New Risk Factor for Type 2 Diabetes Discovered
Just when you thought you had heard about every possible risk factor for type 2 diabetes, researchers uncover another one. This new risk factor was discovered by an international team of scientists and it is a genetic marker that could mean a great deal to a certain segment of the population.
Who is affected by the new risk factor?
The new study was the largest one ever done among Mexican and Mexican American people. This is significant, especially given that the prevalence of diabetes is 13.3 percent among Mexican Americans compared with 7.1 percent among non-Hispanic whites and 8.4 percent among Asian Americans, according to the American Diabetes Association.
The investigative team, known as the SIGMA (Slim Initiative in Genomic Medicine for the Americas) Type 2 Diabetes Consortium, discovered a previously undetected gene, which they named SLC16A11, that increases a carrier’s risk by 25 to 50 percent. That is:
- People who have the higher risk form of the gene are 25 percent more likely to develop diabetes than people who don’t have this gene
- Anyone who inherits a copy of the gene from both parents is 50 percent more likely to develop diabetes
- The higher risk form of the gene can be found in up to 50 percent of people who have recent Native American geneology, including people from Latin American countries (also see "Native Americans and diabetes” below)
- This higher risk gene is rarely seen in people from Europe and Africa and is found in about 20 percent of East Asians
According to one of the study’s co-authors, Jose Florez, an associate professor of medicine at Harvard Medical School and an assistant physician in the Diabetes Unit and the Center for Human Genetic Research at the Massachusetts General Hospital (MGH), this finding marks “one of the strongest genetic risk factors discovered to date.”
Why the discovery is important
Discovery of the new genetic risk factor opens several doors for investigators and patients. For example:
- Provides a deeper understanding and appreciation of the disease, including how it may have an impact on metabolism
- May help improve individual risk assessment
- May suggest new ways to target drugs for treatment and help in designing new studies
What is SLC16A11?
Scientists have had little information about SLC16A11 and its role in human diseases until now. Thus far the team is trying to put the puzzle pieces together to determine the connection between this gene and type 2 diabetes.
They do know that SLC16A11 belongs to a category of genes involved in transporting molecules that play a role in chemical reactions. In addition, they noted that modifying the levels of the protein causes a change in the amount of a type of fat associated with the risk of diabetes.
More research is necessary to help put all the pieces together, and some of that work is already planned. David Altshuler, co-senior author of the study as well as deputy director and chief academic officer at the Broad Institute and a Harvard Medical School professor at MGH, “We are now hard at work trying to figure out what is being transported, how this influences triglyceride metabolism, and what steps lead to the development of type 2 diabetes.”
Native Americans and diabetes
Previous research resulted in some interesting theories about the high prevalence of diabetes among Native Americans, who are about 2.2 times more likely to develop the disease then are non-Hispanic whites. Rates among Native Americans are about 16.3 percent with an estimated 30 percent of the population having prediabetes.
One theory about why the diabetes rate is so high among Native Americans is that they developed thrifty genes during prehistoric times. The effect of these thrifty genes, which helped them accumulate fat during times of famine, lives on today.
This theory comes from a research team at the University of Nebraska-Lincoln’s School of Natural Resources, which studied the fossilized feces of Native Americans who lived in the Southwest. The low-glycemic, high-fiber diet they typically consumed (e.g., sunflower seeds, wild grasses, amaranth, prickly pear) is in extreme contrast to the high-fat, low-fiber diet they often eat today, and the body responds by packing on the fat.
Despite the fact that type 2 diabetes is commonplace and indeed an epidemic, there is still much we don’t understand about the disease. That’s why the continued efforts to uncover new risk factors and other information about the disease is critical if we are to beat diabetes.
American Diabetes Association
SIGMA Type 2 Diabetes Consortium. Sequence variants in SLC16A11 are a common risk factor for type 2 diabetes in Mexico. Nature 2013; DOI:10.1038/nature12828. Published online 25 Dec.
University of Nebraska-Lincoln
Image: Ms Phoenix