Glycogen Storage Diseases

Question 1

What is the enzyme deficient in Type I - Von Gierke disease?

Answer 1

Glucose-6-phosphatase (G6P => Gluc)

Question 2

What tissues does Type I - Von Gierke disease affect?

Answer 2

Liver and kidney

Question 3

What are the clinical features of Type I - Von Gierke disease?

Answer 3

Severe fasting hypoglycemia
Lactic acidosis
Hepatomegaly
Short stature
Delayed puberty
Bleeding diathesis (especially epistaxis)
Hepatic adenomas, renal failure, gout in 20s and 30s

Question 4

What is the enzyme deficient in Type II - Pompe disease?

Answer 4

a-1,4,-glucosidase (acid maltase) => enzyme is in lysosomes

Question 5

What tissues does Type II - Pompe disease affect?

Answer 5

All organs

Question 6

What are the clinical features of Type II - Pompe disease?

Answer 6

Progressive muscle weakness
Breathing and feeding difficulties
Hyporeflexia or areflexia due to glyogen accumulation in spinal motor neurons
Cardiomegaly leading to CHF and death before age 2

Question 7

What is the enzyme deficient in Type III - Cori disease?

Answer 7

Debranching enzyme (a-1,6-glucosidase)

Question 8

What tissues does Type III - Cori disease affect?

Answer 8

Muscle and liver

Question 9

What are the clinical features of Type III - Cori disease?

Answer 9

Similar to Type I without lactic acidosis
-Hypoglycemia
-Hepatomegaly
-Delayed (ultimately normal) growth
Symptoms usually regress in adulthood

Question 10

What is the enzyme deficient in Type IV - McArdle disease?

Answer 10

Myophosphorylase

Question 11

What tissues does Type IV - McArdle disease affect?

Answer 11

Muscle

Question 12

What are the clinical features of Type IV - McArdle disease?

Answer 12

Muscle weakness and cramps after exercise

Myoglobinuria (burgundy urine) after exercise