Medical Evaluation of Athletes: Genetic Testing

Abstract

Sports Cardiology practice commonly involves evaluation of athletes for genetically determined cardiac conditions that predispose to exercise-induced malignant arrhythmias and sudden cardiac death (SCD). Differentiation of “athlete’s heart” from heart disease may be challenging due to the effects of exercise on the electrical and structural cardiac remodeling; prolongation of the QT interval, left ventricular hypertrophy and cavity dilatation create significant overlap between physiology and inherited channelopathies and cardiomyopathies also known as the “grey zone”. Genetic studies over the last 30 years have identified gene abnormalities that underpin these conditions. In addition, technological advances have made genetic testing a more readily available and cheaper tool, raising questions relating to its exact role in the investigation of athletes. Before considering genetic testing, the athlete should have appropriate genetic counselling relating to the potential implications of the result on the athlete and their family, as well as the challenges and limitations of the testing. Genetic testing in an athlete can have diagnostic, prognostic and therapeutic implications, including guiding exercise recommendations. The yield of genetic testing varies depending on the condition under assessment and importantly, is significantly lower for athletes with borderline phenotypes (“grey zone”). Genetic testing results are not binary but there is a probabilistic spectrum of pathogenicity. To avoid confusion, accurate assessment of the information is required by individuals with expertise in cardio-genetics, using established scoring criteria.