digestive & Kidney Diseases

Office of Communications & Public Liaison

Bldg 31, Rm 9A06

31 Center Drive, MSC 2560

Bethesda, MD 20892-2560

Tel: (301)496-3583

Email: NDDIC@info.niddk.nih.gov

Internet: http://www2.niddk.nih.gov/



Association for Glycogen Storage Disease (UK) Ltd

Old Hambledon Racecourse

Sheardley Lane, Droxford

Hampshire, SO32 3QY

United Kingdom

Tel: 03001232790

Email: info@agsd.org.uk

Internet: http://www.agsd.org.uk



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/



Madisons Foundation

PO Box 241956

Los Angeles, CA 90024

Tel: (310)264-0826

Fax: (310)264-4766

Email: getinfo@madisonsfoundation.org

Internet: http://www.madisonsfoundation.org



For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into myCigna.com. For non-Cigna members, a copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html.

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