Sickle Cell Disease

Many may not have heard of Sickle Cell Disease but it is actually common, affecting around 300 million people worldwide and about 15,000 people in the UK. This article will look into what the condition is, how people get it and what testing and treatment options are available.

Sickle Cell Disease is an inherited condition in which sufferers produce a different type of haemoglobin to the general population. 

Haemoglobin is the molecule in red blood cells that allows those cells to transport oxygen around the body. In people with Sickle Cell Disease, their form of haemoglobin causes their red blood cells to have an unusual crescent of ‘sickle’ shape. 

These cells are more easily damaged as they pass through the small blood vessels of the body which causes them to break down more quickly resulting in anaemia (low levels of haemoglobin).

We all carry two genes that determine what kind of haemoglobin we produce.

If you inherit genes from both parents that produce normal haemoglobin, then you will also produce normal haemoglobin.

• To suffer from Sickle Cell Disease people must inherit the sickle cell gene from both parents.

• If you inherit the gene from just one parent, then you have Sickle Cell Trait. 

Sickle Cell Trait usually does not cause any symptoms but it means that you may have a child with Sickle Cell Disease if your partner also has Sickle Cell Trait. 

If you and your partner both have Sickle Cell Trait then there is a:

• 1 in 4 chance that your child will have normal haemoglobin 
• 1 in 4 chance your child will have Sickle Cell Disease
• 2 in 4 chance your child will have Sickle Cell Trait. This is called ‘recessive inheritance’. 

Sickle Cell Disease is most common in Sub-Saharan Africa and is also relatively common in populations who have migrated from Africa (such as into the Caribbean), although Sickle Cell genes can be found in people from the Middle East, the Mediterranean and Asia. 

The reason that it exists most commonly in Africa is that people with Sickle Cell Trait are naturally more resistant to malaria. Having Sickle Cell Trait is therefore an advantage in this part of the world.

Symptoms of Sickle Cell Disease usually start at a young age – between 3 and 6 months old.

These symptoms can include:

• Poor growth
• Susceptibility to infections
• Jaundice (yellowing of the eyes and skin)
• Pallor and weakness relating to the underlying anaemia

The other symptoms of Sickle Cell Disease tend to relate to different kinds of ‘sickle cell crisis’. The most common form of crisis is called a ‘vaso-occlusive’ crisis which happens when the damaged and abnormally shaped red blood cells block small blood vessels. This can be caused by infection, exertion, dehydration, or exposure to the cold, but sometimes it appears to happen for no reason.

The symptoms of these crises depends on where the blood vessels are blocked. There may be extreme joint pains if the joints are affected, loin pain if the kidneys are involved, symptoms of a stroke if the brain is involved, or breathing difficulties if the lungs are involved. 

Other kinds of crisis can result in sudden and dramatic falls in haemoglobin levels that causes the symptoms of severe anaemia such as feeling:

• Breathless
• Lightheaded
• Tired and weak

A Sickle Cell crisis should be treated as an emergency. 

Sickle Cell Disease is screened for in the UK. Pregnant women are screened early in pregnancy. 

In areas of the UK where Sickle Cell is more common, this is in the form of a blood test in which the haemoglobin is analysed. If a woman is found to be a carrier of Sickle Cell, then the father is offered testing to see if he is also a carrier. Where the disease is less common, women undertake a family history questionnaire. 

Because it is an inherited condition there is usually an obvious family history of people either having the disease or the trait.

Newborn babies are also screened for Sickle Cell Disease. This happens as part of the ‘heel prick test’ when a small drop of blood is taken from the baby’s heel at about five days old, and this blood is used to screen for a variety of inherited conditions.

Blood tests for Sickle Cell can of course be taken at other times. These tests usually involve a Full Blood Count which checks for anaemia, as well as a direct analysis of the haemoglobin. 

All people with Sickle Cell Disease should be under the care of a specialist Sickle Cell centre to ensure that they receive the best care possible. 

This should include prophylactic antibiotics to reduce the risk of infection, and a clear action plan on how to manage pain during a crisis. Sufferers may also need treatments such as regular blood transfusions and may be considered for more advanced treatments like bone marrow transplant and monoclonal antibody treatment. 

Because it is a complex condition, specialist advice should be sought during other periods of risk such as during pregnancy or before any operation. 

Sickle Cell Disease is relatively common, affecting around 300 million people worldwide and about 15,000 people in the UK. Management of the condition involves early recognition and high quality, specialist input.