Glycogen Storage Diseases

Question 1

Pompe Disease (Type II)

Answer 1

Deficient Enzyme: Lysosomal a(1,4) glucosidase (acid maltase)

Symptoms: Cardiomegaly, hypertrophic cardiomyopathy, exercise intolerance, systemic findings leading to early death

Notes: Autosomal recessive, Pompe trashes the Pump (heart, liver, muscle)

Question 2

Cori Disease (Type III)

Answer 2

Deficient enzyme: Debranching enzyme a(1,6-glucosidase)

Symptoms: Milder form of Type I with normal blood lactate.

Notes: Autosomal recessive, gluconeogenesis is intact

Question 3

McArdle Disease (Type V)

Answer 3

Deficient enzyme: Skeletal muscle glycogen phosphorylase (myophosphorylase)

Symptoms: inc glycogen in muscle but muscle cannot break it down –> painful muscle cramps, myoglobinuria (red urine) with strenuous exercise, and arrhythmia from electrolyte abnormalities

Notes: Autosomal recessive, Blood glucose levels typically normal, McArdle = Muscle, tx with vit B6 (cofactor)

Question 4

Von Gierke Disease (Type 1)

Answer 4

Deficient Enzyme: Glucose-6-Phosphatase

Symptoms: severe fasting hypoglycemia, inc liver glycogen, inc triglycerides, inc uric acid, inc blood lactate, hepatomegaly

Notes: Autosomal recessive, Tx: frequent oral glucose/corstarch, avoid fructose/galactose