Barreto, Mauricio Lima “Documento produzido em parceria ou por autor vinculado à Fiocruz, mas não consta à informação no documento”. Cibele C. Cesar1, Jackson S. Conceição2, Gustavo N.O. Costa2, Nubia Esteban3, Rosemeire L. Fiaccone2, Camila A. Figueiredo2, Josélia O.A. Firmo4, Andrea R.V.R. Horimoto3, Thiago P. Leal5, Moara Machado5, Wagner C.S. Magalhães5, Isabel Oliveira de Oliveira3, Sérgio V. Peixoto4, Maíra R. Rodrigues, Hadassa C. Santos3 & Thiago M. Silva2 1Universidade Federal de MinasGerais, Instituto de Ciências Exatas, Belo Horizonte, Brazil, 2Universidade Federal da Bahia, Instituto de Saúde Coletiva, Salvador, Brazil, 3Universidade de São Paulo, Instituto do Coração, São Paulo, Brazil, 4Fundação Oswaldo Cruz, Instituto de Pesquisas Rene Rachou, Belo Horizonte, Brazil, 5Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Belo Horizonte, BrazilDepartment of Science and Technology (DECIT,Ministry of Health) and National Fund for Scientific and Technological Development (FNDCT, Ministry of Science and Technology), Funding of Studies and Projects (FINEP, Ministry of Science and Technology, Brazil), Coordination of Improvement of Higher Education Personnel (CAPES, Ministry of Education, Brazil). MFLC, MLB, BLH, ACP, CGV, ETS, CBC, JOAF and SVP are supported by the Brazilian National Research Council (CNPq).Brazil never had segregation laws defining membership of an ethnoracial group. Thus, the composition of the Brazilian population is mixed, and its ethnoracial classification is complex. Previous studies showed conflicting results on the correlation between genome ancestry and ethnoracial classification in Brazilians. We used 370,539 Single Nucleotide Polymorphisms to quantify this correlation in 5,851 community-dwelling individuals in the South (Pelotas), Southeast (Bambui) and Northeast (Salvador) Brazil. European ancestry was predominant in Pelotas and Bambui (median = 85.3% and 83.8%, respectively). African ancestry was highest in Salvador (median = 50.5%). The strength of the association between the phenotype and median proportion of African ancestry varied largely across populations, with pseudo R(2) values of 0.50 in Pelotas, 0.22 in Bambui and 0.13 in Salvador. The continuous proportion of African genomic ancestry showed a significant S-shape positive association with self-reported Blacks in the three sites, and the reverse trend was found for self reported Whites, with most consistent classifications in the extremes of the high and low proportion of African ancestry. In self-classified Mixed individuals, the predicted probability of having African ancestry was bell-shaped. Our results support the view that ethnoracial self-classification is affected by both genome ancestry and non-biological factors.