Gene frequencies of the HPA‐15 (Gov) platelet alloantigen system in Brazilians

Abstract

The HPA-15 (Gov) alloantigen is a biallelic co-dominant system on human platelets, and its allele HPA-15a and HPA-15b differ by an A-->C single nucleotide polymorphism at nucleotide 2108 of the coding sequence resulting in a Tyr682Ser substitution in the mature CD109 glycoprotein. Employing the polymerase chain reaction-restriction fragment length polymorphism technique, we determined the HPA-15 gene frequencies among 276 subjects of distinct Brazilian ethnic groups including, 15 Caucasians, 15 African Brazilians, 15 Orientals, 106 Amazon Xikrin Indians, 31 Amazon Gavioes Indians and 94 blood donors. The calculated HPA-15a and HPA-15b allele frequencies found in Caucasians (0.53/0.47), African Brazilians (0.57/0.43), Orientals (0.57/0.43) and Brazilian blood donors (0.52/0.48) did not differ significantly. However, the HPA-15a and HPA-15b gene frequencies of Xikrin Indians (0.78/0.22) were significantly different from that of all other groups (P < 0.01). The HPA-15a/a, HPA-15a/b and HPA-15b/b genotype frequencies observed in Gavioes Indians were significantly different from those seen in African Brazilians (P = 0.04) and blood donors (P = 0.017). The present data showed that the distribution of the HPA-15 (Gov) system alleles observed among the Brazilian population is quite similar to the distributions already reported among Asian, Canadian and European populations. Moreover, the data indicated differences in the frequency of the HPA-15 system between Amazon Indians and other distinct Brazilian ethnic groups suggesting that Amerindians would be at higher risk of HPA-15 alloimmunization in the need of receiving blood components collected from blood donors of other ethnic groups.

Frequency of human platelet antigens in oncohematological patients with thrombocytopenia and the probability of incompatibility to platelet transfusions

“…The result of the A allele on HPA-1, -2, -3, -4, -5 and -15 when compared to the results reported by Medeiros (16) for HPA -1, -2, -3, -4 and -5 and by Cardone (15) for HPA-15 presented no statistically significant differences as can be seen in Table 2.…”

“…The results for allele and genotype frequencies of this study were compared to the results obtained by Medeiros (16) , who determined the allele frequencies for HPA-1 to -13 using the SSP-PCR technique in 150 healthy blood donors of the Hemocentro de São Paulo (FPSHSP) and to the study of Cardone et al (15) for the frequency of HPA-15 in 139 individuals of which 94 were blood donors.…”

“…For participants with the AB genotype, that is with both alleles, the probability of incompatibility is either minimal or zero. The probabilities of incompatibility for participants with the AA genotype (IN AA ) and for those homozygous for B (IN BB ) were calculated in respect to the frequencies of donor genotypes as estimated by Medeiros (16) and Cardone (15) . The results are shown in Table 3.…”

“…The genotype and allele frequencies were estimated by direct counting and the result compared to values published for healthy Brazilian individuals (15,16) .…”

Molecular typing of human platelet antigens in immune thrombocytopenia patients in northern Brazil

“…In addition, the GPIa/IIa complex carries the HPA-5 (1600G>A), HPA-13w (2483C>T), HPA-18w (2235G>T) and HPA-25w (3347C>T) polymorphic systems 7, 8. Moreover, the HPA-15 (Gov) polymorphism is located in the CD109 molecule and its alleles differ at a single nucleotide polymorphism (C2108A) that causes a Tyr682Ser amino acid substitution 9, 10. These polymorphisms can be recognized as alloantigens or autoantigens and trigger the clearance of opsonized platelets by phagocytes in the reticuloendothelial system or inhibition of platelet production 11 .…”