Glycogen Storage Diseases

Question 1

Von Gierke disease (Type I)

Answer 1

• Glucose-6-phosphatase deficiency
• Impaired gluconeogenesis, glycogenolysis
• Severe fasting hypoglycemia, gout, hepatomegaly
• Highly elevate glycogen in liver, elevated blood lactate, triglycerides, uric acid

Question 2

Von Gierke disease treatment

Answer 2

• Frequent oral glucose, corn starch overnight

- avoidance of fructose and galactose

Question 3

Pompe disease (Type II)

Answer 3

• Lysosomal alpha-1,4-glucosidase deficiency with alpha-1,6-glucosidase activity (acid maltase)
• Cardiomegaly, hypertrophic cardiomyopathy, exercise intolerance
• Early death

Question 4

Cori disease (Type III)

Answer 4

• Debranching enzyme (alpha-1,6-glucosidase) deficiency
• Milder form of Von Gierke with normal blood lactate levels
• Accumulation of limited dextrin-like structures in cytososol
• Gluconeogenesis intact

Question 5

McArdle Disease (Type V)

Answer 5

• SKM glycogen phosphorylase (myoposphorylase) deficiency
• increased glycogen in muscle, but cannot be broken down
• Painful muscle cramps, myoglobinuria with strenuous exercise, arrhythmia from electrolyte abnormalities
• Second wind phenomenon during exercise due to increased BF
• Blood glucose levels unaffected