A 6-month-old infant who is failing to thrive is brought to your clinic. Tests reveal hepatosplenomegaly, muscle weakness and atrophy, hypotonia, and decreased deep tendon reflexes. Blood tests reveal that the infant has normal glucose levels. Biopsy of the liver reveals initial stages of cirrhosis due to the accumulation of an abnormal glycogen with few branch points whose structure resembles amylopectin. The clinical and laboratory results presented are indicative of which GSD?

Question

Quizplus · Accepted Answer

The symptoms and biopsy findings are indicative of Andersen disease (type IV glycogen storage disease), which is characterized by the accumulation of an abnormal glycogen with few branch points, resembling amylopectin, leading to liver cirrhosis and other systemic symptoms.  Andersen disease, glycogen storage disease type IV (GSDIV), is also known as amylopectinosis. The disease results from defects in the gene encoding glycogen-branching enzyme, also called amylo-(1,4 to 1,6) transglycosylase. The disease manifests with progressive hepatosplenomegaly along with the storage of an abnormal glycogen that exhibits poor solubility in the liver. The abnormal glycogen is characterized by few branch points with long outer chains containing more α-1,4-linked glucose than normal glycogen. This resultant structure is similar to that of amylopectin (the structure of starch in plants), thus the associated name of amylopectinosis.

A 6-Month-Old Infant Who Is Failing to Thrive Is Brought