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

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 SCD they can become rigid and shaped like a crescent (or sickle). The sickle-shaped cells contain defective haemoglobin (Hb), the iron-rich protein that enables red blood cells to carry oxygen from your lungs to the rest of the body. SCD is caused by a mutation in the haemoglobin, known as the ‘sickle’ mutation.

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

Such episodes are known as sickle cell crises or a vaso-occlusive crises. They can last from a few minutes to several weeks. A sickle cell crisis is often described by a number of conditions. For example, it can cause an individual indescribable pain – anywhere in their body, result in a cerebrovascular accident (CVA/stroke) and acute chest syndrome (ACS – see below).

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.

Currently, treatment for SCD is limited and there is no cure except for bone marrow transplantation, which can be associated with many other risks. Experience with transplant in sickle cell is limited but specialists are becoming more skilled in the area and the number of bone marrow transplants undertaken is increasing. Treatment offered to individuals with SCD aims to be preventative and stop serious complications before they arise.

NHS film - sickle cell amaenmia

Sickle cell disease is caused by a mutation (an abnormal change) in the gene that instructs the body to produce haemoglobin.

To have a diagnosis of a sickle cell disorder you will have to inherit the defective or mutated gene from both your mother and father.

If you only inherit the gene from one parent, you are known as a sickle cell carrier, this is also referred to as sickle cell trait. It's likely that your blood will contain some sickle cells, but you will be able to produce normal haemoglobin and will not usually experience symptoms. In England, about 250,000 people are thought to have the sickle cell trait, with those of African-Caribbean origin primarily affected.

As a carrier of SCD you may pass the gene on to any children you have. If you know you are a carrier of SCD it is important that you seek advice from your GP or are referred for genetic counseling before you and your partner conceive. This enables your partner to be screened for SCD and other blood disorders (such as Thalassaemia) and informs you of the chances of your child inheriting SCD. If you are your partner are both affected by SCD there are services that you can be referred to in order to reduce the risk of conceiving a child with a sickle cell disorder. If two people with the sickle cell trait have a child, there's a one in four chance (25%) that the child will be born with sickle cell anaemia. More information can be found at:

The symptoms and process of sickle cell anaemia can have a significant impact on a person's quality of life, both physically and psychologically. If complications develop, these can be very serious and potentially life threatening. There are numerous problems that someone with SCD can come up again; some individuals will experience numerous complications and some minimal difficulties throughout their life. Possible complications include (but are not limited to):

  • Neurological damage. This can lead to cerebrovascular accidents (stroke) – where the blood supply to part of the brain is cut off. This can occur at any age and a high percentage of individuals with SCD will have had a stroke by the time they reach 18 years old. Regular monitoring is offered to children, which includes blood testing and Transcranial Dopplers (TCD) - which is similar to an ultrasound scan - looks at the rate of blood flow through the brain. Once any problems are detected treatment, such as blood exchanges are offered as a preventative measure. Once a person with SCD has had a stroke they are more likely to have further episodes. They will require close monitoring and on going treatment.
  • Increased vulnerability to infection. People with SCD do not have a functioning spleen and so are predisposed to infection. The spleen plays an important part in the ability to fight infection, as such individuals are recommended to take antibiotics for life in order to reduce the risk of certain infections. People with SCD are also encouraged to have an extended vaccination schedule. Although antibiotics are taken regularly, the risk of infection is still very high. Severe infections in someone with SCD are potentially fatal and often require hospital admission for intensive antibiotic treatment.
  • Acute Chest Syndrome (ACS). In an ACS sickled red blood cells pool in the lung tissues. This can be precipitated by infection, fat embolism or decreased respiratory effort (often due to pain or following abdominal surgery). The pooling of sickle red blood cells in the lungs causes decreased air entry into the lungs and subsequently starves the body and its organs of oxygen. Emergency treatment is required, if left untreated an ACS can be fatal. Acute Chest Syndrome is the leading cause for death in adults with SCD; individuals who have had one ACS are more likely to have further episodes.
  • Pulmonary Hypertension – where the blood pressure inside the pulmonary arteries of the heart are raised. It causes the heart to become less efficient at moving the blood from the heart to the lungs. This decreases the amount of oxygen available to the muscles and around the body. It can cause shortness of breath and fatigue as well as many other associated problems. Once a person with SCD is found to have pulmonary hypertension, treatment is offered with the aim of slowing the progression of the disorder.
  • Acute and chronic pain. Pain is a common occurrence in SCD due to the blockages caused by the sickled red blood cells. Treatment involves a multimodal approach. This includes analgesia, psychological support, distraction techniques and complementary therapies. Pain can cause great distress and someone with SCD can experience pain every day. As such, it is important to support individuals and provide education on how best it can be managed. Many patients with SCD will manage their pain at home, however, at times people will need to be admitted to hospital and receive stronger and alternative treatments. After a flare up of pain or sickle cell crisis, it can take some time for an individual to recover completely and people often require a long period of recuperation.
  • Leg ulcers are common in sickle cell disorders and have a high rate of reoccurrence. Leg ulcers can occur after injury or spontaneously. They can cause extreme pain and take months to heal. If an individual with SCD has a leg ulcer, once healed the skin at the site of the ulcer is extremely fragile and minimal trauma can cause a further breakdown. Treatment for leg ulcers can include frequent bandaging/ dressing, compression bandaging is sometimes necessary, bed rest, vitamin or mineral supplementation (zinc replacement). In severe cases blood transfusion or exchange can often aid the recovery process. 
  • Eye complications. Complications related to sickle cell can occur slowly over a period of time or be instant. People with SCD should have yearly eye checks to ensure any problems are identified and acted on as appropriate. Eye complications can result in visual changes/ reduced vision or complete loss of vision.