Sickle Cell Trait: What You Should Know

A Hereditary Genetic Change

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Sickle cell trait is the condition of carrying only one copy of the gene that causes sickle cell disease. Having only one copy of the gene does not cause the disease.

Sickle cell disease is a hereditary blood disorder that affects people who have genes coding for an abnormal formation of the hemoglobin molecule, which carries oxygen in red blood cells. People who have sickle cell trait may have a parent, child, or other family members with sickle cell disease.

This article will discuss sickle cell trait, its relation to sickle cell disease, and how sickle cell disease is inherited. It will also explore how you might be diagnosed as having sickle cell trait and what effects this may have on your health.

Parent and child. Sickle cell trait is hereditary

Tara Moore / Getty Images

Sickle Cell Trait vs. Disease

Sickle cell trait and sickle cell disease have similarities and differences. The main difference is that sickle cell disease causes symptoms and has a major impact on an affected person’s health, but sickle cell trait does not.

There have been many research studies examining whether sickle cell trait can affect a person’s health. Results suggest that there may be some effects, but most people who have sickle cell trait will not develop health consequences. 


Genes are located on structures called chromosomes. A defect in the beta globin gene causes sickle cell disease. It is located on chromosome 11, and it codes for the formation of a portion of the hemoglobin molecule. People inherit two copies of this gene, one from each biological parent.

Hemoglobin carries oxygen in red blood cells. When it is malformed, it can predispose the red blood cells to become sickle shaped, especially under physically stressful circumstances. The sickle cells may clump together, causing many of the symptoms of sickle cell disease. 

Sickle cell disease occurs when a person inherits two abnormal genes that code for hemoglobin (one from each genetic parent), which leads to the red blood cell sickling reaction. 

Sickle cell trait describes the condition of having one copy of the gene that causes sickle cell disease. When the other copy of the gene is normal, the red blood cells will have normal hemoglobin proteins, so symptoms and effects of sickle cell disease will not develop. 

How Likely Is Inheritance?
  If one of your parents has sickle cell trait If both your parents have a sickle cell trait If one of your parents has sickle cell disease and the other parent does not have the gene If one of your parents has sickle cell disease and the other parent has sickle cell trait If both your parents have sickle cell disease
Chance of having sickle cell disease  0%  25%  0% 50% 100%
Chance of having sickle cell trait  50%  50%  100% 50% 0%
Chance of not having sickle cell trait or sickle cell disease  50%  25%  0% 0% 0%


Sickle cell trait is diagnosed with a genetic test. This is a blood test that can detect abnormal genes. It can identify whether a person has any copies of the mutation that causes sickle cell disease.


The effects of sickle cell trait have been examined. Researchers have studied whether it has any effects on health. In general, sickle cell trait is not associated with pain crisis or with the symptoms of sickle cell disease. However, sickle cell trait is associated with some complications.

A study published in 2021 showed that people who have sickle cell disease have a high risk of complications from COIVID-19 infection, but people with sickle cell trait are not at an increased risk of complications from COVID-19 infection.

Sickle cell trait is partially protective against malaria, a mosquito-transmitted disease caused by a parasite that infects red blood cells.

Some complications associated with sickle cell trait include:

Sickle Cell Nephropathy

Sickle cell trait is associated with an increased risk of hematuria (blood in the urine), and sometimes protein can be present in the urine as well. The condition is not associated with kidney or bladder damage, and it can resolve with hydration and gamma epsilon-aminocaproic acid.

Renal Medullary Carcinoma

This type of tumor is associated with sickle cell trait, not sickle cell disease. It is described as a tumor in the medullary region of the kidney. This tumor does require treatment, and it can be aggressive.

Postoperative Complications

Complications can occur after surgery if you have sickle cell trait.

For example, one study found that after hip replacement surgery, people with sickle cell trait had a higher likelihood of stroke (blockage of blood flow or bleeding in the brain), anemia (low numbers of healthy red blood cells), acute renal (kidney) failure, pneumonia (lung infection), sepsis (severe reaction to a blood infection), deep vein thrombosis (clot in a large vein), pulmonary embolism (clot traveling to the lungs), and respiratory failure.

Prevention of post operative complications involves close maintenance of oxygen, fluids, and acid-base balance.


Athletes with sickle cell trait are at an increased risk of exercise-induced collapse and have a 37-fold increase in exercise-related sudden death. The reasons are not clear. However, sickle cell trait is not associated with heat injury or heatstroke.

Suggested strategies for staying safe while exercising include getting enough fluids, resting, keeping a moderate intensity, allowing body temperature to cool down, and getting immediate medical attention if you start to feel sick.


Sickle cell trait is a condition of having one sickle cell gene mutation. Having sickle cell trait doesn’t cause sickle cell disease. You may have a small risk of surgical complications or a risk of serious complications from athletics if you have sickle cell trait.

Your children can also have a risk of inheriting sickle cell disease if their other genetic parent has sickle cell trait or sickle cell disease. 

A Word From Verywell 

If you have sickle cell trait, you might have some concerns about your health or your children's health. Overall, there are a few risks associated with sickle cell trait, including risks in athletics and postoperative complications.

You can talk to your healthcare provider about taking precautions to reduce your risk. You may also consider whether to use genetic testing for family planning purposes. 


Frequently Asked Questions

  • Is sickle cell trait the same as sickle cell disease?

    No, they are not exactly the same. Both conditions are caused by a sickle hemoglobin (HbS) mutation in the β-globin gene (HBB). All people have two copies of this gene. People who have one gene with the mutation and one normal gene have sickle cell trait and do not have the disease. People who have the mutation on both copies of the gene have sickle cell disease.

  • What are the side effects of sickle cell trait?

    Most people who have sickle cell trait do not develop any symptoms. The biggest risk of having sickle cell trait is passing it on to a child. If you have sickle cell trait, there is a 50% chance that your children would inherit the mutation from you. A child will develop sickle cell disease if they inherit the gene mutation from both parents.

  • Is the sickle cell trait genetic?

    Yes, sickle cell trait is genetic. It is an inherited defect in the gene that codes for part of the hemoglobin molecule.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.