Conclusion is from a study published in the magazine Scientific Reports by researchers from the Brazilian Institute of Neuroscience and Neurotechnology, which works at Unicamp
José Tadeu Arantes | FAPESP Agency – Evolutionary adaptations that occurred in the past may have left the population of Campinas and other locations in the interior of the State of São Paulo with a greater genetic propensity to accumulate sugars and fats in the body and, consequently, predisposed to developing diseases such as obesity and diabetes.
This is the conclusion of a study disclosed in the magazine Scientific Reports by researchers from Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), a Research, Innovation and Dissemination Center (CEPID) supported by FAPESP at the State University of Campinas (Unicamp).
The investigation was coordinated by Iscia Lopes-Cendes, head of the Molecular Genetics Laboratory at the Faculty of Medical Sciences at Unicamp, within the scope of the Brazilian Precision Medicine Initiative (BIPMed), also supported by FAPESP.
“We mapped around 900 thousand genetic markers distributed in the genomes of 264 people from the Campinas region. It was the first study carried out with this level of resolution in Brazil. Most ancestry studies carried out in the Brazilian population used no more than 40 markers”, Lopes-Cendes told FAPESP Agency.
The genomic data were obtained from volunteers without a specific disease, but which represent the genetic diversity of individuals treated at the Unicamp Hospital de Clínicas. The sample was designed to explore in detail the so-called “local ancestry”. The expression does not refer to the geographic locality, but to the genomic locality. That is, the researchers investigated all regions of the genome to find out the origin – whether European, African, indigenous or others – of each marker. “Until we carried out the research, we had no idea of the enormous variability in the distribution of local ancestry in the Brazilian population. It was something that surprised us”, said Lopes-Cendes.
Due to the significant presence of descendants of immigrants from southern Europe in the interior of São Paulo, mainly Italians, the mapped genomes showed a strong predominance of markers of European origin, in the range of 80%, with the remaining 20% distributed, almost half and half. , between African and indigenous ancestries.
However, what particularly intrigued researchers and motivated the article published in Scientific Reports was that the 10% of indigenous ancestry provided the most relevant element from a public health point of view: the gene PPP1R3B, associated with the body's ability to accumulate carbohydrates and lipids, and, therefore, predisposing to the development of obesity and related metabolic syndromes, such as type 2 diabetes.
“We analyzed the distribution of local ancestry. And we discovered that it was quite homogeneous in most of the genome, except in a specific region of chromosome 8, where the gene is located PPP1R3B. In this region, we see an increased representation of segments of indigenous origin and a significant decrease in segments of European and African origin. This required a lot of calculation, a lot of checking, it was quite heavy work from a mathematical point of view. But he led us to the conclusion that there really is a deviation from local ancestry in this region,” said Lopes-Cendes.
To explain the deviation, the researchers formulated the hypothesis that, most likely, this region of chromosome 8 was subjected to a process of selective pressure in the past, aimed at better adapting individuals to the environment. At a time when food was scarce, the gene PPP1R3B, related to the accumulation of carbohydrates and lipids, would give an evolutionary advantage to its carriers, enabling them to live longer, reproduce more, and transmit this characteristic to their offspring.
But what was an advantage in the past has become a problem in the present, in a context of high caloric intake and sedentary lifestyle, aggravated by habits such as smoking and excessive alcohol consumption.
“This information is extremely important from a public health point of view. We raise the hypothesis that, most likely, there is an increased genetic predisposition to obesity and its complications in the population of the Campinas region – and we are confirming this in populations from other regions of the State of São Paulo as well. If I were the manager of the region's public health system, I would place great emphasis on obesity and diabetes prevention programs, with specific teams to promote changes in eating habits, encourage physical exercise and warn about the dangers of smoking and alcohol intake,” said Lopes-Cendes.
precision medicine
With this objective, the researcher has presented the results of the research in different forums, opening dialogue with academics in the health sector, especially in the area of epidemiology. “This is a process that we call 'implementation science or medicine', that is, implementing in practice, especially in medical practice, what we discover through scientific research,” she said.
“Our goal is to apply the results in precision medicine. Given the genetic characteristics of the Brazilian population, which are extremely heterogeneous, it is likely that each medical center that wants to implement precision medicine practices will have to carry out this type of study in its population of interest. This mapping is very important because we know, in medicine, that the greater or lesser predisposition to this or that disease depends on the presence of certain genes in specific regions of the genome, that is, local ancestry”, he stated.
The research was conducted during the post-doctorate of Rodrigo Secolin, main author of the article and scholarship holder of FAPESP.
The article Distribution of local ancestry and evidence of adaptation in admixed populations, by Rodrigo Secolin, Alex Mas-Sandoval, Lara R. Arauna, Fábio R. Torres, Tânia K. de Araujo, Marilza L. Santos, Cristiane S. Rocha, Benilton S. Carvalho, Fernando Cendes, Iscia Lopes-Cendes and David Comas, as it can be accessed at www.nature.com/articles/s41598-019-50362-2.
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