Von Gierke, Pompe, Cori and McArdle, by the organ affected
Expansion
“Liver forms starve you; muscle forms cramp you.”
| Type | Name | Enzyme | Features |
|---|---|---|---|
| I | Von Gierke | Glucose-6-phosphatase | Severe fasting hypoglycaemia, hepatomegaly, lactic acidosis, hyperuricaemia, hyperlipidaemia, doll-like face |
| II | Pompe | Lysosomal acid maltase | Cardiomegaly and heart failure in infancy, hypotonia. The only lysosomal one |
| III | Cori | Debranching enzyme | Milder von Gierke, normal lactate |
| V | McArdle | Muscle phosphorylase | Exercise intolerance, cramps, myoglobinuria, second wind phenomenon. Normal blood sugar |
“Pompe trashes the pump” for the cardiomyopathy of type II, and “McArdle affects the muscle” for type V.
The second wind phenomenon in McArdle disease is characteristic: after a few minutes of rest, exercise becomes easier as the muscle switches to using fatty acids and blood glucose instead of glycogen. The ischaemic forearm exercise test shows a failure of lactate to rise with a normal ammonia rise.
Von Gierke’s biochemistry follows from the block: glucose-6-phosphatase is the final step of both glycogenolysis and gluconeogenesis, so neither can release glucose. Glucose-6-phosphate is shunted to lactate, urate and triglyceride, explaining the whole clinical picture.