Prevalence of the HPA-18w to -21w alleles in the Chinese Han population

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.

Variants of CD36 gene and their association with CD36 protein expression in platelets

BACKGROUND

The relationship between CD36 expression level in platelets and polymorphism of the CD36 gene still needs to be explored. Here, we investigated polymorphisms of the CD36 gene and CD36 expression level in platelets in the Chinese Han population.

MATERIALS AND METHODS

A total of 477 samples were sequenced for exons 2 to 14 of the CD36 gene using a polymerase chain reaction sequence-based typing method. In 192 of these individuals the expression levels of CD36 antigen were analysed by flow cytometry. The genotype-phenotype relationship in platelets was analysed.

RESULTS

A total of 22 variants of the CD36 gene were identified, of which five variants (111 A>T, 681 C>A, 1172-1183 del12b, 1236 delT and 1395 A>C) were novel variations, and nine were also found in single nucleotide polymorphism database (dbSNP) but had not been confirmed in individuals with CD36 deficiency. Two variants (329-332 delAC and 1228-1239 del12bp) in the coding region are the most frequent mutations in the Chinese population. Type II CD36 deficiency was identified in seven of 192 individuals, giving a frequency of 3.6%. Individuals with CD36 variations or wild-type genotypes both showed CD36 antigen negative, low-level and high-level expression patterns in platelets. The frequency of the nt-132 A>C polymorphism in the 5'-UTR is relatively high in the Chinese population (0.3516): the expression of CD36 was lower in individuals with nt-132 A>C than in those with the wild-type genotype.

DISCUSSION

The distribution of CD36 gene variants in the Chinese population is different from that previously reported. The levels of expression of CD36 antigen in platelets are not determined directly by the genotypes of the CD36 coding region. This suggests that the molecular basis of type II CD36 deficiency may be derived from combined effects of coding region and potential cis-regulatory elements in the 5'-UTR of the CD36 gene.

Simultaneous genotyping of HPA-17w to -21w by PCR-SSP in Chinese Cantonese

Studies have reported the polymorphism of human platelet antigen (HPA)-17w, -18w, -19w, -20w, and -21w. However, the distribution of these five antigens in Chinese Cantonese is still unknown. In this study, we designed new sequence-specific primers for HPA-19w to -21w and used published primers for HPA-17w and -18w to develop a polymerase chain reaction with the sequence-specific primers (PCR-SSP) method for simultaneously genotyping HPA-17w to -21w. A total of 820 unrelated Cantonese apheresis platelet donors in Guangzhou were involved in this study. Among the five HPAs, complete a/a homozygosity was observed for HPA-17w to -20w with an allele frequency of 1.0000. For HPA-21w, nine individuals (9/820, 1.10%) were found to be HPA-21a/bw heterozygous and the allele frequencies of HPA-21a and HPA-21bw were 0.9945 (1631/1640) and 0.0055 (9/1640), respectively. The reliability of the PCR-SSP method was determined by comparing with the genotyping results by DNA sequencing, and no inconsistencies were observed between the two methods. This study provides a reliable PCR-SSP method for simultaneously genotyping HPA-17w to -21w and could improve HPA-matched platelet transfusion in Chinese Cantonese.