Glycogen storage disease type IV

Glycogen storage disease type IV, abbreviated GSD IV, is a form of glycogen storage disease caused by an inborn error of metabolism. It results from a mutation in the GBE1 gene, which causes a defect in the glycogen branching enzyme, so glycogen is not made properly and abnormal glycogen molecules called polyglucosan accumulate in cells, possibly in the liver, skeletal muscle, heart or nervous system. It is autosomal recessive. An early-onset form is called Andersen disease and an adult-onset form is called adult polyglucosan body disease. GSD IV is estimated to affect about 1 in 236,000 people worldwide, about 3 percent of all glycogen storage diseases.