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Genetic testing conundrums: sickle cell trait

In my Genomic and Precision Medicine course on Coursera, we were asked:

In the US, the National Collegiate Athletic Association (NCAA) requires screening of all college student athletes for mutations in the gene that causes sickle cell anemia, an autosomal recessive disease that manifests early in life. Name one pro and one con of this policy.

Here’s my answer. It will not win any prizes for eloquence, but it got the job done of summarizing the issues in a few sentences or less. (I cheated and included more than one con):

Pro: Individuals who are carriers for sickle cell anemia (that is, they carry only one copy of the mutated sickle cell gene) do not have sickle cell anemia. However, they are at greater risk of hypoxia (inadequate oxygen supply to a region of the body) and rhabdomyolysis (sudden death of muscle tissue) during intense exercise than non-carriers. These conditions can be life-threatening. By knowing who carries the gene, coaches can alter training programs to reduce risks — for example, by making sure that carriers get rest breaks and don’t get dehydrated.

Con: The sickle cell trait is far more common in African-Americans and Africans than in other groups. In the past, the higher prevalence of sickle cell trait in blacks was used as an excuse to refuse healthy blacks entry into competitive sports and the military. Coaches may offer less rigorous training and playing opportunities to NCAA athletes who are identified as carrying the sickle cell trait, even when these athletes are perfectly healthy. (Although carriers in general are at higher risk for exercise-related complications, risk varies by individual, with some individuals being very affected, and others seeming not to be affected at all.) Professional sports teams may avoid recruiting players with sickle cell trait for fear that they will not perform as well as their non-carrier counterparts. In addition, focusing on sickle cell may distract trainers from preventing other, more common causes of sudden death in athletes, such as undetected heart problems.

Sources:

  • Lecture notes from Nussbaum RL and Norton M. Genomic and Precision Medicine, Week 2: Applying Genomics to Medicine. 2015. Coursera.org.
  • Lecture notes from Noor M. Introduction to Genetics and Evolution. 2015. Coursera.org.
  • Stein R. Colleges mandate sickle cell testing. The Washington Post. 20 Sept. 2010.

I wanted to add that making sure that all athletes get reasonably frequent rest breaks and are taught to avoid dehydration would dramatically reduce rhabdomyolosis risk, plus many other health risks, without requiring testing. But that’s not the question that was asked, so I didn’t. In a world where colleges are okay with putting students at regular risk of concussion and other serious injuries, expecting them to suddenly embrace good preventive health practices might be overly optimisitic.

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