10 sickle cell disease (SCD) facts
In this article, we will describe 10 sickle cell disease (SCD) facts.
1. What is sickle cell disease (SCD)? – genetic disorder
Sickle cell disease (SCD) is a genetic blood disorder caused by a mutation in the haemoglobin-Beta gene found on chromosome 11.
There are various types of sickle cell disease, each with varying severity. Haemoglobin SS (the most common type) and sickle beta zero thalassaemia (Sβ0-thalassaemia) are the most severe forms, followed by haemoglobin SC and sickle beta+ thalassaemia.
2. Red blood cell shape
SCD inhibits the ability of haemoglobin in red blood cells to carry oxygen. In SCD, red blood cells are abnormally shaped like a crescent or sickle, and tend to stick together; blocking small blood vessels causing painful and damaging complications.
Sickle cells in human blood film – both normal red blood cells and sickle-shaped cells are present.
3. Inheritance
SCD is inherited in an autosomal recessive pattern. This means, if both parents have sickle cell trait, their child may be born with sickle cell disease.
- A person will be born with sickle cell disease only if two genes are inherited – one from the mother and one from the father
- A person who inherits just one gene is healthy is said to be a ‘carrier’ of the disease, or have ‘sickle cell trait’. A carrier can have a child with sickle cell disease, if the other parent is a carrier.
For parents who are each carriers of a sickle cell gene, there is a 1 in 4, or a 25 % chance of having a child with sickle cell disease.
A person with sickle cell trait cannot develop the disease but can pass the gene on to their children, as described above.
4. Malaria connection
Areas with a high prevalence of sickle cell trait often coincide with regions where malaria is common. Sickle cell trait can offer some protection against malaria, although it doesn’t guarantee immunity.
5. Epidemiology
Whilst sickle cell disease has long been associated with people of African descent, it can also affect individuals of other races. People of Central and South American, Middle Eastern, Asian, Indian, and Mediterranean heritage, can also develop sickle cell disease.
6. Symptoms
Common symptoms include: symptoms of chronic anaemia, chronic pain, frequent infections (precipitating sickle cell crises), gallstones, eye disease, delayed growth, and vision problems.
7. Diagnosis
Newborn screening programmes typically diagnose SCD at birth through blood tests that detect the presence of sickle haemoglobin.
8. Complications
SCD can lead to severe complications such as stroke, acute chest syndrome, organ damage (including CKD and ESRF in some patients, and AKI), and increased risk of infections.
Splenic sequestration (pooling)
Crises are a result of sickle cells pooling in the spleen. This can cause a rapid drop in haemoglobin and can be life-threatening if not treated promptly. The spleen can also become enlarged and painful from the increase in blood volume.
After repeated episodes, the spleen becomes scarred, and permanently damaged. Most children, by age 8, do not have a working spleen either from surgical removal, or from repeated episodes of splenic sequestration. The risk of infection is a major concern of children without a working spleen.
9. Treatment
Treatments include pain management, blood transfusions, hydroxyurea (a medication that can reduce the frequency of pain episodes), other medication (see below); and bone marrow transplants, which can potentially cure the disease.
Hydroxyurea
This medication helps increase the production of foetal haemoglobin, which can prevent the formation of sickle-shaped cells and reduce complications.
Vaccinations and long-term antibiotics
These are used to prevent infections.
Folic acid
Folic acid can help prevent severe anemia.
New treatments
New treatments are now available, including gene-editing therapies such as Casgevy (exagamglogene autotemcel) and Lyfgenia (lovotibeglogene autotemcel).
10. Prognosis
Advances in treatment have improved the life expectancy of individuals with SCD, allowing many to live into their 50s and beyond. However, the disease still significantly impacts quality of life and requires ongoing medical care.
Racism and stigma
- Black people are disproportionately affected by SCD
- Factors that contribute to stigma in SCD include racism, pain and opioid use, disease severity, and sociodemographic characteristics
- It is important to be aware that patients with SCD presenting to A&E for care, experience longer wait times than other groups, and are often falsely accused of exaggerating their pain or seeking drugs – for the reasons outlined above.
Summary
We have described 10 sickle cell disease (SCD) facts. We hope it has been helpful.
Other resource
What is sickle cell nephropathy?
Last Reviewed on 27 June 2024