Glycogen storage diseases

Question 1

Type 1: Von Gierke’s disease

Answer 1

Cause: deficiency of G6Phosphatase Characteristics: Liver cells and renal tubule cells loaded with glycogen. Hypoglycemia, lactic-acidemia, ketosis, hyperlipidemia Structure: normal

Question 2

Type 2: Pompe’s disease

Answer 2

Cause: Deficiency of lysosomal alpha1-4 and 1-6 glucosidase (acid maltase) Characteristics: Fatal, accumulation of glycogen in lysosomes, heart failure Structure: normal

Question 3

Type 3: Limit dextrinosis, Forbes’ or Cori’s disease

Answer 3

Cause: Absence of deb ranching enzymes Characteristics: Accumulation of a characteristic branched polysaccharide Structure: abnormal very long inner and outer unbranched chain Structure: normal

Question 4

Type 4: Amylopectinosis, Andersen’s disease

Answer 4

Cause: Absence of branching enzyme Characteristics: Accumulation of a polysaccharide having few branch points. Death due to cardiac or liver failure in first year of life Structure: abnormal outer chains missing or very short; increased number of branch points

Question 5

Type 5: Myophosphorylase deficiency, McArdle’s syndrome

Answer 5

Cause: Absence of muscle phosphorylase Characteristic: Diminished exercise tolerance; muscles have abnormally high glycogen content (2.5-4.1%). Little or no lactate in blood after exercise Structure: normal

Question 6

Type 6: Hers’ disease

Answer 6

Cause: Deficiency of liver phosphorylase Characteristics: High glycogen content in liver, tendency toward hypoglycemia Structure: normal

Question 7

Type 7: Tarui’s disease

Answer 7

Cause: Deficiency of phosphofructokinase in muscle and erythrocytes Characteristics: As for type 5 but also possibility of hemolytic anemia Structure: normal

Question 8

Type 8

Answer 8

Cause: Deficiency of liver phosphorylase kinase Characteristics: As for type 6 Structure: normal