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New Study Findings: Sickle Cell Disease – do you know your status?

African-American FamilyMost people know very little about sickle cell disease, the difference between sickle cell disease (SCD) and sickle cell trait (SCT), and how SCD and SCT are inherited (passed down from parent to child).   Thankfully, newborn screening programs in the United States are very successful at identifying babies with sickle cell disease and getting those babies the care and treatment that they need.  However, when adults are not sure if they themselves, have SCD or SCT, this can lead to extra testing and treatment.  Not knowing their or their partner’s sickle cell status, or believing that it is different from the true status, makes it difficult to inform adults of their risk of having a child with sickle cell disease.  Knowledge of personal sickle cell status, community awareness of how sickle cell disease is inherited, and the health and reproductive impact of both of these remain inadequate and a barrier to better treatment and care. 

 

About this Study

To figure out whether adults correctly report whether they have sickle cell disease or sickle cell trait, researchers selected a subset of the Southern Community Cohort Study participants, an ongoing study of nearly 86,000 older adults, between the ages of 40 and 79, living in 12 states in the southeastern United States.  They compared the study participant’s self-reported sickle cell status to the results from laboratory confirmed blood tests.   Of the 126 adults included in this study, 51 (40%) reported that they had SCD while 75 (60%) reported they did not have SCD.  Of the 51 reporting SCD, 3 (6%) actually had SCD confirmed with laboratory results, 32 (63%) had SCT, 3 (6%) had hemoglobin C trait (but not sickle cell trait), and 13 (25%) had neither SCD nor trait. 

This article, published in the journal Public Health Genomics,  is the first population-based study to directly compare people’s understanding of their own disease status (also called, “self-reported disease status”) with laboratory results (genetic testing) and we invite you to read the abstract here.

 

Do You Know?

Why is it called Sickle Cell Disease (SCD)?

Red blood cells contain a protein called hemoglobin (HEE-muh-glow-bin), which carries oxygen from the lungs to the rest of the body.  Red blood cells are usually shaped like a donut with the hole filled in.  For people with SCD, their red blood cells contain only abnormal hemoglobin called sickle hemoglobin.  Sickle hemoglobin can cause the red blood cells to change shape from a donut to a C-shape.  A sickle is a farm tool that is shaped like a “C” so the disease is named for that C-shape. 

drawing of sickle cell

What is Sickle Cell Disease?

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, stick to one another and can’t squeeze through.    

What are some of the problems of Sickle Cell Disease?

Because the C-shaped red blood cells stick to each other, they don’t work as well as they should and they can form 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.”

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 hemoglobins.  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 SCD in the family, please visit To learn more about SCT and how it can lead to SCD in the family, please visit the sickle cell trait section of our website.

What is Hemoglobin C Trait?

Hemoglobin C is another inherited condition that can cause problems with the shape and function of red blood cells.  People with hemoglobin C trait don’t have any problems with their red blood cells. However, people with Hemoglobin C trait could have children with a condition called sickle-hemoglobin C disease, which is a generally less severe form of SCD.

Main Findings from this Study

  • Often, older adults incorrectly reported whether they had sickle cell disease or sickle cell trait.  This was true for men and women and was regardless of their level of education.  
  • Most adults reporting that they had sickle cell disease were actually persons with sickle cell trait, based on their laboratory results.
  • One in four adults claiming to have sickle cell disease did not have sickle cell disease or sickle cell trait.

 

Critical Gaps & Future Directions

In the United States, about 100,000 people live with sickle cell disease and there are about 3 million persons with sickle cell trait.  The health problems that occur with sickle cell disease have a major impact on people and families with the disease making it a significant public health concern.   Knowledge of personal sickle cell status, community awareness of how sickle cell disease is inherited, and the health and reproductive impact of both of these remain inadequate.  The results of this pilot study highlight the need for more education among adults about sickle cell disease, sickle cell trait, and hemoglobin C trait in the public health and primary care settings.

 

More Information

 

To learn more about CDC’s activities related to sickle cell disease and sickle cell trait, check out our Annual Report.

To learn more about sickle cell disease and sickle cell trait, please visit our sickle cell disease homepage.

To obtain free resources on sickle cell disease and sickle cell trait, please visit the free materials section of our website.

To learn more information about the Southern Community Cohort Study, please visit their website.

 

Paper Reference

Bean CJ, Hooper WC, Ellingsen D, DeBaun MR, Sonderman J, Blot WJ. Discordance between self-report and genetic confirmation of sickle cell disease status in African-American adults. Public Health Genomics. 2014 epub ahead of print: March 28, 2014.

 
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