What Is Sickle Cell Trait?

Overview

People who inherit one sickle cell gene and one normal gene have sickle cell trait (SCT). People with SCT usually do not have any of the symptoms of sickle cell disease (SCD), but they can pass the trait on to their children.

How sickle cell trait is inherited

If both parents have SCT, there is a 50% (or 1 in 2) chance that any child of theirs also will have SCT, if the child inherits the sickle cell gene from one of the parents. Such children will not have symptoms of SCD, but they can pass SCT on to their children.

If both parents have SCT, there is a 25% (or 1 in 4) chance that any child of theirs will have SCD. There is the same 25% (or 1 in 4) chance that the child will not have SCD or SCT.

Get screened for sickle cell trait

Did you know there's more than one way to inherit sickle cell trait? Learn how it is inherited.

Diagnosis

SCT is diagnosed with a simple blood test. People at risk of having SCT can talk with a doctor or health clinic about getting this test.

Complications

Most people with SCT do not have any symptoms of SCD. However, some people with SCT experience complications of SCD, such as pain crises.

In their extreme form, and in rare cases, the following conditions could be harmful for people with SCT:

• Increased pressure in the atmosphere (which can be experienced, for example, while scuba diving)
• Low oxygen levels in the air (which can be experienced, for example, when mountain climbing, exercising extremely hard in military boot camp, or training for an athletic competition)
• Dehydration (when one has too little water in the body)
• High altitudes (which can be experienced, for example, when flying, mountain climbing, or visiting a city at a high altitude)

Additionally, there are a few rare health problems that may affect people with SCT.

Hematuria

Sometimes people with SCT experience blood in the urine, a condition called hematuria. This can be a sign of a serious medical condition, so it requires a thorough medical evaluation. The exact reasons that some people with SCT have blood in their urine are unknown. Some possible reasons are dehydration (not getting enough fluids) or intense exercise. In very rare cases, blood in the urine may be associated with a rare type of cancer that affects the kidney called renal medullary carcinoma.

Splenic infarct

People with SCT are generally healthy and rarely have problems with their spleens. However, some people with SCT experience a serious condition called splenic infarct, the death of tissue in the spleen. The risk for splenic infarct is increased in people with SCT who are at high altitudes, have severe dehydration, or engage in very high intensity physical activity. Thus, steps people with SCT can take to reduce their risk for splenic infarct include drinking plenty of water to stay hydrated, starting out slowing when exercising and gradually building up to the desired amount to give the body time to adjust, and taking frequent rest breaks while exercising, particularly at high altitudes.

Eye problems

People with SCT who experience an eye injury are more likely to develop eye problems including bleeding in the eye followed by a buildup of pressure inside the eye. This can lead to blurry vision or loss of vision. It may even cause permanent eye damage. Therefore, if you have SCT and have suffered an eye injury, it is important that you get checked out right away by an eye specialist who can closely monitor your care.

More research is needed to find out why some people with SCT have complications and others do not.

SCT and athletes

Some people with SCT have been shown to be more likely than those without SCT to experience heat stroke and muscle breakdown when doing intense exercise, such as competitive sports or military training under unfavorable temperatures (very high or low) or conditions (such as high humidity).

Studies have shown that the chance of this problem can be reduced by avoiding dehydration and not getting too hot during training.

People with SCT who participate in competitive or team sports (such as student athletes) should be careful when doing training or conditioning activities. To prevent illness, it is important to

• Set your own pace and build your intensity slowly.
• Rest often in between repetitive sets and drills.
• Drink plenty of water before, during and after training and conditioning activities.
• Keep the body temperature cool when exercising in hot and humid temperatures by misting the body with water or going to an air-conditioned area during breaks or rest periods.
• Immediately seek medical care when feeling ill.