Glycogen storage disease type 4 (transglucosidase deficiency or Andersen disease) is a rare and deadly autosomal recessive disease characterized by the buildup of abnormal glycogen in the liver and muscle. Caused by mutation on gene GBE1 that results in defective glycogen-branching enzymes. Five variations exist. In the classic variation, cases present within the first few months of life with failure to thrive, hypotonia, and hepatomegaly. Other common features of this variant include hypoglycemia, hepatic cirrhosis, and liver failure. Liver transplantation is typically required for survival by age 5.

The other 4 variations are less common. A fatal perinatal neuromuscular variant consists of hydrops fetalis, fetal akinesia deformation sequence, atrophy, polyhydramnios, and severe hypotonia. These patients typically do not survive past the neonatal period. A congenital neuromuscular variant results in severe muscle weakness, respiratory distress, cardiomyopathy, and death in early infancy.  A nonprogressive hepatic variant results in less severe hepatomegaly, myopathy, hypotonia, and liver dysfunction. These patients usually have lifespans into adulthood. Finally, a childhood neuromuscular variant presents in late childhood with myopathy and dilated cardiomyopathy. Some patients with this variant are severely affected and may die by early adulthood, but others only present with mild weaknesses.