What Is Thalassaemia?

Thalassaemia is an inherited blood disorder which is caused by an abnormal gene. A person with thalassaemia is unable to produce normal, functioning haemoglobin in the blood.

Haemoglobin carries oxygen from the lungs to all parts of the body. When the body is not able to produce normal, functioning haemoglobin, the affected person suffers from anaemia.

Thalassaemia is passed on from parent to child and can affect both males and females. In Singapore, about 3% of the population are carriers of the thalassaemia gene.

What Are The Types Of Thalassaemia?

There are two types of thalassaemia: 

(1) Thalassaemia minor (thalassaemia trait).
(2) Thalassaemia major.

A person who has inherited one thalassaemia gene is said to have thalassaemia minor (thalassaemia trait).He or she is healthy and leads a normal life. Most people with thalassaemia minor do not know that they have it. However, the affected persons can pass on the abnormal gene to their children.

Thalassaemia major is a severe form of anaemia. The affected person has inherited two thalassaemia genes, one from each parent. He or she may look normal at birth but within 1 - 2 years of life, will suffer from severe anaemia, which leads to poor growth and development as well as a shorter lifespan.

The affected person will need blood transfusion every month to sustain life. At present, a bone marrow transplant is the only hope of possible cure for thalassaemia major.

How Is Thalassaemia Inherited?

If only one parent has thalassaemia minor, the following can occur:

• 50% chance of having a child with thalassaemia minor
• 50% chance of having a normal child
• None of the couple’s children will get thalassaemia major.

If both parents have thalassaemia minor, the following can occur:

• 25% chance of having a child with thalassaemia major
• 50% chance of having a child with thalassaemia minor
• 25% chance of having a normal child

The chances are the same with each pregnancy, no matter how many children the couple may have.