Gene test marks breakthrough

SCIENTISTS have reached a milestone in human genetics by showing that a type of diabetes which often occurs in children is triggered by at least four genes. It is the first time researchers have screened all the human chromosomes to find the several genes involved in a common disorder.

The research is important not so much for what was achieved, but for how it was done. Techniques for identifying the diabetes genes could be adapted to find the many genes involved in other such 'polygenic' disorders involving more than one gene, ranging from asthma to schizophrenia.

Up to now scientists investigating human genetics have had to concentrate on diseases caused by defects in single genes - such as cystic fibrosis - because of the enormous difficulties of researching disorders where two or more genes are implicated.

But a research team led by John Todd, of the John Radcliffe Hospital, Oxford, has screened all the 23 pairs of chromosomes of about 600 people with a family history of diabetes, using a powerful technique to identify genetic 'signposts' pointing to the diabetes genes.

The scientists conclude in an article in Nature magazine that there are at least four genes that appear to predispose some of the family members to the disease.

Stephen Gough, a senior registrar at the John Radcliffe Hospital, said the semi-automatic technique of screening all the chromosomes has not been used before for finding the genetic basis of a complex common disorder.

The method could easily be adapted to find the genes involved in high blood pressure, heart disease, asthma, multiple sclerosis and various cancers 'because you can do so much, so quickly, so accurately', Dr Gough said.