Beta Thalassaemia

Question 1

What is thalassaemia?

Answer 1

Caused by a genetic defect in the protein chains that make up Hb.

Normal Hb consist of 2x alpha-globin and 2x beta-globin chains.

Defects in alpha-globin chains lead to alpha thalassaemia.

Defects in the beta-globin chains lead to beta thalassaemia.

The result is varying degrees of anaemia, depending on the type and mutation.

Question 2

Inheritance of ALL types of thalassaemia?

Answer 2

Autosomal recessive

Question 3

What type of anaemia is seen in thalassaemia?

Answer 3

Haemolytic anaemia (RBCs are more fragile and break down easily).

This causes microcytic anaemia (low MCV).

Question 4

What causes splenomegaly in thalassaemia?

Answer 4

The spleen collects all the destroyed RBCs, resulting in splenomegaly.

Question 5

Features of thalassaemia?

Answer 5

• Microcytic anaemia (low mean corpuscular volume)
• Fatigue
• Pallor
• Jaundice
• Gallstones
• Splenomegaly
• Poor growth and development

Question 6

FBC & ferritin results in thalassaemia?

Answer 6

1) FBC - microcytic anaemia

2) Raised ferritin

Question 7

Cause of a raised ferritin in thalassaemia?

Answer 7

Iron overload:

1) Increased iron absorption in GI tract
2) Bloof transfusions

Question 8

What is used to diagnose globin abnormalities?

Answer 8

Haemoglobin electrophoresis

Question 9

What group of patients is offered a screening test for thalassaemia? (2)

Answer 9

1) All pregnant women at booking visit

2) Expectant fathers, when antenatal testing screen shows the mother has beta-thalassemia trait

Question 10

Features of iron overload in thalassaemia?

Answer 10

1) Liver cirrhosis
2) Hypogonadism
3) Hypothyroidism
4) Heart failure
5) Diabetes
6) Osteoporosis

Question 11

Mx of iron overload in thalassaemia?

Answer 11

Limiting transfusions & iron chelation

Question 12

What chromosome is implicated in beta-thalassaemia?

Answer 12

Mutations in the HBB gene on chromosome 11

Question 13

Beta thalassaemia major trait?

Answer 13

1) Heterozygous (one affected gene): beta-thalassaemia trait

2) Homozygous (two affected genes): beta-thalassemia intermedia or major

As the inheritance is autosomal recessive.

Question 14

Clinical features of beta thalassaemia trait?

Answer 14

Patients usually do not have any symptoms or signs on examination.

Microcytic and hypochromic anaemia (can become symptomatic).

Question 15

When can anaemia in beta thalassaemia trait become particularly apparent?

Answer 15

During pregnancy.

During pregnancy and labour, patients with beta-thalassemia trait have:

1) 25% increased rate of anaemia

2) 250% increased rate of requiring blood transfusions

Question 16

Can beta-thalassemia trait progress to beta-thalassemia major?

Answer 16

No

Question 17

Mx of beta thalassaemia trait?

Answer 17

Majority of patients don’t require treatment.

Question 18

How does beta thalassaemia major present?

Answer 18

Severe anaemia and failure to thrive in early childhood.

Question 19

Features of thalassaemia major?

Answer 19

1) Frontal bossing (prominent forehead)

2) Enlarged maxilla (prominent cheekbones)

3) Depressed nasal bridge (flat nose)

4) Protruding upper teeth

5) Increased risk of fractures

Question 20

What causes the bony changes seen in thalassaemia major?

Answer 20

The bone marrow is under so much strain to produce extra RBCs to compensate for the chronic anaemia that it expands enough to increase the risk of fractures and change the patient’s appearance.

Question 21

Mx of thalassaemia major?

Answer 21

1) regular transfusions

2) iron chelation

3) splenectomy

4) bone marrow transplant (curative)