Credit: Darren Lewis/public domain
By studying identical twins, researchers from Lund University in Sweden have identified mechanisms that could be behind the development of type 2 diabetes. This may explain cases where one identical twin develops type 2 diabetes while the other remains healthy.
The study involved 14 pairs of identical twins in Sweden and Denmark. One twin had type 2 diabetes and the other was healthy.
"Twins are a good model for finding mechanisms, but the results are applicable to all", said Emma Nilsson, who carried out the study with Charlotte Ling.
We know that fat tissue can release hormones and regulate metabolism in different organs in the body. The question the researchers posed was whether epigenetic* changes in the DNA lead to changes in the fat tissue that in turn can lead to the development of type 2 diabetes.
The researchers investigated DNA methylation* at 480 000 points on the DNA and looked at how it affected the expression of the genes in the identical twins. They found that genes that are involved in inflammation were up-regulated and that genes involved in the fat and glucose metabolism were down-regulated in those who had diabetes.
"This means that they are not able to process fat as well, which leads to raised levels of fat in the blood and uptake of fat by other organs instead, such as the muscles, liver or pancreas. This causes insulin resistance, which leads to type 2 diabetes", said Emma Nilsson.
They found that the sets of twins had very similar DNA methylation, which according to Emma Nilsson suggests strong heredity.
The researchers went on to compare non-identical twins with identical twins and found that the similarities were greater in identical twins.
"Non-identical twins generally share 50 per cent of their DNA and it is usually said that identical twins share 100 per cent of theirs. Despite this, we found 1 400 places on the identical twins' DNA where there was a difference in DNA methylation between the diabetic and the non-diabetic. It is believed that these differences are due to differences in lifestyle and this confirms the theory that type 2 diabetes is strongly linked to lifestyle."
A further discovery in the DNA was that there were certain changes in the actual DNA sequence – the genetic code – that differed between the diabetic and non-diabetic twin. This was a new finding.
Put in simple terms, small parts of the genetic code can be duplicated or be absent. Having too many or too few copies of a certain DNA sequence leads to changes in the properties of the specific gene.
"We found six cases where one of the set of twins had more or fewer of these copies in his or her DNA, and we suspect that this could be another cause of the disease", said Emma Nilsson, continuing:
"This is interesting because it is usually taken for granted that identical twins are genetically 100 per cent alike. However, there are in fact differences and it is not known whether, or how, these affect the development of type 2 diabetes. More studies are needed to investigate their impact."
Explore further: Twins talk half as much at two
More information: diabetes.diabetesjournals.org/… ntent/63/9/2962.full
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© Medical Xpress 2011-2014, Science X network
Credit: Darren Lewis/public domain
By studying identical twins, researchers from Lund University in Sweden have identified mechanisms that could be behind the development of type 2 diabetes. This may explain cases where one identical twin develops type 2 diabetes while the other remains healthy.
The study involved 14 pairs of identical twins in Sweden and Denmark. One twin had type 2 diabetes and the other was healthy.
"Twins are a good model for finding mechanisms, but the results are applicable to all", said Emma Nilsson, who carried out the study with Charlotte Ling.
We know that fat tissue can release hormones and regulate metabolism in different organs in the body. The question the researchers posed was whether epigenetic* changes in the DNA lead to changes in the fat tissue that in turn can lead to the development of type 2 diabetes.
The researchers investigated DNA methylation* at 480 000 points on the DNA and looked at how it affected the expression of the genes in the identical twins. They found that genes that are involved in inflammation were up-regulated and that genes involved in the fat and glucose metabolism were down-regulated in those who had diabetes.
"This means that they are not able to process fat as well, which leads to raised levels of fat in the blood and uptake of fat by other organs instead, such as the muscles, liver or pancreas. This causes insulin resistance, which leads to type 2 diabetes", said Emma Nilsson.
They found that the sets of twins had very similar DNA methylation, which according to Emma Nilsson suggests strong heredity.
The researchers went on to compare non-identical twins with identical twins and found that the similarities were greater in identical twins.
"Non-identical twins generally share 50 per cent of their DNA and it is usually said that identical twins share 100 per cent of theirs. Despite this, we found 1 400 places on the identical twins' DNA where there was a difference in DNA methylation between the diabetic and the non-diabetic. It is believed that these differences are due to differences in lifestyle and this confirms the theory that type 2 diabetes is strongly linked to lifestyle."
A further discovery in the DNA was that there were certain changes in the actual DNA sequence – the genetic code – that differed between the diabetic and non-diabetic twin. This was a new finding.
Put in simple terms, small parts of the genetic code can be duplicated or be absent. Having too many or too few copies of a certain DNA sequence leads to changes in the properties of the specific gene.
"We found six cases where one of the set of twins had more or fewer of these copies in his or her DNA, and we suspect that this could be another cause of the disease", said Emma Nilsson, continuing:
"This is interesting because it is usually taken for granted that identical twins are genetically 100 per cent alike. However, there are in fact differences and it is not known whether, or how, these affect the development of type 2 diabetes. More studies are needed to investigate their impact."
Explore further: Twins talk half as much at two
More information: diabetes.diabetesjournals.org/… ntent/63/9/2962.full
Medical Xpress on facebook
Related Stories
Twins talk half as much at two
Jun 04, 2014
(Medical Xpress)—A world first study of language development in toddler twins confirms the widely held belief that twins start to talk later than single-born children.
What you eat and not just the number of calories, is a significant factor in diabetes risk
Sep 02, 2014
If you think losing weight is enough to prevent Type 2 diabetes, don't get your hopes up. A new research report in September 2014 issue of The FASEB Journal, suggests that you don't have to be overweight to develop Type 2 ...
There is no such thing as identical where twins are concerned
Oct 14, 2011
Identical twins have identical genomes, but that is where it stops. There are subtle differences in their personalities, how they look, how they act and in their susceptibility to disease. How can this be?
Identical twins share breast cancer, rare surgery
Nov 15, 2013
(AP)—Identical twins who both had breast cancer are recovering after rare reconstruction surgery at the University of Chicago Medical Center.
Pain sensitivity may be influenced by lifestyle and environment, twin study suggests
Feb 04, 2014
Researchers at King's College London have discovered that sensitivity to pain could be altered by a person's lifestyle and environment throughout their lifetime. The study is the first to find that pain sensitivity, ...
Recommended for you
Women with gestational diabetes don't have to avoid carbs
1 hour ago
"They think they can't eat toast. That's what killed me," says Teri Hernandez, PhD, RN. "Pregnant women don't feel well in the morning. If they can't have toast, what can they eat?"
Attacking type 2 diabetes from a new direction with encouraging results
20 hours ago
Type 2 diabetes affects an estimated 28 million Americans according to the American Diabetes Association, but medications now available only treat symptoms, not the root cause of the disease. New research ...
Only DM duration independently tied to microvascular events
Oct 03, 2014
(HealthDay)—In patients with type 2 diabetes, age or age at diabetes diagnosis and diabetes duration are independently associated with macrovascular events and death, but only duration of disease is independently ...
Viral infection may trigger childhood diabetes in utero
Oct 03, 2014
The incidence of type 1 childhood diabetes has been increasing rapidly worldwide. If blood sugar levels aren't well-controlled, juvenile diabetes can affect nearly every organ of a child's body. And while ...
Low-carbohydrate diet improved quality of life in diabetes patients
Oct 03, 2014
Low-carbohydrate diet has a good effect not only on blood glucose, but also on physical functions, bodily pain and general health, according to a diet study including patients with type 2 diabetes.
Gout linked to heightened diabetes risk
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User comments
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