A registry of human platelet antigen (HPA)–typed platelet donors who are available to provide on-demand blood donations is a key resource in the treatment of fetal and neonatal alloimmune thrombocytopenia (FNAIT) in Greece, according to findings from a study published recently inVox Sanguinis.
It is well recognized that HPAs play a fundamental role in the development of FNAIT and posttransfusion purpura, as well as platelet refractoriness in some situations. Prior to the initiation of the presently described registry of HPA-typed apheresis platelet donors, in which donors have their blood separated into its various components, the frequency distribution of HPA had not yet been evaluated in the Greek population.
The researchers of the current analysis sought to determine the frequency of various HPAs in the population of Greece via the establishment of a registry of voluntary, uncompensated typed platelet donors. This is an integral part in the timely, successful treatment of patients with FNAIT, because these donors can be called upon to donate blood upon request, based on optimal combined HPA, ABO, and Rhesus D antigen (RhD) compatibility.
Beginning in 2019, all of the blood donors who visited the Blood Center at AHEPA University General Hospital of Thessaloniki, located in Thessaloniki, Greece, were provided with information regarding the aims of the proposed registry. Most of these individuals offered informed written consent to be HPA-typed and provided an additional blood sample for this procedure.
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Each of the donors underwent genotyping for antithetical antigens (HPA-1 through HPA-35). Antigen frequencies were computed, as were allele frequencies. The results obtained were compared with published reports with respect to other European populations, as well as non-European populations.
The current study reports on the initial 1000 platelet donors of Greek origin who provided their informed consent. These individuals were then genotyped for 12 pairs of antithetical HPA antigens via the use of single specific primer–polymerase chain reaction. Included among the HPAs typed were HPA-1, HPA-3, HPA-5 and HPA-15.
Study results showed that antigen and allele frequencies in Greece are very similar to those in other countries with majority White populations. In the present analysis, the frequency of HPA-1bb was 2.9%. Additionally, the frequencies of HPA-2b, HPA-4b, HPA-9b, and HPA-15b were somewhat higher than those in literature reports regarding other populations. Of note, the frequency of HPA-15b was shown to be higher than the frequency of HPA-15a.
“This is the first study, to the best of our knowledge, investigating antigen and allele frequency of . . . HPA in the Greek population,” the authors stated. “The allele frequencies found in this registry are similar to [those in] other European populations; however, a slightly higher frequency of HPA-1bb could indicate an increased risk [for] . . . [FNAIT] cases in Greece due to HPA-1a alloimmunization.”
