Glucose-6-phosphatase deficiency

Question 1

Glucose-6-phosphatase deficiency is a rare genetic disorder that is characterised by low levels of Glucose-6-phosphatase. Does this typically result in hypoglycaemia or hyperglycaemia?

Answer 1

• hypoglycaemia

Question 2

What is the incidence of Glucose-6-phosphatase deficiency?

1 - 1:100,000
2 - 1:10,000
3 - 1:1000
4 - 1:100

Answer 2

1 - 1:100,000

Question 3

Glucose-6-phosphatase deficiency is a rare inborn genetic mutation. However, which population have a much higher incidence of 1:20,000 when compared to the current 1:100,000?

1 - south east asians
2 - ashkenazi Jews
3 - caribbean
4 - finish

Answer 3

2 - ashkenazi Jews

Question 4

What is the most common glycogen storage disease?

1 - glucose 6 phosphotase deficiency
2 - Phosphofructokinase deficiency
3 - Phosphoglycerate mutase deficiency
4 - Lactate dehydrogenase A deficiency

Answer 4

1 - glucose 6 phosphotase deficiency
- a Type 1 glycogen storage disorder

Question 5

The most common glycogen storage disease is glucose 6 phosphotase deficiency, and is a type 1 glycogen storage disorder. What is the common name for this?

1 - Von willebrand factor
2 - Von Gierke’s disease
3 - Leiden deficiency
4 - Vancity disease

Answer 5

2 - Von Gierke’s disease

Question 6

What type of genetic inheritance is glucose 6 phosphotase deficiency, commonly known as Von Gierke disease?

1 - autosomal dominant
2 - X linked dominant
3 - autosomal recessive
4 - X-linked recessive

Answer 6

3 - autosomal recessive

Question 7

Once glucose enters the cells through GLUT transporters is has a phosphate added to it by which enzyme, creating glucose 6 phosphotase?

1 - glucose 6-phosphotase
2 - hexokinase
3 - glycolygenase
4 - fructose 1,6-biphosphotase

Answer 7

2 - hexokinase
- this means the glucose cannot leave the cell

Question 8

Once glucose has been converted into glucose 6 phosphotase by hexokinase it can be used in glycolysis to produce ATP. What is part of the negative feedback loop that eventually inhibits glycolysis?

1 - glucose 6-phosphotase
2 - ATP
3 - glycolygenase
4 - fructose 1,6-biphosphotase

Answer 8

2 - ATP
- levels rise and inhibit glycolysis

Question 9

If glucose 6 phosphate (G6P) does not enter glycolysis as the levels of ATP are sufficient, the G6P can be converted into glycogen. Which 2 cell types in the body can this typically occur in?

1 - liver
2 - brain
3 - muscle
4 - bone

Answer 9

1 - liver
3 - muscle

Question 10

In order to convert glucose 6 phosphate (G6P) into glycogen, there are 4 steps. Which of the following is step 1?

1 - glycogen primer, glycogenin is added
2 - branches are added to glycogen
3 - attaching a uridine diphosphate (UDP) molecule to glucose
4 - glucose being added to glycogenin

Answer 10

3 - attaching a uridine diphosphate (UDP) molecule to glucose

• makes UDP-glucose

Question 11

In order to convert glucose 6 phosphate (G6P) into glycogen, there are 4 steps. Which of the following is step 2?

1 - glycogen primer, glycogenin is added
2 - branches are added to glycogen
3 - attaching a uridine diphosphate (UDP) molecule to glucose
4 - glucose being added to glycogenin

Answer 11

1 - glycogen primer, glycogenin is added
- tricks glycogen synthase into thinking there are at least 4 glycogen molecules present as it only works on >4

Question 12

In order to convert glucose 6 phosphate (G6P) into glycogen, there are 4 steps. Which of the following is step 3?

1 - glycogen primer, glycogenin is added
2 - branches are added to glycogen
3 - attaching a uridine diphosphate, or UDP molecule to glucose
4 - glucose being added to glycogenin

Answer 12

4 - glucose being added to glycogenin
- this makes long linear chains
-bonds are alpha 1-4 glycosidic bonds

Question 13

In order to convert glucose 6 phosphate (G6P) into glycogen, there are 4 steps. Which of the following is step 4?

1 - glycogen primer, glycogenin is added
2 - branches are added to glycogen
3 - attaching a uridine diphosphate, or UDP molecule to glucose
4 - glucose being added to glycogenin

Answer 13

2 - branches are added to glycogen
- this makes branched chains
-bonds are alpha 1-6 glycosidic bonds

Question 14

Which 2 of the following hormones tell the body to break glycogen down and release it as glucose?

1 - dopamine
2 - insulin
3 - glucagon
4 - noradrenaline

Answer 14

3 - glucagon
4 - noradrenaline

Question 15

Glycogenolysis is the catabolic state when glycogen is converted into glucose and released into the blood. To begin this the alpha 1-,6 glycosidic branches need to be cleaved. Which enzyme is responsible for this?

1 - hexokinase
2 - glycogenin phosphorylase
3 - glycogen phosphorylase
4 - glucose-6-phosphotase

Answer 15

3 - glycogen phosphorylase
- removes 1 glucose-1-phosphate at a time
- does this until 4 remain on the branch
- branch is then cleaved by debranching enzyme

Question 16

Once we have glucose-1-phosphate, it can be transferred into glucose-6-phosphote. What enzyme is responsible for this?

1 - hexokinase
2 - glycogenin phosphorylase
3 - phosphoglucomutase
4 - glucose-6-phosphotase

Answer 16

3 - phosphoglucomutase

Question 17

Once we glucose-6-phosphote. What enzyme is responsible for removing the phosphate group and releasing glucose into the blood from the liver?

1 - hexokinase
2 - glycogenin phosphorylase
3 - phosphoglucomutase
4 - glucose-6-phosphotase

Answer 17

4 - glucose-6-phosphotase
- this is in the liver

Question 18

Once we glucose-6-phosphote (G6P). What enzyme is responsible for removing the phosphate group and releasing glucose into the blood from skeletal muscle?

1 - no enzymes, G6P enters glycolysis
2 - glycogenin phosphorylase
3 - phosphoglucomutase
4 - glucose-6-phosphotase

Answer 18

1 - no enzymes, G6P enters glycolysis
- this basically shows that even without G6P, we can still make some glucose in the blood

Question 19

Which of the following are clinical signs of Glucose-6-phosphatase deficiency?

1 - Growth retardation/poor weight gain in children,
2 - Exercise intolerance
3 - Hypoglycaemia
4 - Hepatomegaly
5 - Low muscle tone
6 - Lactic acidosis
7 - Cardiomyopathy/conduction defects
8 - all of the above

Answer 19

8 - all of the above

Question 20

If glucose-6-phosphate (G6P) cannot be used for glucose, it can be moved into other pathways. If G6P enters the ribose-5-phosphate pathway, what can this lead to an increase of?

1 - lactic acidaemia
2 - hyperuricaemia
3 - hyperlipidaemia
4 - hypoglycaemia

Answer 20

2 - hyperuricaemia
- can cause gout

Question 21

If glucose-6-phosphate (G6P) cannot be used for glucose, it can be moved into other pathways. If G6P enters the glycolysis pathway, what can this lead to an increase of?

1 - lactic acidaemia
2 - hyperuricaemia
3 - hyperlipidaemia
4 - hypoglycaemia

Answer 21

1 - lactic acidaemia

Question 22

If glucose-6-phosphate (G6P) cannot be used for glucose, it can be moved into other pathways. If G6P enters the fat pathway, what can this lead to an increase of?

1 - lactic acidaemia
2 - hyperuricaemia
3 - hyperlipidaemia
4 - hypoglycaemia

Answer 22

3 - hyperlipidaemia

Question 23

In a patient with glucose-6-phosphotase, what is the definitive diagnosis?

1 - liver ultrasound
2 - glucose-6-phosphatase activity in fresh and frozen liver tissue specimens
3 - plasma glucose
4 - renal function

Answer 23

2 - glucose-6-phosphatase activity in fresh and frozen liver tissue specimens

• may show normal glycogen and fatty liver

Question 24

What is the treatment of choice in a patient with glucose 6 phosphotase deficiency, commonly known as Von Gierke disease?

1 - corn starch (slow glucose release)
2 - soy milk
3 - liver transplant
4 - allopurinol (lower uric acid)

Answer 24

3 - liver transplant