Abstract
Aims: Human platelet antigens (HPA) are involved in several clinical conditions, such as neonatal alloimmune thrombocytopenia (NAIT), platelet transfusion purpura (PTP), and refractoriness to platelet transfusion.The frequency of platelet antigens varies among populations. So far, typing of HPA systems has not been carried on Moroccan population. The frequencies of these antigens, their risk of alloimmunization, and their clinical implications and complications within Moroccan population are unknown. Our purpose is to define allele frequencies and genotypes in Moroccan population of the five HPA-1 to HPA-5 systems. Evaluate of the risk of anti-platelet alloimmunization among Moroccan blood donors, and estimate the mismatch probability of different platelet alloantigens, after random transfusions of platelet concentrates. Methods: The gene polymorphisms of HPA-1, -2, -3, -4, and -5 were determined by the PCRSSP technique on a DNA sample of 110 healthy Moroccan blood donors randomly chosen. Results: Alleles frequencies for the HPA systems were: HPA-1a: 0.704, HPA-2a: 0.709, HPA3a: 0.773, HPA-4a: 0.99, and HPA-5a: 0.760. The alleles were HPA-1b: 0.296, HPA-2b: 0.291, HPA-3b: 0.227, HPA-4b: 0.01, and HPA-5b: 0.240. The theoretical frequencies of descendants at risk of alloimmunization are ranged between 0.99% for HPA-4 to 20.76% for HPA-1. The estimated mismatch probability regarding platelet antigens HPA-1, -2, -3, -4, and –5 in Moroccan blood donors, after random platelet transfusion, varies from 1.96% for HPA-4, to 32.9% for HPA-1. Conclusion: Taking consideration of the previous studies, and our results, a clinical research associated with platelet disorders, such as: neonatal alloimmune thrombocytopenia (FNAIT), post transfusion purpura (PTP), and, multi-platelet transfusion refractoriness (MPR), are needed to ensure the proper diagnosis and the blood transfusion safety.
Highlights
Platelets are small (~1–2 μM) anucleate discoid cells that are abundantly (150 000–450 000/ μl) present in blood during normal health
Human platelet antigens (HPA) systems are classified into six biallelic systems, HPA-1, HPA-2, HPA-3, HPA-4, HPA-5, and HPA-15, and the other twenty three systems are monoallelic [6], all of which, were formed by single amino acid substitution, caused by a single nucleotide polymorphism (SNP) in the genes that encode them [7]
HPA-1, -2, -3, -4 and 5 systems were genotyped among 110 healthy unrelated blood donors from Regional Blood Transfusion Center of Casablanca
Summary
Platelets are small (~1–2 μM) anucleate discoid cells that are abundantly (150 000–450 000/ μl) present in blood during normal health. As the distribution of HPA varies between ethnic groups and in different geographical locations [5] studying the frequency of HPA in each population, will help in understanding the association between the alloimmunization to these antigens and its clinical consequences. Such information is important for the correct diagnosis and the administration of a safe transfusion therapy. The collective results were analyzed to evaluate the mismatch probabilities after transfusion of incompatible platelets in Moroccan population
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