10. Glycogen Storage Diseases

Question 1

Type I

Answer 1

Von Gierke’s

Question 2

Which enzyme is effected by Type I?

Answer 2

Glucose-6-phosphatase

Question 3

Explain Type I in terms of cells and molecules

Answer 3

Build up of intracellular G-6-P, leading up to glycogen build up in the liver

Question 4

Symptoms of Type I

Answer 4

Hepatomegaly and hypoglycaemia

Question 5

Treatments for Type I

Answer 5

Liver transplant
Hypoglycaemia treatment
Transposition of portal vein

Question 6

Type II

Answer 6

Pompe’s

Question 7

Which enzyme is effected by Type II?

Answer 7

a-1,4-glucosidase

Question 8

Explain Type II in terms of cells and molecules

Answer 8

Build up of glycogen in lysosomes

Question 9

Symptoms of Type II

Answer 9

Cardiorespiratory failure
Death in first year of life
Most severe GSD

Question 10

Treatments of Type II

Answer 10

Enzyme replacement therapy

Question 11

Type III

Answer 11

Cori’s

Question 12

Which enzyme is effected by Type III?

Answer 12

Amylo-1,6-glucosidase

Debranching enzyme

Question 13

Explain Type III in terms of cells and molecules

Answer 13

Incomplete degradation of glycogen - very short outer branches

Question 14

Symptoms of Type III

Answer 14

Muscle weakness and Von Gierke-like liver issues

Question 15

Treatments of Type III

Answer 15

High protein diet - counteracts loss of amino acids during gluconeogenesis

Question 16

When is onset prevalent in sufferers of Type III?

Answer 16

During puberty

Question 17

Type IV

Answer 17

Anderson’s

Question 18

Which enzyme is effected by Type IV?

Answer 18

Amylo-1,4 -> 1,6-Transglycolyase

Branching enzyme

Question 19

Explain Type IV in terms of cells and molecules

Answer 19

Very long outer chains, therefore insoluble

Question 20

Symptoms of Type IV

Answer 20

Death before 4 years of age
Liver dysfunction
2nd most severe GSD

Question 21

Type V

Answer 21

McArdle’s

Question 22

Which enzyme is effected by Type V?

Answer 22

Muscle phosphorylase

Question 23

Explain Type V in terms of cells and molecules

Answer 23

Lack of degradation of muscular glycogen

No glucose - no ATP - no lactate

Question 24

Symptoms of Type V

Answer 24

Muscle weakness after exertion

Not very severe as long as strenuous exercise is avoided

Question 25

Type VI

Answer 25

Her’s

Question 26

Which enzyme is effected by Type VI?

Answer 26

Liver phosphorylase

Question 27

Explain Type VI in terms of cells and molecules

Answer 27

Build up of glycogen in the liver

Question 28

Symptoms of Type VI

Answer 28

Similar to Von Gierke's
Mild Ketosis 
Hypoglycaemia 
Retarded Growth
Hepatomegaly

Question 29

Type VII

Answer 29

Tarui’s

Question 30

Which enzyme is effected by Type VII?

Answer 30

Muscle phosphofructokinase

Question 31

Explain Type VII in terms of cells and molecules

Answer 31

Disrupts glycolysis, leads to build up of G-6-P and F-6-P, in turn causes increased glycogen synthase activity and UDP-Glucose Pyrophosphorylase, subsequently leading to high glycogen concentration in muscles

Question 32

Symptoms of Type VII

Answer 32

Similar to McArdle’s

Question 33

Type VIII

Answer 33

X-Linked Phosphorylase Kinase Deficiency

Question 34

Which enzyme is effected by Type VIII?

Answer 34

Defective phosphorylase kinase

Question 35

Explain Type VIII in terms of cells and molecules

Answer 35

Lack of glycogen breakdown, phosphorylase kinase cant add phosphate to convert glycogen phosphorylase from B to A

Question 36

Symptoms of Type VIII

Answer 36

Similar to Her’s

Question 37

Type IX

Answer 37

Phosphorylase Kinase Deficiency

Question 38

Explain Type IX in terms of cells and molecules

Answer 38

Autosomal recessive; mutation in gene that encodes phosphorylase kinase sub units. Affects different organs due to different isoenzymes.

Question 39

Symptoms of Type IX

Answer 39

Similar to Her’s and Type VIII

Question 40

Type 0

Answer 40

Liver Glycogen Synthase Disease

Question 41

Explain Type 0 in terms of cells and molecules

Answer 41

Too little glycogen as a result of decreased glycogen synthase activity

Question 42

Symptoms of Type 0

Answer 42

Some are unaffected, and others are hypoglycaemic