Abstract
In a large variety of genetic studies, probabilistic inferences are made based on information available in population databases. The accuracy of the estimates based on population samples are highly dependent on the number of chromosomes being analyzed as well as the correct representation of the reference population. For frequency calculations the size of a database is especially critical for haploid markers, and for countries with complex admixture histories it is important to assess possible substructure effects that can influence the coverage of the database. Aiming to establish a representative Brazilian population database for haplotypes based on 23 Y chromosome STRs, more than 2,500 Y chromosomes belonging to Brazilian, European and African populations were analyzed. No matter the differences in the colonization history of the five geopolitical regions that currently exist in Brazil, for the Y chromosome haplotypes of the 23 studied Y-STRs, a lack of genetic heterogeneity was found, together with a predominance of European male lineages in all regions of the country. Therefore, if we do not consider the diverse Native American or Afro-descendent isolates, which are spread through the country, a single Y chromosome haplotype frequency database will adequately represent the urban populations in Brazil. In comparison to the most commonly studied group of 17 Y-STRs, the 23 markers included in this work allowed a high discrimination capacity between haplotypes from non-related individuals within a population and also increased the capacity to discriminate between paternal relatives. Nevertheless, the expected haplotype mutation rate is still not enough to distinguish the Y chromosome profiles of paternally related individuals. Indeed, even for rapidly mutating Y-STRs, a very large number of markers will be necessary to differentiate male lineages from paternal relatives.
Highlights
From the genetic point of view, Brazil is known as one of the most heterogeneous population in the world, with an important genetic contribution from three main continental groups: Europeans, Africans and Native Americans.The first people arriving in Brazil were Europeans, coming mainly from Portugal, who arrived in 1500 to a territory that was already inhabited by the Native Americans for at least 11,000 years [1].During the slave trade period, which officially lasted from 1538 to 1850, a huge number of African people were forced to move to Brazil
We studied three reference samples from Native Americans, Europeans and Africans because they represent the main ancestral sources of modern Brazilian populations
The compiled data were used to compare the Y-STR haplotype genetic profiles of the 17 different admixed populations in Brazil grouped in 5 different geopolitical regions
Summary
From the genetic point of view, Brazil is known as one of the most heterogeneous population in the world, with an important genetic contribution from three main continental groups: Europeans, Africans and Native Americans.The first people arriving in Brazil were Europeans, coming mainly from Portugal, who arrived in 1500 to a territory that was already inhabited by the Native Americans for at least 11,000 years [1].During the slave trade period, which officially lasted from 1538 to 1850, a huge number of African people were forced to move to Brazil. From the genetic point of view, Brazil is known as one of the most heterogeneous population in the world, with an important genetic contribution from three main continental groups: Europeans, Africans and Native Americans. The first people arriving in Brazil were Europeans, coming mainly from Portugal, who arrived in 1500 to a territory that was already inhabited by the Native Americans for at least 11,000 years [1]. During the slave trade period, which officially lasted from 1538 to 1850, a huge number of African people were forced to move to Brazil. Approximately 3.6 million slaves are estimated to have entered the country [2,3]. The number of new incomers was approximately 6 million, coming from Portugal, Italy, Spain, Germany, Syria, Lebanon and Japan [4]
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