Tour de France Champions born or made: where do we take the genetics of performance?

Abstract

(200 words)Cyclists in the Tour de France are endurance specialists. Twin and family studies haveshown that approximately 50% of the variance in a number of performance related phenotypes (whether measured at baseline, i.e. natural talent, or in response to training) including those important to cycling can be explained by genetic variation. Research into the specific genetic variants that are responsible has identified over 200 genes containing common genetic variants involved in the genetic predisposition to physical performance.However, typically these explain only a small portion of the variance, perhaps 1-2% and collectively they rarely explain anything approaching the 50% of the variance identified in the twin and family studies. Thus, there is a gap in our understanding of the relationship between heritability and performance. This gap may be bridged by investigation of rare variants or epigenetic variation or by altering study designs through increased collaborations to pool exiting cohorts together. Initial findings from such efforts show promising results. This mini-review will touch on the genetics and epigenetics of sporting performance, how they relate to cyclists in the Tour de France and where best future efforts may be directed as well as discuss some preliminary research findings.

Can Genetic Testing Identify Talent for Sport?

“…A further avenue for exploration is that of rare gene variants that may predispose to elite performance. Generally, research focuses on common variants present in >1% of the population (i.e., polymorphisms) [2]. However, there are a few identified genetic variants which are very rare, and yet have the potential to positively affect performance.…”

“…One such variant occurs at rs121917830 within the erythropoietin receptor (EPOR) gene. This variation is linked to a disease called erythrocystosis-1, where affected people have increased red blood cell production, and hence greater oxygen carrying capacity [2]. This outcome is potentially advantageous for endurance sports, and in fact one elite athlete, the Finnish cross-country skiing champion Eero Mantyranta, is known to possess this variant [40].…”

“…The finding of significantly lower frequencies of the X allele and XX genotypes in elite speed-power athletes has been replicated [8,9], although equivocal findings have also been reported elsewhere [10]. Consequently, despite generally being estimated to explain around 1-3% of the variance in speed-power phenotype [2,11,12], ACTN3 has subsequently been labelled a "gene for speed" [13][14][15]. ACTN3, however, is not the only gene associated with elite athlete status, with a recent review reporting that at least 155 genetic markers are potentially linked to elite athlete status, at least in some cohorts or ethnicities [16].…”

“…It is widely recognised that some individuals are naturally talented in specific physical traits that are, in turn, related to sports performance [1]. In some cases, talented individuals come from talented families, suggesting that genetics is partially responsible for the physical, physiological or anthropometric characteristics that are needed for attaining athletic success [2]. Indeed, elite athlete status is partially heritable, with twin studies suggesting that 30-80% of the variance in this trait is explained by heritable factors [3].…”

Annual banned‐substance review: Analytical approaches in human sports drug testing

“…Genetic predisposition is an important determinant of athletic performance. Both genetic variants and epigenetic modifications are known to be heritable, with the latter being malleable by lifestyle, training and dietary regimens . Modifying genetic material by gene transfer for therapeutic purposes has been pursued in clinical settings for a variety of conditions, and although selected approaches yielded a promising outcome, a current misuse by athletes as gene‐based physical enhancement strategy has been considered less likely than initially suspected .…”