Glycogen Storage & Fatty Acid Metabolism Diseases

Question 1

What are the findings in McArdle disease? What enzyme is deficient? How is it inherited?

Answer 1

Autosomal Recessive. Deficiency in skeletal muscle glycogen phosphorylase (myophosphorylase). Results in : increased glycogen in muscle but an inability to break it down, causing painful muscle ramps & myoglobinuria with strenuous exercise. At worst, can cause arrythmias from electrolyte disturbances.

Question 2

What are the findings in Pompe disease? What is the deficient enzyme? How is it inherited?

Answer 2

Autosomal Recessive. Deficiency in lysosomal a-1,4-glucosidase (acid maltase). Causes cardiomyopathy and systemic findings w/ early death.

Question 3

What are the findings in Von Gierke disease? What is the deficient enzyme? How is it inherited and treated?

Answer 3

Autosomal Recessive. Deficiency in glucose-6-phosphatase. Results in severe fasting hypoglycemia w/ increased glycogen in the liver, increased blood lactate, and hepatomegaly. Treatment is frequent oral glucose and avoidance of fructose and galactose.

Question 4

What are the findings in Cori disease? What is the deficient enzyme? How is it inherited?

Answer 4

This is a mild form of Von Gierke disease – Autosomal Recessive. Deficiency in a-1,6-glucosidase (debranching enzyme).

Question 5

What is carnitine needed for? What happens in deficiency?

Answer 5

Needed for transportation and degradation of long-chain FAs into the mitochondrial matrix. With deficiency, toxic accumulation occurs, leading to weakness, hyptonia, hypoketotic hypoglycemia.

Question 6

What happen with an acyl-CoA dehydrogenase deficiency?

Answer 6

Increaed dicarboxylic acids, with decreased glucose and ketones. Also, decreases in acetyl-CoA lead to decreased fasting glucose.