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Sickle Cell Trait vs. Sickle Cell Disease

Your Health / Conditions / Rare Diseases​​​​​​​ / Sickle Cell Trait vs. Sickle Cell Disease​​​​​​​

Published on Nov 22, 2017
​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Medically reviewed by Krupa Sivamuthy, MD


Millions of people worldwide are affected by the sickle cell blood disorder. The genes for this disease are common in people of African, Middle Eastern, Southern European, Indian, Pakistani and Caribbean origin. It is becoming more prevalent with increasing immigration from sub-Saharan Africa and the Indian subcontinent.

Having sickle cell trait (SCT) however, is not the same as having sickle cell disease (SCD). And this can cause a lot of confusion, even among doctors. As a practicing haematologist, I would occasionally get referrals from paediatricians asking me to see a child who had sickle cell trait—even though a child with SCT doesn’t necessarily need to be followed by a specialist.

Why not? And what is the difference between having sickle cell trait and sickle cell disease? Read on to find out—and learn the next steps to take if you or someone in your family is diagnosed with these conditions.

Sickle Cell Disease

People with sickle cell disease have red blood cells that are crescent (or sickle) shaped. This abnormal shape makes it difficult for the cells to travel through the blood vessels. As the sickle cells clog the blood vessel, they can block blood flow to various parts of the body, causing painful episodes (known as sickle cell crises) and raise the risk of infection.

SCD is diagnosed by a blood test. There are many forms of sickle cell disease, including sickle cell anaemia, which is the most common and also the most severe, and sickle cell thalassaemia. With all forms of SCD, symptoms can vary in form and severity from one person to another, but include serious pain, fatigue, shortness of breath, headaches and dizziness.

People with SCD are at a higher risk for health complications such as infections, stroke, eye damage, and pulmonary hypertension, so working to prevent these problems should be a primary goal for anyone with SCD. Currently, there is no widely available cure for sickle cell disease, so it’s important that people with the condition work with their healthcare team to manage their symptoms.

Sickle Cell Trait

When someone has sickle cell trait (SCT), it means they have inherited one sickle cell gene and one normal gene. People with SCT have both normal red blood cells and some sickle-shaped red blood cells. Most people with SCT do not have any symptoms of sickle cell disease. If both parents are carriers of the sickle cell gene, though, there is a 50% chance of passing the gene on to their children. That means people with sickle cell trait can be at risk of having a child with SCT or SCD.

In the U.S., all newborns are now screened for sickle cell before leaving the hospital. Parents will usually be given the results of this test at the child’s one-month check-up. If a child is diagnosed with SCT, his or her parents may wish to see a genetic counsellor. Genetic counsellors can help parents better understand what it means to be a carrier of the gene and what the chances of having a child with either SCD or SCT are.

Dr. Krupa Sivamurthy is a Paediatric Haematologist-Oncologist and a Medical Director in Haematology at Pfizer.


    1. Genome diseases. WHO Accessed 14/2/2017.
    2. How is sickle cell trait inherited? US Centers for Disease Control. Accessed 14/2/2017.
    3. What causes sickle cell disease. US National Heart Lung and Blood Institute. Accessed 14/2/2017.

    Last reviewed 15/08/2019


    External Resources

    -Thalassaemia and Sickle Cell Society of Australia
    -Health Direct - Sickle cell disease
    -NIH: What is Sickle Cell Disease?
    -CDC: Living Well with Sickle Cell Disease

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