Glycogen storage diseases

Question 1

Type 0 - Lack of LIVER glycogen synthase

Answer 1

Symptoms include:

• fasting hypoglycemia
• liver has very low or no glycogen
• hyperketonemia

Feeding alleviates symptoms but leads to hyper hyperglycemia and lactic academia

Treatment - eat uncooked corn start which allows for slow glucose release from digestive system

Question 2

Type I - Lack of G6Pase (von Gierke’s disease)

Answer 2

Symptoms include:

• hepatomegaly
• sever fasting hypoglycemia
• increased glycogen in liver which cause the hepatomegaly
• no ketone body synthesis
• gout b/c of excess purine synthesis from HMP shunt pathway
• lactic acidemia

Question 3

Type II - lack of lysosomal alpha-glucosidase activity (Pompe disease)

Answer 3

-death w/in 2 years

Question 4

Type III - lack of debranching enzyme

Answer 4

-IIIa subtype occurs in both liver and muscle

Symptoms include:

• fasting hypoglycemia
• hepatomegaly
• glycogen with short outer chains

Question 5

Type IV - lack of branching enzyme (anderson’s disease)

Answer 5

-liver has low levels of non-branched glycogen, which presents solubility problems

Symptoms = cirrhosis

• liver transplant may be needed
• Can be fatal

Question 6

Type V - lack of MUSCLE phosphorylase (McArdle’s disease)

Answer 6

Symptoms include:

• weakness and muscle cramping after exercise
• inability to use muscle glycogen as an energy source (KEY)

Question 7

Type VI - lack of LIVER glycogen phosphorylase (Her’s disease)

Answer 7

The new classification also includes mutations in the activation system for glycogen phosphorylase (i.e. phosphorylase kinase and PKA)

Symptoms include:

• hepatomegaly
• fasting hypoglycemia

Question 8

Type VII - lack of MUSCLE PFK-1 (Tarui syndrome)

Answer 8

Symptoms include:

-exercise intolerance -> similar to type V

Question 9

Type XI - GLUT-2 mutations (Fanconi-Bickel syndrome)

Answer 9

-affects liver, kidney, intestines, pancreas

Symptoms - glycogen accumulation in liver and kidney