Researchers uncover novel genetic markers for diabetes-related traits

18 January 2010

Researchers have found new genetic clues to the development of type 2 diabetes. This will aid studies to understand the biology of disease and the search for treatments.

Five genetic variants that directly influence the risk of developing diabetes have emerged in two major studies published in 'Nature Genetics'. The research, by an international team that includes scientists from the Wellcome Trust Sanger Institute, analysed genetic data from more than 100 000 people of European descent.

The first study identified ten novel genetic markers for biological traits that underlie type 2 diabetes. In a companion paper the same consortium identified three new variants that are associated with raised levels of glucose seen in a common test for type 2 diabetes.

Diabetes occurs when the body does not produce sufficient insulin or when cells fail to recognise and react to insulin; this results in abnormally high levels of glucose or sugar in the blood.

The research was carried out by the Meta-Analyses of Glucose and Insulin-related Traits Consortium (MAGIC). The group examined measures such as levels of glucose in the blood after a period of not eating, and insulin and blood sugar levels following a glucose tolerance test.

They searched data from population studies of people without diabetes to examine the links between glucose levels and SNPs - single letter changes in the genome that can act as markers for particular physical traits or disease. They found nine new genetic regions associated with fasting glucose levels, 16 regions associated with the production of insulin but only a single region associated with insulin resistance.

"The genetics is telling us that the two measures, insulin and glucose, have different architectures, with fewer genes, rarer variants or greater environmental influence affecting insulin resistance," said Dr Inês Barroso, from the Sanger Institute.

The team have strong evidence that other genetic factors remain to be found: their study explains about 10 per cent of the genetic effect on fasting glucose levels. Further studies may reveal rarer variants with a larger impact.

Image: Type II diabetes, amyloid in pancreatic islets. Credit: Anne Clark, Wellcome Images

References

Dupuis J et al. New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk. Nat Genet. [Epub ahead of print]

Saxena R et al. Genetic variation in GIPR influences the glucose and insulin responses to an oral glucose challenge. Nat Genet. [Epub ahead of print]