A 2-year-old boy presents with progressive abdominal distension and poor weight gain. Examination shows hepatomegaly and splenomegaly. Liver biopsy reveals glycogen with abnormally short outer chains, and portal fibrosis is noted. The child has no fasting hypoglycemia. Which enzyme defect is most likely?

• A Glycogen phosphorylase
• B Phosphoglucomutase
• C Glycogen synthase
• D Branching enzyme (glycogen-branching enzyme) ✓

Explanation

Andersen disease (GSD type IV) results from branching enzyme deficiency. Glycogen is synthesized with long unbranched outer chains resembling amylopectin, which is poorly soluble and triggers progressive hepatic fibrosis and cirrhosis. Because cytosolic glycogenolysis can still release glucose from available ends, fasting hypoglycemia is characteristically absent, which distinguishes it from GSD types I and III. Phosphorylase defects cause hypoglycemia or exercise intolerance, not cirrhosis.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.