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)
|
 |
| They would, therefore, produce normal amounts of BETA
and ALPHA to make healthy red blood cells. |
Diagram
1 |
Some people inherit one usual and one unusual Beta gene, in which
case they have a condition known as
Beta Thalassaemia minor, (Hb A
bThal),
sometimes referred to as a trait.
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 information here is about
BETA THALASSAEMIA only; for
information about Alpha thalassaemia,
click here.
WHAT IS BETA THALASSAEMIA
MINOR?
Beta thalassaemia minor occurs when an individual inherits one usual Beta
gene from one parent and one unusual Beta gene from the other (Hb A
bThal).
It is found in areas of the world where malaria is, or was, common. Because
of migration and intermarriage, it is seen in other areas of the world. It
is most common in peoples whose ancestors originate from
Mediterranean,
Asian, and
Far Eastern countries. It is also found in people of
African, Afro-Caribbean, and
European origin.
For example, it is estimated that approximately:
- 1 in every 7 Greek Cypriots
- 1 in every 12 Turks
- 1 in every 20 Asians
- 1 in every 20-50 Africans/Afro-Caribbeans
- (this depends on which part of Africa one comes
from)
- 1 in every 1000 English Caucasians
have beta thalassaemia minor trait.
People with beta thalassaemia minor have red blood cells which are smaller,
paler, and have less red pigment, but this does not cause any health
problems. Generally, their red blood cells are still able to carry oxygen
around the body as efficiently as someone with the two usual Beta genes.
Because these individuals are themselves healthy, they will not know that
they have this unusual trait unless they have a special blood test.
If a couple
BOTH have beta thalassaemia minor,
EACH time
they expect a child there is a 1 in 4 chance that their child could inherit
a serous blood disease called
beta thalassaemia major.
WHAT IS BETA THALASSAEMIA
MAJOR?
It is a serious anaemia affecting people who have inherited the two
unusual beta thalassaemia genes, one from each parent.
People with Beta thalassaemia major do not produce enough healthy, mature
red blood cells; therefore, they become very pale and anaemic. Without
enough mature red blood cells to carry oxygen around the body a person
cannot live very long. Red blood cells are vital for life. The condition is
sometimes known as Cooley's anaemia, Thalassaemia disease, or Mediterranean
anaemia.
From about the age of 3 months children with this condition become very
pale, lethargic, lose their appetite and soon fail to thrive, and usually
die between 1 and 10 years of age. But with proper medical care they can
have long life.
HOW IS BETA THALASSAEMIA
MAJOR TREATED?
To be able to live to adulthood, a person born with the serious form of
this condition is totally dependent on blood transfusions, which need to be
given about every four to six weeks, right through life.
There is no simple cure for beta thalassaemia major. Although bone marrow
transplantation can cure the condition, the success rate is unpredictable.
Although it is an anaemia, it is
not caused by lack of IRON.
Individuals are still able to take in iron from the food they eat. This,
combined with the iron in the blood they are given during blood transfusions
means that too much iron builds up in the body. This excess iron can cause
serious health problems.
To get rid of the excess iron, people with beta thalassaemia major usually
need to inject themselves with a special drug called Desferal. Treatment is
monitored and adjusted according to the individual's needs. With good
medical care, family support and encouragement, people with beta
thalassaemia major are able to cope with their condition.
WHAT IS THE DIFFERENCE
BETWEEN BETA THALASSAEMIA MAJOR AND MINOR?
Beta thalassaemia minor (trait) is not a disease and cannot change later in
life. It is significant when one is considering having children because the
child may inherit this unusual gene from both parents.
Beta thalassaemia major (disease) is a serious blood condition.
Individuals with it are unable to make enough healthy red blood cells and
depend on blood transfusions all their life.
HOW DO YOU GET BETA
THALASSAEMIA?
A person can only get beta thalassaemia minor or beta thalassaemia major
from their parents. These conditions
CANNOT be transmitted like an
infection; they can only be inherited through the genes.
Here is how it works: Each parent is born with two haemoglobin genes. Each
time a couple are expecting a child, only one haemoglobin gene from each
parent will be taken to make the child's own pair of haemoglobin genes. In
EACH pregnancy, there are always
FOUR possible combinations
the child can take. These are known as
CHANCES.
HOW CAN I FIND OUT IF I
HAVE BETA THALASSAEMIA TRAIT?
You can find out by having a simple blood test done by your GP or by
contacting one of the specialist Centres. (
Click
here for details 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 BETA
THALASSAEMIA TRAIT AND WE WANT TO HAVE A BABY?
Since you and your partner both have beta thalassaemia trait, you have the
following options:
- wait until the baby is born to find out what haemoglobin genes the
baby has inherited from each of you
- have the baby tested in the womb in early pregnancy
Other options
- adopting a child
- egg or sperm donation
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 - 14
days, 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 (click
here for details 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, BETA THALASSAEMIA IS MOST
SIGNIFICANT IF BOTH PARENTS HAVE THIS OR ANY OTHER UNUSUAL HAEMOGLOBIN.
