There are three common types of sickle cell disease:

• sickle cell anaemia or haemoglobin SS — this is the most common
• haemoglobin SC, where the genes for sickle cell and haemoglobin C are both inherited — this is generally milder than sickle cell anaemia
• Sickle-beta thalassemia, where there is both a severe and mild form of the disease.

Most people who ‘carry’ the disease do not generally experience any problems, often remaining healthy and leading normal lives. For those who develop the condition, it is both serious and painful. A child born to parents who carry or have the disease, will have a one in four chance of inheriting and developing the condition.

The disease is caused by changes in the haemoglobin in red blood cells, the substance that carries oxygen inside the cells.

Normal blood cells are round, like doughnuts, and are highly flexible. This allows them to move rapidly through the tiny blood vessels (capillaries). In sickle cell disease, the red blood cells can alter in shape under certain circumstances, resembling a half-moon or farmer’s sickle — spiky and sharp. The trigger factors for this are thought to include low oxygen levels, dehydration, cold or damp housing, and over-exertion.

The stiffened and deformed cells rupture easily and can dam up in small blood vessels, causing blockage of the blood supply to parts of the body, leaving individuals gasping for air and in great pain. This pain can be experienced anywhere in the body, but often occurs in the back, limbs and abdomen.

Additionally, children with sickle cell disorders are extremely susceptible to infection, including meningitis and septicaemia. Strokes are another devastating complication. Whilst rare in children generally, strokes are potentially one of the most common causes of disability in a child with sickle cell disease.

Patients who are not severely affected may have only a few minor crises each year, which can usually be treated at home. However, those who are severely affected may have complications every month, requiring hospitalisation. Often the bone marrow is affected by the loss of blood supply and this causes deep-seated, severe pain, requiring powerful pain killers given by injection under hospital supervision. An acute sickle-cell crisis is often treated with blood transfusion.

There is not yet an effective form of drug treatment which can be given daily to prevent the crises and other complications that can arise from obstruction to blood vessels by sickle cells, although some modern drugs can reduce the pain and severity of attacks.