Frequency of platelet-specific alloantigens in a Danish population

This study reports the first data on gene frequencies of platelet alloantigens HPA-1, HPA-2, HPA-3, HPA-4 and HPA-5 in a population of unrelated Danish blood donors using PCR-techniques. The observed gene frequencies fit the Hardy-Weinberg equilibrium, and the calculated phenotype frequencies are similar to those obtained in other Caucasian populations: HPA-1a and -1b occur in 96.6% and 30.3% of 557 unrelated respectively. HPA-2a and -2b in 99.4% and 15.9% of 163 tested, HPA-3a and -3b in 88.3% and 63.2% of 163 tested, HPA-4a and -4b in 100% and 0% of 131 tested, and finally HPA-5a and -5b in 100% and 15.7% of 427 tested. It is a major technical improvement to use PCR techniques for genomic typing of HPA. Not only is it possible to perform HPA typings in severely thrombocytopenic patient and on amniotic fluid cells of the fetus of alloimunized mothers, but it must be expected that accuracy of the HPA typing will increase considerably, as has been the case with genomic HLA class II typing. Finally, use of PCR technique combined with allele-specific primers is suitable for accurate large scale typing of platelet donors, which may be useful in special clinical settings.