Thalassaemia

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:

Thalassaemia minor (thalassaemia trait).
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.

Who Should Go For Thalassaemia Screening?

Since thalassaemia can be passed on from one generation to another, you and your partner should go for a thalassaemia screening if you are:

Planning to get married
Starting a family

Thalassaemia screening involves a simple blood test and is available at all polyclinics.

What Should I Do If I Have Thalassaemia Minor?

If you or your partner has thalassaemia minor, both of you should see a doctor for genetic counselling before you plan to get married or have a child. The doctor will explain the risks and discuss the choices you have. He may refer you to the National Thalassaemia Registry for further counselling.

The National Thalassaemia Registry provides genetic counselling for people with thalassaemia and screening for their families. The staff at the Registry will be able to answer your questions about this blood disorder.

NATIONAL THALASSAEMIA REGISTRY
Level 6 Children’s Tower
KK Women’s & Children’s Hospital
100 Bukit Timah Road
Singapore 229899
Tel: 6394 1863 or 6394 1864
Fax: 6394 1867
Email: Nat.Thal.Reg@kkh.com.sg

What If I Am Already Pregnant?

If you are already pregnant and both you and your husband have thalassaemia minor, you should go for a prenatal diagnostic test to find out whether your unborn baby has thalassaemia major.

Prenatal diagnosis can be done by chorionic villus sampling or by fetal blood sampling. Both tests are conducted under ultrasound guidance.

Chorionic villus sampling involves obtaining some cells from the placenta for testing. This is done during the 10th to 12th week of pregnancy.

Fetal blood sampling involves obtaining a small amount of fetal blood from the umbilical cord for testing. This procedure is done at about 18 - 20 weeks of pregnancy.