Search

Background: Neonatal alloimmune thrombocytopenia (NAIT), caused by maternal antibodies raised against alloantigens carried on foetal platelets, is a very common haematological abnormality in newborns worldwide. However, baseline data on NAIT in China are lacking. Therefore, this study seeks to explore the incidence of alloantibody against the human platelet antigen (HPA) in pregnant women and its associations with NAIT in China., Methods: A multicentre, prospective cohort study design will be used, and 55,497 pregnant women will be recruited for the first screening of the anti-HPA antibody at 12 to 28 weeks of gestational age. Subjects who are positive in the first screening for the anti-HPA antibody will be included in the exposure group. Re-tests of the antibody titre, antigen-specificity and genotyping of HPA and HLA will be conducted during admission. A ratio of 1:1 paired individuals with the same ethnicity and parity but testing negative for the anti-HPA antibody will be randomly selected to be included in the non-exposure group. NAIT will be diagnosed in the newborns on day one of the birth. The HPA of the neonates in the exposure group will also be genotyped by sequencing. Associations of maternal HLA with the occurrence of the anti-HPA antibody and correlation of the severity of NAIT with the titre of the anti-HPA antibody will be further analysed., Discussion: The study is expected to provide baseline data on NAIT in China. Besides, we hope to find out a population who expresses particular HLA molecules has significant higher risk of HPA alloimmunization in Chinese individuals. We also hope to find a Chinese-specific cut-off antibody titre for the prediction of the severity of NAIT and to provide a means to evaluate the necessity of antenatal treatment., Trial Registration: ClinicalTrials.gov: NCT02934906 (date registered: 13.10.2016).

Objective: To study the polymorphism of human platelet alloantigens HPA-3 and HPA-9w in the Chinese Han population., Methods: A total of 1000 unrelated Chinese Han blood donors from different provinces of China were genotyped for HPA-3 and HPA-9w using PCR-sequence specific primer assay., Results: Gene frequencies of 1000 Chinese Hans for HPA-3a and HPA-3b were 0.5935 and 0.4065 respectively, and all of them were HPA-9a positive. The distributions of HPA-3, HPA-9w of Chinese Hans which detected by chi-square criterion fit Hardy-Weinberg equilibrium. There were significant differences of the HPA-3 alleles gene frequency between Guangdong province and other five investigated provinces which included Shanxi, Heilongjiang, Zhejiang, Yunnan and Jiangsu. In comparison to other ethnic groups, no significant differences were observed in the distributions of HPA-3 except the Vietnamese and Australian., Conclusion: The results show that the chance of HPA-3 incompatibility were 0.3661 in random transfusion, and also provide a basis for researching on alloimmune thrombocytopenia and HPA-matched transfusion.

The frequencies of six platelet-specific antigens among Chinese in Taiwan are reported, which have not previously been well studied. HPA-1a (PlA1) antigen was positive in all 1100 Chinese tested. HPA-4b (Yukb) antigen was positive in all 100 persons tested. HPA-2b (Ko(a), Sib(a)) antigen was positive in 9 percent of 100 persons tested, HPA-3a (Bak(a)) in 77 percent, and NAKa in 96 percent. HPA-4a (Yuk(a)) antigen occurred in 0 percent in this study but is estimated to be present in 0.5 percent of the Taiwanese population.