Key takeaways

  • Sickle cell trait (SCT) is a genetic condition where individuals carry one copy of the sickle cell gene, making them carriers but generally symptom-free. This trait can be passed to offspring, potentially leading to sickle cell disease (SCD) if both parents have it.
  • While SCT typically doesn’t cause symptoms, certain stressors like intense physical exertion can provoke sickle cell-like symptoms, including heatstroke and muscle breakdown. Athletes and military personnel with the trait should take preventive measures to minimize risks.
  • Testing for SCT is recommended for people with a family history of the condition or those from high risk populations. Healthcare professionals can provide guidance on managing the trait and understanding genetic implications

Sickle cell disease (SCD) is a group of inherited blood disorders. People with SCD have two copies of a gene that affects hemoglobin, an essential component of red blood cells. People with only one copy of the gene have sickle cell trait (SCT).

SCT affects 1 to 3 million Americans, according to the American Society of Hematology (ASH). It’s especially common among Black people and African Americans.

Because a person with SCT has only one copy of the gene, they’ll never develop SCD. Instead, they’re carriers of the disease, meaning they can pass the gene on to their children.

Having SCT isn’t the same as having SCD. But in rare cases, people who carry the trait can experience some of the same severe symptoms of SCD.

SCD affects the form and function of your red blood cells. People with SCD have hemoglobin, the oxygen-carrying component of red blood cells, that does not function properly.

This impaired hemoglobin causes red blood cells, which are typically flattened disks, to become crescent-shaped. The cells resemble a sickle, a tool commonly used in farming.

These red blood cells can’t live as long as healthy red blood cells and can block your blood vessels. This causes serious health problems, such as:

On the other hand, SCT rarely leads to deformed red blood cells, and only under certain conditions.

People with SCT typically have enough regular hemoglobin to prevent the cells from becoming sickle-shaped. Without sickling, red blood cells function properly, transporting oxygen-rich blood to your tissues and organs.

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How people inherit sickle cell disease or sickle cell trait
Medical Illustration by Bailey Mariner

SCT can be passed on from parent to child. If both parents have SCT, they may have a child with SCD.

According to the Centers for Disease Control and Prevention (CDC), if both parents have SCT, there is:

  • a 50% chance their child will have the trait
  • a 25% chance their child will have SCD
  • a 25% chance their child will have neither the trait nor the disease

If only one parent has SCT, there is a 50% chance that their child will have the trait.

SCD symptoms can start as early as 5 months old, and early diagnosis is critical, so it’s routine in the United States to test all newborns.

Most people with SCT don’t experience any symptoms.

However, under certain stressful conditions, healthy red blood cells in people with SCT can become sickle-shaped, leading to symptoms associated with SCD. Such conditions may include:

In rare cases, some people with SCT may experience complications like:

Athletes with SCT need to take precautions when performing, according to the CDC. Staying hydrated is extremely important.

Sickle cell trait in athletes

In 2010, after a 19-year-old college athlete suddenly died during intense football training, the National Collegiate Athletic Association (NCAA) implemented a mandatory screening policy for SCT to prevent future deaths.

Athletes and others with SCT who exert themselves physically have a greater risk of experiencing more severe symptoms during exercise, such as heatstroke and muscle breakdown.

The risk is highest under extreme temperatures and severe conditions, but you can minimize this risk by:

  • drinking lots of water before, during, and after training and competition
  • maintaining a cool body temperature during exercise, such as by moving to a shaded or air-conditioned space during breaks or rest periods
  • setting your own pace for physical activities and building intensity slowly
  • getting immediate medical treatment if you feel unwell

SCT is a lifelong genetic trait. People with SCT prone to medical complications should avoid situations that will put their bodies under additional stress, including:

  • dehydration or drinking too little water
  • exposure to increased atmospheric pressure, such as when scuba diving
  • high altitudes, such as air travel, visiting a high-altitude place, or mountain climbing
  • low oxygen levels in the air, such as when mountain climbing, training for athletic competition, or completing military boot camp
  • extreme exercise
  • sudden temperature changes
  • smoking tobacco or drinking alcohol

When mild symptoms of SCT arise, you may be able to manage them at home. Some people find the following actions can help ease symptoms:

  • Apply a warm towel or wrapped heating pad to the affected part of your body.
  • Distract yourself with a movie or book.
  • Drink plenty of water.
  • Take over-the-counter pain relievers, such as ibuprofen.

If you experience severe symptoms, it’s important to get immediate medical attention.

SCT and SCD are most common among populations with ancestors from regions where malaria is or was prevalent, as SCT may have evolved as a protective response against malaria.

The region with the highest number of cases of SCT is sub-Saharan Africa. Other regions where SCT is more prevalent may include:

  • South America, the Caribbean, and Central America
  • India
  • Saudi Arabia
  • Mediterranean countries, such as Greece, Turkey, and Italy

In the United States, SCT appears most frequently in the African American population, affecting 8% to 10% of individuals, according to ASH. The CDC notes that about 1 in 13 Black or African American babies is born with SCT. That’s compared to:

  • 1 in 145 Hispanic births
  • 1 in 333 white births
  • 1 in 455 Asian or Pacific Islander births

Healthcare professionals can diagnose SCT with a blood test.

Consider speaking with a primary care doctor about SCT testing if you have one or more family members who carry the trait or have SCD.

You may also wish to speak with a genetic counselor to learn more about an SCT diagnosis and how it can affect you and your family.

People with SCT tend to have a similar life expectancy to people without the trait. But they’re at higher risk of serious complications that may significantly decrease a person’s life span.

SCT can affect people with all blood types equally.

SCT is a genetic trait in which you have one copy of the gene that causes SCD.

Speak with a doctor about SCT testing and management if someone in your family has the condition. In rare but severe cases, SCT may cause pregnancy complications, muscle breakdown, and even sudden death. In milder cases, you can manage symptoms at home.

It’s possible to live a fulfilling, healthy life with SCT. Knowing how to avoid serious complications can help you live life to the fullest with little to no symptoms.