The futureNatasha Woods

GENE DOPING is defined by the World Anti-Doping Agency as "the non-therapeutic use of cells, genes, genetic elements, or of the modulation of gene expression, having the capacity to improve athletic performance".

An example of gene doping would involve the non-therapeutic use of gene therapies used to treat muscle-wasting disorders and which will soon be entering human clinical trials.

The chemicals are indistinguishable from their natural counterparts and are only generated locally in the affected tissue. Nothing unusual enters the bloodstream, so officials will have nothing to detect in a blood or urine test.

The first product to be associated with genetic doping emerged in the build-up to the Torino 2006 Olympic Winter Games, where Repoxygen was discussed as a possible substance in use at the Games.

A German court hearing evidence in the trial of a running coach accused of giving performance-enhancing drugs to young athletes was told that a search of his email inbox turned up references to a product called Repoxygen.

The substance, developed by UK firm Oxford Biomedica, delivers the gene for erythropoietin (EPO) to muscle cells. In one email, according to German news service Deutsche Welle, the coach Thomas Springstein wrote that "new Repoxygen is hard to get" and "please give me new instructions soon so that I can order the product before Christmas".