Amazonian Populations Have Genetic Protection Against Chagas Disease

An international study led by the Institute for Evolutionary Biology (IBE-CSIC-UPF) and University of Sao Paulo, in collaboration with Harvard Medical School and the Department of Medicine and Life Sciences (MELIS) at the UPF, has discovered a genetic variant that confers resistance to Chagas infection in Amazonian populations.

The study, which analysed genomic data from 118 contemporary individuals from 19 different Amazonian populations, revealed that, before the arrival of Europeans, Amazonian populations acquired genetic adaptations that gave them resistance to infectious diseases, such as that caused by the Chagas pathogen, which allowed them to adapt to their lifestyle in the jungle.

“We focused on finding evidence of positive natural selection related to tropical diseases in the Americas.” Points out Tábita Hünemeier, Principal Investigator at the Institute of Evolutionary Biology (IBE-CSIC-UPF) who led the study.

Through genome analysis and functional studies, a variant of the PPP3CA gene has been identified at high frequency in the inhabitants of Amazonia, which reduces the risk of infection by the Chagas pathogen. The results of the study show that this variant, expressed in heart tissue and immune cells, decreases the internalisation of the parasite in cardiac cells.

“The presence of the PPP3CA gene variant could be the cause of milder disease or less infection in these populations.” Adds David Comas, Professor of Biology in the MELIS-UPF department, Principal Investigator at IBE (CSIC-Pompeu Fabra University) and co-author of the research.

“The presence of the PPP3CA gene variant could be the cause of milder disease or less infection in these populations.”

Natural selection for increased resistance to Chagas disease began 7,500 years ago, after populations in the Amazon separated from populations in the Andes and on the Pacific coast. This increased resistance to tropical diseases, as well as genes that determine novelty-seeking behavior, would have been an advantage for the lifestyle in the jungle, which would have helped fix these traits in the Amazonian population.

Reference: Couto-Silva CM, Nunes K, Venturini G, et al. Indigenous people from Amazon show genetic signatures of pathogen-driven selection. Sci Adv. 2023;9(10):eabo0234. doi: 10.1126/sciadv.abo0234

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