News | Brazil unveils its largest-ever human genome database, revealing disease risks and population history
Since the human genome was first fully decoded in 2003, scientists have continued trying to interpret this “book of life written with only four letters.” Yet most global genomic data still lack population diversity, leaving many ethnic groups underrepresented in precision medicine and evolutionary research.
An international study jointly led by Spain’s Institute of Evolutionary Biology (IBE) and the University of São Paulo in Brazil has helped fill this gap by decoding large-scale whole-genome data from Brazil’s population for the first time. Published in Science, the findings reveal genetic patterns in this highly diverse population, helping identify disease risks and trace 500 years of ancestry and migration in Brazil.
More than 2,700 complete genomes across five regions
The team completed high-coverage whole-genome sequencing for 2,723 people from urban, rural, and riverside communities across Brazil, representing the three main ancestry groups: African, European, and Indigenous American. This is Brazil’s largest genomic database to date. It identified more than 8 million previously unknown genetic variants, 36,637 of which may be harmful to health.
Lead scientist and IBE professor Tábita Hünemeier said: “Brazil has the richest African ancestry in the Americas, combined with a highly admixed population. Genomic research reveals not only disease risks but also our past.”
Potential disease variants in 450 heart- and obesity-related genes and 815 infectious-disease variants
Lead author and University of São Paulo postdoctoral researcher Marcos Araújo Castro e Silva said the study found potentially pathogenic mutations in 450 genes associated with heart disease and obesity, as well as 815 variants related to malaria, hepatitis, influenza, tuberculosis, salmonella infection, and leishmaniasis.
These findings may help explain why some people are more susceptible to infection or disease and provide a data foundation for future public-health interventions in Brazil.
How do genes record 500 turbulent years of Brazilian history?
The study estimated that Brazil’s population is approximately 60% European, 27% African, and 13% Indigenous American by ancestry. African ancestry is more prevalent in the north, while European ancestry predominates in the south.
However, the researchers noted that this ancestry distribution is disproportionate to historical Indigenous and African population shares because of strongly asymmetric mating patterns early in the colonial period.
The data show:
71% of Y chromosomes, inherited through the paternal line, came from European men
42% of mitochondrial DNA, inherited through the maternal line, came from African women and 35% from Indigenous American women
This reflects a history from the 16th to 18th centuries in which male European colonists systematically fathered children with Indigenous and African women. Modern society has gradually shown a greater tendency toward marriage within ancestry groups.
Genetic adaptation and natural selection: rapid evolution over nearly 500 years
The team also found variants retained through natural selection over recent centuries, involving fertility, immune responses, and metabolic regulation.
“Natural selection usually takes thousands of years, but in a highly admixed society such as Brazil, substantial adaptive genetic evolution occurred in only 500 years,” researcher David Comas said. This was partly driven by selection pressures as newcomers encountered tropical diseases.
Health implications: some pathogenic mutations are ancestry-related, but this is not about racial differences
Some high-risk variants were more common in people with Indigenous or African ancestry, but the team stressed that this does not mean these groups are inherently more prone to disease. Rather, they have long been underrepresented in global genomic databases, making their mutations appear rarer or less familiar in the data.
Another key mechanism is the “founder effect”:
Machado-Joseph Disease, for example, is rare in Europe but common in parts of Brazil. The study suggests this may reflect the influence of a small number of Portuguese immigrants and settlers with Northern European ancestry on later generations.
Indigenous genomic data remain scarce, but can be partly reconstructed from modern admixed populations
Although samples from modern Indigenous groups are limited, the team said that analyzing the genomes of today’s admixed populations can partly reconstruct Indigenous American genetic information, with important implications for anthropology and medicine.
“We are not only learning about health risks in Brazil; we are assembling an important piece of the broader puzzle of human migration and evolution,” Hünemeier concluded.
News | Brazil unveils its largest-ever human genome database, revealing disease risks and population history
News | Brazil unveils its largest-ever human genome database, revealing disease risks and population history
Since the human genome was first fully decoded in 2003, scientists have continued trying to interpret this “book of life written with only four letters.” Yet most global genomic data still lack population diversity, leaving many ethnic groups underrepresented in precision medicine and evolutionary research.
An international study jointly led by Spain’s Institute of Evolutionary Biology (IBE) and the University of São Paulo in Brazil has helped fill this gap by decoding large-scale whole-genome data from Brazil’s population for the first time. Published in Science, the findings reveal genetic patterns in this highly diverse population, helping identify disease risks and trace 500 years of ancestry and migration in Brazil.
More than 2,700 complete genomes across five regions
The team completed high-coverage whole-genome sequencing for 2,723 people from urban, rural, and riverside communities across Brazil, representing the three main ancestry groups: African, European, and Indigenous American. This is Brazil’s largest genomic database to date. It identified more than 8 million previously unknown genetic variants, 36,637 of which may be harmful to health.
Lead scientist and IBE professor Tábita Hünemeier said: “Brazil has the richest African ancestry in the Americas, combined with a highly admixed population. Genomic research reveals not only disease risks but also our past.”
Potential disease variants in 450 heart- and obesity-related genes and 815 infectious-disease variants
Lead author and University of São Paulo postdoctoral researcher Marcos Araújo Castro e Silva said the study found potentially pathogenic mutations in 450 genes associated with heart disease and obesity, as well as 815 variants related to malaria, hepatitis, influenza, tuberculosis, salmonella infection, and leishmaniasis.
These findings may help explain why some people are more susceptible to infection or disease and provide a data foundation for future public-health interventions in Brazil.
How do genes record 500 turbulent years of Brazilian history?
The study estimated that Brazil’s population is approximately 60% European, 27% African, and 13% Indigenous American by ancestry. African ancestry is more prevalent in the north, while European ancestry predominates in the south.
However, the researchers noted that this ancestry distribution is disproportionate to historical Indigenous and African population shares because of strongly asymmetric mating patterns early in the colonial period.
The data show:
71% of Y chromosomes, inherited through the paternal line, came from European men
42% of mitochondrial DNA, inherited through the maternal line, came from African women and 35% from Indigenous American women
This reflects a history from the 16th to 18th centuries in which male European colonists systematically fathered children with Indigenous and African women. Modern society has gradually shown a greater tendency toward marriage within ancestry groups.
Genetic adaptation and natural selection: rapid evolution over nearly 500 years
The team also found variants retained through natural selection over recent centuries, involving fertility, immune responses, and metabolic regulation.
“Natural selection usually takes thousands of years, but in a highly admixed society such as Brazil, substantial adaptive genetic evolution occurred in only 500 years,” researcher David Comas said. This was partly driven by selection pressures as newcomers encountered tropical diseases.
Health implications: some pathogenic mutations are ancestry-related, but this is not about racial differences
Some high-risk variants were more common in people with Indigenous or African ancestry, but the team stressed that this does not mean these groups are inherently more prone to disease. Rather, they have long been underrepresented in global genomic databases, making their mutations appear rarer or less familiar in the data.
Another key mechanism is the “founder effect”:
Machado-Joseph Disease, for example, is rare in Europe but common in parts of Brazil. The study suggests this may reflect the influence of a small number of Portuguese immigrants and settlers with Northern European ancestry on later generations.
Indigenous genomic data remain scarce, but can be partly reconstructed from modern admixed populations
Although samples from modern Indigenous groups are limited, the team said that analyzing the genomes of today’s admixed populations can partly reconstruct Indigenous American genetic information, with important implications for anthropology and medicine.
“We are not only learning about health risks in Brazil; we are assembling an important piece of the broader puzzle of human migration and evolution,” Hünemeier concluded.
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