A 7-year-old boy has moderate hepatomegaly and mild fasting hypoglycemia. Exercise tolerance is normal, there is no myoglobinuria, and postprandial glucagon produces a normal rise in lactate but fails to raise blood glucose. Liver phosphorylase activity is markedly reduced. What is the most likely diagnosis?

• A Von Gierke disease (glycogen storage disease type I)
• B Tarui disease (glycogen storage disease type VII)
• C Cori disease (glycogen storage disease type III)
• D Hers disease (glycogen storage disease type VI) ✓

Explanation

Hers disease is hepatic glycogen phosphorylase deficiency. Because the defect is confined to liver, muscle performance is entirely normal, distinguishing it from McArdle and Tarui disease. Hepatomegaly with mild fasting hypoglycemia occurs, but lactic acidosis and hyperuricemia are characteristically absent because gluconeogenesis remains intact, which separates it from von Gierke disease. Failure of glucagon to raise glucose reflects inability to mobilize hepatic glycogen stores.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.