A new genetic variant associated with type 2 diabetes, typical of Native Americans, including Mexicans, was detected by an international team of experts, in which María Teresa Tusié Luna, of the Institute of Biomedical Research (IIBm) of the University, participates. National Autonomous Government of Mexico (UNAM).
"From the analyzes, we identified a risk gene for this disease, called SFI1; We know very little about its function, but it contributes to the risk of acquiring diabetes, mainly in subjects with Native American ancestry, "he said.
The Mexican population is among the human populations most predisposed to diabetes. According to the 2016 National Health and Nutrition Survey, this condition is the second cause of mortality in Mexico: 10.3 percent of women suffer from it, and 8.4 percent of men.
In the study, the largest that has been done so far, the exome (part of the genome formed by exons, fragments of DNA that are transcribed to give rise to proteins) of people with and without diabetes was sequenced. We reviewed more than 45,000 worldwide: 20,791 with type 2 diabetes, and 24,440 without diagnosis, belonging to five different ethnic groups. About 10 percent of those analyzed originate in our country.
Together, the detected signals explain about 25 percent of the genetic risk to develop this disease. Some of the variants are found in genes previously associated with it, and genes that have been proposed as pharmacological targets for its treatment are included.
The researcher explained that the genome is the result of selection processes; each population went through different events throughout its history; current individuals carry genetic variants that at some point conferred some evolutionary advantage. Then, to know the factors that predispose us to different diseases, it is necessary to study the different human groups.
"Mestizos-Mexicans have a European and Native American genetic background, mainly; then, the advantages obtained by native peoples to survive with lack of food and extreme climatic conditions selected individuals efficient in accumulating fat; Today, this genetic structure predisposes us to different diseases, because our current lifestyle includes a highly caloric diet and less exercise. "
There are two main types of diabetes: 1 and 2. Within type 2 different clinical subtypes are distinguished, that is, some patients develop it at an early age, others are affected by obesity, some more present complications quickly, and others require of insulin or they can control it properly with hypoglycemic drugs.
"It is estimated that hundreds of genes interact and influence each of its variants, some with a greater effect, particularly in the Mexican population."
To identify these variants in Mexicans, Tusié Luna has collaborated for years with the Broad Institute, in the United States.
Now that more genetic variants have been identified, the university and its team will continue with the analysis of proteins that are affected with this disease, with a view to their being used in the development of better medicines.
"The potential application of this new knowledge requires prospective studies in carriers or non-carriers, to whom a specific treatment is offered for a specific period of time, also controlling the presence of other factors such as obesity and dyslipidemias. This is possible with long-term collaborations such as the one carried out by UNAM and the National Institute of Medical Sciences and Nutrition Salvador Zubirán (INCMNSZ), "he said.
The genome includes the complete sequence of genes that contain the information necessary for the synthesis of all the proteins of a living organism. These data are arranged in the form of double chains called deoxyribonucleic acid (DNA).
The segments that give instruction for functioning are known as exons, and their analysis is the exome, one of the most complete ways to study the DNA chain.
Tusié Luna emphasized that studies such as the one presented consider the value of including different human populations to identify sets of genes related to alterations such as insulin resistance.
Until now, genetic research to analyze complex conditions such as cancer or diabetes depended on the use of special chips, where thousands of genetic variants were sought, but with the limitation that they should be known or previously identified in other populations.
"But nowadays technology allows to sequence or read the genome directly without depending on known variables; thus, thousands of new variants have been found that influence different human populations, "explained the expert from the IIBm peripheral unit at INCMNSZ.
In this international research, led by Jason Flannick, of the Broad Institute, Clicerio González, from the National Institute of Public Health, also participated with patient files that were followed up for a decade, which will help to better understand the factors that predispose to diabetes.
(Source: UNAM / DICYT)