As the Winter Olympics open today in Sochi, the race is on between athletes who try to get an artificial advantage from banned substances and the anti-doping experts trying to catch them. A new substance may be in the mix: On 2 February, television reporters for the German WDR network broadcast their undercover investigation (link in German) of a Russian scientist willing to sell them 100 milligrams of something called “full-size MGF” for $100,000. The reporters brought a sample to anti-doping expert Mario Thevis, a forensic chemist at the Center for Preventive Doping Research at the German Sport University Cologne. He confirmed the sample contained mechano growth factor (MGF), a variant of the human insulin-like growth factor-1 (IGF-1) protein, which can prompt muscle growth. It would be undetectable by current testing methods.Q.: What is the substance you found in the journalists’ sample?M.T.: The closest way to describe it is human IGF-1 isoform 4. It’s a splice variant of the IGF-1 gene. The reason it’s called MGF—mechano growth factor—is that the mRNA [messenger RNA] of isoform 4 is elevated when mechanical stress is applied to muscle tissue.Many gray market manufacturers offer something called MGF, but that usually refers to just a short peptide [at the end of the full protein]. That was claimed to be biologically active 15 years ago, but more recent studies have shown it has no biological effect. The full-size MGF is a molecule that according to the literature is biologically highly active, similar to IGF-1, but with different molecular weight and different size.
