Glycogen storage disease type 4

What causes glycogen storage disease type 4?

Glycogen storage disease type 4 (GSD 4) is caused by mutations in the GBE1 gene. The GBE1 gene normally provides instructions for making the glycogen branching enzyme. This enzyme is necessary for making glycogen, a major source of stored energy in the body. Glycogen is formed by assembling many molecules of glucose. The glycogen branching enzyme is involved in the formation of "branches" of glucose chains, which help to make glycogen more compact for storage and allows it to break down more easily when it is needed for energy. The GBE1 gene mutations that cause GSD 4 lead to a decrease in the amount or functionality of the glycogen branching enzyme. Glycogen is then not formed properly, and substances called polyglucosan bodies build up in cells throughout the body, causing the signs and symptoms of the condition.

Last updated on 05-01-20

How is glycogen storage disease type 4 inherited?

Glycogen storage disease type 4 is inherited in an autosomal recessive manner. This means that an individual must have 2 abnormal copies of the GBE1 gene to be affected (one abnormal copy inherited from each parent). Individuals with one abnormal copy of the GBE1 gene, such as the parents of an affected individual, are referred to as carriers. Carriers typically do not have signs or symptoms of an autosomal recessive condition. When two carriers of an autosomal recessive condition are having children, each of their children has a 25% (1 in 4) risk to be affected, a 50% (1 in 2) risk to be a carrier like each parent, and a 25% chance to not be a carrier and not be affected.

Last updated on 05-01-20

What are the chances for a couple who has had a baby with glycogen storage disease type 4 to have a baby that is not affected?

At conception, each sibling of an affected individual has a 25% chance of being affected, a 50% chance of being a carrier (without symptoms), and a 25% chance of being unaffected and not a carrier. That means that in each future pregnancy, there is a 1 in 4 (25%) chance that another baby with glycogen storage disease type 4 will be conceived.

Last updated on 05-01-20

Is prenatal diagnosis available for pregnancies at-risk for glycogen storage disease type 4?

Prenatal diagnosis for pregnancies at increased risk for glycogen storage disease type 4 is possible by analysis of DNA extracted from fetal cells obtained by amniocentesis usually performed at approximately 15 to 18 weeks’ gestation or chorionic villus sampling (CVS) at approximately ten to 12 weeks’ gestation. Both disease-causing alleles of an affected family member must be identified before prenatal testing can be performed.

Last updated on 05-01-20

Are there procedures that can detect glycogen storage disease type 4 at the in vitro fertilization (IVF) level?

Preimplantation genetic diagnosis (PGD), a procedure which can be used in conjunction with in vitro fertilization (IVF), may be available for families in which the disease-causing mutations have been identified. Click here to access a listing of laboratories which offer PGD.

Last updated on 05-01-20

How might glycogen storage disease type 4 be treated?

Management of glycogen storage disease type 4 typically focuses on the signs and symptoms that are present in each individual. Studies have show that in some cases, strict dietary therapy can help to maintain normal levels of glucose in the blood, reduce liver size, reduce symptoms, and allow for improved growth and development. Growing evidence indicates that a high- protein diet may improve muscle function in individuals with weakness or exercise intolerance and slow disease progression. Supportive care is typically needed for complications such as liver failure, heart failure, and neurologic dysfunction. Liver transplantation may be necessary for individuals with progressive liver disease. Individuals with cardiomyopathy may require the use of certain medications.

Last updated on 05-01-20

Name: Metabolic Support UK 5 Hilliards Court Sandpiper Way
Chester Business Park
Chester, CH4 9QP, United Kingdom
Phone: 0845 241 2173 Toll Free: 0800 652 3181 Email: Url:
Name: Association for Glycogen Storage Disease PO Box 896
Durant, IA, 52747 , United States
Phone: 1-563-514-4022 Email: Url:
Name: Association for Glycogen Storage Disease UK Old Hambledon Racecourse Sheardley Lane
Droxford, Southampton, SO32 3QY
United Kingdom
Phone: 0300 123 2790 (Office hrs, Mon-Thurs) or 0300 123 2799 (Out of hours) Url:

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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