Worldwide diversity of the Y-chromosome tetra-local microsatellite DYS464.

Of all DNA markers on the human Y-chromosome, the tetra-local Y-linked microsatellite DYS464 is the most polymorphic. We genotyped DYS464 in 677 male samples collected worldwide, maintained in the HGDP-CEPH Human Genome Diversity Cell Line Panel. Fourteen different alleles were found, with allele lengths varying from 9 to 23 repeats. One hundred and seventy-five different genotypes were detected, of which 90 appeared to be continent-specific. The region with the highest percentage of unique genotypes was Africa. Genotype diversity was 0.98 for Europe, 0.97 for Central and East Asia, 0.95 for Africa, 0.94 for Oceania, 0.92 for the Middle East, and 0.90 for the Americas. A hierarchical analysis of molecular variance showed low levels of worldwide genetic structure; 88.42% of the genetic variance was found within populations, 9.62% between populations within regions and 1.96% between regions. Since the four DYS464 repeats are identical, one cannot assign each peak in the electropherogram to a specific locus. Thus, the same genotype may correspond to several haplotypes, with different permutations of alleles. Consequently, genotypes are degenerate, which limits phylogeographical analyses. Yet, because of its high variability, DYS464 still constitutes an informative tool for population and evolutionary studies.

The Iberian legacy into a young genetic xeroderma pigmentosum cluster in central Brazil.

In central Brazil, in the municipality of Faina (state of Goiás), the small and isolated village of Araras comprises a genetic cluster of xeroderma pigmentosum (XP) patients. The high level of consanguinity and the geographical isolation gave rise to a high frequency of XP patients. Recently, two founder events were identified affecting that community, with two independent mutations at the POLH gene, c.764 + 1 G > A (intron 6) and c.907 C > T; p.Arg303* (exon 8). These deleterious mutations lead to the xeroderma pigmentosum variant syndrome (XP-V). Previous reports identified both mutations in other countries: the intron 6 mutation in six patients (four families) from Northern Spain (Basque Country and Cantabria) and the exon 8 mutation in two patients from different families in Europe, one of them from Kosovo. In order to investigate the ancestry of the XP patients and the age for these mutations at Araras, we generated genotyping information for 22 XP-V patients from Brazil (16), Spain (6) and Kosovo (1). The local genomic ancestry and the shared haplotype segments among the patients showed that the intron 6 mutation at Araras is associated with an Iberian genetic legacy. All patients from Goiás, homozygotes for intron 6 mutation, share with the Spanish patients identical-by-descent (IBD) genomic segments comprising the mutation. The entrance date for the Iberian haplotype at the village was calculated to be approximately 200 years old. This result is in agreement with the historical arrival of Iberian individuals at the Goiás state (BR). Patients from Goiás and the three families from Spain share 1.8 cM (family 14), 1.7 cM (family 15), and a more significant segment of 4.7 cM within family 13. On the other hand, the patients carrying the exon 8 mutation do not share any specific genetic segment, indicating an old genetic distance between them or even no common ancestry.

Study of the cytogenetic effects of occupational exposure to pesticides on sanitation workers in Belo Horizonte, Brazil.

Sanitation workers handling pesticides in the control of disease vectors constitute an occupationally exposed population to genotoxic substances. The aim of the present study was to investigate the relation between the occupational exposure to various pesticides and the presence of cytogenetic damage. Fifty-nine men were selected (29 sanitation workers and 30 control individuals) with ages varying between 18-57 years who lived and worked in the same area in Belo Horizonte (Brazil). The following parameters were determined for all individuals using the cytokinesis-block micronucleus (MN) assay in peripheral blood lymphocytes: MN/1000 binucleated cells (BC), BC with MN (BCMN)/1000 BC, nucleoplasmic bridges (NB)/1000 BC, apoptotic and necrotic cells/500 cells and nuclear division index. The analysis of covariance showed significantly higher (p < 0.05) mean frequencies of MN (15.81 +/- 1.31 vs 4.71 +/- 0.42), BCMN (15.10 +/- 1.22 vs 4.62 +/- 0.44), NB (4.59 +/- 0.76 vs 1.00 +/- 0.34), and necrotic cells (12.07 +/- 1.45 vs 5.17 +/- 0.70) in the exposed group when compared to the control group. There was no significant difference in the apoptotic cell frequency between the two groups, while the nuclear division index was significantly lower (1.49 +/- 0.02 vs 1.61 +/- 0.02) in the control group. Neither the time of exposure nor the smoking or alcohol drinking habit influenced the cytogenetic parameters examined. According to these results, occupational exposure to pesticides induced genotoxic and cytotoxic effects in sanitation workers.

Study of the cytogenetic effects of occupational exposure to pesticides on sanitation workersin Belo Horizonte, Brazil

Sanitation workers handling pesticides in the control of disease vectors constitute an occupationally exposed population to genotoxic substances. The aim of the present study was to investigate the relation between the occupational exposure to various pesticides and the presence of cytogenetic damage. Fifty-nine men were selected (29 sanitation workers and 30 control individuals) with ages varying between 18-57 years who lived and worked in the same area in Belo Horizonte (Brazil). The following parameters were determined for all individuals using the cytokinesis-block micronucleus (MN) assay in peripheral blood lymphocytes: MN/1000 binucleated cells (BC), BC with MN (BCMN)/1000 BC, nucleoplasmic bridges (NB)/1000 BC, apoptotic and necrotic cells/500 cells and nuclear division index. The analysis of covariance showed significantly higher (p < 0.05) mean frequencies of MN (15.81 ± 1.31 vs 4.71 ± 0.42), BCMN (15.10 ± 1.22 vs 4.62 ± 0.44), NB (4.59 ± 0.76 vs 1.00 ± 0.34), and necrotic cells (12.07 ± 1.45 vs 5.17 ± 0.70) in the exposed group when compared to the control group. There was no significant difference in the apoptotic cell frequency between the two groups, while the nuclear division index was significantly lower (1.49 ± 0.02 vs 1.61 ± 0.02) in the control group. Neither the time of exposure nor the smoking or alcohol drinking habit influenced the cytogenetic parameters examined. According to these results, occupational exposure to pesticides induced genotoxic and cytotoxic effects in sanitation workers.