Genotyping for human platelet alloantigen polymorphisms: applications in the diagnosis of alloimmune platelet disorders.
ABSTRACT Molecular typing for platelet allelic polymorphisms was first made possible by discovery of the HPA-1a/1b single nucleotide polymorphism in 1989. Since then, six other biallelic human platelet antigen (HPA) systems have been determined and can be typed using genomic DNA. The introduction of polymerase chain reaction enabled development of several different assays including polymerase chain reaction-sequence-specific primer, melting curve analysis by LightCycler, and 5'-nuclease assays. More recently, multiplex polymerase chain reaction has allowed for the development of high-throughput assays for genotyping large numbers of patients and blood donors for not only platelet gene polymorphisms but also for those of other blood cell genes. Platelet genotyping is a valuable tool in confirming platelet antigen specificities of alloantibodies detected in patient sera to complement the clinical history in the diagnosis of alloimmune platelet disorders such as fetal and neonatal alloimmune thrombocytopenia (FNAIT), posttransfusion purpura, and multiplatelet transfusion refractoriness. In addition, it has made possible prenatal platelet typing of the fetus in suspected cases of FNAIT and large-scale blood donor typing for provision of antigen-negative platelets to transfuse highly alloimmunized patients. Platelet genotyping may also someday prove important as an aid in determining the relative risk of patients for various thrombotic disorders.
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ABSTRACT: Human platelet antigens (HPA) are determinant in several platelet-specific alloimmune disorders, such as neonatal alloimmune thrombocytopenia, post-transfusion purpura and platelet transfusion refractoriness. The distribution of HPA systems in the Malaysian population is not known. Defining the patterns of HPA systems provides a basis for risk assessment and management of the above complications. The aim of this study was to investigate the distribution of HPA -1 to -6 and -15 in the three major ethnic groups (Malay, Chinese and Indian) in the Malaysian population. A total of 600 random donor samples, 200 from each of the three ethnic groups, were genotyped by means of real time polymerase chain reaction (PCR) with hydrolysis probes and PCR-restriction fragment length polymorphism (PCR-RFLP). The most common genotype observed in this study was HPA-1a/1a-2a/2a-3a/3b-4a/4a-5a/5a-6a/6a-15a/15b (17%) followed by HPA-1a/1a-2a/2a-3a/3a-4a/4a-5a/5a-6a/6a-15a/15b (14.33%). The allele frequencies of HPA in Malays and Chinese were found to be similar those of other East and South-East Asian populations, while those of Indians were comparable to the frequencies found in Europeans. The results of this study have been useful for determining the distribution of HPA polymorphisms in this region and for potential clinical implications.Blood transfusion = Trasfusione del sangue 05/2012; 10(3):368-76. · 1.86 Impact Factor
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ABSTRACT: Polymorphism of human platelet antigens (HPAs) leads to alloimmunizations and immune-mediated platelet disorders including fetal-neonatal alloimmune thrombocytopenia (FNAIT), posttransfusion purpura (PTP), and platelet transfusion refractoriness (PTR). HPA typing and knowledge of antigen frequency in a population are important in particular for the provision of HPA-matched blood components for patients with PTR. We have performed allele genotyping for HPA-1 through -6 and -15 among 998 platelet donors from 6 blood centers in Taiwan using sequence-specific primer polymerase chain reaction. The HPA allele frequency was 99.55, and 0.45% for HPA-1a and -1b; 96.49, and 3.51% for HPA-2a and -2b; 55.81, and 44.19% for HPA-3a and -3b; 99.75, and 0.25% for HPA-4a and -4b; 98.50, and 1.50% for HPA-5a and -5b; 97.75 and 2.25% for HPA-6a and -6b; 53.71 and 46.29% for HPA-15a and -15b. HPA-15b and HPA-3a, may be considered the most important, followed by HPA-2, -6, -1, -5, and -4 systems, as a cause of FNAIT, PTP, and PTR based on allele frequency. HPA-4b and HPA-5b role cannot be excluded based on their immunogenicity. A larger-scale study will now be conducted to confirm these hypotheses and to establish an apheresis donor database for the procurement of HPA-matched apheresis platelets for patients with PTR.BioMed research international. 01/2013; 2013:973789.
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ABSTRACT: Neonatal alloimmune thrombocytopenia (NAIT) is the most common cause of severe thrombocytopenia and intracranial hemorrhage in the perinatal period. While the gold standard for making a diagnosis of NAIT is detection of a human platelet antigen (HPA)-specific antibody in maternal serum, together with identifying an incompatibility between the parents for the cognate HPA antigen, platelet genotyping is the gold standard method for HPA typing. Platelet genotyping is critical in screening at-risk fetuses for the presence ofthe HPA corresponding to the maternal antibody. In addition, platelet genotyping may play a role in population screening to identify women at risk for sensitization, and thus, fetuses at risk for NAIT. The most commonly used methods of platelet genotyping are sequence-specific primer-polymerase chain reaction (PCR-SSP), restriction fragment length polymorphism-PCR (PCR-RFLP), and TaqMan real-time PCR. PCR-SSP and PCR-RFLP are relatively inexpensive and technically simple methods, but they are not easily automated and require expertise for reliable interpretation of results. Newer methods that allow for multiplexing, automation, and easily interpretable results, such as bead arrays, are currently in development and available for research purposes.American Journal of Hematology 12/2011; 87(5):525-8. · 4.00 Impact Factor