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.
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.
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
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.
[boxibt style=”success”]Information Courtesy of:
The Sickle Cell Society
5 Lauderdale House
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.[/boxibt]