What is Sickle
Cell Anaemia?
This page will give you
a brief guide to Sickle Cell Disorders and provide links to more
detailed information for different groups of users
Contents
The
disorder affects the red blood cells which contain a special protein
called haemoglobin (Hb for short). The function of haemoglobin is
to carry oxygen from the lungs to all parts of the body.
People with Sickle Cell
Anaemia have Sickle haemoglobin (HbS) which is different from the
normal haemoglobin (HbA). When sickle haemoglobin gives up its oxygen
to the tissues, it sticks together to form long rods inside the
red blood cells making these cells rigid and sickle-shaped. Normal
red blood cells can bend and flex easily.
Because of their shape,
sickled red blood cells can't squeeze through small blood vessels
as easily as the almost donut-shaped normal cells. This can lead
to these small blood vessels getting blocked which then stops the
oxygen from getting through to where it is needed. This in turn
can lead to severe pain and damage to organs.
Everyone has two copies
of the gene for haemoglobin; one from their mother and one from
their father. If one of these genes carries the instructions to
make sickle haemoglobin (HbS) and the other carries the instructions
to make normal haemoglobin (HbA) then the person has Sickle Cell
Trait and is a carrier of the sickle haemoglobin gene. This
means that this person has enough normal haemoglobin in their red
blood cells to keep the cells flexible and they don't have the symptoms
of the sickle cell disorders. They do however have to be careful
when doing things where there is less oxygen than normal such as
scuba diving, activities at high altitude and under general anaesthetics.
If both copies of the haemoglobin gene carry instructions
to make sickle haemoglobin then this will be the only type of haemoglobin
they can make and sickled cells can occur. These people have Sickle
Cell Anaemia and can suffer from anaemia and severe pain. These
severe attacks are known as Crises. Over time Sickle Cell
sufferers can experience damage to organs such as liver, kidney,
lungs, heart and spleen. Death can be a result.
Another problem is that
red blood cells containing sickle haemoglobin do not live as long
as the normal 120 days and this results in a chronic state of anaemia.
In spite of this, a person with sickle cell disorder can attend
school, college and work. People with sickle cell disorder need
regular medical attention particularly before and after operations,
dental extraction and during pregnancy. Many
hospitals arrange follow-up appointments and it is advisable to
discuss with the doctors questions concerning schooling, strenuous
exercise, family planning, suitable types of employment and air
travel. When a person is found to have a sickle cell disorder it
is important that all members of the family be tested. They will
not necessarily have sickle cell disorder but may be healthy carriers
of a sickle cell trait.
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Other types of
Sickle Cell Disorders (SCDs)
There are also other different
types of haemoglobin such as HbC and beta thalassaemia, that can
combine with sickle haemoglobin to cause sickling disorders. When
someone carries the gene for beta-thalassaemia they cannot make
as much HbA as they should. If this is combined with the HbS gene
then more of their total amount of haemoglobin is HbS and they can
suffer from what is usually a milder form of sickle cell disorder
than sickle cell anaemia.
Who Gets SCDs?
The different kinds of SCD
and the different traits are found mainly in people whose
families come from Africa, the Caribbean, the Eastern Mediterranean,
Middle East and Asia.* In Britain SCD is most common in people of
African and Caribbean descent (at least 1 in 10-40 have sickle cell
trait and 1 in 60-200 have SCD). It is estimated there are over
6,000 adults and children with SCD in Britain at present. There
are other inherited conditions that mainly affect other groups,
e.g. Cystic Fibrosis in Europeans, and Tay-Sachs disease in Jewish
people.
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Testing for SCDs
A special blood test (haemoglobin
electrophoresis) can tell you whether you have a sickle cell disorder
or are a healthy carrier, e.g. for sickle cell trait. Routine screening
should take place for people in the groups listed during pregnancy
and before anaesthesia, either at hospital or dental clinics.
Tests can be arranged by
your general practitioner or at our local sickle cell centre. (Contact
us for an up-to-date list of centres in the UK.) After a blood test
you may be told that you or your child is `sickle positive' or has
`sickle cell'. It is important to ask whether this means sickle
cell trait or a type of sickle cell disorder.
Testing unborn
babies
It is now possible to test
the unborn child to detect a haemoglobin disorder from as early
as 11 weeks of pregnancy. For more information see the Prenatal
Testing page and contact your local sickle
cell centre, local obstetrician, haematologist or general practitioner.
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What Sickle Cell
Disorders are Not
People are often confused
and disturbed by some of the incorrect information they have received
about SCD.
Sickle Cell Disorders
- are not leukaemia
- are not cancer
- are not white
blood cells eating up red blood cells
- are not infectious
- you cannot `catch it' as you would catch measles or a cold.
Sickle Cell Disorder is
a condition which is inherited from both parents. This means that
people are born with it, just as they are born with other characteristics
such as eye colour, hair texture and height.
More Detailed Information
Follow the links to get more information on different
aspects on sickle cell disorders.
For further information contact:
Sickle Cell Society
54 Station Road
London, NW10 4UA
UK
Tel 020 8961 7795
Fax 020 8961 8346
info@sicklecellsociety.org
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