Pompe disease is one of those Step “gimme points” if you have a crisp mental image: a baby who’s “pumped up” (huge heart + weak muscles) because their lysosomes can’t break down glycogen.
The Mnemonic: “POMPE = PUMP”
Think: a “PUMP” that’s clogged with sugar.
Visual you should picture
A heart-shaped pump stuffed with glycogen (sugar cubes). The pump gets bigger and stiffer, and the baby gets floppy and weak.
POMPE → PUMP problem
- Pumped-up heart (hypertrophic cardiomyopathy)
- Unable to break down glycogen in lysosomes (acid α-glucosidase deficiency)
- Muscle weakness (hypotonia, myopathy)
- Purple-ish tongue / feeding trouble + respiratory issues (classic infant presentation vibe)
One-liner (the shareable version)
Pompe = lysosomal acid α-glucosidase deficiency → glycogen accumulates in lysosomes → cardiomegaly + hypotonia (“floppy baby”).
High-yield USMLE facts (what they love to test)
What enzyme is deficient?
- Acid α-glucosidase
- a.k.a. acid maltase
- lysosomal enzyme that degrades glycogen
What accumulates?
- Glycogen in lysosomes, especially in cardiac and skeletal muscle
Classic presentation (Infantile Pompe)
- Hypertrophic cardiomyopathy → cardiomegaly, heart failure
- Hypotonia (“floppy baby”)
- Macroglossia, feeding difficulties
- Respiratory distress (weak diaphragm)
Key Step 1 differentiator
- Pompe is a lysosomal storage disease and a glycogen storage disease.
- It’s the glycogen storage disease that screams “cardiomyopathy + hypotonia”.
Pompe vs other glycogen storage diseases (quick compare table)
| Disease | Enzyme deficiency | Main organs | Hallmark clue |
|---|---|---|---|
| Pompe (GSD II) | Acid α-glucosidase (acid maltase) | Heart + skeletal muscle | Hypertrophic cardiomyopathy + hypotonia |
| Von Gierke (GSD I) | Glucose-6-phosphatase | Liver, kidney | Severe fasting hypoglycemia, lactic acidosis |
| McArdle (GSD V) | Muscle glycogen phosphorylase | Skeletal muscle | Exercise intolerance, myoglobinuria, “second wind” |
| Cori (GSD III) | Debranching enzyme | Liver, muscle | Milder Von Gierke; limit dextrin |
Extra high-yield pearls (rapid fire)
- Pathogenesis: impaired lysosomal glycogen breakdown → muscle cell dysfunction.
- Course: infantile form can be fatal early from cardiorespiratory failure if untreated.
- Treatment concept (Step-level): enzyme replacement therapy exists (you don’t need drug names unless asked).
10-second recall checkpoint
If you see: infant + cardiomegaly + hypotonia → say out loud:
“Pompe: acid maltase deficiency, glycogen in lysosomes—PUMPED heart.”