Comparative Transcriptional Studies of hGH and Erythropoietin

Code: R11C01TF

We will analyze the effects of HGH and erythropoietin to search for genetic signatures of exposure to those doping agents. We have obtained results from several individual WADA-supported laboratories and will carry out extensive comparisons to identify genes whose expression is indicative of exposure to HGH or erythropoietin.

Main findings

These two related studies were designed to test the concept that exposure of humans to doping agents disturbs the normal expression of many of the 20,000 genes in human cells and whether those changes can be used as a rigorous proof or a “signature” of exposure to specific doping agents. These kinds of studies are made possible by modern genetic techniques that allow an estimate of the extent of expression of all human genes on a single square inch silicon chip. Our studies also were designed to determine if several studies carried out under different conditions in different laboratories could easily be analyzed even though they used slightly different techniques and methods of analysis. This method of analysis of multiple and slightly different sets of data from different studies is called “meta-analysis” and examples of meta-analysis have been successful in many other kinds of research. We therefore carried out meta-analysis of three independent studies of the effects on gene expression in blood samples from athletes of administration of human growth hormone (HGH) and three separate studies of the effects of erythropoietin (Epo) or hypoxia in the blood cells of human athletes and in mice.

As expected, we found that the genes that are expressed incorrectly after exposure to HGH and Epo are different from each other. However, we also discovered that the separate studies identified only a small number of genes that were disturbed in the same way in all three studies, leading to a conclusion that those genes are probably not specific “signatures” for exposure to HGH or Epo. We have concluded that these results could mean that these drugs do not cause significant changes in gene expression in blood cells. We prefer an explanation that the three separate HGH studies and the diverse Epo/hypoxia differed in many details that introduced too many slight differences in the timing of testing, dosages, methods of tissue preparation and methods of analysis that probably have hidden the gene expressions shared by the different studies. We are impressed that in other very recent studies supported by WADA in which one laboratory has carried out very careful studies of humans exposed to Epo, reproducible changes have been found that consistent with a genetic “signature” for exposure to Epo, demonstrating that extensive and well controlled single studies under some conditions can be an effective approach to identifying the genetic changes in blood samples or other tissues. We propose that a reasonable next step is to carry out a similar study with HGH exposure and compare results from such a study with those obtained in our meta-analysis. We are confident the overall concept of genetic signatures of doping is a correct and robust one and will add important new tools to the prevention and detection of doping.