STR data for 15 autosomal STR markers from Paraná (Southern Brazil).

Allelic frequencies for 15 STR autosomal loci, using AmpFℓSTR® Identifiler™, forensic, and statistical parameters were calculated. All loci reached the Hardy-Weinberg equilibrium. The combined power of discrimination and mean power of exclusion were 0.999999999999999999 and 0.9999993, respectively. The MDS plot and NJ tree analysis, generated by FST matrix, corroborated the notion of the origins of the Paraná population as mainly European-derived. The combination of these 15 STR loci represents a powerful strategy for individual identification and parentage analyses for the Paraná population.

Population data of 17 Y-STR loci from Rio Grande do Sul state (South Brazil).

A sample of 255 Brazilian males from Rio Grande do Sul (RS), the Brazilian southernmost state, was typed for 17 Y-STR loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, YGATA_H4.1 and DYS385ab). A total of 247 haplotypes were identified, of which 239 were unique and eight were found in two individuals each. The haplotype diversity (99.98%) and discrimination capacity (96.86%) were calculated. Pairwise haplotype distances showed that the RS population is not significantly different from Brazil, Rio de Janeiro, and Argentina, is different from São Paulo, Italy, and North Portugal, and is very distant from Spain, the Amazon region, Germany, and South Amerindians. When the RS data was separated in the seven geopolitical regions, some pairs of regions were significantly different; however no region was different from the whole Brazilian sample.

Linkage disequilibrium patterns and genetic structure of Amerindian and non-Amerindian Brazilian populations revealed by long-range X-STR markers.

The extent of X-chromosome linkage disequilibrium (LD) was studied in a southern Brazilian population, and in a pool of samples from Amerindian populations. For this purpose, 11 microsatellites, located mostly in a Xq region comprising approximately 86 Mb was investigated. The lower Amerindian gene diversity associated with significant differences between the populations studied indicated population structure as the main cause for the higher LD values in the Amerindian pool. On the other hand, the LD levels of the non-Amerindian Brazilian sample, although less extensive than that of the Amerindians, were probably determined by admixture events. Our results indicated that different demographic histories have significant effects on LD levels of human populations, and provide a first approach to the X-chromosome ancestry of Amerindian and non-Amerindian Brazilian populations, being valuable for future studies involving mapping and population genetic studies.

A single SNP in an evolutionary conserved region within intron 86 of the HERC2 gene determines human blue-brown eye color.

We have previously demonstrated that haplotypes of three single nucleotide polymorphisms (SNPs) within the first intron of the OCA2 gene are extremely strongly associated with variation in human eye color. In the present work, we describe additional fine association mapping of eye color SNPs in the intergenic region upstream of OCA2 and within the neighboring HERC2 (hect domain and RLD2) gene. We screened an additional 92 SNPs in 300-3000 European individuals and found that a single SNP in intron 86 of HERC2, rs12913832, predicted eye color significantly better (ordinal logistic regression R(2) = 0.68, association LOD = 444) than our previous best OCA2 haplotype. Comparison of sequence alignments of multiple species showed that this SNP lies in the center of a short highly conserved sequence and that the blue-eye-associated allele (frequency 78%) breaks up this conserved sequence, part of which forms a consensus binding site for the helicase-like transcription factor (HLTF). We were also able to demonstrate the OCA2 R419Q, rs1800407, coding SNP acts as a penetrance modifier of this new HERC2 SNP for eye color, and somewhat independently, of melanoma risk. We conclude that the conserved region around rs12913832 represents a regulatory region controlling constitutive expression of OCA2 and that the C allele at rs12913832 leads to decreased expression of OCA2, particularly within iris melanocytes, which we postulate to be the ultimate cause of blue eye color.

Y-STR analysis in Brazilian and South Amerindian populations.

A sample of 203 Brazilian males from Rio Grande do Sul (RS), the Brazilian southernmost state, was typed for 11 Y-STR markers (DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS385, DYS437, DYS438, and DYS439). We also typed 42 individuals from two South Amerindian tribes (Kaingang and Guarani) to use the data as parental Amerindian contribution to our analyses. Gene and haplotypic diversities were estimated, with the South Amerindian samples showing smaller values for these parameters than Brazilians. To obtain a more comprehensive picture of the genetic structure of the Brazilian population as a whole, the Y-STR data from the RS sample was compared with those already published. No genetic substructuring was observed in the comparisons performed. Multidimensional scaling confirmed the proposed European source of most Y-chromosome Brazilian patrilineages.

Results of the 2003-2004 GEP-ISFG collaborative study on mitochondrial DNA: focus on the mtDNA profile of a mixed semen-saliva stain.

We report here a review of the seventh mitochondrial DNA (mtDNA) exercise undertaken by the Spanish and Portuguese working group (GEP) of the International Society for Forensic Genetics (ISFG) corresponding to the period 2003-2004. Five reference bloodstains from five donors (M1-M5), a mixed stain of saliva and semen (M6), and a hair sample (M7) were submitted to each participating laboratory for nuclear DNA (nDNA; autosomal STR and Y-STR) and mtDNA analysis. Laboratories were asked to investigate the contributors of samples M6 and M7 among the reference donors (M1-M5). A total of 34 laboratories reported total or partial mtDNA sequence data from both, the reference bloodstains (M1-M5) and the hair sample (M7) concluding a match between mtDNA profiles of M5 and M7. Autosomal STR and Y-STR profiling was the preferred strategy to investigate the contributors of the semen/saliva mixture (M6). Nuclear DNA profiles were consistent with a mixture of saliva from the donor (female) of M4 and semen from donor M5, being the semen (XY) profile the dominant component of the mixture. Strikingly, and in contradiction to the nuclear DNA analysis, mtDNA sequencing results yield a more simple result: only the saliva contribution (M4) was detected, either after preferential lysis or after complete DNA digestion. Some labs provided with several explanations for this finding and carried out additional experiments to explain this apparent contradictory result. The results pointed to the existence of different relative amounts of nuclear and mtDNAs in saliva and semen. We conclude that this circumstance could strongly influence the interpretation of the mtDNA evidence in unbalanced mixtures and in consequence lead to false exclusions. During the GEP-ISFG annual conference a validation study was planned to progress in the interpretation of mtDNA from different mixtures.

STR data for 09 autosomal STR markers from Rio Grande do Sul (southern Brazil).

Allele frequencies for 09 STR autosomal loci (D3S1358, D5S818, D7S820, D8S1179, D13S317, D18S51, D21S11, FGA and VWA) included in the AmpFlSTR Profiler Plus were obtained from a sample of unrelated individuals from Rio Grande do Sul (southern Brazil).