Thalassaemia

Question 1

Synthesis of haemoglobin occurs during…?

Answer 1

Development of RBC
Begins in pro-erythroblast:
- 65% erythroblast stage
- 35% reticulocyte stage

Question 2

What is the structure of haemoglobin?

Answer 2

Haem (synthesised in mitochondria)
Globin (synthesised in ribosomes)

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Question 3

Describe the synthesis of haemoglobin

Answer 3

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Question 4

What is the structure of haem?

Answer 4

Combination of protoporphyrin ring with central iron atom (ferroprotoporphyrin)
Iron usually in ferrous form (Fe2+)
Able to combine reversibly with oxygen
Also contained in other proteins (e.g. myoglobin, cytochromes, peroxidases, catalses, tryptophan)
Same in all types of Hb

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Question 5

Where is haem synthesised?

Answer 5

Mainly in mitochondria which contain the enzyme ALAS

Question 6

Describe the structure of globin

Answer 6

Eight functional globin chains, arranged in two clusters:

• beta cluster (beta, gamma, delta and epsilon globin genes) on the short arm of chromosome 11
• alpha cluster (alpha and zita goblin genes) on the short arm of chromosome 16

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Question 7

What is the structure of haemoglobin A?

Answer 7

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Question 8

What is the structure of haemoglobin A2?

Answer 8

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Question 9

What is the structure of haemoglobin F?

Answer 9

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Question 10

What is the primary structure of globin?

Answer 10

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Question 11

What is the secondary structure of globin?

Answer 11

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Question 12

What is the tertiary structure of globin?

Answer 12

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Question 13

The normal position of the Hb-oxygen dissociation curve depends on…?

Answer 13

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Question 14

What happens when the Hb-oxygen dissociation curve shifts to the right?

Answer 14

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Question 15

What happens when the Hb-oxygen dissociation curve shifts to the left?

Answer 15

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Question 16

What are haemoglobinopathies due to?

Answer 16

Structural variants of haemoglobin or defects in globin chain synthesis (thalassaemia)
Genetic disorders characterised by a defect of globin chain synthesis
Most common inherited single gene disorder worldwide

Question 17

What is beta thalassaemia?

Answer 17

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Presents usually about 3 months

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Question 18

How is beta thalassaemia diagnosed in the lab?

Answer 18

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Question 19

What is thalassaemia major?

Answer 19

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Question 20

What is the clinical presentation of thalassaemia major?

Answer 20

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Question 21

What are the clinical features of beta thalassaemia?

Answer 21

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Question 22

What are other complications of beta thalassaemia?

Answer 22

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Question 23

What are the different treatments for thalassaemia major?

Answer 23

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Question 24

Describe the treatment of thalassaemia using transfusions

Answer 24

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Question 25

How is infection managed during the treatment of thalassaemia?

Answer 25

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Question 26

Describe the treatment of thalassaemia using iron chelation therapy

Answer 26

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Question 27

How is iron overload monitored?

Answer 27

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Question 28

What is HbE beta thalassaemia?

Answer 28

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Question 29

What is alpha thalassaemia?

Answer 29

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Question 30

What is a thalassaemia carrier?

Answer 30

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Question 31

What are the problems associated with treatment of thalassaemia in developing countries?

Answer 31

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Question 32

Describe the screening and prevention of thalassaemia

Answer 32

Screening and prevention