Health: Gene link claimed with intelligence

A UK-based researcher reckons he has found a gene that helps determine intelligence. Is it a vital contribution to the 'nature v nurture' debate, or a muddying of already confused waters? Charles Arthur, Science Editor, reports.

The discovery of a gene which appears to contribute to general intelligence is a finding which Professor Robert Plomin says marks a breakthrough in scientific endeavour.

But Professor Plomin, an American based at the Institute of Psychiatry in London, faces opposition from both scientific and other groups who say that his work is unethical and should not be continued. They say that the availability of genetic testing will lead inevitably to prenatal evaluation of people's intelligence - and in some cases to their being needlessly labelled subnormal.

Yet the results themselves are controversial. They have not yet been published in any scientific journal, though it is understood they are being considered by Nature. That means they have not been reviewed independently for any faults in the testing used.

Furthermore, the gene identified by Professor Plomin, which is called IGF2R, on chromosome 6, has long been known to genetic researchers. But they have identified it as being involved in some way in prenatal growth - hence its name, "insulin-like growth factor 2 receptor". Mutations in this gene are linked to increased incidence of liver cancer, leading other scientists to conclude that it acts as a tumour suppressor in its normal role.

It has never been associated before with intelligence. But on a Channel 4 Equinox programme to be broadcast tonight, Professor Plomin says that his six-year study shows that IGF2R occurs more frequently in smart children than average ones.

David King, editor of GenEthics News and the instigator of the "Campaign for Real Intelligence", has sought to stop MRC funding for Professor Plomin's work. "It will make people believe that everything we are is determined by our genes," he said.

If confirmed, however, Professor Plomin's work seems certain to reopen a long-running argument. Jonathan Glover, a philosopher at Oxford University, says: "Anyone can ignore a new piece of science for a certain amount of time, but then the problems start to catch up with us. This raises huge and important issues which, in a democracy, we should be discussing now."