A 2-year-old boy has progressive hepatomegaly and rising transaminases. Liver biopsy shows cirrhotic nodules containing stored polysaccharide with few branch points and long outer chains. Which enzyme is deficient?

• A Debranching enzyme
• B Glycogen synthase
• C Amylo-1,4 to 1,6 transglucosidase (branching enzyme) ✓
• D Glycogen phosphorylase

Explanation

Glycogen storage disease type IV (Andersen disease) results from branching enzyme deficiency. Without alpha-1,6 branches, an abnormal, poorly soluble glycogen resembling amylopectin (long unbranched chains) accumulates, provoking progressive hepatic fibrosis and cirrhosis, often leading to liver failure in childhood. Debrancher deficiency causes type III disease with distinct limit dextrin and usually milder hepatic disease, while phosphorylase defects leave normal branched structure intact.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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