Glycogen Storage Diseases

Question 1

Von Gierke disease

What is the inheritance pattern? Deficient enzyme? Findings? Treatment?

Answer 1

Inheritance pattern: AR

Deficient enzyme: Glucose-6-phosphatase (only found in liver and kidney)

Findings: Severe fasting hypoglycemia, high blood lactate, high TGs, high uric acid, hepatomegaly

Treatment: Avoid fructose (galactose+glucose) and galactose, frequent oral glucose

Question 2

Pompe disease (type II GSD)

What is the inheritance pattern? Deficient enzyme? Findings?

Answer 2

Inheritance pattern: AR

Deficient enzyme: Lysosomal alpha-1,4-glucosidase (acid maltase) ->glycogen accumulates in lysosomes

Findings: Normal blood glucose, cardiomegaly, hypertrophic cardiomyopathy, exercise intolerance (severe muscle cramps)

“Pompe trashes the pump” (heart liver and muscle)

Question 3

Cori disease (Type III GSD)

What is the inheritance pattern, deficient enzyme, findings?

Answer 3

Inheritance pattern: AR

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

Findings: (Milder form of von Gierke type I) Normal blood lactate, hepatomegaly, fasting hypoglycemia, stunted growth

Question 4

McArdle disease (GSD Type V)

What is the inheritance pattern? Deficient enzyme? Findings? Treatment?

Answer 4

Inheritance pattern: AR

Deficient enzyme: skeletal muscle glycogen phosphorylase (myophosphorylase) -> increase glycogen in muscle and cannot break down

Findings: Normal blood glucose usually, Painful muscle cramps, myogobinuria with strenuous exercise, arrhythmias

Treatment: Treat with vitamin B6 (cofactor for glycogen phosphorylase)