Screening U.S. College Athletes for Their Sickle Cell Disease Carrier Status

Abstract

There are many issues surrounding the screening of collegiate athletes for their sickle cell disease carrier status (or sickle cell trait), a genetic condition. This paper summarizes the establishment of expert advice given to the Secretary's Advisory Committee on Heritable Disorders in Newborns and Children (SACHDNC) on the issue. The SACHDNC has developed a report to advise the Secretary of the USDHHS about the 2010 rule of the National Collegiate Athletic Association (NCAA) requiring testing for sickle cell trait in all incoming Division I student athletes. The SACHDNC does not support the NCAA's rule to screen collegiate athletes for sickle cell trait.

Introduction

The number of people with sickle cell trait (SCT) in the U.S. is not accurately known; however, extrapolating U.S. newborn screening data (genes-r-us.uthscsa.edu/resources/newborn/00/ch13_complete.pdf) to the U.S. population (2010.census.gov/2010census/data/) would yield approximately 4 million people, and worldwide, the estimate is more than 300 million people with SCT (also known as hemoglobin [Hb] AS).¹ Sickle cell trait occurs in high frequency among people of African or Middle Eastern descent, but it is also common among those of Indian, or Mediterranean origin.² People with SCT are generally healthy carriers of the gene that causes sickle cell disease (SCD). Sickle cell disease is a serious health condition that requires medical treatment. Unlike people with SCD, those with the trait do not require regular medical treatment, and for the overwhelming majority, SCT does not affect their health. People with SCT can pass the sickle cell gene to their children and, depending on what genes their reproductive partners carry, they can have children with SCD. For this reason, it is advisable for people to know whether they have SCT.

This paper represents the work of a committee of experts set up by the Secretary's Advisory Committee on Heritable Disorders in Newborns and Children (SACHDNC) to develop a briefing paper to assist the SACHDNC on developing its recommendations (http://www.hrsa.gov/advisorycommittees/mchbadvisory/heritabledisorders/recommendations/correspondence/sicklecell061410.pdf) for the Secretary of the USDHHS regarding the rule made by the National Collegiate Athletic Association (NCAA) in 2010 requiring all incoming Division I student athletes to be tested for SCT. The SACHDNC advised the Secretary that there was an insufficient scientific and public health basis for the mass screening of athletes for SCT.

An important aspect of the public health approach to screening is the recognition that screening for SCD, SCT, and related hemoglobinopathies, like all genetic testing, should include health education to explain the benefits and risks of testing, and genetic counseling to explain the results and their implications. For nearly 3 decades, screening for SCD and related hemoglobinopathies has been part of state public health newborn screening programs in the U.S. to identify affected children early and to provide preventive medical treatment and health education to their parents in order to prevent early death from infection. Screening of other members of the general public for sickle cell carrier status and other hemoglobin disorders is not mandatory, but voluntary, and is done usually for genetic counseling purposes.

Sickle cell trait is defined by the inheritance of a normal β-globin gene (β^A) from one parent and sickle β-globin gene (β^S) from the other parent. In SCT, every red blood cell contains both the normal hemoglobin A (Hb A) and the sickle hemoglobin S (Hb S), with Hb A always predominant in quantity. The predominance of Hb A in SCT explains the normal behavior of SCT red cells under most physiologic conditions. Sickle cell trait is different from SCD because in SCD, unlike SCT, both β-globin genes, one from each parent, are abnormal; either both are β^S, or one is β^S and the other is a gene for another β-globin variant, or a gene for β-thalassemia. In SCD, Hb S is the predominant hemoglobin (beyond the neonatal period) and that accounts for the pathology associated with the disease. SCD is a serious lifelong disorder that is characterized by chronic hemolytic anemia, acute and chronic vasoocclusive complications, and organ damage.