Study of the frequency of human platelet antigen-1 in Egyptian thrombocytopenic patients with hematologic disorders

Patients undergoing treatment for hematological disorders associated with thrombocytopenia are at increased risk of developing platelet transfusion refractoriness when receiving prophylactic platelet concentrates. Human platelet antigens (HPAs), which arise from polymorphisms in platelet membrane glycoproteins, play a major role in alloimmunization and transplant rejection, with the HPA-1 system being the most clinically significant. This study aimed to determine the allele and genotype distribution of HPA-1 among Egyptian healthy donors and thrombocytopenic patients with hematologic diseases and to explore the possible association between specific HPA variants, alloimmunization, and platelet transfusion refractoriness. A total of 50 thrombocytopenic patients with hematologic disorders were compared with 50 healthy blood donors, and HPA-1 genotyping was performed using the PCR-restriction fragment length polymorphism method. The most common genotype among patients was HPA-1a/1a (58%), followed by HPA-1a/1b (38%) and HPA-1b/1b (4%), with allele frequencies of 77% for 1a and 23% for 1b. Patients homozygous for the 1b allele showed a higher likelihood of antigen incompatibility after platelet transfusion, making them more susceptible to alloimmunization and refractoriness. Consistent with earlier Egyptian studies, our findings confirm that the HPA-1a allele is more prevalent than the 1b allele in the Egyptian population, suggesting that individuals with the 1b/1b genotype are at greater risk of immune-mediated transfusion refractoriness. These results highlight the clinical significance of platelet genotyping in diagnosing alloimmune thrombocytopenia and optimizing the selection of antigen-matched platelet units to improve transfusion outcomes.