Human platelet antigen polymorphisms (HPA-1, -2, -3, -4, -5 and -15) in major ethnic groups of Pakistan

PLT antigen discrepancy pattern among couples with recurrent abortion

Background

Recurrent abortion refers to a condition of two or more consecutive pregnancies without known etiology affected by miscarriage before the completion of the 20th week of gestational age. However, several hypotheses have been proposed, but not much data are available concerning the relationship between human platelet antigens (HPAs) polymorphisms and recurrent abortion. This study was conducted to evaluate the genetic differences between HPA-1, -2, -3, -5, and - 15 in Iranian couples with a history of recurrent abortion.

Methods

In this cross-sectional study, a total of 74 couples with at least 2 recurrent abortions without any known specified reasons enrolled in the study. HPA polymorphisms genotyping was performed by single-specific primer PCR. Genotype frequency was calculated using the Hardy-Weinberg equation.

Results

A total of 39 couples (52.7%) had HPA genotyping partial mismatches. The most common partial mismatch pairs were found concomitantly on both HPA-15a and HPA-15b in three couples (4%), followed by two (2.7%) on HPA-3a and one (1.3%) in each HPA-2b and HPA-5b. There was a deviation from the Hardy-Weinberg equilibrium in the HPA-2 and -5 systems.

Conclusion

The present study declared that partial mismatches of HPA-3 and -15 genotypes were common among Iranian couples due to the history of recurrent abortion and approximately half of the couples carried at least one HPA gene that was absent in their partners. Further studies might be helpful to clarify the association between HPA polymorphisms and recurrent abortion, such as an investigation into the alloantibodies against HPAs.

Association of the human platelet antigens polymorphisms with platelet count in patients with COVID-19

Polymorphism in human platelet antigen (HPA)-1 and HPA-3 (GPIIb/IIIa), HPA-2 (GPIb/IX), HPA-4 (GPIIIa), HPA-5 (GPIa/IIa), & HPA-15 (CD109) was investigated in 86 COVID-19-infected patients with thrombocytopenia (Group A) and 136 COVID-19-infected patients without thrombocytopenia (Group B). HPA genotyping was done by the sequence-specific primers PCR method. Lower HPA-3a and higher HPA-3b (P = 0.028) allele frequencies were seen in Group A than in Group B, and homozygosity for HPA 3b (P = 0.038) alleles was more prevalent in Group A than in Group B. The allele and genotype distributions of the other HPA polymorphic variants were similar between the two groups. Univariate analysis identified the CCGGGC (P = 0.016) combined genotype to be negatively associated & the TCGGGC (P = 0.003) and CCGGGC (P = 0.003) to be positively associated with thrombocytopenia. The frequency of anti-HPA-1a and anti-HPA-3a antibodies was significantly higher in all patients compared to other anti-HPAs antibodies (P < 0.05). These results highlight the role of HPAs in the thrombocytopenia of COVID-19 infected patients. This is the first evidence demonstrating the differential association of the six common HPA gene variants and specific HPA genotype combinations with thrombocytopenia in COVID-19-infected patients.

Human platelet antigen 1-6, 9 and 15 in the Iranian population: An anthropological genetic analysis

Human platelet antigens (HPAs) are membranous glycoproteins considered as alloantigens due to their polymorphisms. HPA-incompatibility in multiple pregnancies or blood transfusion can induce the development of alloantibodies leading to thrombocytopenia. The frequency of HPAs varies among populations, so that deep knowledge of HPA frequencies will help us to reduce those incompatibilities. Herein, we studied the allele and genotype frequencies of HPA1-6, HPA9, and HPA15 among the Iranians with intra- and inter-populations analyses on 36 worldwide populations with diverse ethnicities. The analysis shows that the HPA2 and HPA5 have the greatest differences in genotype distribution between the Iranians and other nations, although similar to other populations, the sole allele found in HPA4, 6, and 9 is “a”. Despite other HPAs, the most frequent allele in HPA15 is “b”, which is also abundant in HPA3. Hierarchical clustering indicates the highest degree of global similarity in HPA genotype frequency among Iranian, Argentinian, Brazilian, and German Turkish populations. Our findings can be applied to decrease the risk of alloimmunizations and platelet disorders, especially in neonates.

High-Throughput Screening of Blood Donors for Twelve Human Platelet Antigen Systems Using Next-Generation Sequencing Reveals Detection of Rare Polymorphisms and Two Novel Protein-Changing Variants

Background

Exposure to non-matching human platelet alloantigens (HPA) may result in alloimmunization. Antibodies to HPA can be responsible for post-transfusion purpura, refractoriness to donor platelets, and fetal and neonatal alloimmune thrombocytopenia. For the supply of compatible apheresis platelet concentrates, the HPA genotypes are determined in a routine manner.

Methods

Here, we describe a novel method for genotyping twelve different HPA systems simultaneously, including HPA-1 to HPA-5, HPA-9w, HPA-10w, HPA-16w, HPA-19w, HPA-27w, and the novel HPA-34w by means of amplicon-based next-generation sequencing (NGS). Blood donor samples of 757 individuals with a migration background and 547 of Western European ancestry were genotyped in a mass-screening setup. An in-house software was developed for fast and automatic analysis. TaqMan assay and Sanger sequencing results served for validation of the NGS workflow. Finally, blood donors were divided in several groups based on their country of origin and the allele frequencies were compared.

Results

For 1,299 of 1,304 samples (99.6%) NGS was successfully performed. The concordance with TaqMan assay and Sanger sequencing results was 99.8%. Allele-calling dropouts that were observed for two samples with the TaqMan assay caused by rare single nucleotide polymorphisms were resolved by NGS. Additionally, twenty rare and two novel variants in the coding regions of the genes ITGB3, GPB1A, ITGBA2, and CD109 were detected. The determined allele frequencies were similar to those published in the gnomAD database.

Conclusions

No significant differences were observed in the distribution of allele frequencies of HPA-1 through HPA-5 and HPA-15 throughout the analyzed groups except for a lower allele frequency for the HPA-1b allele in the group of donors with Southern Asian ancestry. In contrast, other nucleotide variants that have not yet been phenotypically characterized occurred three times more often in blood donors with a migration background. High-throughput amplicon-based NGS is a reliable method for screening HPA genotypes in a large sample cohort simultaneously. It is easily upgradeable for genotyping additional targets without changing the setup or the analysis pipeline. Mass-screening methods will help building up blood donor registries to provide matched blood products.

Human platelet antigens polymorphisms; association to the development of liver fibrosis in patients with chronic hepatitis C

Recently, human platelet antigens (HPAs) polymorphisms are found to play a role in susceptibility to hepatitis C virus (HCV) infection and fibrosis progression. The aim of the current study was to evaluate the possible association between the HPAs polymorphisms with liver fibrosis progression in HCV patients. HPAs polymorphisms genotyping was performed in HCV patients (n = 71) by Sequence-specific primers-polymerase chain reaction. Fibrosis progression was evaluated using the Metavir scoring system and liver biopsy, and the patients were assigned to two groups, namely, G1 (n = 35) that included patients with F1 (portal fibrosis without septa) or F2 (few septa) and G2 (n = 36) that comprised patients with F3 (numerous septa) or F4 (cirrhosis). The data analyses were performed using Pearson's χ² test. The genotype frequency of HPA-3ab was significantly higher in G1 patients than in G2 patients (P = 0.015). No statistically significant differences were found between the patient groups (G1 and G2) regarding the distributions of the allelic and genotypic frequencies of the HPA-1, -2, -4, -5, and -15 systems. Multivariate logistic regression showed an independent association between the genotype HPA-3aa/BB and severe fibrosis (F3-F4), when compared with genotype HPA-3ab, independent of the viral genotype, high alanine transaminase, sex, age, time of infection, diabetes, and high cholesterol as risk factors. The present study suggested that the HPA-3ab genotype could be noticed as a potential protecting factor against hepatic fibrosis. Therefore, the antigenic variation of integrins might be considered as a part of the coordinated inflammatory process involved in the progression of liver fibrosis.

Allele and haplotype frequencies of human platelet and leukocyte antigens in platelet donors

OBJECTIVE

To described the allele and haplotype frequencies of human leukocyte antigen genes at the -A, -B loci and human platelet antigen genes for human platelet antigen systems 1 to 9, 11 and 15 in blood.

METHODS

We included 867 healthy unrelated volunteer donors who donated platelets between January 2011 and December 2014. Microarray genotyping was performed using a BeadChip microarray. Medium resolution typing of the human leukocyte antigen at loci A and B was carried out using sequence-specific oligonucleotide probe hybridization. We used multivariate analysis and our human leukocyte antigen population was compared to data from the United States national bone marrow donor program. Human platelet antigen results were compared to a literature review and data from around the world.

RESULTS

Our human leukocyte antigen haplotype results were more similar to those of hispanics, followed by caucasians. Likewise, our human platelet antigen sample is more similar to those of Argentina, Rio Grande do Sul and Italy.

CONCLUSION

This was the first article that discusses human platelet antigen and human leukocyte antigen data together. Rare genotypes or antibody associations can make patient management difficult. A blood bank with genotyped donors allows for optimal transfusion and can contribute to better results. Our information can serve as basis for a database of platelet antigen polymorphisms.

Human platelet antigen 1, 2 and 5 gene polymorphisms in Egyptians and their potential association with susceptibility to immune thrombocytopenic purpura in Egyptian patients

OBJECTIVES

This study determined the incidence of HPA1, HPA2 and HPA5 polymorphisms in 120 Egyptian immune thrombocytopenic purpura (ITP) patients and 120 healthy Egyptian subjects.

METHODS

Human platelet antigen (HPA) genotyping was done using the polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The frequency of HPA1 allele a and b was 78.75 and 21.25% in controls, 80.8 and 19.2% in ITP, respectively. HPA2 allele a and b frequency was 86.25 and 13.75% in controls and of 74.6 and 25.4% in patients, respectively. HPA5 allele a and b frequency was 87.5 and 12.5% in controls, in patients it was 85 and 15%, respectively. With the exception of HPA2, no other significant difference was encountered in HPA allele frequency between controls and ITP patients.

DISCUSSION

Egyptian HPA profile is closely linked to Middle East and neighboring Arabs. The current study noted that in all the studied HPA systems 1, 2 and 5, the 'a' allele is more prevalent than the b allele; the most frequent genotype was the homozygous a/a genotype. HPA2b frequency, homo- and hetero-zygous HPA2b genotype frequencies were significantly higher in ITP patients compared to controls.

CONCLUSION

HPA 2b are 2.37 times more likely to develop ITP compared to those without this allele. The relatively high allele frequency of the HPA-1b in the Egyptian population suggests that this ethnic group has a higher risk of alloimmunization.

Simultaneous genotyping of human platelet alloantigen-1 to 28bw systems by multiplex polymerase chain reaction sequence-based typing

BACKGROUND AND OBJECTIVES

Human platelet alloantigen (HPA) genotyping is important for the diagnosis and prevention the alloimmune platelet disorders. In this study, a simultaneous genotyping method for HPA-1 to -28bw systems was established using multiplex PCR-SBT and the frequencies of genotypes and alleles of HPA-1 to -28bw systems in the Zhejiang Han population were analysed.

MATERIALS AND METHODS

The specific primers were designed according to the nucleotide sequences of HPA-1 to 28bw systems which are located in ITGB3, GP1BA, ITGA2B, ITGA2, GP1BB and CD109, respectively. The multiplex PCR amplification systems were used, and then, the amplicons were purified and sequenced. A total of 335 healthy volunteer blood donors were detected.

RESULTS

The genotypes of ten reference samples from Platelet Immunology Workshop of ISBT were in concordance with the known genotypes. Among the 28 HPA systems, HPA a and b alleles were found in HPA-1 to 6w, HPA-15 and HPA-21w systems in the Chinese Han population, while only HPA aa genotype was detected in the other HPA systems. The frequencies of HPA-1a and HPA-1b were 0·993 and 0·007, with 0·943 and 0·057 for HPA-2a and HPA-2b, 0·527 and 0·473 for HPA-3a and HPA-3b, 0·997 and 0·003 for HPA-4a and HPA-4b, 0·991 and 0·009 for HPA-5a and HPA-5b, 0·980 and 0·020 for HPA-6wa and HPA-6wb, 0·508 and 0·492 for HPA-15a and HPA-15b and 0·994 and 0·006 for HPA-21wa and HPA-21wb.

CONCLUSIONS

One multiplex PCR-SBT method for HPAs was established and the data of the study could help to prevent and treat for alloimmune thrombocytopenia.

Human platelet antigens in Burmese, Karen and north-eastern Thais

OBJECTIVES

A comparative study of allele frequencies at HPA-1 to -6 and HPA-15 in Burmese and Karen populations as well as at HPA-15 in north-eastern Thais (NET) is presented.

BACKGROUND

Human platelet antigens (HPAs) are clinically important in several immune platelet disorders, including foetal and neonatal alloimmune thrombocytopenia (FNAIT), post-transfusion purpura (PTP) and platelet transfusion refractoriness (PTR). The knowledge of antigen frequencies in a population is essential for the evaluation of patients suffering from immune-mediated platelet disorders.

METHODS

A total of 285 unrelated, healthy Burmese, 242 Karen and 300 NET were recruited to this study. Genotype and allele frequencies of HPA-1 to -6 and HPA-15 were defined using polymerase chain reaction sequence-specific primers (PCR-SSP) RESULTS: No individuals homozygous for HPA-1bb, -2bb, -4bb, -5bb and -6bb were detected. HPA-1a, -2a, -4a, -5a and -6a were present in all samples of Burmese and Karen origin. HPA-1b, -2b, -4b, -5b and -6b were rare in these populations. The frequencies of HPA-3a/-3b were 60·4/39·6% in Burmese and 55·8/44·2% in Karen, respectively. Frequencies of HPA-15a/-15b were 57·2/42·8% in Burmese, 52·5/47·5% in Karen and 49·8/50·2% in NET.

CONCLUSIONS

The frequencies of HPA genotypes in our study indicates that HPA-1a, -2a, -4a, -5a and -6a are unlikely involved in FNAIT, PTP and PTR in Burmese and Karen populations. However, HPA-1b, -2b, -3a, -3b, -4b, -5b, -6b, -15a and -15b may likely stimulate alloantibodies in these populations.

Gene frequency of human platelet alloantigens-1 to -6 and -15 in Saudi blood donors

BACKGROUND

Human platelet antigens (HPAs) are involved in the pathogenesis of several clinical conditions, such as platelet transfusion purpura (PTP), refractoriness to platelet transfusion and neonatal alloimmune thrombocytopenia (NAITP). Typing of HPA (1-6 and 15) has not been carried on the Saudi population. This is the first study of all the seven HPA systems on Arabs. The aim of this prospective study was to determine the frequency of HPA (1-6 and 15) in Saudis.

STUDY DESIGN AND METHODS

A total of 100 randomly selected Saudi blood donor samples were genotyped using the polymerase chain reaction with sequence-specific primers (PCR-SSP).

RESULTS

The most common HPA genotypes among Saudis were HPA-1 a + b- (75%), HPA-2 a + b- (62%), HPA-3 a + b- (51·5%), HPA-4 a + b- (99%), HPA-5 a + b- (76·5%), HPA-6 a + b- (100%) and HPA-15 a + b + (50%). The prevalent allele among the HPA systems was (a), except in the HPA-15 system where the (b) allele was found in 52% of the subjects. Comparisons with other ethnic populations uncovered marked differences in the distribution of HPA alleles.

CONCLUSION

Studying the prevalence of HPA antigens in Saudi population will help in the understanding of its role in platelet-related disorders. It will also enable the blood bank to establish an HPA-based donor registry that will be a valuable source of compatible platelet-therapeutic products to alloimmunised patients. This will also enhance the safety and efficacy of platelet transfusion. This data obtained will form an addition to the existing body of literature in transfusion research.

Gene frequencies of human platelet alloantigens 1-5 in two Arab populations

BACKGROUND

Polymorphisms of the human platelet alloantigens (HPA) arise from single base pair substitutions in alleles and lead to changes in amino acids of glycoproteins expressed on platelets. The aim of this study was to determine the gene frequencies of the five common HPA (HPA-1 to -5) in Egyptians and Jordanians and to compare these data with those established for other populations.

MATERIALS AND METHODS

HPA genotyping was done by polymerase chain reaction with sequence-specific primers.

RESULTS

The gene frequencies obtained in Egyptians were: HPA-1a/b, 0.767/0.233; HPA-2a/b, 0.759/0.241; HPA-3a/b, 0.704/0.296; HPA-4a/b, 1/0; HPA-5a/b, 0.728/0.272, while the frequencies in Jordanians were: HPA-1a/b, 0.821/0.179; HPA-2a/b, 0.877/0.123; HPA-3a/b, 0.660/0.340; HPA-4a/b, 1/0; HPA-5a/b, 0.795/0.205. The observed gene frequencies in both populations were in Hardy-Weinberg equilibrium. The gene frequencies for HPA-2b and HPA-5b among Egyptians were the highest reported among Arabs. Except for HPA-2, there were no significant differences in the distribution of HPA-1 to -5 between the two populations.

CONCLUSION

The distributions of HPA alleles among Egyptians and Jordanians are similar to those reported for other Arabs. This study reports the first data on gene frequencies of HPA in Egyptians and Jordanians.

Frequency of human platelet antigens in oncohematological patients with thrombocytopenia and the probability of incompatibility to platelet transfusions

OBJECTIVE

The objective of this study was to evaluate the frequencies of human platelet antigens in oncohematological patients with thrombocytopenia and to analyze the probability of their incompatibility with platelet transfusions.

METHODS

Platelet antigen genotyping was performed by sequence-specific primer polymerase chain reaction (SSP-PCR) for the HPA-1a, HPA-1b, HPA-2a, HPA-2b, HPA-3a, HPA-3b, HPA-4a, HPA-4b, HPA-5a, HPA-5b; HPA-15a, HPA-15b alleles in 150 patients of the Hematology Service of the Hospital das Clínicas (FMUSP).

RESULTS

THE ALLELE FREQUENCIES FOUND WERE: HPA-1a: 0.837; HPA-1b: 0.163; HPA-2a: 0.830; HPA-2b: 0.170; HPA-3a: 0.700; HPA-3b: 0.300; HPA-4a: 1; HPA-4b: 0; HPA-5a: 0.887; HPA-5b: 0.113; HPA-15a: 0.457 and HPA-15b: 0.543.

CONCLUSIONS

Data from the present study showed that the A allele is more common in the population than the B allele, except for HPA-15. This suggests that patients homozygous for the B allele are more predisposed to present alloimmunization and refractoriness to platelet transfusions by immune causes. Platelet genotyping could be of great value in the diagnosis of alloimmune thrombocytopenia and to provide compatible platelet concentrates for these patients.

Allelic polymorphisms of human platelets-specific alloantigens in South Tunisian population

OBJECTIVES

Human platelet-specific alloantigens (HPA) are polymorphic epitopes which vary among ethnic groups.

BACKGROUND

In Tunisia, HPA frequencies were determined in North and centre; however, the pattern of HPA in South Tunisian population is not been studied yet. The aim of this work was to determine allelic frequencies of HPA-1, -3, and -5 systems in south Tunisian population, in order to estimate the risk of anti-platelet allo-immunization and to create a register of HPA-typed blood donors.

METHODS

Our study concerned 212 unrelated healthy, regular blood donors from southern Tunisia. Allelic polymorphisms of each system were determined using a polymerase chain reaction with sequence-specific primers.

RESULTS

Genotype frequencies a/a, a/b, and b/b were, respectively, 0.670, 0.288, and 0.042 for HPA-1 system, 0.430, 0.462, and 0.108 for HPA-3 system, and 0.750, 0.241, and 0.009 for HPA-5 system. The allele frequencies were 0.814 and 0.186 for HPA-1a and -1b alleles; 0.660 and 0.340 for HPA-3a and -3b alleles and 0.870, and 0.130 for HPA-5a and -5b alleles.

DISCUSSION

The reported frequencies are more similar to those of Caucasians than those of north Tunisian population.

The relevance of HPA-15 antigen expression for anti-HPA-15 antibody detection

INTRODUCTION

The HPA-15 antigen system is characterized by a low antigen expression on platelets. The antibodies against this antigen are implied in fetal/neonatal alloimmune thrombocytopenia (F/NAIT), post-transfusion purpura, and refractoriness to platelet transfusions. Detection of these antibodies appears to be related to the level of HPA-15 expression on the platelets used in the monoclonal antibody-specific immobilization of platelet antigen (MAIPA) assay.

METHODS

We performed genotyping of 300 healthy blood donors for HPA-15 by TaqMan real-time PCR technology, and the HPA-15 antigen expression was investigated in 13 HPA-15aa and 19 HPA-15bb individuals. We also investigated the relevance of HPA-15 antigen expression on donor platelets used in MAIPA for antibody detection in 223 multitransfused hematological patients and 271 women with suspected F/NAIT.

RESULTS

In Polish donors, the HPA-15a allele frequencies were lower than the HPA-15b (0.480 vs. 0.515). We identified three HPA-15 expression groups: high (36.7 ± 8.36 MFI - eight cases), medium (19.5 ± 6.2 MFI - 21 cases), and low (6.5 ± 5.9 MFI - three cases). The HPA-15 expression was stable over time. The HPA-15aa and HPA-15bb platelets with high antigen expression were used for anti-HPA-15 antibody detection; anti-HPA-15 antibodies were detected in 4/223 (1.8%) patients receiving multiple transfusions but in none of the 271 women with suspected F/NAIT. Further examination of the four sera by MAIPA with various platelets revealed the optical density in the assay to be closely related to the level of HPA-15 antigen expression.

CONCLUSION

Anti-HPA-15 antibody detection should be based on carefully selected platelets with high HPA-15 expression level.

Genotyping of human platelet antigen-15 by single closed-tube Tm-shift method

INTRODUCTION

Genotyping of human platelet antigens (HPA) is useful for the diagnosis and prevention of platelet alloimmune syndromes. HPA-15 might play an important role in the development of platelet alloimmune syndromes. There are several disadvantages in the conventional methods for HPA-15 genotyping. The aim of this study was to develop a new method for HPA-15 genotyping by using single closed-tube melting temperature (T(m))-shift genotyping.

METHODS

Two GC-rich tails of different lengths were attached to 5'-end of HPA-15 allele-specific PCR primers, such that HPA-15 alleles can be discriminated by the T(m)s of the PCR products. One hundred blood samples were genotyped for HPA-15 by the T(m)-shift and conventional polymerase chain reaction with sequence-specific primers (PCR-SSP).

RESULTS

The comparison of the PCR-SSP and the T(m)-shift method showed four discordant results in one hundred samples tested. Confirmatory results demonstrated that the PCR-SSP produced several errors, whereas HPA-15 genotyping by T(m)-shift is correct. The retesting results of T(m)-shift method were consistent with those of the initial testing.

CONCLUSION

The single closed-tube T(m)-shift method for HPA-15 genotyping is high-throughput, rapid, reliable, reproducible and cost-effective and it is superior to conventional PCR-SSP used in routine genotyping of HPA-15.