Scientists from the University of São Paulo (USP) discovered that indigenous peoples living in the Amazon carry a mutation that increases their levels of protection against Chagas disease, transmitted by kissing bugs (triatomine bugs). With the variant in the PPP3CA gene, the risk of contracting severe forms of the disease is lower than that of other populations.
The mutation that confers greater resistance to the parasite trypanosoma cruzi it emerged approximately 7,500 years ago, when the indigenous peoples of the Amazon separated from the peoples of the Andes, according to mathematical modeling. The discovery would justify the fact that the disease is not endemic for groups in the Amazon forest and is for those who live in southern Peru and northern Chile.
Why do Amazonian indigenous people have greater protection against Chagas?
Published in the magazine Science Advances, the USP study analyzed 600,000 genome markers from 118 people, coming from 19 indigenous peoples — including inhabitants of the Brazilian Amazon. According to the authors, one of the variants of the PPP3CA gene that protects against Chagas disease was present in 80% of the analyzed individuals.
“When we analyze the endemic regions of the disease in South America, the area of the analyzed populations [na Amazônia] it is precisely where the disease least occurs. This could be due to a low frequency of the barber, but this is not the case, as this is where it has the greatest diversity. [e os casos são menos frequentes]”, explains Tábita Hünemeier, a professor at the Institute of Biosciences (IB-USP), in a statement.
Genetic variant can be found in other populations
In addition to the peoples of the Amazon, the variant is also present in other populations. However, the frequency is significantly lower. For example, it is found in 10% of Europeans and 59% of Africans. Even the authors of the study defend that the percentage is higher in Africa, because, there, there is a similar parasite, the Trypanosoma brucei, which causes sleeping sickness. In both cases, natural selection favored individuals with this ability.
Benefits of genetic mutation that protects against Chagas disease
“This factor probably led the ancestors of Amazonian indigenous people who had the protective variant to be less infected and to survive the disease longer, passing this trait on to their descendants”, says researcher Kelly Nunes about the impact of the mutation on their lives.
However, this is not the same as being 100% immune to disease. “It doesn’t mean that native Amazonian peoples never have Chagas, but those who are infected might not develop this chronic and even deadly phase as often”, reinforces Nunes on the findings of the discovery.
Source: Science Advances and FAPESP Agency