Genetic signatures of parental contribution in black and white populations in Brazil

Two hundred and three individuals classified as white were tested for 11 single nucleotide polymorphisms plus two insertion/deletions in their Y-chromosomes. A subset of these individuals (n = 172) was also screened for sequences in the first hypervariable segment of their mitochondrial DNA (mtDNA). In addition, complementary studies were done for 11 of the 13 markers indicated above in 54 of 107 black subjects previously investigated in this southern Brazilian population. The prevalence of Y-chromosome haplogroups among whites was similar to that found in the Azores (Portugal) or Spain, but not to that of other European countries. About half of the European or African mtDNA haplogroups of these individuals were related to their places of origin, but not their Amerindian counterparts. Persons classified in these two categories of skin color and related morphological traits showed distinct genomic ancestries through the country. These findings emphasize the need to consider in Brazil, despite some general trends, a notable heterogeneity in the pattern of admixture dynamics within and between populations/groups

Meta-analysis of genome-wide association studies identifies 8 novel loci involved in shape variation of human head hair

Shape variation of human head hair shows striking variation within and between human populations, while its genetic basis is far from being understood. We performed a series of genome-wide association studies (GWASs) and replication studies in a total of 28 964 subjects from 9 cohorts from multiple geographic origins. A meta-analysis of three European GWASs identified 8 novel loci (1p36.23

Monomorphic and polymorphic enzyme genetic markers of the Waiãpi Indians of Amapá and of inhabitants of Manaus, Amazonas

One hundred nineteen Waiãpi Indians and 348 inhabitants of Manaus, Amazonas, were tested using nine enzyme genetic systems in the first population and two in the second. The Waiãpi showed some marked differences compared to South American Indian averages in ACP*A (1% vs. 14 ± 9%), GLO1*1 (9% vs. 30 ± 14%) and ESD*1 (99.6% vs. 70 ± 17%), while ESD*1 and CA2*1 prevalences in the Manaus population were within the range previously found in the northern region of Brazil (ESD*1: 85% vs. 80-94%; CA2*1: 98% vs. 89-99.8%). The almost identical frequencies obtained for these two markers in this population, when the sample was subdivided according to skin color, suggest that such morphological classifications have little value in this region. Genetic distances between the Waiãpi and other tribes, obtained using these and other genetic markers, showed good parallelism with the geographical distances which separate these Indians from the other groups considered.<br>Um total de 119 índios Waiãpi e 348 habitantes de Manaus, Amazonas, foram testados usando nove sistemas genéticos enzimáticos na primeira população e dois na segunda. Os Waiãpi mostraram algumas diferenças marcantes quanto às médias dos indígenas sul-americanos em ACP*A (1% vs. 14 ± 9%), GLO1*1 (9% vs. 30 ± 14%) e ESD*1 (99,6% vs. 70 ± 17%), enquanto as prevalências de ESD*1 e CA2*1 na população de Manaus mostraram-se dentro do intervalo encontrado previamente na região norte do Brasil (ESD*1: 85% vs. 80-94%; CA2*1: 98% vs. 89-99.8%). As freqüências quase idênticas obtidas para esses dois marcadores nesta população, quando a amostra foi subdividida de acordo com a cor da pele, sugerem que tais classificações morfológicas têm pouco valor nesta região. Distâncias genéticas entre os Waiãpi e outras tribos, obtidas usando esses e outros marcadores genéticos, mostraram bom paralelismo com as distâncias geográficas que separam esses índios dos outros grupos considerados

Frequency of CCR5delta32 in Brazilian populations

A sample of 103 randomly chosen healthy individuals from Alegrete, RS, Brazil, was tested for the CCR5delta32 allele, which is known to influence susceptibility to HIV-1 infection. The CCR5delta32 allele was identified by PCR amplification using specific primers flanking the region of deletion, followed by electrophoresis on a 3% agarose gel. The data obtained were compared to those reported for other populations and interpreted in terms of Brazilian history. The individuals studied came from a highly admixed population. Most of them were identified as white (N = 59), while blacks and browns (mulattoes) were N = 13 and N = 31, respectively. The observed frequencies, considering the white, black and brown samples (6.8, 3.8, and 6.4%, respectively), suggest an important European parental contribution, even in populations identified as black and brown. However, in Brazil as a whole, this allele shows gradients indicating a relatively good correlation with the classification based on skin color and other physical traits, used here to define major Brazilian population groups