General Condition Information
Other Names
- Hemoglobin S trait
- Hemoglobin S trait (carrier)
- Sickle Cell Carrier
Condition Type
Birth Prevalence
1 in 13 African American babies are born with sickle cell trait in the United States.
Screening Finding
What is sickle cell trait
Sickle cell trait is an inherited (genetic) condition that affects some of the hemoglobin in blood. Hemoglobin is a part of your red blood cells, which carry oxygen in your body. In sickle trait, some of the body’s normal hemoglobin is replaced with hemoglobin S, which is also called sickle hemoglobin.
Normal blood cells are round and shaped like doughnuts. Babies with sickle cell trait typically have enough normal hemoglobin to have normal shaped red blood cells, so they do not usually have any signs and symptoms.
However, when individuals with sickle cell trait experience certain extreme conditions (very high altitude, severe dehydration, or very extreme exercise), the sickle hemoglobin inside their cells may turn their blood cells sickle or crescent moon-shaped. When red blood cells become sickle shaped, they have a harder time bringing oxygen to the body, they break down more quickly, and can get stuck in the blood vessels.
Newborn Screening and Follow-Up
Sickle cell trait is found in the same newborn screening test done testing for S,S disease. This screening requires collecting a small amount of blood from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
Screening measures certain types of hemoglobins in your baby’s blood. Babies with different types of hemoglobins (specifically hemoglobin S) might have sickle cell trait.
If your baby’s blood spot screening result shows that your baby might have sickle cell trait, your baby’s health care provider should let you know before or at your baby’s first well child visit. Together, you will discuss the results.
An out-of-range screening result suggesting sickle cell trait usually means that your baby does have sickle cell trait, but your baby will need more follow-up testing to know for sure. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after a sickle cell trait screening result:
- Blood tests
- Genetic testing using a blood sample
False-positive newborn screening results for this condition are rare. However, screening samples that are collected after a baby receives red blood cells from someone else (a red cell transfusion) will be inaccurate.
Condition Details
Newborn screening helps babies lead healthier lives. If your baby has a sickle cell trait screening result, follow up with your baby’s health care provider.
Most individuals with sickle cell trait will never have any signs and symptoms of the condition. Rarely, signs of sickle cell trait may appear when a baby or individual is under certain conditions. Conditions that can lead to signs and symptoms of sickle cell trait are:
- Low oxygen levels (like after extreme exercise or training)
- Dehydration (too little water in the body)
- High altitudes (flying or visiting a city located high above sea level)
Signs of the condition may include the following:
- Pain or painful swelling in hands or feet
- Difficulty breathing
Sickle cell trait is caused by a change in the HBB gene. This gene gives the body instructions for making beta-globin, a protein found in hemoglobin.
The change in HBB creates an abnormal beta-globin called hemoglobin S (HbS). Under extreme conditions, the abnormal beta-globins may cause red blood cells to be sickle-shaped instead of round.
Sickle cell trait is a genetic condition. Babies inherit it from their biological (birth) parents. To learn more about genetic conditions, visit MedlinePlus Genetics.
- Babies inherit sickle cell trait when one parent passes down a nonworking HBB gene to their baby.
- People with one normal copy and one hemoglobin S copy of the HBB gene are said to have sickle cell trait (sometimes also called being a carrier).
- People with sickle cell trait may pass down a hemoglobin S copy of the gene to their children.
- If two parents both have sickle cell trait, each have a hemoglobin S copy of the HBB gene. They have a 1 in 2 chance of having a child with sickle cell trait and they have a 1 in 4 chance of having a child with S,S disease.
- People with sickle cell trait often do not know they are carriers of a hemoglobin S copy of the HBB gene before having a child with sickle cell trait or S,S disease.
- Parents who already have a child with sickle cell trait still have a 1 in 2 chance of having another child with sickle cell trait. This 1 in 2 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
Most individuals with sickle cell trait will never need treatment. Treatment is only usually needed if an individual starts to have signs or symptoms.
Community-based organizations (CBOs) are local agencies that provide services, education, and support to families affected by sickle cell conditions like sickle cell trait. To find a CBO near you, please visit the Sickle Cell Disease Association of America’s list of member organizations.