GLYCOGEN STORAGE DISEASES

Question 1

Which enzyme is deficient in Von Gierke disease?

Answer 1

Glucose-6-phosphatase

Von Gierke disease (Type I GSD) is characterized by impaired gluconeogenesis and glycogenolysis.

Question 2

Which GSD is associated with cardiomegaly, muscle hypotonia, and death due to heart failure by age 2?

Answer 2

Pompe

Pompe disease (Type II GSD) results from a deficiency in lysosomal acid alpha-glucosidase.

Question 3

What will liver biopsy findings show in a patient with Cori disease?

Answer 3

Glycogen with short outer branches

Cori disease (Type III GSD) is due to a deficiency in the debranching enzyme.

Question 4

McArdle disease is caused by deficiency of which enzyme?

Answer 4

Muscle glycogen phosphorylase

McArdle disease (Type V GSD) impairs glycogen breakdown in skeletal muscles.

Question 5

What clinical feature distinguishes McArdle disease?

Answer 5

Muscle cramps with exercise

This feature is due to impaired glycogenolysis in muscle.

Question 6

A 5-year-old with McArdle disease does moderate exercise and develops dark-colored urine. What complication is most likely?

Answer 6

Acute tubular necrosis from myoglobinuria

Muscle breakdown releases myoglobin, leading to this condition.

Question 7

Which GSD shows normal blood glucose but lysosomal glycogen accumulation?

Answer 7

Pompe

Pompe disease involves glycogen accumulation in lysosomes without significant hypoglycemia.

Question 8

What is the deficient enzyme in Hers disease (Type VI)?

Answer 8

Hepatic glycogen phosphorylase

Hers disease leads to mild hypoglycemia and hepatomegaly.

Question 9

A baby has hepatomegaly, fasting hypoglycemia, and mild lactic acidosis. Glycogen has abnormal outer branches. What’s the diagnosis?

Answer 9

Cori

This presentation is due to debranching enzyme deficiency.

Question 10

Which GSD presents with hypotonia, cardiomegaly, and glycogen in lysosomes?

Answer 10

Pompe

Pompe disease affects muscle function due to glycogen accumulation.

Question 11

Glycogen in Pompe disease is not degraded due to a deficiency in which enzyme?

Answer 11

Lysosomal alpha-1,4-glucosidase

This deficiency leads to glycogen accumulation in lysosomes.

Question 12

Which GSD leads to ketoacidosis, hyperlipidemia, and severe fasting hypoglycemia due to inability to release free glucose from the liver?

Answer 12

Von Gierke

This condition results from impaired glucose-6-phosphatase.

Question 13

Why is glycolysis not impaired in muscle in Von Gierke disease?

Answer 13

Muscle doesn’t need glucose-6-phosphatase

Muscle uses glucose-6-phosphate for its own energy needs.

Question 14

Which GSD presents with short glycogen branches and mild hypoglycemia, but normal lactate levels?

Answer 14

Cori

Cori disease features abnormal glycogen structure due to debranching enzyme deficiency.

Question 15

In which GSD would you see exercise intolerance with failure to elevate lactic acid after exertion?

Answer 15

McArdle

McArdle disease impairs glycogen breakdown in muscle.