Just a single change in the gene's DNA code determines whether people will be taller or shorter by up to 1cm, scientists announced yesterday. But hundreds of other genes are also likely to play a role in height, they add.

In a paper published by the journal Nature Genetics, British and US researchers analysed DNA from nearly 5,000 white people of European descent, mainly individuals living in Britain, Sweden and Finland.

The trawl revealed a gene called HMGA2.

The change of just a single base 'letter' in HMGA2's genetic code - a 'C' (for cytosine) instead of a 'T' (for thymine) - adds nearly 1cm in height to individuals who inherited this variant from both parents.

Those who got the 'C' variant from only one of their parents were about half a centimetre taller than their 'T' counterparts.

But HMGA2 explains only 0.3 per cent of the variability in human stature.

'Height is a typical 'polygenic' trait; in other words, many genes contribute towards making us taller or shorter,' said lead researcher Tim Frayling of the Peninsula Medical School in Exeter, England.

Interest in 'height' genes is spurred by more than idle curiosity for there could also be a windfall in knowledge about disease.

Taller people are statistically more likely to be at risk from some kinds of cancer (prostate, bladder and lung, for instance), which implies that genes that regulate cell multiplication may also play some part in letting cancer cells proliferate.

Statistics also throw up an association between shortness and heart disease.

'This is the first convincing result that explains how DNA can affect normal variation in human height,' said US researcher Joel Hirschhorn of the Broad Institute, Massachusetts, and a professor of genetics at Harvard Medical School.

'Because height is a complex trait, involving a variety of genetic and non-genetic factors, it can teach us valuable lessons about the genetic framework of other complex traits, such as diabetes, cancer and other common human diseases.'

AGENCE FRANCE-PRESSE