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 4.5% of the population are carriers of the thalassaemia gene.
There are two types of thalassaemia:
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.
If only one parent has thalassaemia minor, the following can occur:
If both parents have thalassaemia minor, the following can occur:
The chances are the same with each pregnancy, no matter how many children the couple may have.
Since thalassaemia can be passed on from one generation to another, you and your partner should go for a thalassaemia screening if you are:
Thalassaemia screening involves a simple blood test and is available at all polyclinics.
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.
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 weeks 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 12 to 19 weeks of pregnancy.
Based on the result of the test, the doctor will advise you and your husband accordingly.
Reproduced with permission from
Health Promotion Board.
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