More type 2 diabetes genes discovered


More type 2 diabetes genes discovered

Several teams of scientists this week report discovering more genes linked to Type 2 Diabetes and describe the achievement as bringing science closer to understanding the genetics of the origins and progress of this modern disease.

The various papers are published in Science and Nature Genetics this week.

The unravelling of the human genome five years ago opened the door to a cascade of research projects looking for genes that might be involved in many common diseases. These studies have acquired the name genome-wide association (GWA) projects.

Although the progress of diabetes in the world closely follows non-genetic trends, such as increased sedentary lifestyles and rise in obesity, many scientists now believe some people's genes make them more vulnerable than others.

An article in Science describes how scientists have found three new segments of DNA in the human genome that appear to increase the risk of getting type 2 diabetes by between 10 and 40 per cent.

Between them the scientists searched the whole human genome from 50,000 people from different countries, some of whom had diabetes and some did not. There are 22,000 known genes in the human genome.

They found 8 genes that are common to most people and clearly linked to diabetes type 2, of which 5 were already known to science, and 3 were new. They also found others that need further investigation.

Although the genes are common to most people, there are two common variants of each. Some people may have a variant of a gene that is linked with higher risk, and other people may have the variant that is linked to lower risk.

One of the teams involved in the international GWA collaboration was based at the University of Oxford and the Peninsula Medical School, Exeter, UK, and formed part of the Wellcome Trust Case Control Consortium.

They reported looking at over 2 billion items of DNA information in 6,000 people with type 2 diabetes and 8,000 controls without diabetes to track down the three new genes.

The total number of genes now known to be involved in type 2 diabetes is 9. This includes the FTO gene that this UK group reported two weeks ago, when they suggested FTO played a role in type 2 diabetes through affecting a person's weight.

The role played by the newly discovered genes is not clear, but the UK team thinks two of them might affect how insulin-producing beta-cells in the pancreas are made and work.

There is currently a debate in this field about whether it is reduced function of pancreatic beta-cells or reduced numbers that affects the progress of the disease, and these findings will hopefully help scientists to resolve the issue.

One of the UK team, Professor Andrew Hattersley of the Peninsula Medical School, said:

"We now have significantly more pieces to the jigsaw that will help us understand the mechanisms behind type 2 diabetes."

Other teams involved in the international collaboration are from the US and Scandinavia, who studied people with and without diabetes in Sweden and Finland and also came up with the same 3 genes. Their findings are also published alongside the UK study in Science.

One of the genes was also discovered by by scientists at deCODE genetics in Reykjavik, Iceland in a study of 1,399 diabetes patients and 5,275 controls. Their paper is published in Nature Genetics.

Although these various findings have been confirmed in a unique international collaboration covering over 32,000 people, the scientists say it will be some time before they are useful to patients.

The number of people developing type 2 diabetes (as opposed to type 1, formerly known as childhood or insulin dependent diabetes) has increased rapidly in the last 30 years, at first in America and Europe, and more recently in Asia where it is said to be reaching epidemic proportions..

Over 200 million people have diabetes worldwide and according to the World Health Organization (WHO), this figure will reach 300 million by 2025.

Type 2 diabetes is characterized by insulin resistance and reduced insulin production. This results in glucose building up in the blood instead of being metabolised and used for energy.

Diabetes is a leading cause of heart disease, stroke, blindness, and kidney failure.

Welcoming these findings, Iain Frame, Research Manager at Diabetes UK, said:

"It's important to remember that type 2 diabetes is a genetic condition and not just associated with lifestyle factors."

"This discovery will help us get closer to unravelling the genetics of the condition. If we can understand more about the genetics we can make real progress towards the prevention and treatment of type 2 diabetes," he added.

Click here for the journal Science.

Click here for the journal Nature Genetics.

Click here for an introduction to Human Genome Project and Type 2 Diabetes (1997, New Mexico State University).

Writer: Medical-Diag.com

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