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What is Sickle Cell Disorder?

Sickle cell disorder is a serious inherited blood disorder where the red blood cells, which carry oxygen around the body, develop abnormally.

normal cells sickle cells
Normal red blood cells Sickled red blood cells


The disorder mainly affects people of African, Caribbean, Middle Eastern, Eastern Mediterranean and Asian origin. In the UK, sickle cell disorders are most commonly seen in African and Caribbean people.

Normal red blood cells are flexible and disc-shaped, but in sickle cell anaemia they can become rigid and shaped like a crescent (or sickle).

The sickle-shaped cells contain defective haemoglobin, the iron-rich protein that enables red blood cells to carry oxygen from your lungs to the rest of the body.

The abnormal cells are also unable to move around as easily as normal shaped cells and can block blood vessels, resulting in tissue and organ damage and episodes of severe pain.

Such episodes are known as a sickle cell crisis or a vaso-occlusive crisis. They can last from a few minutes to several months, although on average most last five to seven days. The abnormal blood cells also have a shorter lifespan and aren't replaced as quickly as normal blood cells. This leads to a shortage of red blood cells, known as anaemia.

Symptoms of anaemia include lethargy (a lack of energy), tiredness and breathlessness, particularly after exercise.

What causes sickle cell disorder?

Sickle cell disorder is caused by a mutation (an abnormal change) in the gene that instructs the body to produce haemoglobin. The sickle cell gene is inherited (passed on between family members). To get sickle cell disorder you have to inherit the defective gene from both parents. If you only inherit the gene from one parent, you have what's known as the sickle cell trait. It's likely that your blood will contain some sickle cells, but you'll be able to produce normal haemoglobin and won't usually experience symptoms. However, you'll be a carrier of sickle cell disorder and may pass the abnormal gene on to your children.

In England, about 250,000 people are thought to have the sickle cell trait, with those of African-Caribbean origin primarily affected. If two people with the sickle cell trait have a child, there's a one in four chance that the child will be born with sickle cell disorder.

Diagnosing and screening for sickle cell disorder

Sickle cell disorder can be diagnosed using a simple blood test, which can be done at the centre, your GP, a routine hospital admission or during pregnancy. All pregnant women are offered screening for sickle cell as part of their antenatal care. The blood is checked for defective haemoglobin. A small level of defective haemoglobin would indicate that a person has the sickle cell trait but not sickle cell disorder. A high level would indicate sickle cell disorder.

People in high risk groups should be tested for the sickle cell before having a general anaesthetic. This is because this type of anaesthesia temporarily lowers the amount of oxygen in the blood, which could be dangerous for someone with these blood conditions.

Treating sickle cell disorder

If you are diagnosed with sickle cell disorder, you should be referred to a specialist sickle cell centre. Sickle cell centres are specialist units usually based in large hospitals. The staff at these units have a high level of expertise in treating people with sickle cell disorder. A detailed plan outlining future medical care will be drawn up and you'll be given information and support to help manage your condition. Following simple lifestyle advice, such as drinking plenty of fluids, can help reduce the risk of experiencing a sickle cell crisis.

Sometimes, a person with sickle cell disorder will continue to experience pain despite taking preventative measures. In such cases, a medication may be called recommended.

Complications of sickle cell disorder

The symptoms of sickle cell disorder can have a significant impact on a person's quality of life. If complications develop, these can be very serious. Possible complications include:

  • stroke - where the blood supply to part of the brain is cut off
  • increased vulnerability to infection
  • acute chest syndrome - where the lungs suddenly lose their ability to breathe in oxygen (often the result of an infection)
  • pulmonary hypertension - where the blood pressure inside the blood vessels that connect the heart to the lungs becomes dangerously high

However, following improvements in preventative treatment, many complications associated with sickle cell disorder can be avoided.

The life expectancy of a person with sickle cell disorder has increased significantly over recent decades. A person with the condition can expect to live into their 50s and beyond.

When to seek urgent medical advice

Because of the risk of potentially life-threatening complications, it's important to look out for any signs or symptoms that the health of a person with sickle cell disorder has suddenly deteriorated. These include:

  • a high temperature (fever) of 38C (100.4F) or above
  • breathing difficulties
  • severe pain that develops during a sickle cell crisis that can't be controlled using over-the-counter painkillers, such as paracetamol or ibuprofen.