GENE-FREQUENCIES OF THE HPA-1 AND HPA-2 PLATELET ANTIGEN ALLELES AMONG THE AMERINDIANS

Background and objectives: Platelet-specific alloantigens are importan t in neonatal alloimmune thrombocytopenia, posttransfusion purpura, re fractoriness to platelet transfusions, and population genetics. Data a re scarce on allele frequencies in ethnic groups other than whites and Asians. Materials and methods: Using allele-specific restriction enzy me analysis, we studied the distribution of HPA-1 and HPA-2 alleles in six Brazilian Amazon tribes of Amerindians, belonging to five differe nt language stocks. We compared these with the values obtained for bla cks and whites. Results: Only the HPA-1a allele was found among 132 Am erindian chromosomes, compared with a gene frequency of HPA-1b of 0.11 5 and 0.133, respectively, among blacks and whites. The frequency of H PA-2b among the Amerindians (0.042) is lower than that obtained for bl acks and whites (0.148 and 0.100, respectively), and the lowest thus f ar observed in a population of Asian origin. Conclusion: Differences i n DNA polymorphisms in Amerindian populations have not only anthropolo gical and genetic interest, but also practical applications when they involve coding regions that may change the functional or immunologic f eatures of the protein.