Glycogen Storage Diseases

Question 1

Von Gierke disease (type I)

Answer 1

• Severe fasting hypoglycemia, increased glycogen in liver, increased blood lactate, hepatomegaly
• Deficiency: Glucose-6-phosphatase
• Autosomal recessive
• Treatment: frequent oral glucose/cornstarch; avoidance of fructose & maltose

Question 2

Pompe disease (type II)

Answer 2

• Cardiomyopathy & systemic findings leading to early death
• Deficiency: Lysosomal alpha-1,4-glucosidase (acid maltase)
• Autosomal recessive

Question 3

Cori disease (type III)

Answer 3

• Milder form of type I with normal blood lactate levels
• Deficiency: Debranching enzyme (alpha-1,6-glucosidase)
• Autosomal recessive
• Gluconeogenesis is intact

Question 4

McArdle disease (type V)

Answer 4

• Increased glycogen in muscle, but can’t break it down, leading to painful muscle cramps, myoglobinuria (red urine) w/ strenuous exercise, & arrhythmia from electrolyte abnormalities
• Deficiency: Skeletal muscle glycogen phosphorylase (myophosphorylase)
• Autosomal recessive