Glycogen storage diseases

Question 1

Von Gierke Disease (type I) findings

Answer 1

• -Severe fasting hypoglycemia
• -Greatly increased glycogen in the liver
• -Increased blood lactate
• -Increased triglycerides
• -Increased uric acid (gout)
• -Hepatomegaly
• -Autosomal recessive

Question 2

Von Gierke Disease (type I) deficiency

Answer 2

–Glucose-6-phosphate

Question 3

Von Gierke Disease (type I) treatment

Answer 3

• -Frequent oral glucose/cornstarch
• -Avoidance of fructose and galactose
• -Treatment based on compensating for impaired gluconeogenesis and glycogenolysis

Question 4

Pompe disease (type II) findings

Answer 4

• -Cardiomegaly
• -Hypertrophic cardiomyopathy
• -Exercise intolerance
• -Glucose levels normal
• -Glycogen in lysosomes
• -Presents early
• -Leads to early death
• -Autosomal recessive

Question 5

Pompe disease (type II) deficient enzyme

Answer 5

–Lysosomal Alpha-1,4-glucosidase with alpha-1,6-glucosidase activity (acid maltase)

Question 6

Cori disease (type III) findings

Answer 6

• -Milder form of Von Gierke
• -Normal blood lactate levels
• -Accumulation of dextrin-like structures in cytosol
• -Gluconeogenesis still intact

Question 7

Cori disease (type III) deficient enzyme

Answer 7

Debranching enzyme (Alpha-1,6-glucosidase)

Question 8

McArdle Disease (type V) findings

Answer 8

• -Increased glycogen in muscle, but muscle can’t break it down–> painful muscle cramps
• -Myoglobinuria with strenuous exercise and arrhythmia from electrolyte abnormalities
• -Second-wind phenomenon due to increased muscular blood flow
• -Blood glucose levels unaffected

Question 9

McArdle Disease (type V) deficient enzyme

Answer 9

Skeletal muscle glycogen phosphorylase (Myophosphorylase)

Question 10

McArdle Disease (type V) treatment

Answer 10

–Consume simple sugars before exercise