Sickle cell disease is caused by faulty genes that a child inherits from their parents.
It's not caused by anything the parents did before or during the pregnancy and you can't catch it from someone who has it.
How sickle cell disease is inherited
Genes come in pairs. You inherit one set from your mother and one set from your father.
To be born with sickle cell disease, a child has to inherit a copy of the faulty sickle cell gene from both of their parents.
This usually happens when both parents are "carriers" of the faulty gene – also known as having the sickle cell trait.
Sickle cell carriers don't have sickle cell disease themselves, but there's a chance they could have a child with the condition if their partner is also a carrier.
If both parents are sickle cell carriers, there's a:
- 1 in 4 (25%) chance each child they have will not inherit any faulty genes and won't have sickle cell disease or be able to pass it on
- 1 in 2 (50%) chance each child they have will just inherit a copy of the faulty gene from one parent and be a carrier
- 1 in 4 (25%) chance each child they have will inherit copies of the faulty gene from both parents and will be born with sickle cell disease
The Sickle Cell Society has more information about the inheritance of sickle cell disease, including what the risks are if a parent has sickle cell disease themselves.
Who's most at risk of sickle cell disease?
Sickle cell disease mainly affects people with an African, Caribbean, Middle Eastern, Eastern Mediterranean and Asian family background.
In the UK, it's most commonly seen in people of African and Caribbean backgrounds. It's estimated that one in every 10 people in this group carries sickle cell.
A simple blood test will show whether you're a carrier. This is done routinely during pregnancy and after birth, but you can ask to have the test at any time.
Read more about getting tested for the sickle cell trait and being a sickle cell carrier.
How sickle cell disease affects the body
Your genes are the set of instructions found inside every cell in your body. They determine characteristics such as the colour of your eyes and hair.
People with sickle cell disease have a problem with the genes involved in the development of haemoglobin – a substance found in red blood cells that carry oxygen around the body.
Normal red blood cells are flexible and disc-shaped, but in sickle cell disease they can become rigid and shaped like a crescent or sickle because the haemoglobin inside them clumps together.
These unusual cells can cause symptoms of sickle cell disease because they don't live as long as normal red blood cells and can become stuck in blood vessels.