Gene frequencies of the HPA-3 and HPA-5 platelet antigen alleles among theAmerindians

Platelet antigens are of importance in several clinical situations and in p opulation genetics. Data are scarce on allele frequencies in ethnic groups other than whites, Asians and African Americans. The frequencies of the all eles of the systems HPA-3 and HPA-5 were determined using the allele-specif ic restriction enzyme for five South-American Amerindian populations and co mpared with those obtained for Afro-Americans, Japanese and whites from Bra zil. The frequency of the HPA-3a allele among the Amerindians as a group di d not differ from the values obtained for the other populations. However, d ifferences were observed among the Amerindians, varying from 0.27 to 0.75, the highest frequency thus far observed for a population of Asian origin. O nly the HPA-5a allele was found among 130 Amerindian chromosomes. The deter mination of gene frequencies of the HPA systems in different populations al lows inference of gene flows and genetic constitution of populations and th e estimation of the risk of platelet-specific alloimmunization.