Gene frequencies of human platelet antigens 1-5 in indigenous Australians in Western Australia

Neonatal Thrombocytopenia: Differing Characteristics of NAIT Versus Non-NAIT

While neonatal alloimmune thrombocytopenia (NAIT) is the most common cause of severe neonatal thrombocytopenia good clinical predictors are lacking. We analyzed cases of neonatal thrombocytopenia in Schneider Children's Medical Center of Israel to pinpoint qualifiers of NAIT (NAIT+) in comparison to non-NAIT (NAIT-) thrombocytopenia. Patient and maternal data were retrospectively collected on all thrombocytopenic newborns undergoing a workup for NAIT in our tertiary center between 2001 and 2016. Among 26 thrombocytopenic neonates, the mean nadir in NAIT+ patients (25×10 9 /L) was significantly lower than NAIT- patients (64×10 9 /L) ( P <0.001). 61.5% of NAIT+ infants required treatment compared with 23% of non-NAIT ( P =0.015). NAIT+ patients also required more therapeutic modalities than infants with NAIT- thrombocytopenia. Human platelet antigen (HPA)-1a and HPA-5b alloantibodies most frequently caused NAIT. In summary, thrombocytopenia in NAIT+ was significantly more severe compared with NAIT- and more likely to require treatment. In addition, despite the varied ethnic population in Israel, the HPA alloantibodies found in our population were most similar to those common in Western countries. In the absence of rigorous prenatal screening options, we suggest platelet counts below 40 to 50×10 9 /L in a healthy newborn be considered most suggestive for NAIT and warrant urgent NAIT-specific analysis.

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.

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.

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.

Allele frequencies of human platelet antigens in Banjar, Bugis, Champa, Jawa and Kelantan Malays in Peninsular Malaysia

OBJECTIVES

The major aims of this study are to characterise and compile allelic data of human platelet antigen (HPA)-1 to -6 and -15 systems in five Malay sub-ethnic groups in Peninsular Malaysia.

BACKGROUND

HPAs are polymorphic glycoproteins expressed on the surface of platelet membranes and are genetically differentiated across ethnogeographically unrelated populations.

METHODS

Blood samples were obtained with informed consent from 192 volunteers: Banjar (n = 30), Bugis (n = 37), Champa (n = 51), Jawa (n = 39) and Kelantan (n = 35). Genotyping was done using polymerase chain reaction-sequence specific primer method.

RESULTS

In general, frequencies of HPAs in the Malay sub-ethnic groups are more similar to those in Asian populations compared with other more distinct populations such as Indians, Australian Aborigines and Europeans.

CONCLUSIONS

This study provides the first HPA datasets for the selected Malay sub-ethnic groups. Subsequent analyses including previously reported HPA data of Malays, Chinese and Indians revealed details of the genetic relationships and ancestry of various sub-populations in Peninsular Malaysia. Furthermore, the comprehensive HPA allele frequency information from Peninsular Malaysia provided in this report has potential applications for future study of diseases, estimating risks associated with HPA alloimmunization and for developing an efficient HPA-typed donor recruitment strategy.

Human platelet antigens frequencies in Maori and Polynesian populations

BACKGROUND

Allele frequencies of human platelet antigens (HPA) reflect population history and possibility of platelet-specific alloimmunization. Here, we report on screening of variants at HPA loci for Polynesian and Maori subjects.

OBJECTIVES

Our aims are to evaluate new HPA genotyping methods, compile and analyse new HPA datasets for these subjects, use HPA data for tracing ancestry, migration patterns, genetic admixture and its potential influence on health.

MATERIALS AND METHODS

A total of 75 Maori and 25 Polynesian DNA samples were genotyped using commercial BAGene HPA-TYPE DNA-SSP kits, BLOODchip hybridization SNP assays and DNA sequence based typing.

RESULTS

Genotyping was successful and cross validation of PCR-SSP and BLOODchip gave 100% agreement. Among the HPA loci tested, only six are dimorphic (HPA-1 to -3, -5, -6 and -15) and all others are monomorphic. The Polynesians and Maori have the 'a' allele form as the most common for all loci except HPA-15.

CONCLUSIONS

The newly observed HPA data as well as principal coordinate analysis clearly indicate genetic contributions from both, Asia and Australasia in Maori and Polynesian populations together with recent admixture with Europeans. In addition, different prevalences of HPA alleles among Polynesian, Maori and European populations contribute towards different risk profiles for platelet-specific alloimmunization. This is the first report for these populations and our findings are of direct practical relevance for blood transfusion centres, the management of pregnancies, assessment of neonatal alloimmune thrombocytopenia and management of multi-transfused patients.

Review of neonatal alloimmune thrombocytopenia

Neonatal alloimmune thrombocytopenia (NAIT), with an incidence of one in 1000 live births, is the most common cause of severe thrombocytopenia and intra-cerebral haemorrhage in term neonates. NAIT results from trans-placental passage of maternal antibodies against a paternally derived fetal platelet alloantigen. Clinical presentation varies from unexpected thrombocytopenia on a blood film in a well newborn to intracranial haemorrhage (ICH). In contrast to haemolytic disease of the newborn, NAIT can present in a first pregnancy, and subsequent pregnancies are usually more severely affected. The role of antenatal screening for maternal alloantibodies instead of fetal blood sampling to identify at-risk fetuses remains uncertain, but there is a trend towards less invasive maternally directed treatment for at-risk pregnancies. Neonatal management is aimed at preventing or limiting thrombocytopenic bleeding with transfusion of antigen-matched platelets.

The allele frequencies of HPA 1-16 determined by PCR-SSP in Chinese Cantonese donors

BACKGROUND

Typing of human platelet antigens (HPA) has proven to be useful in some clinical situations related to platelet alloimmunization.

OBJECTIVE

The objective of this study was to investigate HPA 1-16 and to determine genotype and allele frequencies by polymerase chain reaction-sequence specific primer (PCR-SSP) in apheresis platelet donors in Guangzhou Blood Center.

METHODS

A total of 200 random samples from donors were involved in the study. Genotype and allele frequencies of HPA 1 to 16 were detected by PCR-SSP method.

RESULTS

The frequencies obtained from these donors were 99·50 and 0·50% for HPA-1a and -1b; 96·25 and 3·75% for HPA-2a and -2b; 54·25 and 45·75% for HPA-3a and -3b; 99·50 and 0·50% for HPA-4a and -4b; 99·00 and 1·00% for HPA-5a and -5b; 97·00 and 3·00% for HPA-6a and -6b and 42·25 and 57·75% for HPA-15a and -15b. There is only a/a homozygosis detected in HPA-7, -8, -9, -10, -11, -12, -13, -14 and -16. In this study, none of HPA-1b/ 1b, -2b/2b, -5b/5b homozygosis were detected which were found in other racial groups. One homozygosis of HPA-6b/6b in 200 individuals was detected which was not found in a study involving 1000 Chinese (Feng et al., 2006).

CONCLUSION

The HPA-3 and -15 appear to the highest priority and HPA-2, -6, -5 -1 and -4 to be the second priority in Chinese Cantonese when it comes to the diagnosis of neonatal alloimmune thrombocytopenia and to provide the HPA-matched platelet for patients with platelet transfusion refractoriness. The PCR-SSP method makes it possible to detect genotype of HPA-1 to -16 in less than 4 h and to establish a donor database for HPA genotype in a blood bank.

The haematology of indigenous Australians

Prior to European settlement indigenous Australians were hunter-gatherers who lived in geographically isolated small clan groups, also separated by elaborate totemic rules. Today they still reside in isolated communities throughout Australia but many have moved to the cities. They share a high incidence of a range of health problems including cardiovascular disease, renal disease and infectious diseases largely attributed to a change to a more sedentary lifestyle. This paper reviews the haematology of indigenous Australians, including blood count, frequency and causes of anaemia, inherited risk factors for thrombophilia, blood groups and the incidence and types of haematological malignancies. There are some significant genetic differences between indigenous and non-indigenous Australians particularly in the frequency of blood groups, factor V Leiden and prothrombin mutations and presence of -alpha3.7 kb thalassaemia. These findings may have practical therapeutic implications (e.g. HPA phenotype for transfusion therapy and pregnancy risk) and in predicting disease risk. Other differences are acquired, related to lifestyle and living conditions (e.g. eosinophilia secondary to parasitic infections; iron and folate deficiencies), and are largely preventable.