$Unique_ID{BRK03777} $Pretitle{} $Title{Glycogen Storage Disease VIII} $Subject{Glycogen Storage Disease VIII Glycogenosis Type VIII Hepatic Phosphorylase Kinase Deficiency Phosphorylase Kinase Deficiency of Liver PYKL Forbes Disease Andersen Disease Hers Disease} $Volume{} $Log{} Copyright (C) 1987, 1989, 1991 National Organization for Rare Disorders, Inc. 400: Glycogen Storage Disease VIII ** IMPORTANT ** It is possible the main title of the article (Glycogen Storage Disease VIII) is not the name you expected. Please check the SYNONYMS listing on the next page to find alternate names, disorder subdivisions, and related disorders covered by this article. Synonyms Glycogenosis Type VIII Hepatic Phosphorylase Kinase Deficiency Phosphorylase Kinase Deficiency of Liver PYKL Information on the following diseases can be found in the Related Disorders section of this report: Von Gierke Disease Forbes Disease Andersen Disease Hers Disease General Discussion ** REMINDER ** The information contained in the Rare Disease Database is provided for educational purposes only. It should not be used for diagnostic or treatment purposes. If you wish to obtain more information about this disorder, please contact your personal physician and/or the agencies listed in the "Resources" section of this report. Glycogen Storage Disease VIII is a sex-linked genetic disorder caused by a deficiency of the enzyme liver phosphorylase kinase. The disorder is characterized by slightly low blood sugar (hypoglycemia). Excess amounts of glycogen (the stored form of energy that comes from carbohydrates) are deposited in the liver, causing enlargement of the liver (hepatomegaly). Symptoms 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. Causes Glycogen Storage Disease VIII is a sex-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. (X-linked recessive traits are expressed predominantly in males. Females carry the gene on one of their two X chromosomes. The second X chromosome will usually "mask" the trait, however, if the trait is x-linked recessive. The trait is expressed in males because instead of a second X chromosome, they have a Y chromosome which does not "mask" the harmful gene. Affected males cannot transmit the trait to their sons.) Affected Population All Glycogen Storage Diseases together affect less 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 with only very mild symptoms. Related Disorders Glycogen Storage Diseases are caused by inborn errors of metabolism in which the balance between stored energy (glycogen) and available energy (sugar or glucose) is disturbed. Too much glycogen tends to be stored in the liver and muscles and too little sugar is available in the blood. Symptoms of the following diseases may be similar to Glycogen Storage Disease VIII. Comparisons may be useful for a differential diagnosis: Von Gierke Disease (Glycogenosis I) is a glycogen storage disease. This hereditary metabolic disorder is caused by an inborn lack of either the enzyme glucose-6-phosphatase or the enzyme glucose-6-phosphate translocase. These enzymes are needed to convert the main carbohydrate storage material (glycogen) into sugar (glucose) which the body uses for its energy needs. A deficiency of these enzymes causes deposits of excess glycogen in the liver and kidney cells. Forbes Disease (Glycogenosis III; Cori Disease) is another genetic glycogen storage disease. This disorder is caused by a lack of a debrancher enzyme (amylo-1,6-glucosidase). This enzyme deficiency causes excess glycogen (the main carbohydrate storage material) to be deposited in the liver and muscles. The heart may be involved in some cases. Andersen Disease (Glycogenosis VI) is a glycogen storage disease inherited through recessive genes. Symptoms of this disorder are caused by a lack of a brancher enzyme (alpha-1,4-glucan 6-glucosyltransferase). The lack of this enzyme causes an abnormality in the structure of the main carbohydrate storage material (glycogen). Andersen Disease is characterized by scarring of the liver (cirrhosis) sometimes leading to liver failure. Hers Disease is a genetic form of mild glycogen storage disease. The disorder is caused by a deficiency of the enzyme liver phosphorylase. Hers Disease is characterized by enlargement of the liver (hepatomegaly), low blood sugar (hypoglycemia), elevated levels of acetone and other ketone bodies in the blood (ketosis), and growth retardation. Symptoms are not always evident during childhood, so children are usually able to lead normal lives. In other cases symptoms may be more severe. For more information on the above disorders, choose "Gierke," "Forbes," "Andersen," and "Hers" as your search terms in the Rare Disease Database. Therapies: Standard Treatment is usually not necessary for this disorder in its mild form. Therapies: Investigational Genetic counseling will be helpful for families of children with Glycogen Storage Disease VIII. Dr. Y.T. Chen at Duke University Medical Center, at the request of the Glycogen Storage Disease Association, is collecting DNA from patients with Glycogen Storage Disease Type I to form a DNA bank for GSDI. Interested patients may contact the Glycogen Storage Diseases Association for further information. The address and phone number of the organization are listed in the Resources section of this report. This disease entry is based upon medical information available through February 1991. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder. Resources For more information on Glycogenosis Type VIII, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 Association for Glycogen Storage Diseases Box 896 Durant, IA 52747 (319) 785-6038 Research Trust for Metabolic Diseases in Children Golden Gates Lodge, Weston Rd. Crewe CW1 1XN, England Telephone: (0270) 250244 National Digestive Diseases Information Clearinghouse Box NDDIC Bethesda, MD 20892 (301) 468-6344 For information on genetics and genetic counseling referrals, please March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue White Plains, NY 10605 (914) 428-7100 Alliance of Genetic Support Groups 35 Wisconsin Circle, Suite 440 Chevy Chase, MD 20815 (800) 336-GENE (301) 652-5553 References GLYCOGEN STORAGE DISEASES: A PATIENT-PARENT HANDBOOK: Ed. by R. Rodney Howell; University of Texas Health Science Center, 1980. Pp. 32-33.