Sickle cell trait is a blood disorder that affects the red blood cells. It is not the same as sickle cell disease — in fact, it is not a disease at all.

It is a "trait," which means it is inherited. In the case of sickle cell trait (SCT), a person has inherited one abnormal hemoglobin gene from one parent and one normal gene from the other. Hemoglobin is a protein in red blood cells that carries oxygen around the body.

In this article, learn how SCT is diagnosed and what it means for the people who have it.

Sickle cell anemia Image credit: Dr Graham Beards, (2012, February 18)Share on Pinterest
Sickle cell trait affects the blood cells, causing blood cells to be 'sickle' shaped.
Image credit: Dr Graham Beards, (2012, February 18)

Sickle cell trait (SCT) is an inherited blood disorder that affects the red blood cells. It affects between 1 and 3 million Americans and 8 to 10 percent of African Americans.

People with SCT have inherited one gene for normal hemoglobin and one for sickle hemoglobin.

Inheriting only one abnormal gene is what makes SCT different from sickle cell disease (SCD).

SCD occurs when a person inherits two sickle cell genes, one from each parent.

SCD makes the red blood cells hard, sticky, and shaped like a sickle.

The sickle cells die quickly, so people with SCD always have a shortage of red blood cells. They can also clog up smaller blood vessels and cause other serious problems.

Most people who have SCT have no medical problems as a result of the condition. It does not usually have any symptoms and cannot develop into SCD.

In very rare cases, people with SCT can have some symptoms.

  • blood in their urine
  • pain or discomfort at high altitudes
  • problems exercising in hot, humid weather

SCT does not usually cause health problems. However, it is important to be tested, as a person with SCT can pass on their abnormal gene to their child.

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Parents with SCT increase the risk of their children having SCT.

Two parents who have SCT can have a child who has SCD.

That is why it is important for people with SCT to understand how it is passed on and the likelihood of their children or grandchildren developing SCD.

If both parents have SCT, there is a 50 percent chance their child will have SCT, a 25 percent chance their child will have SCD, and a 25 percent chance they will have neither SCT or SCD.

If only one parent has SCT, there is a 50 percent chance their child will have SCT and a 50 percent chance they will not.

It is important for people with SCT to understand the condition and its implications before they have a baby and talk about newborn testing with their doctor.

SCT is diagnosed with a simple blood test that is available at most hospitals or medical centers.

This blood test is usually done as a routine with newborns, but older children and adults can also be tested.

A blood sample will be taken from the end of the finger or a vein in the arm and then sent to a laboratory.

SCT does not usually require treatment, as most people do not experience any symptoms.

However, SCT may require intervention if the person wants to be an athlete, join the military, or have children.

SCT and extreme exercise

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Those with SCT should make sure to rest between intense workouts, and stay hydrated.

People with SCT are more likely to have muscle breakdown or heat stroke when doing intense physical exercise, such as in competitive sports or military training.

Therefore, people with SCT should avoid getting overheated and dehydrated during physical activity and should take necessary preventative measures. These include:

  • building workout intensity slowly
  • resting between sets and drills
  • drinking plenty of water before, during, and after activity
  • keeping the body cool by misting it with water or going to an air-conditioned area during breaks
  • seeking medical care immediately if feeling ill

Considerations for pregnancy

People with SCT may pass on SCT or SCD to their children, so seeing a genetic counselor is recommended before having children.

Genetic counselors are experts in genetic disorders and will look at an individual's family history and discuss any relevant risks and considerations.

Most people with SCT do not have any health problems, although situations can cause symptoms to occur. These include:

  • dehydration
  • low oxygen from strenuous exercise
  • low oxygen while flying, mountain-climbing, or visiting places at high altitude
  • increased pressure in the atmosphere, such as when scuba diving

A person with SCT may experience discomfort or pain in these situations due to lack of oxygen.