The largest study ever to examine the genetic basis of type 2 diabetes has uncovered seven new regions of the genome linked to the disease. The study is also notable because it includes DNA from Asian and Hispanic groups.
A large international consortium comprising researchers from 20 countries on four continents came together for the study and gathered data from over 48,000 patients and 139,000 healthy controls from four different ethnic groups: European, east Asian, south Asian and Mexican and Mexican American ancestry.
A team from the Wellcome Trust Centre for Human Genetics at Oxford University in the UK co-led the study, which is published in Nature Genetics.Mark McCarthy, professor and Wellcome Trust Senior Investigator at Oxford, says they brought together results from 50 studies from around the world and found:
"One of the striking features of these data is how much of the genetic variation that influences diabetes is shared between major ethnic groups."
Most genome-wide association studies only use data from populations of European descent. But he and his colleagues believe that as more and more studies, like this one, begin to include data from other ethnic groups, the closer we get to mapping the genes for type 2 diabetes, as he explains:
"The overlap in signals between populations of European, Asian and Hispanic origin argues that the risk regions we have found to date do not explain the clear differences in the patterns of diabetes between those groups."
Large data set helped tease out subtle effects on type 2 diabetes risk
For this study, the investigators looked at over 3 million DNA variants across the whole genome to find those that have a measurable effect on type 2 diabetes.
Having access to DNA data from so many thousands of individuals meant - for the first time - they could tease out some regions that have quite subtle effects on diabetes risk.
First author Dr. Anubha Mahajan, also of Oxford's Wellcome Trust Centre, says:
"Although the genetic effects may be small, each signal tells us something new about the biology of the disease."
Two of the regions the researchers identified lie near the genes ARL15 and RREB1, which are known to be associated with abnormal levels of insulin and glucose in the body - both hallmarks of type 2 diabetes.
Discovery may lead to new ways of thinking about type 2 diabetes
They believe this discovery will help scientists find out more about the biochemistry that increases risk for type 2 diabetes.
Dr. Mahajan says the findings may lead to new ways of thinking about type 2 diabetes and new ways to treat and prevent it, and:
"There's every reason to expect that drugs acting on these biological processes would have a far larger impact on an individual's diabetes than the genetic effects we have discovered."
The researchers also expect, because of the way they covered different ethnic groups, their study will be relevant for other common human diseases.
Funds for the study came from the Wellcome Trust, the Medical Research Council, the US National Institutes of Health, the Canadian Institutes of Health Research and other sources.
In another intriguing study that Medical News Today recently covered about the genetic legacy of the Neanderthals, researchers found that modern humans carry remnants of Neanderthal DNA that are linked to genes affecting diseases like type 2 diabetes, traits like hair and skin types, and behaviors, like smoking.
Written by Catharine Paddock PhD