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Most of our physical characteristics are inherited through the genes we take from our parents; for example, the shape of our nose, the colour of our skin and eyes. We also inherit our haemoglobin (Hb) type from our parents, through the genes.
Haemoglobin (Hb) is the substance in the blood which gives it its red colour. It carries the oxygen we breathe to all our body parts; it is vital for maintaining life. Without red blood cells, the body cannot function.
| The usual and most common adult haemoglobin type is
called haemoglobin A and contains two chains called BETA
(b) and ALPHA (a). The amount of beta and alpha chains a person makes is controlled by the haemoglobin gene they inherit from their parents. Where a person has inherited haemoglobin A from both parents they will have TWO usual beta genes (b^b^), one from each parent, and FOUR alpha genes (aa/aa), one pair from each parent. (see Diagram 1) |
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| They would, therefore, produce normal amounts of BETA and ALPHA to make healthy red blood cells. | Diagram 1 |
Some people do not inherit the usual number of Alpha genes in which case they would have a condition known as Alpha thalassaemia minor (trait). The terms "minor" and "trait" refer to the same thing.
The information here is about ALPHA THALASSAEMIA only; for information about Beta thalassaemia, click here.
WHAT IS ALPHA THALASSAEMIA TRAIT?
Alpha thalassaemia trait is an inherited characteristic which affects red blood cells. It is not an illness or disease, and it does not make people feel unwell or weak. There are no outward signs to show if a person has alpha thalassaemia trait. They are perfectly healthy.
Millions of people world wide have alpha thalassaemia trait, especially in areas where malaria is, or was, common.
- The blood of people who have alpha thalassaemia trait has a slightly lower level of haemoglobin. However they do not need to take iron medicines, unless special blood tests have shown that they are lacking in iron and a doctor advises this treatment.
HOW IS ALPHA THALASSAEMIA INHERITED
This characteristic of the blood is passed on from parents to their children through the genes, in the same way that other physical characteristics are passed on through the genes.
If a person is born with alpha thalassaemia trait, they will have it all their life but it does not cause them to ill in any way. Because there are no outward signs that someone has alpha thalassaemia trait, it may be passed unrecognised through a family for many generations.
THERE ARE TWO TYPES OF ALPHA THALASSAEMIA TRAIT
The most common is ALPHA PLUS THALASSAEMIA TRAIT. The less common is ALPHA ZERO THALASSAEMIA TRAIT.
ALPHA PLUS THALASSAEMIA TRAIT
This type of alpha thalassaemia is very common in people whose families come from any of the following parts of the world.
Africa, the Caribbean, the Mediterranean islands, India, Pakistan, Bangladesh, the Middle East, and South East Asia.
| If you have one of these traits (see diagrams 2 &
3), you will have inherited it from your parents. It does NOT affect
your own health. |
 |
| Diagram 2 | |
| One reason that it is important for you to know
that you have alpha plus thalassaemia trait is that it may be
mistaken for iron deficiency anaemia, and you may then be treated
with iron medicines unnecessarily. |
 |
| Diagram 3 |
ALPHA ZERO THALASSAEMIA TRAIT
| This type of alpha thalassaemia trait (diagram 4)
is less common but can be inherited by people whose families come
from any of the following parts of the world: the Middle East, South East Asia, China, and the Mediterranean islands |
 |
| In this instance, no alpha genes are inherited from one parent, but two normal alpha genes are inherited from the other. | Diagram 4 |
Having this type of alpha thalassaemia trait does not affect your own health; you have sufficient alpha genes for making haemoglobin. If you and your partner both have alpha zero thalassaemia trait, and are planning to have children, there will be a 1 in 4 chance in EACH pregnancy that the baby could inherit a severe anaemia called ALPHA THALASSAEMIA MAJOR. In this instance the child has not inherited any alpha genes at all and, therefore, he or she will not be able to make haemoglobin.
| This is how it works. If both parents have alpha zero thalassaemia trait, each time they are expecting a child there is a 1 in 4 chance that the child could inherit the usual number of alpha genes, a 2 in 4 chance the child could inherit alpha zero thalassaemia trait (like theri parents), and a 1 in 4 chance the child could inherit alpha thalassaemia major. |  |
| Example 1 |
WHAT IS ALPHA THALASSAEMIA MAJOR?
Alpha (a) genes are essential for making haemoglobin. If a child inherits alpha thalassaemia major, (s)he will not have any alpha genes and will not be able to make normal haemoglobin, which is essential for carrying oxygen around the body.
Alpha thalassaemia major is a serious blood disorder because it affects the baby whilst it is growing in its mother's womb. If a baby inherits this condition, the mother will also be at risk of serious complications during pregnancy.
This condition is life threatening: babies who have alpha thalassaemia major are unlikely to survive pregnancy.
If you and your partner both have alpha thalassaemia tyrait, you will need to see a specialist who will explain what this may mean for you and your children. This can be arranged by your GP, family planning clinic, antenatal clinic, or by contacting one of the centres listed on this website. (List of Centres)
A baby can only inherit alpha thalassaemia major if:
- both parents have alpha zero thalassaemia trait, or
- one parent has a condition known as H disease and the other has alpha thalassaemia trait, or
- both parents have H disease
WHAT HAPPENS IF ONE PARENT HAS ALPHA PLUS THALASSAEMIA TRAIT AND ONE HAS ALPHA ZERO THALASSAEMIA TRAIT?
| If one parent has alpha thalassaemia trait and other parent has alpha zero thalassaemia trait (see example 2); in this instance EACH time they are expecting a child there is a 1 in 4 chance the child could inherit the usual number of alpha genes, a 1 in 4 chance of inheriting alpha zero thalassaemia trait (just like one of their parents), a 1 in 4 chance of inheriting alpha plus thalassaemia trait, (like the other parent) or a 1 in 4 chance of inheriting a condition called HAEMOGLOBIN H DISEASE. |  |
| Example 2 |
WHAT IS HAEMOGLOBIN H DISEASE?
In this condition the baby usually makes sufficient haemoglobin to allow for normal life; however, the red blood cells have less red pigment than usual. On occasions, this condition may need medical treatment; for example, blood transfusion or medication. .
HOW CAN I FIND OUT IF I HAVE ALPHA THALASSAEMIA TRAIT?
You can find out by having a simple blood test done by your GP or by contacting one of the specialist Centres. (List of Centres)
Results are confidential and are usually available in 2 to 3 weeks. Specialist nurses are available to explain the result to you.
WHAT IF WE BOTH HAVE ALPHA THALASSAEMIA TRAIT AND WE WANT TO HAVE A BABY?
Since you and your partner have alpha zero thalassaemia trait or H disease, you have the following options:
- have the baby tested in the womb in early pregnancy
Other options
- adopting a child
- egg or sperm donation
Remember a baby with alpha thalassaemia major poses a threat to the health of the pregnant woman and the unborn baby.
Testing the baby in the womb is called prenatal diagnosis and can be done as early as ten weeks of pregnancy in most cases. The test is done in a hospital and the result is usually available within 2 - 4 weeks, depending on the type of test you are offered.
You can discuss the various options with your GP, Midwife, hospital doctor, or a specialist counsellor at one of the Centres listed (List of Centres). They will be able to give you more information, advice, and support to help you and your partner reach a decision.
There is a leaflet which explains prenatal diagnosis in more detail and you can get this from one of the specialist Centres.
You will be given as much information, advice, counselling, and support as you need as this can be an emotionally difficult time.
REMEMBER, ALPHA THALASSAEMIA IS ONLY SIGNIFICANT IF ONE OR BOTH PARENTS HAVE ALPHA ZERO THALASSAEMIA TRAIT OR H DISEASE.