The genetic causes of sickle cell disease
The reason for the change in the red blood cells lies in the genes within our DNA.3 You can think of DNA as a construction manual for all components of our body - even for our proteins.4 The blueprints consist of one or more genes, which determine things like how we look, what hair and eye colour we have, etc. However, they also control processes in our body that we don't even know anything about, 4 like how our digestive system works, how our blood is produced or how our organs are supplied with oxygen. When the DNA changes, this is referred to as a mutation.3 When mutations happen, genes can be defective, as can the proteins produced by them. This can result in conditions such as sickle cell disease. 3 As these conditions are inherited, they are known as inherited diseases. In sickle cell disease, the construction manual for haemoglobin, i.e., the haemoglobin (Hb) gene, has been changed.3 This mutated form of haemoglobin is known as sickle cell haemoglobin HbS.3 People with sickle cell disease have two of these sickle cell haemoglobin HbS genes.3 Let's take a look at this in more detail:
- Everybody inherits one set of genes from their mother and one set from their father.4 These are responsible for how we look and they also control all metabolic processes in our body.4
- Genes make up part of your genetic information (DNA) and tell your body how to produce certain components (proteins).4 Each gene contains the blueprint for a very specific protein.4
- Hb genes determine how the haemoglobin in the red blood cells is structured and how it functions.3 Haemoglobin is a protein which transports oxygen through your body to all tissues and organs while simultaneously transporting carbon dioxide (a by-product) away from
them.5 In people with sickle cell disease, haemoglobin has been changed, and is known as sickle cell haemoglobin (HbS gene).3
Children inherit one Hb gene each from their mother and their father, and it is this that responsible for haemoglobin structure and function:3
- When a child inherits a mutated HbS gene from one parent and a normal Hb gene (HbA) from the other parent, the child is a carrier of sickle cell disease, but is not ill and has no symptoms.3 However, this child is a carrier of this gene and can therefore pass it on.3
- If a child has two mutated genes, i.e., if they inherit 2 HbS genes, they will have sickle cell disease.3
Who is affected by sickle cell disease?
There are people living with sickle cell disease around the world, and it is assumed that over 300,000 children are born with the condition each year.6
Theoretically, sickle cell disease can be inherited by anyone, but it occurs more frequently in people in the tropical regions of Africa, in the Middle East, in large parts of India, in Eastern Turkey and in certain areas of Greece and Southern Italy – or in people with ancestors from these regions.
How sickle cell disease affects the blood
Healthy red blood cells are elastic.10 This means that they can move through the smallest, narrowest blood vessels without being damaged or getting stuck.10 Red blood cells transport oxygen, which is vital for our bodies, from the lungs throughout the body to all organs and body parts.5 Our body needs oxygen to produce energy.5
Once the sickle cell haemoglobin (HbS) has delivered its oxygen, it changes its structure, and the blood cells take on the sickle shape typical of the disease instead of the normal round shape.7,10 They are no longer elastic and can therefore get stuck in and block small and minute
The symptoms of sickle cell disease
Sickle cell disease can affect a person's body in many different ways.6 The following symptoms may occur:
- Sudden severe pain ("pain crisis")6
- Frequent infections6
- Anaemia (a shortage of healthy red blood cells, which can lead to feelings of weakness and
fatigue)6
Find out more about how to manage pain and complications here .
As the sickle-shaped red blood cells are less mobile and have a tendency to stick to one another, blood vessels can become blocked.7,10 This is often associated with further complications, such as:
- Stroke: When blood vessels in the brain are affected, part of the brain tissue dies, as it is not receiving enough oxygen.6
- Acute chest syndrome (ACS): Reduced blood flow leads to lung damage, which causes severe chest pain.6 Fever, a cough and breathlessness may also occur.6
In the long term, sickle cell disease can cause damage to your organs, including your heart, lungs and kidneys.2,7 In addition, your bones, particularly those in your arms and legs, may be damaged.2,7 Abdominal pain may also occur, in part due to poor blood flow and swelling of the liver and
Talk to your doctor if your symptoms change. Together, you will be able to manage your condition more effectively.
- Top tips for self-management
- Your wellbeing diary
- Set targets that work for you
- Get the most out of your medical appointments
