Y-STR diversity and ethnic admixture in White and Mulatto Brazilian population samples

Abstract

We investigated 50 Mulatto and 120 White Brazilians for the Y-chromosome short tandem repeat (Y-STR) markers (DYS19, DYS390, DYS391, DYS392 and DYS393) and found 79 different haplotypes in the White and 35 in the Mulatto sample. Admixture estimates based on allele frequencies showed that the admixture of the white sample was 89% European, 6% African and 5% Amerindian while the Mulatto sample was 93% European and 7% African. Results were consistent with historical records of the directional mating between European males and Amerindian or African females. The Brazilian population is a result of interethnic crosses of Europeans, Africans and Amerindians, and is one of the most heterogeneous populations in the world. When the first European colonizers arrived (1500 AD), 1-5 million Amerindians already lived in the region that now is known as Brazil (Salzano and Callegari-Jacques, 1988). Before 1820, European colonization was almost exclusively composed of Portuguese while between 1820 and 1975 the great majority of immigrants were from Portugal and Italy, followed by a small number by people from Spain, Germany, Syria and Japan . Between the 16 th and 19th centuries approximately 3.5 million Africans were brought as slaves to Brazil, coming mainly from West, West-Central and Southeast Africa (Curtin, 1969). The colonization of Brazil involved mostly European men, many of whom produced children with Amerindian and African females.Although the classification of races is wrong from genetic standpoint (Templeton, 1998), Brazilians are classified for census purposes based on color. According to the last Brazilian government census of the 170 million Brazilians, 84 million were males, of which 52% were White, 39% were Brown, 6% were Black and 3% were classified in other categories (IBGE, 2000). Mulatto is the term commonly used in Brazil to designate the offspring result from the union of White and Black people. We used five Ychromosome short tandem repeat (Y-STR) markers, recognized as good markers for population studies, to investigate genetic polymorphism and ethnic admixture in White and Mulatto Brazilian population samples.We investigated 170 healthy, unrelated, individuals seeking paternity investigation at the Ribeirão Preto University Hospital, in the city of Ribeirão Preto, São Paulo state, Southeastern Brazil. The race of the individuals in the sample was determined based on their biomedical records, 120 individuals being White and 50 Mulatto, from Ribeirão Preto and the surrounding towns.We assessed the Y-STR loci DYS19, DYS390, DYS391, DYS392 and DYS393 (Kayser et al., 1997) using blood samples taken from the individuals in our sample, DNA being extracted by an adaptation of the protocol of Higuchi (1989). The PCR reactions were performed according to the conditions described by Kayser et al. (1997) and products separated using 10% denaturing polyacrylamide gel electrophoresis and visualized by silver staining (Sanguinetti et al., 1994). Allele designations were determined by comparison of the sample f...

TP53 codon 72 polymorphism in pigmentary phenotypes

“…Regarding skin colour, other studies demonstrated that Pro allele occurs at a high frequency in black (>60%) and the Arg allele in white-coloured (>70%) individuals (Själander et al 1996;Sucheston et al 2011). Our results could then be related to the ethnic admixture described in Brazilian population (Ferreira et al 2006). Although we have observed no association between TP53 codon 72 polymorfism and hair or eye colour, to the best our knowledge this is the first time reported for a Brazilian population sample.…”

Y-chromosomal STR haplotype diversity in males from Santa Catarina, Brazil

“…This value is higher than those found in other studies from the Brazilian population, based on five and eight Y-STR core markers. 11,18 Gene diversity values of these 16 Y-STR ranged from 0.5262 (DYS393) 7 to 0.8962 (DYS385). 7 The Neighbor-Joining Tree constructed from the FST values shows that Santa Catarina and Portuguese populations are in the same cluster.…”