Scientists map major diabetes genes

Canadian and international researchers say they've found five different areas of DNA that may account for 70 per cent of the genetic risk of developing Type 2 diabetes.

British, French and Canadian scientists identifieddifferent regions on our gene map linked to the risk of developing Type 2 diabetes.

Obesity and a family link are two major reasons why people develop Type 2 diabetes, said study author Professor Philippe Froguel of Imperial College London.

"Our new findings mean that we can create a good genetic test to predict people's risk of developing this type of diabetes," said Froguel.

"If we can tell someone that their genetics mean they are pre-disposed towards Type 2 diabetes, they will be much more motivated to change things such as their diet to reduce their chances of developing the disorder.

We can also use what we know about the specific genetic mutations associated with Type 2 diabetes to develop better treatments."

Evolutionary clue

Froguel and his colleagues at Montreal's McGill University looked for the mutations, called single nucleotide polymorphisms or SNPs, in samples of 700 people with the condition. The results were compared to 500 others who did not have Type 2 diabetes.

The team then went a step further, confirming their findings by looking for the mutation in another 5,000 people with Type 2 diabetes and a family history of the disorder.

In Sunday's online issue of the journal Nature, Froguel and his colleagues said a previously discovered gene called SLC30A8 encodes a protein that helps move zinc and is found only in beta cells that make and release insulin.

Many of the mutations appear to be in "older" parts of our genome, which adds to the suggestion that the genes may have evolved to help humans survive famines but are now contributing to disease as people in the developed world consume a rich diet and exercise less.

"These findings underscore how [genome-wide association] studies may not only deliver 'new' genes, but permit advances in our understanding of how human evolution has 'made' the diseases that are common today," wrote Nelson Freimer and Chiara Sabatti of the University of California Los Angeles in a commentary accompanying the study.

Type 2 diabetes affects about 1.3 million Canadians, and the number is expected to reach three million by 2010.

Type 2 diabetes occurs when the pancreas either does not make enough insulin or makes it but cannot use it properly. It is usually controlled through diet.

The research was funded by Genome Canada, Genome Quebec, and the Canada Foundation for Innovation.