SICKLE CELL ANAEMIA
Sickle Cell in Brief
• Sickle cell disease is the result of an inherited
abnormality in the red blood cells.
• It is commonest among people whose forebears lived
in parts of the world where malaria was once a scourge.
• It impairs social, educational, career and economic
fulfilment.
• Despite improvements in its management, it reduces
life-expectancy, may be suddenly life-threatening, and is
often disabling.
• In Britain, an estimated thirteen thousand people
have sickle cell disease, and are known colloquially as
‘Sicklers’.
• Red blood cells that ‘sickle’ change
shape irreversibly when they are low in oxygen.
• Sickling may happen as a result of exertion, worry,
dehydration, or cold.
• Sickled red cells obstruct the flow of oxygen-bearing
blood to the body’s major joints and internal organs.
• When the red blood cells sickle, a sickler is said
to be in ‘crisis’.
• A sickling crisis can be agonisingly painful; it
may last many days and need hospital treatment.
• Repeated crises may lead to permanent difficulty
in walking, lifting, and climbing stairs, and to impaired
lung or kidney function - to take only a few examples.
• A crisis can prove fatal within hours of onset.
• The oxygen-carrying protein in the red blood cells
is called haemoglobin.
• There are several variants of normal haemoglobin.
• People can only have sickle cell disease if they
inherit a certain abnormal (sickle)haemoglobin gene from
each parent.
• A person with only one sickle haemoglobin gene is
said to have a sickle ‘trait’.
• Since people with sickle trait also have a gene
for normal haemoglobin, they can produce properly functioning
red blood cells.
• Couples with sickle trait can become the parents
of healthy children but, because of the way in which sickle
cell disease is inherited; they can also produce children
with sickle cell disease.
• A simple blood test will show people if they have
sickle trait. Expert counsellors will explain its significance
to them.
• Not everyone who has a sickle gene is black. However,
one black Briton in ten could become the parent of a child
with sickle cell disease.
Historical Perspective.
Medical reports of Sickle Cell were in western
medical literature as far back as the late 19th Century,
but it was first described in medical textbooks, in 1910,
by an American Physician named James Herrick. One of Herrick’s
medical students, who came from Grenada, complained of frequent
episodes of joint pain.
Blood examinations revealed that the young man’s
red blood cells were elongated instead of round. Herrick
described these as resembling the blade of a “Farmer’s
Sickle”. We as City dwellers may not know what a Farmer’s
Sickle looks like, but it is half moon shaped.
Although this was the first description in western medicine,
a prominent Ghanaian physician named Konotey-Ahulu was able
to demonstrate that many African tribes were able to trace
the presence of Sickle Cell in their family for many generations.
Most of the tribal names for Sickle Cell tended to describe
symptoms. For example, the Yoruba tribe, from Southern Nigeria,
call it “Arun aro omo Legungun” which means
‘illness that aches the child’s bones’,
(Konotey-Ahulu) 1991. Interestingly, this is one of the
classic symptoms associated with this painful blood condition.
What is Sickle Cell
Our blood is made up of many parts, one of these
are red blood cells. It is the job of the red blood cells
to carry this vital oxygen from the lungs to all the body
parts. When our blood contains oxygen it is bright red,
when it has given up its oxygen to the tissues of our body
it becomes blue.
Considering that red blood cells are so small we cannot
see them with the naked eye. They are also soft, spongy,
and able to squeeze through the tiniest blood vessels, so
as to provide vital oxygen to all our body parts, even our
small toe.
Red blood cells contain a substance called haemoglobin,
abbreviated as Hb. It is this haemoglobin which holds the
oxygen and transports it around the body. All of us inherit
the type of haemoglobin we have, from our parents, through
the genes. We inherit our haemoglobin type though the genes
that we take from both parents. So far nature has decided
that we must inherit one haemoglobin gene from a woman and
one from a man.
Haemoglobin
The usual and most common haemoglobin is described with
the letter A, therefore, if a person has inherited two usual
haemoglobins they would have haemoglobin AA (Hb AA). Their
red blood cells would be round, soft, pliable and able to
carry oxygen well.
However, a small number of people world-wide inherit an
unusual haemoglobin, for example, Sickle Haemoglobin, described
with the letter S. In fact Sickle Haemoglobin is only one
out of about 400 unusual haemoglobins known in humans.
Where a person has inherited one usual haemoglobin A from
one parent and a Sickle Haemoglobin S from the other, the
person is said to have Sickle Cell Trait AS (Hb AS)
Sickle Cell trait is not an illness. People with Sickle
Cell Trait are referred to as healthy carriers. Because
they still have usual haemoglobin A, their red blood cells
remain round, soft, spongy, pliable and able to carry oxygen
well.
However, because they are healthy have had a special blood
test which will reveal this.
Or when they have a child who is later discovered to have
inherited Sickle Haemoglobin from both of them and has a
serious blood condition called Sickle Cell Anaemia, 55 (Hb
SS).
Which populations have Sickle Cell?
Sickle Cell is found in people whose ancestors
originate from
Africa, Asia, the Mediterranean Islands, South America and
the
Middle and Far East. Due to migrations it is also seen in
Afro-Caribbeans, African Americans, and other migrants here
in the
UK.
It is estimated that:
- 1 in 10 Afro-Caribbeans
- 1 in 4 West Africans
- 1 in 50 Asians
- 1 in 100 Northern Greeks
have Sickle Cell. However, they are healthy.
Where a couple both have Sickle Cell Trait, each time they
are expecting a child, there is a 1 in 4 chance their child
will inherit the usual haemoglobin combination (HbAA), a
2 in 4 chance s/he will inherit Sickle Cell Trait (Hb AS),
just like the parents, or a I in 4 chance s/he will inherit
Sickle Cell Anaemia (HbSS), which is a serious blood disorder.
Sickle Cell trait is very useful in areas of the world
where malaria is or was endemic, because it protected very
young children from the effects of a serious type of malaria.
Therefore, before we discovered anti-malarial drugs Sickle
Cell Trait was a friend not a foe. Of course, the price
that parents pay for their protection is the potential for
their offspring to inherit both Sickle Haemoglobin from
them.
How does Sickle Cell Anaemia affect people?
The red blood cells of people with Sickle Cell
Anaemia, and other types of Sickle Cell syndromes, change
into a Sickle Shape when they give up theft Oxygen to the
body’s tissues.
These red blood cells are fragile, become hard, rigid, brittle
and break easily. People with this condition are anaemic
because their red blood cells have a shorter life in circulation,
only 15-30 days, instead of the 120 days life span of a
normal red blood cell.
Sometimes, due to their shape these Sickle Cells can clog
together and block the small blood vessels in the body.
Due to this blockage vital Oxygen cannot get through to
the affected part of the body. This leads to pain. If this
blockage is not corrected the pain intensifies and can become
excruciating. These episodes are called ‘Sickle Cell
Crisis’.
Hospitalisation may be required to relieve, that pain,
find out what triggered the episode, and give vital treatment
if required. Sometimes long term blood transfusions may
be required, but finding an exact match is often difficult
because very few black people donate blood.
The frequency of ‘crisis’ is unpredictable,
once a year, once a month, once a week, three times a week?
No one knows, how long the pain will last. The cause of
each episode is often unknown, although ‘crisis’
may be triggered by certain situations, for example, cold
weather, infection, even stress, unemployment bad housing.
Information Courtesy of:
The Sickle Cell Society
OSCAR Trust
5 Lauderdale House
Gosling Way
SW9 6JS
Tel:0207 735 4166
Registered as a Charitable Trust Registration No:1054516
The OSCAR trust does not have a website but is an invaluable
resource for those with an interest in Sickle Cell Anaemia.
