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New Study Findings: Incidence of Sickle Cell Trait in the US

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Although the occurrence of sickle cell trait (SCT) varies greatly from state-to-state and among different races and ethnicities, every state and racial/ethnic population includes people living with the condition and many are unaware of their personal sickle cell status. Because people with SCT are at risk of having a child with sickle cell disease if their partner also has SCT or one of several other abnormal hemoglobin genes, it is important to properly inform them of their status and educate them about possible health problems and reproductive considerations.

About this Study

To obtain up-to-date measures of the occurrence of SCT among newborns by race/ethnicity and state of birth, researchers from CDC examined data collected by newborn screening programs in 2010. On December 12, 2014, CDC published the results of this research study in the Morbidity and Mortality Weekly Report (MMWR). Key findings from this report are highlighted below and we invite you to read the abstract here.

Main Findings from this Study

  • In 2010, the total U.S. incidence estimate for sickle cell trait was 15.5 cases per 1,000 births, ranging from 0.8 cases per 1,000 births in Montana to 34.1 cases per 1,000 births in Mississippi.
  • The U.S. incidence estimate for sickle cell trait (based on information provided by 13 states) was 73.1 cases per 1,000 black newborns, 3.0 cases per 1,000 white newborns, and 2.2 cases per 1,000 Asian or Pacific Islander newborns. The incidence estimate for Hispanic ethnicity (within 13 states) was 6.9 cases per 1,000 Hispanic newborns.
  • The total number of babies born with sickle cell trait in 2010 was estimated to be greater than 60,000.
  • The incidence of sickle cell trait varies greatly from state-to-state and among different races and ethnicities; however every state and racial/ethnic population has people living with the condition.

What is Sickle Cell Trait (SCT)?

When a person has inherited the sickle hemoglobin gene from one parent and the gene for normal hemoglobin from their other parent, they have sickle cell trait (SCT). Their red blood cells make both normal and sickle hemoglobin. Hemoglobin (HEE-muh-glow-bin) is a protein in red blood cells which carries oxygen from the lungs to the rest of the body. People with SCT don’t have sickle cell disease, and in most situations, they have no problems with how their red blood cells work. However, people with SCT can have children with sickle cell disease. To learn more about SCT and how it can lead to sickle cell disease (SCD) in the family, please visit the sickle cell trait section of our website.

What is Sickle Cell Disease (SCD)

People are born with SCD. It is an inherited life-long disease that can run in families. People with SCD inherited the gene (the instructions in the cell for making sickle hemoglobin) from both of their parents; their red blood cells can make only sickle hemoglobin so they have SCD. SCD causes the red blood cells to change their shape from the usual donut shape to a C-shape. When the red blood cells are shaped like a donut, they can bounce off the walls of blood vessels like bumper cars, and they can squeeze through tiny blood vessels. However, when red blood cells are C-shaped, they get caught on the walls of tiny blood vessels, and stick to one another forming clumps inside the blood vessels. These clumps can cause severe pain and other serious problems, such as infections, organ damage, and blood vessels clogged with sickle cells in the lungs, called “acute chest syndrome.”

Critical Gaps & Future Directions

This study shows that as many as 1.5% of babies born in the United States have SCT. Based on previous studies, there are no standardized methods or protocols for alerting families or healthcare providers to this information, educating them about the potential health outcomes that might be associated with the condition, or counseling them about the impact that this might have on the family’s future reproductive choices. By including educational materials and providing genetic counseling at the same time that families are given positive SCT results, the occurrence and public health burden of SCD might be reduced.

More Information

Paper Reference

Centers for Disease Control and Prevention (CDC).Incidence of Sickle Cell Trait – United States, 2010, 2014. MMWR Morb Mortal Wkly Rep. 2014;December 12, 2014 / 63(49);1155-1158.

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