Sickle cell anaemia
Sickle cell anaemia is a genetic (passed from parent to child) disorder that affects the body's blood cells. In this disease, faulty haemoglobin (a substance that carries oxygen in the blood) causes the red blood cells to change shape when oxygen is released to tissues.
There are between 12,500 – 15,000 people with sickle cell disease in the UK. There are also an estimated 240,000 genetic carriers of the condition.
Normal red blood cells are round and are able to move through small blood vessels in the body to deliver oxygen. In sickle cell anaemia, a chemical change in haemoglobin causes the substance to form long rods in the red blood cell as the haemoglobin releases oxygen. These rigid rods change the shape of the red blood cell into a sickle shape.
The disease gets its name because the faulty blood cells are shaped like sickles - old farming tools used to cut wheat. When the deformed cells go through blood vessels, they clog the blood flow and can break apart.
Sickle cells can cause pain, damage the blood vessels or other areas of the body and cause anaemia (low blood count).
Sickle cell anaemia is found most often in black people. However, other ethnic groups also can have sickle cell disease. Antenatal screening can be offered if family origin suggests a risk for the condition.
What causes sickle cell disease?
A chemical change in haemoglobin causes the substance to form long rods in the red blood cell as the haemoglobin releases oxygen. These rigid rods change the shape of the red blood cell into a sickle shape.
Sickle cell anaemia is not contagious. Children are born with sickle cell haemoglobin, which they inherit from their parents. Individuals may be carriers who have sickle cell trait or may actually have sickle cell disease. People who inherit only one sickle cell gene are carriers, but people who inherit two sickle cell genes have sickle cell disease.
What are the symptoms of sickle cell anaemia?
Sickle cell anaemia can cause a painful sickle cell crisis. A sickle cell crisis is also known as a vaso-occlusive episode or VOE.
Other symptoms of sickle cell disease include:
- Swelling and inflammation of the joints
- Sickling crisis - blood blockage in the spleen or liver
Sickle cell anaemia can also cause damage to the heart, lungs, kidneys and bones.
How is sickle cell anaemia diagnosed?
Sickle cell anaemia is diagnosed by examining a sample of blood under a microscope. When the abnormal sickle-shaped cells in the blood are identified, a diagnosis is made. Also, a blood test called the haemoglobin electrophoresis can determine if a person has the disease or is a carrier.
How is sickle cell anaemia treated?
The only cure for sickle cell anaemia is a bone marrow transplant, where affected bone marrow is replaced with bone marrow from somebody who does not have the condition.