Glycogen Storage Disease VIII

Glycogen Storage Disease VIII

National Organization for Rare Disorders, Inc.


It is possible that the main title of the report Glycogen Storage Disease VIII 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.


  • Glycogenosis Type VIII
  • Hepatic Phosphorylase Kinase Deficiency
  • Phosphorylase Kinase Deficiency of Liver
  • PYKL

Disorder Subdivisions

  • None

General Discussion

Glycogen storage disease VIII is one of a group of hereditary disorders caused by a lack of one or more enzymes involved in glycogen synthesis or breakdown and characterized by deposition of abnormal amounts or types of glycogen in tissues. Excessive amounts of glycogen (which acts to store energy for later use) are deposited in the liver, causing it to become enlarged (hepatomegaly).


Glycogen storage disease VIII is usually a mild disorder. Symptoms may include an enlarged liver, increased liver glycogen (the stored form of energy from carbohydrates), and mild hypoglycemia (low blood sugar). Although inflammation of the liver may sometimes occur, liver function is usually normal and the disorder may be undetected throughout life.


Glycogen storage disease VIII is an X-linked genetic disorder caused by a deficiency of the enzyme liver phosphorylase kinase. This deficiency causes deposits of excessive amounts of glycogen in the liver. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother.

X-linked recessive disorders are conditions that are coded on the X chromosome. Females have two X chromosomes, but males have one X chromosome and one Y chromosome. Therefore, in females, disease traits on the X chromosome can be masked by the normal gene on the other X chromosome. Since males only have one X chromosome, if they inherit a gene for a disease present on the X, it will be expressed. Men with X-linked disorders transmit the gene to all their daughters, who are carriers, but never to their sons. Women who are carriers of an X-linked disorder have a 50 percent risk of transmitting the carrier condition to their daughters, and a 50 percent risk of transmitting the disease to their sons.

Affected Populations

All glycogen storage diseases together affect fewer than 1 in 40,000 persons in the United States. Glycogen storage disease VIII affects more males than females and usually begins during infancy; about 10% of patients with this disorder are females whose symptoms are mild.

Standard Therapies

Treatment is usually not necessary for this disorder in its mild form.

Investigational Therapies

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

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


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

Genetic counseling will be helpful for families of children with glycogen storage disease VIII.



The Merck Manual. M. H. Beers and R. Berkow, Eds., 17th ed., Merck Research Laboratories, 1999, Pp. 2387-89.

Cecil Textbook of Medicine. J.C. Barnett and F. Plum, Eds. 20th ed., W. B. Saunders Company, 1996, Pp. 1082-83.


[Glycogen Storage Disease Type VIII. T. Nishigaki. Ryoikbetsu Shokogun Shirizu. (1998, (18 Pt 1)). Pp. 56-9.

A Female Case of Type VIII Glycogenosis Who Developed Cirrhosis of the Liver and Hepatocellular Tumor. S. Shiomi et al., Gastroenterol Jpn. (Dec 1989, 24 (6)). Pp. 711-14.

Glycogen Storage Disease: Recommendations for Treatment. J. Fernandes et al., Eur J Pediatr. (Apr 1988, 147 (3)). Pp. 226-28.

Glycogenosis Type VIII. M. Kornfeld et al., J Neuropathol Exp Neurol. (Nov 1984, 43 (6)). Pp. 568-79.


CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building

176 Nantwich Road

Crewe, CW2 6BG

United Kingdom

Tel: 4408452412173

Fax: 4408452412174



Association for Glycogen Storage Disease

P.O. Box 896

Durant, IA 52747


Tel: (563)514-4022

Fax: (563)514-4022



March of Dimes Birth Defects Foundation

1275 Mamaroneck Avenue

White Plains, NY 10605

Tel: (914)997-4488

Fax: (914)997-4763

Tel: (888)663-4637



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



Association for Glycogen Storage Disease (UK) Ltd

Old Hambledon Racecourse

Sheardley Lane, Droxford

Hampshire, SO32 3QY

United Kingdom

Tel: 03001232790



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


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 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

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use . How this information was developed to help you make better health decisions.

Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.