🧬 Glycogen Storage Diseases: Mnemonics, Pathways, and Step 1 Clues

Glycogen Storage Diseases (GSDs) are a group of inherited disorders caused by enzyme deficiencies that affect glycogen synthesis or breakdown. These conditions are classic Step 1 and Step 2 CK material, especially when they present as pediatric metabolic crises. Today, we’ll give you high-yield clinical clues, memory hacks, and a visual map to master these diseases quickly and confidently.

🔍 GSD Classification Overview

Type	Name	Deficient Enzyme	Main Clue
I	Von Gierke	Glucose-6-phosphatase	Fasting hypoglycemia, hepatomegaly, ↑ lactate
II	Pompe	Lysosomal acid α-1,4-glucosidase	Cardiomegaly, hypotonia, early death
III	Cori	Debranching enzyme	Milder Von Gierke, normal lactate
IV	Andersen	Branching enzyme	Hepatosplenomegaly, cirrhosis
V	McArdle	Muscle glycogen phosphorylase	Muscle cramps, myoglobinuria
VI	Hers	Liver glycogen phosphorylase	Mild hypoglycemia, hepatomegaly

💡 Mnemonic for Types I–V: “Very Poor Carbohydrate Metabolism”

V – Von Gierke
P – Pompe
C – Cori
A – Andersen
M – McArdle

💡 Add H for Hers (VI) = "Very Poor Carbs Are Metabolized Horribly"

🧾 Step 1 & Step 2 CK Clinical Clues

Von Gierke (Type I)

• Presents at infancy

• Severe hypoglycemia between feeds

• ↑ Lactate, triglycerides, uric acid

• G6PC gene

Pompe (Type II)

• Cardiomegaly

• Early hypotonia

• Enlarged tongue

• Death by 2 years if untreated

McArdle (Type V)

• Teen/young adult with exercise intolerance

• Myoglobinuria after workouts

• Second-wind phenomenon

🧠 Use KOTC’s Q-Bank to simulate these case vignettes under timed pressure.

🔍 KOTC Visual Learning Tools

• “GSD Enzyme Pathway Map” (color-coded by organ)

• Disease summaries on 1-page cheatsheets

• Mnemonic-based flashcards in the KOTC app

• Gamified learning with Curve Coins + QOTD

📌 Before You Go…

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