Von Gierke Disease, Andersen's disease, Tarui Disease

Question 1

Glycogen storage diseases

Answer 1

Glycogen Storage Diseases are genetic enzyme deficiencies associated with excessive glycogen accumulation within cells. Glycogen cannot be used by cells.

Some enzymes whose deficiency leads to glycogen accumulation are part of the inter-connected pathways shown here.

Question 2

Von Gierke disease Type 1

Answer 2

Genetically linked.

Deficiency of glucose-6-phosphatase, therefore conversion of glycogen to glucose & gluconeogenesis disrupted.

Causes severe hypoglycemia within 2-4 hours of meal

Organs affected: liver and kidney

Patients kept alive by regular carbohydrate feeding day and night.

Synthesis of glucose by our liver is important to keep us alive

Question 3

Hypoglycemia

Answer 3

Blood glucose level is lower than normal, liver and kidney

Question 4

Recap glucose 6 phosphatase

Answer 4

Enzyme that hydrolyses glucose 6 phosphate, found in kidney and liver. It forms phosphate and free glucose, used to breakdown glycogen into glucose.

Question 5

Andersen disease type 4

Answer 5

Absence or defect in trans-glucosidase, a branching enzyme in gluconeogenesis.

Result in the formation of long unbranched glucose chain known as amylopectin.

Low solubility of amylopectin causes amylopectin deposit to build up in heart and liver.

End results is liver failure and death in first year of life.

Question 6

Why glycogen needs to be branched?

Answer 6

Normal glycogen needs to be branched out to increase its solubility.

it also increase the rate of glycogen synthesis and degradation.

Question 7

Tarui disease type 7

Answer 7

Phosphofructokinase deficiency

More limited in muscles than liver. Liver is still healthy.

Enzyme deficiency decrease the rate of conversion of fructose-6-phosphate to fructose 1,6 bi-phosphate.

Glycogen is not able to breakdown to glucose in muscles and it builds up in muscles.

Cause muscle cramps during strenuous exercise

Patients are able to live normal day to day life except doing strenuous exercise.

Question 8

List 4 issues associated with Tarui Disease

Answer 8

• Slows breakdown of glycogen
• Prevents normal breakdown of glucose
• Accumulation of glycogen in muscles
• Lack of fuel sources for muscles