Basic Facts About Sickle Cell Trait (SCT)

Nevada Newborn Screening Program

All newborns should be screened for Sickle Cell Disease (SCD), even if they look healthy. If left undetected and untreated, SCD can lead to severe health problems and even death, early in childhood.

What is Sickle Cell Trait?

Sickle Cell Trait (SCT) is not a disease, but having it means that a person has inherited the sickle cell gene from one of his or her parents. People with SCT usually do not have any of the symptoms of sickle cell disease (SCD) and live a normal life.

What is Sickle Cell Disease?

Sickle Cell Disease (SCD) is a genetic condition that is present at birth. In SCD, the red blood cells become hard and sticky and look like a C-shaped farm tool called a "sickle." The sickle cells die early, which causes a constant shortage of red blood cells. Also, when they travel through small blood vessels, they get stuck and clog the blood flow. This can cause pain and other serious problems. It is inherited when a child receives two sickle cell genes-one from each parent. A person with SCD can pass the disease or SCT on to his or her children.

Who is Affected by Sickle Cell Trait?

SCT is more common among people whose ancestors come from Africa, the Mediterranean region, Middle East, and South Asia, but anyone can have SCT.

  • 1 in 12 blacks or African Americans in the United States has SCT.
  • Approximately 3 million people living in the United States have SCT and many are unaware of their status. (National Center on Birth Defects and Developmental Disorders)
How Does Someone Get Sickle Cell Trait?

People who have inherited one sickle cell gene and one normal gene have SCT. This means the person won’t have the disease, but will be a trait “carrier” and can pass it on to his or her children.

The most important thing to know about having SCT is that you could have a baby with SCD if your partner also has an abnormal hemoglobin gene.

If both parents have SCT, each child that they have together has a:

  • 1 in 2 (50%) chance of having SCT. Children with SCT will not have symptoms of SCD, but they can pass SCT on to their children
  • 1 in 4 (25%) chance of having sickle cell anemia, one of several types of SCD. Sickle cell anemia is a serious medical condition
  • 1 in 4 (25%) chance that they will not have SCD or SCT.

If one parent has SCT and the other parent has another abnormal hemoglobin gene (like hemoglobin C trait or beta- thalassemia trait), each of their children has a:

  • 1 in 2 (50%) chance of having SCT
  • 1 in 4 (25%) chance of having SCD (not sickle cell anemia). These other types of SCD can be more or less severe depending on the specific abnormal hemoglobin gene
  • 1 in 4 (25%) chance that they will not have SCD or SCT. If only one parent has SCT, each of their children has a
  • 1 in 2 (50%) chance of having SCT 1 in 2 (50%) chance that they will not have SCT.
What Health Problems Might Occur in People With Sickle Cell Trait?

Most people with SCT do not have any health problems caused by sickle cell trait. However, there are a few, rare health problems that may potentially be related to SCT. For example, if people with SCT have pain when traveling to or exercising at high altitudes, they should tell their healthcare provider. People with SCT and eye trauma should seek out medical attention and inform the physician about the trait status. People with SCT should drink plenty of water during exercise. People with SCT should contact and inform their doctor if they notice blood in their urine. To find out more about SCT and to get specific answers to your questions, call your healthcare provider.

What is Sickle Cell Screening?

Screening for sickle cell means testing a person’s blood for abnormal types of hemoglobin:

  • Hemoglobin is a substance inside the red blood cell that delivers oxygen to all organs in the body.
  • There are many types of altered hemoglobin,̧ but people with SCD or SCT make a form of hemoglobin which is abnormal and it is called hemoglobin S or sickle hemoglobin.
  • A blood test for hemoglobin S or sickle hemoglobin can tell you if your hemoglobin is normal, you have SCD or SCT (carrier status) or if you have another type of abnormal hemoglobin. A simple blood test can be done to find out if someone has SCT.

If the results of the test reveal that someone has SCT, it is important that he or she know what SCT is, how it can affect him or her, and if and how SCD runs in his or her family.

When Should Sickle Cell Screening Occur?
At Birth
  • Newborn babies should be screened for sickle cell status (SCD or SCT) as early as 24-48 hours after birth.
  • In the U.S. (all 50 states and the District of Columbia), babies are screened for sickle cell status as part of the newborn screening program.
  • A positive newborn screening test means your baby likely has a condition reported but you need more testing by your baby’s doctor to know for sure.
In Adulthood

Screening for sickle cell status may be done as part of the care you and your partner receive before or during pregnancy, or after your baby is born.

Both SCT and SCD are conditions that are genetically inherited or passed down from your parents.

SCD is different from SCT; one cannot turn into the other. SCD causes many disabling symptoms like anemia (causes a person to feel tired, weak or short of breath), severe pain, or even stroke. SCT does not make you sick. In fact, screening tests might show that you have SCT and yet you usually never have physical symptoms.

The best way to find out if and how SCD runs in a person’s family is for the person to see a genetic counselor. These professionals have experience with genetic blood disorders. The genetic counselor will look at the person’s family history and discuss with him or her what is known about SCD in the person’s family. It is best for a person with SCD to learn all he or she can about this disease before deciding to have children.

Visit the following websites for more information:


  • Centers for Disease Control
  • National Center on Birth Defects and Developmental
  • Disorder