What causes 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.