mtDNA structure: the women who formed the Brazilian Northeast

Abstract

BackgroundThe distribution of mitochondrial DNA (mtDNA) lineages in Brazil is heterogeneous due to different regional colonization dynamics. Northeastern Brazil, although being an important region in terms of human imigration and ethnic admixture, has little information regarding its population mtDNA composition. Here, we determine which mitochondrial lineages contributed to the formation of the Northeastern Brazilian population. Our sample consisted of 767 individuals distributed as follows i) 550 individuals from eight Northeastern states (Piauí, Ceará, Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, and Bahia) which were sequenced for mtDNA hypervariable segments I, II, and III; ii) 217 individuals from Alagoas and Pernambuco (previously published data). Data analysis was performed through sequence alignment and Haplogrep 2.0 haplogroup assignment tools. Furthermore, maternal ancestry distribution was contextualized and, when possible, related to historical events to better understand the biological interactions and population dynamics that occurred in this region since the beginning of colonization.ResultsUnexpectedly, Amerindian mitochondrial ancestry was the highest in the Northeastern region overall, followed by African, European and non-Amerindian Asian, unlike previous results for this region. Alagoas and Pernambuco states, however, showed a larger African mtDNA frequency. The Northeastern region showed an intraregional heterogeneous distribution regarding ancestral groups, in which states/mesoregions located to the north had a prevalent Amerindian ancestral frequency and those to the south had predominance of African ancestry. Moreover, results showed great diversity of European haplogroups and the presence of non-Amerindian Asian haplogroups.ConclusionsOur findings are in disagreement with previous investigations that suggest African mitochondrial ancestry is the most prevalent in the Brazilian Northeast. The predominance of Amerindian lineages exemplifies the importance of indigenous women in the formation of the population, despite intense African slave entry and conflicts with European settlers. The variable distribution of ancestral groups observed in the Northeast is in accordance with historical records showing the similarities with colonization dynamics occurred in the Amazon region and the Brazilian Southeast. Moreover, the variety of European haplogroups suggests multiple origins of founding groups, specially those found in Western European populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-1027-7) contains supplementary material, which is available to authorized users.

New insights on intercontinental origins of paternal lineages in Northeast Brazil

“…Such small contributions of African and, ever more so, of Native American haplogroups are in accordance with Ychromosome data from other European colonies in South America, despite them being the majority in mtDNA studies (46)(47)(48)(49). In fact, previous mtDNA data obtained by Schaan et al (13) for the same samples demonstrated a strong Amerindian (43.5%) and African (37.8%) female component in Northeast Brazil. These findings attest to the strong asymmetric colonization favoring the introgression of European Y lineages in this region, a pattern that has been reported for other Brazilian regions and is typical for South American countries as well (50).…”

“…These samples are a subset of those previously investigated for mtDNA data. See Schaan et al (13) for biological material acquirement and DNA extraction methodology.…”

“…Indeed, previous data from maternal and paternal lineages (using both slow and fast evolving markers) has shown a strong male biased colonization of the Brazilian territory, with the majority of mitochondrial DNA (mtDNA) haplogroups being of Native American and African origin, while Y-chromosome lineages are overwhelmingly dominated by European haplogroups (7)(8)(9)(10)(11)(12)(13)(14). We have demonstrated heterogenous frequencies of mitochondrial Amerindian and African lineages in the Brazilian Northeast, which brought a new perspective to the understanding of the maternal ancestral contributions to this region (13). An insight into the paternal lineages of this same population is important to determine whether male contributions were also distinct from earlier reports and to what extent the numerous historical immigrations influenced the genetic architecture of this region (7,9).…”

Mapeamento por miscigenação em amostra de pacientes brasileiros com insuficiência cardíaca

“…Por outro lado, análises das regiões hipervariáveis do mtDNA revelaram uma realidade diferente: considerando o Brasil como um todo, 39% da ancestralidade materna é de origem europeia, 33% de origem ameríndia e 28% africana (Alves-Silva et al, 2000;Fridman et al, 2014;Schaan et al, 2017). Significativamente, a frequência de ancestralidade do mtDNA variou muito nas diferentes regiões: a maior porcentagem de ancestralidade materna ameríndia (54%) esteve presente na região Norte, enquanto que a ancestralidade africana é maior no Nordeste (44%) e a ancestralidade europeia é predominante no Sul (66%) (Alves-Silva et al, 2000).…”

“…Juntos, esses dados revelam que a contribuição genética europeia foi basicamente por meio dos homens, enquanto que a contribuição genética africana e ameríndia aconteceu, principalmente, pelas mulheres (Alves-Silva et al, 2000;Carvalho-Silva et al, 2001;Carvalho-Silva et al, 2006;Fridman et al, 2014;Pena et al, 2011;Resque et al, 2016;Schaan et al, 2017;Simão et al, 2018).…”