Scots claim to have solved the mystery of thalidomide

Published on Monday 11 May 2009 22:11

THALIDOMIDE, the drug which blighted a generation in the 1960s, was yesterday at the centre of fresh controversy as Scots researchers claimed to have finally solved the cause of its devastating effects on unborn babies.

The drug was marketed as a cure for morning sickness in pregnant women in the late 1950s and early 1960s, but was withdrawn after it emerged that thousands of babies across the globe had been born with missing or shortened limbs and other serious defects.

Previous research has claimed the drug acted as a neurotoxin, destroying the nerves in the developing foetus.

But new research by an Aberdeen University-led team claims to have finally solved the medical mystery which has baffled scientists for almost 50 years – how exactly the drug caused the limb defects in the developing foetus.

Their findings reveal that a component of the drug prevented the growth of new blood vessels in the developing embryo. And their discovery also explains, for the first time, why the drug only caused birth defects during a short timeframe in the developing baby in the womb.

Dr Neil Vargesson, a lecturer in developmental biology who led the research, said: "We have put to rest a 50-year puzzle, in finally deducing how thalidomide triggers limb defects and why it appears to target limbs preferentially.

"This is an important discovery. Many models have been suggested as to how these defects were caused but now we know how it worked.

"This is the first paper to conclusively show that it is the anti-angiogenic property of the drug – that element that inhibits new blood vessel formation – that is to blame for the defects. The drug prevented early blood vessels going into the limb."

He also claimed the team's discovery now opened up the possibility of a safer version of the drug being used to treat a range of conditions from early-stage cancer to leprosy.

The team's claims, however, were challenged by Martin Johnson, the director of the Thalidomide Trust. He said: "These findings are a puzzle to me. A number of people believe this mystery was solved ten years ago when the theory these people are following was comprehensively demolished.

"The theory that is now accepted, and has been for several years, is that the best explanation for thalidomide damage is that the developing nervous system within the embryo was poisoned at the stage the critical nerve endings start to emerge. The fact that this is a nerve poison explains all the known effects – not just limb damage but heart disease and massive central nervous system damage. There was not an organ in the body that could not be trashed by thalidomide."

Ray Stokes, a professor of business history at Glasgow University who is researching the history of thalidomide, said: "I cannot comment on these latest findings, but clearly there does seem to be consensus that it has to do with damage to the neural crest at a particularly important time in the gestation of the child that was the problem.

"The damage that was done to babies was only part of the damage that was done by the drug."