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Old 05-11-2011
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Heart Pompe disease: glycogen in heart muscles?

Can somebody explain why in Pompe disease the glycogen accumulates in the heart??
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Pompe disease differ from other glycogen storage diseases. About 3% of glycogen is degraded by the lysosomal enzyme a(1-4)-glycosidase (or acid maltase). What for glycogen degraded in the lysome? Nobody know. But deficiency of this enzyme causes accumulation of glycogen in VACUOLES in LYSOSOMES.
This is only one glycogen storage disease that is also lysosomal storage disease. So glycogen (normal structure) primarily will accumulate in the liver, then in heart(massive cardiomegaly) and other muscles.
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There isn't a specific tendency for the glycogen to accumulate in the heart, it accumulates in the lysosomal vesicles everywhere. However the most notable effects are on the heart, muscles and liver. The reason for it's accumulation is that around 5% of glycogen is degraded in the lysosomes and when enzymes in this pathway are mising, the glycogen goes on accumulating in the lysososmes.
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Hey thanks for the answers, guys! So theoretically in this disease, glycogen can build up anywhere where there's lysosomes, correct? But the effects are mainly seen in the heart, muscles, and liver.

Yes, I do realize that there are other GSDs... That's why I'm curious as to why only (?) Pomme disease causes cardiomegaly in addition to hepatomegaly... But I get it now. Phew.
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Quote:
Originally Posted by qentank View Post
Hey thanks for the answers, guys! So theoretically in this disease, glycogen can build up anywhere where there's lysosomes, correct?
I think yes. And I think that cardiac muscle differ for examples from skeletal muscles by structure as well as their activity. So I think that activity of lysosomes in the cardiac muscle will be much more in comparing with lysosomes in other muscles.
So I understood that will be much more glycogen accumulation in the heart muscle than in other ("less active") muscles.
NOTE: This is only my suggestion without any proof!
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Old 05-11-2011
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Quote:
Originally Posted by deyneko View Post
Pompe disease differ from other glycogen storage diseases. About 3% of glycogen is degraded by the lysosomal enzyme a(1-4)-glycosidase (or acid maltase). What for glycogen degraded in the lysome? Nobody know. But deficiency of this enzyme causes accumulation of glycogen in VACUOLES in LYSOSOMES.
This is only one glycogen storage disease that is also lysosomal storage disease. So glycogen (normal structure) primarily will accumulate in the liver, then in heart(massive cardiomegaly) and other muscles.
As per Dr. raymon of kaplan, glycogen degraded by the lysosomes , is the excess glycogen that is not been used in between the meals...In pompe's deisease due to deficiency of lysosomal alfa 1,4 glucosidase defi, this does nt occur nd is stored in the organs leading to osmotic damage..
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