Glycogen Storage Diseases

Question 1

Cori Disease

Answer 1

Debranching enzyme deficiency leads to accumulation of glycogen with abnormally short outer chains (limit dextrins) due to inability to degrade alpha 1,6 glycosidic branch points. Pts present with hypoglycemia, ketoacidosis, hepatomegaly and muscle weakness and hypotonia.

Question 2

McArdle disease

Answer 2

Muscle glycogen phosphorylase disease deficiency causes decreased exercise tolerance, muscle pain, and cramping. Blood lactate is often very low after exercise and muscle biopsy shows an excess of normally structured glycogen

Question 3

Hers disease

Answer 3

Liver glycogen phosphorylase deficiency presents early in childhood with mild hypoglycemia, ketosis, and hepatomegaly. Doesn’t affect skeletal muscle and would show an excess of normally structured glycogen (not limit dextrin) on liver biopsy

Question 4

Von gierke disease

Answer 4

Glucose-6-phosphatase deficiency affects mainly the liver and kidney. Symptoms include hypoglycemia, lactic acidosis, hyperlipidemia, and hyperuricemia. Hepatic steatosis is a cardinal manifestation

Question 5

Pompe disease

Answer 5

Acid maltase deficiency (both alpha 1,4 and 1,6 glucosidase activity) characterized by cardiomegaly, severe generalized hypotonia, and lysosomal glycogen accumulation (hypoglycemia is not seen).