Sickle cell anaemia

The sickle cell has a distictive shape

More than 12,500 people in the UK have sickle cell anaemia with an estimated 240,000 carriers of the gene.

It is a disease which affects the ability of red blood cells to carry oxygen and can cause severe pain, and damage to the organs

What is it?

Sickle cell anaemia is a genetic disease which is inherited from your parents.

It is caused by an abnormality in haemoglobin, the oxygen-carrying protein found in red blood cells.

Instead of normal haemoglobin (HbA), they carry a mutated form known as sickle haemoglobin (HbS).

Red blood cells carrying HbA are donut-shaped, but are able to bend and flex, and so can easily travel along even the narrowest of spaces in the tiniest of blood vessels.

Those carrying HbS, however, have a distinctive sickle shape. This is because when HbS gives up its oxygen to the tissues it sticks together to form long rods inside the red blood cells.

This destroys the cells' natural flexibility, making them rigid and less able to squeeze through small blood vessels.

This can lead to blockages in the vessels, preventing oxygen from getting through to the tissues, and causing severe pain and damage to the organs.

What are the symptoms?

When a blood vessel becomes blocked this can trigger an attack of pain known as a crisis.

This is more likely to happen when the person is stressed by other illnesses, exhaustion, cold, dehydration and other problems.

Organs such as the liver, kidney, lungs, heart and spleen become damaged, causing severe pain, especially in the bones.

In addition, 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.

Despite this, there is no reason why people with the condition should not lead normal, active lives.

Who is at risk of sickle cell?

The highest prevalence of sickle cell is found among Black Caribbean, Black African and Black British communities. However, as these are genetic diseases, it is impossible to automatically exclude anyone.

Symptoms are only apparent in people who carry two copies of the mutated gene - one from each parent.

People who inherit a copy of the defective gene from one parent, but a healthy copy from the other are said to have sickle cell trait.

Effectively, they are carriers of the condition, and have the ability to pass it down to their children.

If both parents are carriers, there is a 25% chance with each pregnancy that the child will be affected by the disorder.

Parents do not have to be of the same ethnic background to pass the disease on to their children.

They seldom show any signs of the condition themselves, as they have enough normal haemoglobin to keep their red blood cells flexible.

They do however have to be careful when doing things where there is less oxygen than normal, including scuba diving, activities at high altitude and going under general anaesthetics.

There is one upside of carrying the genes for sickle cell: it renders the carrier immune to malaria.

This helps to explain why sickle cell is more common in areas of Africa where malaria is a serious problem.

Is it easy to spot the condition?

Yes. A simple test will reveal if a person has sickle haemoglobin.

Tests can also identify the haemoglobin type of a baby from about 11 weeks gestation.

Newborn screening for sickle cell is offered to all babies born in England and is integrated into the 'bloodspot programme' - the tests that all children receive at birth.

Is there any treatment?

There is no routine cure for sickle cell, but it can be managed to reduce the frequency and severity of crises and their complications by prompt recognition and treatment.

Minor crises can be safely managed at home on the advice of a doctor with pain killers and increased fluid intake.

When the pain is more severe a patient should be admitted to hospital, where they can be given strong pain relief, intravenous fluids and antibiotics to minimise the risk of infection.

Sometimes it might also be necessary to provide oxygen treatment.

Bone marrow transplants have been used in some cases and, while it is still early days, the procedure holds promise for the future.

What can the patient do?

People with sickle cell anaemia should try to keep themselves in good shape.

They should eat a healthy balanced diet, get plenty of regular sleep, and try, if possible, to keep exposure to stress to a minimum.

It is also important to consult a doctor before considering strenuous exercise, and particularly before planning to start a family.

When a person is found to have a sickle cell disorder it is important that all members of the family be tested.