Next Generation "Omics" Approaches in the "Fight" against Blood Doping.

Despite being prohibited by the World Anti-Doping Agency (WADA), blood manipulations such as the use of recombinant human erythropoietin and blood transfusions are a well-known method used by athletes to enhance performance. Direct detection of illicit blood manipulation has been partially successful due to the short detection window of the substances/methods, sample collection timing, and the use of sophisticated masking strategies. In response, WADA introduced the athlete biological passport (ABP) in 2009, which is an individualised longitudinal monitoring approach that tests primarily haematologic biomarkers of doping in order to identify atypical variability in response(s) in athletes, highlighting a potential doping violation. Although the implementation of the ABP has been an encouraging step forward in the quest for clean/drug-free sport, this detection method has some limitations. To reduce the risk of being detected by the ABP method, athletes are now resorting to microdoses of prohibited blood boosting substances to prevent abnormal fluctuations in haematologic biomarkers, thereby reducing the sensitivity of the ABP detection method. Recent studies from numerous laboratories, including our own, have confirmed the potential of transcriptomic microarrays, which can reveal distinct changes in gene expression after blood manipulations, to enhance the ABP. There is, therefore, an urgent need to intensify research efforts that involve transcriptomics and other state-of-the-art molecular methods, collectively known as "omics", e.g., proteomics (proteins) and metabolomics (metabolites), in order to identify new and even more robust molecular signatures of blood manipulation that can be used in combination with the ABP and, intriguingly, even as a stand-alone test.