An 8-month-old infant has a doll-like facies, protuberant abdomen, and massive hepatomegaly. He presents with a seizure and blood glucose is 32 mg/dL. Investigations show lactic acidosis, hyperuricaemia, and hypertriglyceridaemia. Which enzyme defect is responsible?

• A Lysosomal alpha-glucosidase (acid maltase)
• B Muscle phosphorylase
• C Debranching enzyme
• D Glucose-6-phosphatase ✓

Explanation

Von Gierke disease (glycogen storage disease type Ia) is caused by glucose-6-phosphatase deficiency, blocking the final step of glycogenolysis and gluconeogenesis. This produces fasting hypoglycaemia with lactic acidosis, hyperuricaemia, and hyperlipidaemia plus hepatomegaly and doll-like facies. Acid maltase deficiency (Pompe) causes cardiomyopathy and muscle disease without hypoglycaemia, muscle phosphorylase deficiency (McArdle) causes exercise intolerance with normal liver function, and debrancher deficiency (Cori) causes milder hepatomegaly without prominent lactic acidosis.

Reference: Nelson Textbook of Pediatrics, 22nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.