Frequency of human platelet antigens (HPA) in the Greek population as deduced from the first registry of HPA-typed blood donors

Background and Objectives: Human platelet antigens (HPA) play a central role in foetal and neonatal alloimmune thrombocytopenia (FNAIT), post-transfusion purpura and some cases of platelet therapy refractoriness. The frequency distribution of HPA had not been studied in the Greek population before we started to create a registry of HPA-typed apheresis platelet donors. The aim of this study was the determination of the frequency of various HPA in the Greek population, through the establishment of a registry of typed donors. Materials and Methods: Here, we report on the first 1000 platelet donors of Greek origin who gave informed consent and were genotyped for 12 pairs of antithetical HPA by Single Specific Primer-Polymerase Chain Reaction (SSP-PCR), including HPA-1, HPA-3, HPA-5 and HPA-15. Antigen frequencies are reported, and allele frequencies were calculated and compared with other European and non-European populations. Tested donors cover all ABO and Rhesus D antigen spectrum. Results: Antigen and allele frequencies are very similar to other White populations. The frequency of HPA-1bb is 2.9% in our study, and the frequency of HPA-2b, HPA-4b, HPA-9b and HPA-15b is also slightly higher than in other literature reports, while the frequency of HPA-15b was found higher than that of HPA-15a. Conclusion: We report antigen and allele frequencies for a large array of clinically significant HPA for the first time in the Greek population. Frequencies are consistent with other European populations. This registry of HPA-typed platelet donors, available to donate on demand, is an important asset for the treatment of FNAIT cases in Greece.