Glycogen Storage Diseases

Question 1

Von Gierke’s disease (type I)

Answer 1

Findings: Severe fasting hypoglycemia, very increased glycogen in liver, increased blood lactate, hepatomegaly
Deficient Enzyme: Glucose-6-phosphatase
Comments: Autosomal recessive.

Question 2

Pompe’s disease (type II)

Answer 2

Findings: Cardiomegaly and systemic findings leading to early death
Deficient Enzyme: Lysosomal alpha-1,4-glucosidase (acid maltase)
Comments: Autosomal recessive. Pompe’s trashes the Pump (heart, liver, and muscle).

Question 3

Cori’s disease (type III)

Answer 3

Findings: Milder form of type I with normal blood lactate levels
Deficient Enzyme: Debranching enzyme (alpha-1,6-glucosidase)
Comments: Autosomal recessive. Gluconeogenesis is intact.

Question 4

McArdle’s disease (type V)

Answer 4

Findings: Increased glycogen in muscle, but cannot break it down, leading to painful muscle cramps, myoglobinuria with strenuous exercise
Deficient Enzyme: Skeletal muscle glycogen phosphorylase
Comments: Autosomal recessive. McArdle’s = Muscle.