Scientists find genes linked to diabetes

A diabetic gives herself an insulin injection in the arm. Photograph: Lester V. Bergman/Corbis

Scientists have found six new genes linked to type 2 diabetes, a discovery that will improve understanding of how the disease develops.

Each of the disease variants of the genes raises the risk of developing diabetes by only a small amount, but scientists say the combined impact of the collection of genes could be powerful, and the discovery could help develop new forms of prevention and treatment. One of the genes has also been linked to prostate cancer.

Diabetes occurs when the body cannot regulate its blood sugar levels. It is thought to affect more than 2 million people in the UK and another 750,000 are unaware of their condition. In type 2 diabetes, which is associated with obesity and is the more common form of the disease, the body does not respond properly to insulin produced by beta cells in the pancreas, which also may be making less of the hormone.

In the study, published yesterday in Nature Genetics, 90 researchers from more than 40 European and US centres pooled genetic data gathered from more than 90,000 people. "The sort of studies we're doing are designed to pick up common variants," said Mark McCarthy of the University of Oxford, who led the research. "Across these six, some of the variants are in 10% [of the population], in other cases the one that's increasing the risk is the majority version that is in 90%."

McCarthy said inheriting a disease variant of any of the genes from either parent could increase a person's risk of developing type 2 diabetes by 10%-15%. "There'll be a few individuals who will have many of these risk variants and they'll have higher risk of diabetes than individuals who have been lucky enough to end up with very few."

Since none of the new genes were previously suspected of having a role in diabetes, there is still much work to do in working out what the genes are responsible for, though there are clues. "Virtually all of the genes [found so far] seem to be impacting on the ability of the beta cells to compensate for insulin resistance," he said.

He added that a particular surprise was that one of the genes found linked to type 2 diabetes was recently shown to play a role in prostate cancer. "One of the most exciting bits of this field is that we're finding lots of unexpected connections that sometimes genes seem to influence diseases that we hadn't previously thought of as connected."

Simon Howell, chairman of Diabetes UK, said: "It's remarkable that we still know so little about such a major condition as type 2 diabetes. By revealing new pathways by which the body normally keeps blood glucose levels under control, this research offers new opportunities for more effective ways of treating and preventing this condition."

The findings are the latest success in a relatively recent technique called the genome-wide association study.

A decade ago, genetics research usually involved looking in families with rare conditions, such as cystic fibrosis, to find rare single gene mutations that had big effects. But after the human genome project in 2000, which mapped every gene in the body, and subsequent improvements in screening technology, scientists are now able to carry out large-scale comparisons of huge numbers of people.

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