When the major human genome sequencing projects began at the end of last century, it was thought that the differences in our genetic makeups would be minimal and would be concentrated within the genes. By combining samples from a few individuals, with no concern for population diversity, one of the goals was to obtain a standard, reference genome for humankind.
Along the way, an unexpected discovery was made: humans have far fewer genes than previously thought. A greater emphasis was placed on sections of the genome responsible for activating protein-coding genes, and it became clear that even noncoding DNA performs important functions.
Technological advances have made it possible to identify millions of small changes in the genome—these small errors, known as SNPs, occur when one of the nucleotides (A, T, C, or G) in a person’s DNA changes place. Depending on the location, these variations can alter the shape and function of proteins or the activation and deactivation pattern of the genes that encode them. They can be shared by certain populations and have consequences on health, such as the propensity to develop a particular disease and the way the body reacts to a medication.
A better understanding of the genetic diversity of Brazilians means we can see the history of how the country was formed through the prism of the population’s ancestry—a mix of Indigenous, European, and African. It also allows the country to make advances in precision medicine by identifying variants associated with the most common diseases in different regions of the country or population groups. With this objective, the Ministry of Health’s Department of Science and Technology launched the National Genomics and Precision Health Program (Genomas Brasil) in 2019.
The program is the subject of a study published in Science that detailed the Brazilian profile by sequencing the DNA of 2,700 people from all regions of the country. The scientific article was covered in the press, but the topic deserves more in-depth attention. Maria Guimarães, our editor of biological sciences, takes readers along the path taken toward our understanding of the relevance of genetic diversity, specifically through the steps needed to develop the genomic profile of the Brazilian population and to make it viable to apply in the national health system.
On this subject, it is important to highlight the pioneering work of geneticist Sergio Danilo Pena in his research on the genetic origins of the Brazilian people. When contacted, he declined to comment on the article for our report, saying that his work would speak for itself. The interview he gave us in 2021 is worth a read (see Pesquisa FAPESP issue nº 306).
To illustrate the report and this issue’s cover, we delved into the archive of photographer Luiz Braga, from Pará. His exhibition Arquipélago imaginário (Imaginary archipelago), on display at the Moreira Salles Paulista Institute, presents what Braga calls a “cartography of lives,” which translates the miscegenation recorded within the cells of Brazilians into images.
Diversity (of topics) is a hallmark of this magazine, and this issue is not limited to the human genome. Some of the possible highlights, depending on your perspective, include the importance of specific Indigenous practices in cassava farming to maintain genetic varieties and food security; an ancestral shock that led to the planet Mercury having a core proportionally much larger than Earth’s; and the testimony of a computer scientist who discovered he was autistic at the age of 54. Finally, the anthropology of backyards, such magical and unique spaces.
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