Landmark Study Throws Up Genes Linked to Diabetes

An international team of scientists on Sunday reported it had identified several of the most important genes linked to Type 2 diabetes, a disease that is spreading at epidemic rates.

The discovery should open the way to a test to identify people with an inherited risk of diabetes, thus enabling them to make lifestyle choices that could sidestep the disease, they said.

The researchers, based in Britain, France and Canada, said they had identified four areas on the genome where mutations in the genetic code, called single nucleotide polymorphisms (SNPs), exposed an individual to a higher risk.

As much as 70 percent of the genetic drivers for Type 2 diabetes – a disease that also is linked to a bad diet – could be attributed to these variants, they believe.

“The two major reasons why people develop Type-2 diabetes are obesity and a family link,” said Philippe Froguel of Imperial College London, one of the authors.

“Our two new findings mean that we can create a good genetic test to predict people’s risk of developing this type of diabetes.

“If we can tell someone that their genetics mean they are predisposed 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.”

The study was published online by Nature, the British science journal.

The researchers carried out the gene trawl among samples volunteered by 700 people with Type-2 diabetes, and compared this outcome with 700 “controls,” or matched counterparts who did not have the disease.

They then confirmed their findings by analyzing a further 5,000 individuals with Type-2 diabetes and a family history of the disorder, to verify that the same genetic mutations were the culprit.

The paper provides evidence to back previous suspicions that a variant of a gene called TCF7L2 confers a risk.

It also points the finger at a gene called SLC30A8, a so-called zinc transporter that is involved in regulating the secretion of insulin – the hormone that is at the root of diabetes. This throws up an avenue of research for a treatment: fixing the flawed transporter could boost insulin levels.

And it identifies, but less conclusively, two other genes where flaws may hamper function of beta cells, the cells in the pancreas where insulin is produced.

Diabetes is a chronic condition in which the body does not produce enough or cannot make proper use of the insulin it does produce.

As a result, wild fluctuations of glucose in the blood occur. This can eventually lead to blindness, heart disease, amputations and kidney failure.

Type 1 diabetes is linked to genetic predisposition. The far more common Type 2 diabetes has long been suspected to have a genetic component, but its most immediate cause is an unhealthy diet and inactivity.

This form of diabetes has swept western countries and is now moving quickly into developing countries that are on the fast track to prosperity, driven by high-calorie diets, a switch to a more sedentary lifestyle but also what may be a genetic vulnerability to obesity.

More than one in three Americans born in 2000 will develop Type 2 diabetes, according to a commentary published by Nature on Sunday.

According to research published last November in The Lancet, 960,000 people were killed by diabetes in 2001. In 2003, 194 million people in Asia had diabetes and by 2025, the tally could be 333 million.

To find the baulky genes, the researchers had to examine 392,000 single mutations. They add that further work may unveil more genetic causes.

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