A comprehensive investigation of RHD polymorphisms in the Chinese Han population in Xi'an.

BACKGROUND: This study is a comprehensive analysis of RHD in D-negative phenotypes in saline, in Xi'an, Shanxi province, central China. MATERIAL AND METHODS: DCcEe in saline was measured for each blood sample from every donor between January 2008 and June 2012 in the Xi'an Blood Centre, China. D-negative results were confirmed by an indirect antiglobulin test and further investigated by adsorption-elution as required. The initial step of molecular analysis was RHD zygosity testing. Then RHD was detected by a sequence-specific polymerase chain reaction system for RHD(1227G>A), weak D type 15, and RHD(711delC) alleles for the samples carrying at least one RHD. For the remaining non-identified samples, ten RHD exons were amplified using a previously widely used RHD coding region sequencing method. Some RHD/RHCE conversion alleles were identified while those remaining were submitted to direct sequencing. RESULTS: Overall, 2,493 D-negative samples in saline were detected in a total of 890,403 donors (D-negative rate, 0.28%). Among the D-negative individuals, RHD deletion (d/d) was assessed in 1685 donors (67.59%). Non-functional RHD alleles were detected in 184 donors (7.38%), the most common being the RHD-CE(2-9)-RHD and RHD(711delC) alleles. Two new alleles were observed and family investigations were performed; RHD(1227G>A) DEL was detected in 516 individuals (20.70%), and weak D or partial D variants were identified in 108 donors (4.33%). The most common alleles were weak D type 15, D(VI) type 3 and D(V) type 2. Four new weak D alleles were noted, and two cases of RHD(1227G>A)/weak D type 15 heterozygosity were confirmed. CONCLUSIONS: Currently, it seems to be difficult to observe any new RHD alleles in the Han Chinese population. D prediction in this population is easier because popular alleles are dominant, accounting for about 99.80% of alleles in D-negative people. Weak D types and partial D variants are rare and occur in approximately 0.01% of the population.

DEL RBC transfusion should be avoided in particular blood recipient in East Asia due to allosensitization and ineffectiveness.

Previously, both primary and secondary anti-D alloimmunizations induced by "Asian type" DEL (RHD1227A allele) were observed in two incidents. We investigated how often these alloimmunization events occur. The transfusions of any D-negative patients were investigated in the First Affiliated Hospital of Xi'an Jiaotong University Medical College, China, during the entire 2009. The antigens of D, C, c, E, and e were routinely serotyped. The "Asian type" DEL variant was genotyped and the RHD heterozygote was determined through two published methods. The changes in anti-D levels were monitored by the indirect antiglobulin test (IAT) and flow cytometry. Thirty D-negative transfused patients were included in the study. We focused on 11 recipients who were transfused with packed red blood cells (RBCs) from DEL donors at least one time. Of those 11 recipients, seven were anti-D negative before transfusion and four were anti-D positive (one patient with an autoantibody). One of the seven pre-transfusion anti-D negative patients produced a primary-response anti-D after being transfused with 400 ml of DEL blood twice. All four pre-transfusion antibody positive patients were not observed hemoglobin (Hb) levels increased, as expected after transfusions. Two patients had an increase in anti-D from 1:8 to 1:64 by IAT, which was also shown by flow cytometry. None of the patients experienced an acute hemolytic episode. Our data indicated that the primary anti-D induced by DEL transfusion or the secondary anti-D elevated by DEL in a truly D-negative patient might not be unusual. We suggest that a truly D-negative childbearing-aged woman should avoid DEL transfusion to protect her from primary anti-D allosensitization. In addition, anti-D positive recipients should also avoid DEL red cell transfusion due to the delayed hemolytic transfusion reaction (DHTR).

[Molecular study of two novel RHD alleles and pedigree analysis].

OBJECTIVE: To study the segregation of two novel RHD alleles in Chinese pedigrees. METHODS: The Rh antigens of the samples were identified by using monoclonal antibodies. The 10 exons of the RHD gene for the 2 probands and their family members were amplified separately and sequenced. The parents of proband 2 were analyzed by sequence specific primer-polymerase chain reaction (SSP-PCR). RESULTS: The two probands were RhD negative and the RHD was D/d type. After alignment with the nucleotide sequence in GenBank, a deletion of nucleotide C at position 78 in exon 1 of proband 1 was detected, and her sister also had the deletion, which was confirmed by sequencing. The sequencing results of proband 2 showed a 10 nucleotide deletion in exon 8 as well as a RHD 520 G to A mutation in exon 4. The results of SSP-PCR and sequencing showed that the proband's mother also carried RHD 520 G to A and RHD 1080 del 10 mutation, which was transmitted to proband 2. The sequences of the novel alleles have been submitted to GenBank (accession No. GQ477180 and GU362076). CONCLUSION: The two novel RHD alleles, RHD 78delC and RHD 520 G to A+1080 del 10, were both pseudo genes and stably transmitted.

Allele polymorphism and haplotype diversity of HLA-A, -B and -DRB1 loci in sequence-based typing for Chinese Uyghur ethnic group.

BACKGROUND: Previous studies indicate that the frequency distributions of HLA alleles and haplotypes vary from one ethnic group to another or between the members of the same ethnic group living in different geographic areas. It is necessary and meaningful to study the high-resolution allelic and haplotypic distributions of HLA loci in different groups. METHODOLOGY/PRINCIPAL FINDINGS: High-resolution HLA typing for the Uyghur ethnic minority group using polymerase chain reaction-sequence-based-typing method was first reported. HLA-A, -B and -DRB1 allelic distributions were determined in 104 unrelated healthy Uyghur individuals and haplotypic frequencies and linkage disequilibrium parameters for HLA loci were estimated using the maximum-likelihood method. A total of 35 HLA-A, 51 HLA-B and 33 HLA-DRB1 alleles were identified at the four-digit level in the population. High frequency alleles were HLA-A*1101 (13.46%), A*0201 (12.50%), A*0301 (10.10%); HLA-B*5101(8.17%), B*3501(6.73%), B*5001 (6.25%); HLA-DRB1*0701 (16.35%), DRB1*1501 (8.65%) and DRB1*0301 (7.69%). The two-locus haplotypes at the highest frequency were HLA-A*3001-B*1302 (2.88%), A*2402-B*5101 (2.86%); HLA-B*5001-DRB1*0701 (4.14%) and B*0702-DRB1*1501 (3.37%). The three-locus haplotype at the highest frequency was HLA-A*3001-B*1302-DRB1*0701(2.40%). Significantly high linkage disequilibrium was observed in six two-locus haplotypes, with their corresponding relative linkage disequilibrium parameters equal to 1. Neighbor-joining phylogenetic tree between the Uyghur group and other previously reported populations was constructed on the basis of standard genetic distances among the populations calculated using the four-digit sequence-level allelic frequencies at HLA-A, HLA-B and HLA-DRB1 loci. The phylogenetic analyses reveal that the Uyghur group belongs to the northwestern Chinese populations and is most closely related to the Xibe group, and then to Kirgiz, Hui, Mongolian and Northern Han. CONCLUSIONS/SIGNIFICANCE: The present findings could be useful to elucidate the genetic background of the population and to provide valuable data for HLA matching in clinical bone marrow transplantation, HLA-linked disease-association studies, population genetics, human identification and paternity tests in forensic sciences.

Allelic diversity and haplotype structure of HLA loci in the Chinese Han population living in the Guanzhong region of the Shaanxi province.

The allele and haplotype frequencies of HLA-A, -B and -DRB1 loci in 10,000 healthy unrelated Han individuals living in the Guanzhong region of the Shaanxi Province were analyzed with the methods of SSO, SSP and SBT. Subsequently, these data were compared with results obtained in Han populations living in other regions as well as to other ethnic groups, using genetic distance measurements, neighbor-joining dendrograms and principal component analysis. In total 18 alleles were detected at the HLA-A locus, 46 alleles at the HLA-B locus and 14 alleles at the HLA-DRB1 locus. HLA-A*02 was the most common HLA-A allele (29.70%), followed by A*11 (18.70%), and A*24 (15.75%); whereas at the HLA-B locus, the allele with the highest frequency was HLA-B*13 (10.76 %), followed by B*46 (7.93%), B*51 (7.68%). At the HLA-DRB1 locus, the most common alleles were HLA-DRB1*15 (15.54%), DRB1*09 (13.18%) and DRB1*04 (11.21%). Three-loci haplotype analysis revealed that HLA A*30- B*13- DRB1*07 (4.11%), A*02 -B*46 -DRB1*09 (2.57%) and A*33 -B*58 -DRB1*17 (1.32%) were the most common haplotypes in this population. Four two-loci haplotypes, including HLA-A*30-B*43, A*30-B*53, B*43-DRB1*07 and B*73-DRB1*04 had significant linkage disequilibrium (relative linkage disequilibrium parameter equals to 1). Compared with other populations, our results indicated that the Han populations in different regions had a similar allelic diversity of HLA -A, -B, and -DRB1 loci. The Han population in the Guanzhong region of the Shaanxi Province had a close genetic relationship with the Northern and Southern Han populations. In summary, the similarities and differences of the HLA allelic diversity and haplotype structure between the Han population in the Guanzhong region and related populations, regarding HLA genotype distribution, provide basic information for further studies of the HLA heterogeneity and anthropological studies.

[Correlation between DNA methylation of the ABO gene promoter CpG island and leukemia].

Recent studies have found that ABO blood group antigen is also closely related to the onset and development of many diseases. More and more attention is being paid to the decrease of A/B blood group antigen caused by some tumors. This study was purpose to investigate the correlation between DNA methylation of the ABO gene promoter CpG island and leukemia. The relative contents of ABH antigen on the surface of RBC from kinds of blood disease patients and healthy individuals were detected by using flow cytometry and confocal laser scanning microscopy. The DNA sequences and CpG methylation of ABO gene promoter in patients with hematopathy and healthy individuals, as well as the -102 site methylation of ABO gene promoter in patients with hematopathy and healthy individuals were detected by PCR and MSP-PCR respectively. The results showed that RBC from leukemia patients displayed different degree of A/B antigen decrease. The sequences of ABO gene promotor of patients with hematopathy were not different from healthy individuals indicating high conservation of promoter sequences. Comparison of sequences between patients with hematopathy and healthy individual indicated that CpG islands on ABO gene promoter either from blood disease patients or from healthy individual had no methylated site in AA patients, but C residues at position -102, -101, -100, -99 and -97 on the promoter of ABO gene in AML, CML, ALL and some MDS patients were methylated. It is concluded that methylation of CpG islands in promoter of ABO gene may result in AB antigen decrease in patients with leukemia. The methylation sites -102, -101, -100, -99 and -97 may be specific for leukemia. The methylation of site -102 can be used as a molecular marker in differential diagnosis for leukemias.