High muscle glycogen content (2.5-4.1% versus

0.2-0.9% normal); fall in blood lactate and pyruvate

after exercise (normal is sharp rise) with no

postexercise drop in pH; normal hyperglycemic

response to epinephrine (thus normal hepatic

enzyme); myoglobinuria after strenuous exercise;

autosomal recessive.

Not as serious as glucose-

6

-phosphatase deficiency;

liver cannot make glucose from glycogen but can

make it from pyruvate; mild hypoglycemia and

ketosis; hepatomegaly due to glycogen accumulation;

probably more than one disease; must be distinguished

from defects in the glycogen phosphorylase-

activating system.

Shows properties similar to type V; autosomal

recessive; it is not completely clear why this defect

results in increased glycogen storage.

Hepatomegaly; increased hepatic glycogen stores;

probably X-linked, but there may be more than one

type, with some autosomally inherited; must be

distinguished from glycogen phosphorylase deficiency.