Haematology - thalassemia

Question 1

What causes thalassemia?

Answer 1

A genetic defect in the protein chains that make up haemoglobin.

Normal haemoglobin consists of 2 alpha and 2 beta-globin chains.

Causes more fragile RBCs that break down more easily

Question 2

Two types of thalassemia

Answer 2

Alpha thalassemia - defects in alpha globin chains

Beta thalassemia - defects in betaglobin chains

Question 3

Presentation of thalassemia

Answer 3

Microcytic anaemia Sx - fatigue, pallor

Jaundice

Splenomegaly

Gallstones

Poor growth and development

Pronounced forehead and malar eminences

Question 4

Diagnosis is made by

Answer 4

FBC - shows microcytic anaemia

Haemoglobin electrophoresis - to diagnose electrophoresis

DNA testing - to look for genetic abnormality

Question 5

What is a potential complication of thalassemia and recurrent transfusions?

Answer 5

Iron overload occurs in thalassaemia as a result of faulty creation of red blood cells, recurrent transfusions and increased absorption of iron in response to the anaemia.

Serum ferritin monitored for this

Question 6

How to manage iron overload in thalassemia?

Answer 6

Limiting transfusions

Iron chelation

Question 7

What symptoms can iron overload cause?

Answer 7

Similar symptoms to haemochromotosis:

• Fatigue
• Liver cirrhosis
• Infertility/impotence
• Heart failure
• Arthritis
• Diabetes
• Osteoporosis and joint pain

Question 8

Alpha thalassemia genetic defect

Answer 8

Defect in alpha-globin chains

Gene coding for this protein is on chromosome 16

Question 9

Beta thalassemia genetic defect

Answer 9

Defects in beta-globin chains.

The gene coding for this protein is on chromosome 11.

The genes defect can either consist of abnormal copies that retain some function or deletion genes where there is no function in the beta-globin protein at all.

Question 10

What are the types of beta-thalassemia?

Answer 10

Thalassemia minor (aka thalassemia trait) - carrier of abnormal beta-globin gene (one normal and one abnormal gene)

Thalassemia intermedia -two abnormal copies of the beta-globin gene. This can be either two defective genes or one defective gene and one deletion gene.

Thalassemia major - homozygous for the deletion genes - they have no functioning beta-globin genes at all

Question 11

How do each of the beta-thalassemias present

Answer 11

Thalassemia minor - mild microcytic anaemia

Thalassemia intermedia - more significant microcytic anaemia - patients need monitoring and occasional blood transfusions

Thalassemia major - presents with severe anaemia and failure to thrive in childhood;

• Severe microcytic anaemia
• Splenomegaly
• Bone deformities

Question 12

What is the management of thalassemia major?

Answer 12

Management involves regular transfusions, iron chelation and splenectomy.

Bone marrow transplant can potentially be curative.