Impacto da miscigenaÃÃo na aplicaÃÃo do HapMap para a populaÃÃo brasileira avaliados nos genes PTPN22 e VDR

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The PTPN22 and VDR genes are commonly associated to several autoimmune diseases and complex phenotypes related to bone metabolism. The association of some of those polymorphisms are ethnic-specific, and therefore, admixture population studies must be conditionally evaluated to these factors. The Brazilian population is considered the most heterogeneous in the world and their genetic association studies must be controlled to the stratified levels of ancestry proportions. Linkage disequilibrium is a genetic statistic method to detect association with candidate genes by haplotype blocks. The aim of the present work was to estimate the admixture contribution levels of the Brazilian population, to evaluate the linkage disequilibrium patterns of PTPN22 and VDR genes and to investigate the effects of ancestry proportions on these genes. For that, 200 non-related Brazilian individuals, separated by geographic region were genotyped for 34 ancestry informative markers, six SNPs in the PTPN22 gene and 21 in the VDR gene by single base extension method (SNaPshotâ â Applied Biosystems). The results showed that the markers were able to assign 19,5% of African ancestry proportion and 80,5% of European to the Brazilian population, however they were unable to assign correctly the Amerindian proportion. The PTPN22 gene showed high genetic ancestry influence on the distribution of haplotypes, while the VDR gene showed a similar haplotype block pattern to those described to European population. The transferability of tagSNPs among HapMap populations to Brazilian population was divergent and uncertain for the two genes, with high loss of variability in the PTPN22 gene using tagSNPs of the European derived population and, to the VDR gene, there was higher loss of variability when using the tagSNPs selected for African or Asian derived populations. This indicates that the use of tagSNPs should not be generalized in the Brazilian population. The information generated at this work may contribute to several prospective genetic association studies involving the PTPN22 and VDR genes, and also as a base for population stratification studies in admixture populations.

ASSUNTO(S)

populaÃÃo brasileira genÃtica; genes; miscigenaÃÃo; populaÃÃo brasileira vdr desequilÃbrio de ligaÃÃo, haplÃtipos ptpn22 brazilian population genetica haplotypes linkage disequilibrium snp

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