Genetics and inheritance of GSDs — Flashcards

Flashcard 1: Which glycogen storage disorder is associated with severe fasting hypoglycemia? _____

Answer: Von Gierke disease

Flashcard 2: The hallmark of what glycogen storage disease is a flat venous lactate curve with a rise in ammonia levels during exercise?_____

Answer: McArdle disease

Flashcard 3: X-linked recessive diseases are commonly more severe in _____

Answer: males

Flashcard 4: What is the mode of inheritance of G6PD deficiency? _____

Answer: X-linked recessive

Flashcard 5: What is the inheritance of Menkes disease? _____

Answer: X-linked recessive

Flashcard 6: glycogen synthesis

Answer: glycogen synthase

Flashcard 7: Rate-limiting enzyme of glycogenolysis

Answer: glycogen phosphorylase

Flashcard 8: What is the enzyme deficiency in McArdle's disease (GSD type V)?

Answer: Deficiency of skeletal muscle glycogen phosphorylase (myophosphorylase) :: enzyme deficiency?

Extra: - Presentation: Painful muscle cramps, myoglobinuria (rhabdomyolysis) with strenuous exercise, and "second-wind" phenomenon. - Pathophysiology: Glycogen accumulation in muscle; cannot break down glycogen to glucose-1-phosphate. - Genetics: Autosomal Recessive (AR). - Mnemonic: Very Poor Carbohydrate Metabolism (Von Gierke, Pompe, Cori, McArdle).

Flashcard 9: Cori's disease (GSD type III) is caused by a deficiency in which enzyme?

Answer: Debranching enzyme deficiency (α-1,6-glucosidase) \n\nCharacterized by: hepatomegaly, fasting hypoglycemia, normal blood lactate levels, and accumulation of limit dextrin-like structures.

Extra: Inheritance: Autosomal Recessive (AR)\nMnemonic: Very Poor Carbohydrate Metabolism (Von Gierke, Pompe, Cori, McArdle) - although Cori is Type III. \n\nNote: Blood lactate is normal in Cori's disease, unlike Von Gierke's (Type I) where it is elevated. Muscle involvement (weakness) can also be seen in Cori's.

Flashcard 10: What is the deficient enzyme in Von Gierke disease (GSD type I)?

Answer: Deficient enzyme: Glucose-6-phosphatase

Extra: * **Presentation**: Severe fasting hypoglycemia, increased blood lactate, hepatomegaly, increased uric acid (gout). * **Pathology**: Very increased hepatic glycogen stores (normal structure). * **Inheritance**: Autosomal Recessive (AR). * **Mnemonic**: **V**ery **P**oor **C**arbohydrate **M**etabolism (Von Gierke, Pompe, Cori, McArdle).