Why is type 2 diabetes an increasing problem?

January 9, 2014, Wellcome Trust Sanger Institute

Contrary to a common belief, researchers have shown that genetic regions associated with increased risk of type 2 diabetes were unlikely to have been beneficial to people at stages through human evolution.

Type 2 diabetes is responsible for more than three million deaths each year and this number is increasing steadily. The harmful genetic variants associated with this common disease have not yet been eliminated by .

To try to explain why this is, geneticists have previously hypothesised that during times of 'feast or famine' throughout , people who had advantageous or 'thrifty' genes processed food more efficiently. But in the modern developed world with too much food, these same people would be more susceptible to type 2 diabetes.

"This thrifty gene theory is an attractive hypothesis to explain why natural selection hasn't protected us against these harmful variants," says Dr. Yali Xue, lead author of the study from the Wellcome Trust Sanger Institute. "But we find little or no evidence to corroborate this theory."

The team tested this theory by examining 65 that were known to increase type 2 diabetes risk, the most detailed study of its kind.

If these harmful variants were beneficial in the past, the team would expect to see a genetic imprint of this in the DNA around the affected regions. Despite major developments in tests for positive selection and a four-fold increase in the number of genetic variants associated with diabetes to work with, they found no such imprint.

"We found evidence for positive selection in only few of the 65 variants and selection favoured the protective and risk alleles for type 2 diabetes in similar proportions," notes Dr. Qasim Ayub, first author from The Wellcome Trust Sanger Institute, "This is no more than what we would expect to find for a random set of genomic variants."

This finding poses an intriguing and still unanswered question: if the harmful genetic variants that are associated with were not beneficial in the past, then why have they not been eliminated?

"Geneticists have been able to identify multiple genetic risk variants for many common diseases, such as type 2 ," says Professor Mark McCarthy, co-author from the University of Oxford. "However, the big challenge, if we are to use this information to improve human health, lies in understanding how it is that these differences in DNA sequence lead to an altered risk of disease. Understanding how variants that appear, in the current environment, to have largely harmful consequences, have become so frequent will be an important step on this path towards better treatment and prevention"

Explore further: New clues in hunt for heredity in type 2 diabetes

More information: Qasim Ayub, Loukas Moutsianas, Yuan Chen, Kalliope Panoutsopoulou, Vincenza Colonna, Luca Pagani, Inga Prokopenko, Graham R.S. Ritchie, Chris Tyler-Smith, Mark I. McCarthy, Eleftheria Zeggini,1 and Yali Xue. (2013) 'Revisiting the thrifty gene hypothesis via 65 loci associated with susceptibility to type 2 diabetes' Advanced online publication in American Journal of Human Genetics 09 Jan.

Related Stories

New clues in hunt for heredity in type 2 diabetes

March 19, 2013
Type 2 diabetes has strong hereditary tendencies and the genes we are born with cannot be changed. However, new research from Lund University in Sweden shows that we can modify the function of the genes through the epigenetic ...

Genetic risk score linked to increased risk of diabetes

July 30, 2013
(HealthDay)—A genetic risk score based on 46 gene variants linked to type 2 diabetes is associated with increases in the risk of type 2 diabetes and declines in glucose control and beta-cell function, according to a study ...

Sieving through 'junk' DNA reveals cancer-causing genetic mutations

October 3, 2013
Researchers can now identify DNA regions within non-coding DNA, the major part of the genome that is not translated into a protein, where mutations can cause diseases such as cancer.

Genetics that protects your heart

December 23, 2013
(Medical Xpress)—Researchers have found a key piece of the puzzle as to why an isolated population in Greece may live healthy lives. They have found that a genetic variant known to protect the heart is 40 times more common ...

New genetic analysis method holds promise for understanding causes of disease

December 17, 2013
(Medical Xpress)—University of Michigan School of Public Health researchers have developed a new method for identifying rare gene variants, which scientists now believe are more informative for human disease studies than ...

Researchers produce a catalog of the deleterious and disease-causing genetic variants in healthy people

December 6, 2012
Researchers at Cambridge and Cardiff have found that, on average, a normal healthy person carries approximately 400 potentially damaging DNA variants and two variants known to be associated directly with disease traits. They ...

Recommended for you

Genetic discovery may help better identify children at risk for type 1 diabetes

January 17, 2018
Six novel chromosomal regions identified by scientists leading a large, prospective study of children at risk for type 1 diabetes will enable the discovery of more genes that cause the disease and more targets for treating ...

Thirty-year study shows women who breastfeed for six months or more reduce their diabetes risk

January 16, 2018
In a long-term national study, breastfeeding for six months or longer cuts the risk of developing type 2 diabetes nearly in half for women throughout their childbearing years, according to new Kaiser Permanente research published ...

Women who have gestational diabetes in pregnancy are at higher risk of future health issues

January 16, 2018
Women who have gestational diabetes mellitus (GDM) during pregnancy have a higher than usual risk of developing type 2 diabetes, hypertension, and ischemic heart disease in the future, according to new research led by the ...

Diabetes gene found that causes low and high blood sugar levels in the same family

January 15, 2018
A study of families with rare blood sugar conditions has revealed a new gene thought to be critical in the regulation of insulin, the key hormone in diabetes.

Discovery could lead to new therapies for diabetics

January 12, 2018
New research by MDI Biological Laboratory scientist Sandra Rieger, Ph.D., and her team has demonstrated that an enzyme she had previously identified as playing a role in peripheral neuropathy induced by cancer chemotherapy ...

Enzyme shown to regulate inflammation and metabolism in fat tissue

January 11, 2018
The human body has two primary kinds of fat—white fat, which stores excess calories and is associated with obesity, and brown fat, which burns calories in order to produce heat and has garnered interest as a potential means ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.