Distribution of ABO blood group allele and identification of three novel alleles in the Chinese Han population

One novel single nucleotide polymorphism c.424A>G on A1.02 allele in ABO glycosyltransferases leads to Aweak phenotype

BACKGROUND

The dysfunction of the ABO glycosyltransferase (GT) enzyme, which is caused by mutations in the ABO gene, can lead to weak ABO phenotypes. In this study, we have discovered a novel weak ABO subgroup allele and investigated the underlying mechanism to causing its Aweak phenotype.

MATERIALS AND METHODS

The ABO phenotyping and genotyping were performed by serological studies and direct DNA sequencing of ABO gene. The role of the novel single nucleotide polymorphism (SNP) was evaluated by 3D model, predicting protein structure changes, and in vitro expression assay. The total glycosyltransferase transfer capacity in supernatant of transfected cells was examined.

RESULTS

The results of serological showed the subject was Aweak phenotype. A novel SNP c.424A > G (p. M142V) based on ABO*A1.02 was identified, and the genotype of the subject was AW-var/O.01 according to the gene analysis. In silico analysis showed that the SNP c.424A > G on the A allele may change the local conformation by damaging the hydrogen bonds and reduce the stability of GT. In vitro expression study showed that SNP p.M142V impaired H to A antigen conversion, although it did not affect the generation of A glycosyltransferase (GTA).

CONCLUSIONS

One novel AW allele was identified and the SNP c.424A > G (p.M142V) can cause the Aweak phenotype through damaging the hydrogen bonds and reducing stability of the GTA.

Detection and phenotype analysis of a novel Ael blood group allele

BACKGROUND AND OBJECTIVES

The presence of blood subtypes may lead to difficulties in blood group identification; however, third-generation sequencing (TGS) can help in accurately identifying difficult blood groups, and study the serological characteristics and molecular mechanism of Ael subtypes.

MATERIALS AND METHODS

ABO blood group was identified by the standard serological technique, weak blood group antigen was identified by adsorption-elution experiments, ABH substance in the saliva was determined and glycosyltransferase activity of A and B was detected. The ABO gene full-length sequence and promoter region were amplified by specific primers using single-molecule real-time sequencing, with the amplified products being sequenced directly and analysed in real time.

RESULTS

The patient was serologically identified as Ael subtype, and TGS analysis revealed new intron mutations in Ael patients (c.467C>T; c.29-10T>A).

CONCLUSION

The discovery of the new allele and the identification of ABO subtypes can be combined with serological characterization and molecular biological methods.

Generation of hiPSCs with ABO c.767T>C substitution: resulting in splicing variants

Introduction: The ABO blood group system has important clinical significance in the safety of blood transfusion and organ transplantation. Numerous ABO variations, especially variations in the splice sites, have been identified to be associated with some ABO subtypes. Methods: Here, we performed the c.767T>C substitution of the ABO gene in human induced pluripotent stem cells (hiPSCs) by the adenosine base editor (ABE) system and described its characteristics at the genome level in detail. Results: The hiPS cell line with c.767T>C substitution maintained a normal karyotype (46, XX), expressed pluripotency markers, and showed the capability to spontaneously differentiate into all three germ layers in vivo. The genome-wide analysis demonstrated that the c.767T>C substitution in the ABO gene did not cause any detected negative effect in hiPSCs at the genome level. The splicing transcript analysis revealed that splicing variants were observed in the hiPSCs with ABO c.767T>C substitutions. Conclusion: All these results indicated that some splicing variants occurred in hiPSCs with c.767 T>C substitution of ABO gene, which probably had a significant effect on the formation of the rare ABO*Ael05/B101 subtype.

B-Cell Lymphoma Producing IgM Anti-B Antibody: A Case Report

ABO blood group system is the most important blood group system in transfusion and transplantation medicine. Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphomas (NHLs) worldwide. There have been some studies that lymphoma could affect ABO blood group system and thus affect blood transfusion strategy. However, the mechanisms lymphoma affecting ABO blood group system have not been fully elucidated so far. Here, we report a case of a patient who was a 72-year-old Chinese man came to our hospital for medical advice because of cervical lymphadenophathy. The patient was subsequently diagnosed with diffuse large B-cell lymphoma by lymph-node biopsy. His ABO blood group was initially typed as B on November 7, 2020. He was transfusing B type leukocyte poor RBCs (LPR) before we found the patient’s ABO blood group discrepancy on December 2, 2020 by forward and reverse typing methods, which the discrepancy was verified by genotyping. The patient began to transfuse O type washed RBCs (WRBC) since then. Compared to transfuse B type leukocyte poor RBCs (LPR), the efficiency of transfusing O type washed RBCs (WRBC) was better. Although hemoglobin level did not greatly improve, indirect bilirubin level evidently decreased. Furthermore, we found B-cell lymphoma affected blood transfusion strategy by producing IgM anti-B antibody in this case. Clinicians should need to be aware of the effect of B-cell lymphoma on blood transfusion strategy.

Sperm Cell Capture Based on ABH Antigen Differences to Separate Two Men in Mixed Seminal Stains

Personal identification of two individuals in mixed semen samples in forensic DNA testing in general usually involves analysis using autosomal and Y chromosome short tandem repeats (STRs). Results may exclude unrelated donors but cannot identify individuals. In this study, sperm cell capture based on ABH antigen differences was used to obtain the cells with the single ABO blood type. Immunohistochemical staining using labeled anti-A, anti-B, and anti-H antibodies and the laser microdissection system can be used to enrich sperm with different ABO types in mixed seminal stains from two individuals. Then, PCR amplification and capillary electrophoresis were performed to genotype the STR loci. To some extent, after sperm cell capture based on ABH antigen differences, autosomal STR typing using enriched single blood group cells can be utilized to partially identify different individuals in a mixed seminal stain sample from two individuals.

Six splice site variations, three of them novel, in the ABO gene occurring in nine individuals with ABO subtypes

Background

Nucleotide mutations in the ABO gene may reduce the activity of glycosyltransferase, resulting in lower levels of A or B antigen expression in red blood cells. Six known splice sites have been identified according to the database of red cell immunogenetics and the blood group terminology of the International Society of Blood Transfusion. Here, we describe six distinct splice site variants in individuals with ABO subtypes.

Methods

The ABO phenotype was examined using a conventional serological method. A polymerase chain reaction sequence-based typing method was used to examine the whole coding sequence of the ABO gene. The ABO gene haplotypes were studied using allele-specific primer amplification or cloning technology. In silico analytic tools were used to assess the functional effect of splice site variations.

Results

Six distinct variants in the ABO gene splice sites were identified in nine individuals with ABO subtypes, including c.28 + 1_2delGT, c.28 + 5G > A, c.28 + 5G > C, c.155 + 5G > A, c.204-1G > A and c.374 + 5G > A. c.28 + 1_2delGT was detected in an A_w individual, while c.28 + 5G > A, c.28 + 5G > C, and c.204-1G > A were detected in B_el individuals. c.155 + 5G > A was detected in one B₃ and two AB₃ individuals, whereas c.374 + 5G > A was identified in two A_el individuals. Three novel splice site variants (c.28 + 1_2delGT, c.28 + 5G > A and c.28 + 5G > C) in the ABO gene were discovered, all of which resulted in low antigen expression. In silico analysis revealed that all variants had the potential to alter splice transcripts.

Conclusions

Three novel splice site variations in the ABO gene were identified in Chinese individuals, resulting in decreased A or B antigen expression and the formation of ABO subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03141-5.

A novel allele arising from c.912C>A mutation in the α-1,3-N-acetylgalactosaminyltransferase gene in a Chinese individual

BACKGROUND

The A_m phenotype, which arises from mutations of the α-1,3-N-acetylgalactosaminyltransferase gene, is rare in the Chinese population. The present study focuses on a novel mutation with the A_m phenotype in a Chinese individual.

STUDY DESIGN AND METHODS

The sample with ABO blood group discrepancy was analyzed by serologic techniques. The full coding and flanking regions of the ABO gene, including the Intron 1 transcription factor-binding site, were identified through direct sequencing of polymerase chain reaction (PCR)-amplified products. PCR products of Exons 6 and 7 were validated to isolate the ABO gene haplotypes by cloning and sequencing individual colonies. The impact of the novel mutation on enzyme function was predicted with Polymorphism Phenotyping algorithm V2 and bioinformatic software programs.

RESULTS

The serologic characteristics of ABO blood typing showed the rare A_m phenotype. The c.467C/T and c.912C/A heterozygous sites in Exon 7 were identified by direct sequencing analysis. Further TA cloning and sequencing revealed that the patient carried an ABO*O.01.01 allele and a novel ABO*A allele. The new allele sequence had one nucleotide alteration (C>A) at position 912 on the background of the ABO*A1.02 allele. The c.912C>A mutation was predicted to be "probably damaging" and "deleterious" by PolyPhen-2 and PROVEAN algorithms, respectively.

CONCLUSION

A novel mutation c.912C>A in α-1,3-N-acetylgalactosaminyltransferase gene resulting in A_m phenotype was identified in a Chinese individual.

A Novel c.796 A>C Mutation in the ABO*B.01 Allele Responsible for CisAB Phenotype

Background

Individuals with the CisAB phenotype are rare in the Chinese population. In the present study, we investigated the sequence of the ABO gene and family members of a newborn suspected to have the CisAB phenotype.

Methods

The ABO phenotype was detected using conventional serological tests. The full coding region of exons 1 to 7 of the ABO gene was amplified by polymerase chain reaction and was sequenced. The ABO haplotype was determined by the allele-specific primer sequencing method.

Results

The proband and his father and grandfather were assigned the CisAB phenotype according to the results of the serological tests and family investigation. A novel CisAB allele was identified in the proband and his father and grandfather, which has only one nucleotide difference at position 796 from A to C (c.796A>C) compared with the ABO*B.01 allele.

Conclusion

A novel CisAB (c.796A>C mutation in ABO*B.01) allele is the first identified in the Chinese population.

Molecular Basis of ABO Variants Including Identification of 16 Novel ABO Subgroup Alleles in Chinese Han Population

Introduction

The characteristic of ABO blood subgroup is crucial for elucidating the mechanisms of such variant phenotypes and offering useful information in blood transfusion.

Methods

In total, 211 ABO variants including part of available family members were investigated in this study. The phenotypes of these individuals were typed with serologic methods. The full coding regions of ABO gene and the erythroid cell-specific regulatory elements in intron 1 of them were amplified with polymerase chain reaction and then directly sequenced. The novel alleles were confirmed by cloning and sequencing. Phylogenetic tree was made using CLUSTAL W software. 3D structural analyses of the glycosyltransferases (GTs) with some typical mutations were performed by PyMOL software.

Results

Forty-eight distinctly rare ABO alleles were identified in 211 Chinese variant individuals, including 16 novel ABO alleles. All of the alleles were categorized as 5 groups: 16 ABO*A alleles, 23 ABO*B alleles, 4 ABO*BA alleles, 4 ABO*cisAB alleles, and 1 ABO*O alleles. ABO*A2.08 and ABO*BA.02 were the relatively predominant A and B subgroup alleles, respectively. According to the phylogenetic tree, 28 alleles (5 common alleles and 23 alleles identified in our laboratory) were classified into 3 major allelic lineages. The structural analysis of 3D homology modeling predicted reduced protein stability of the mutant GTs and may explain the reduced ABO antigen expression.

Conclusions

The molecular basis of ABO variants was analyzed, and 16 novel ABO alleles were identified. The results extended the information of ABO variants and provided a basis for better transfusion strategies and helped to improve blood transfusion safety.

Determination of complete sequence information of the human ABO blood group orthologous gene in pigs and breed difference in blood type frequencies

The sequence information of the genomic form of the human ABO blood group orthologous gene (erythrocyte antigen A, EAA) is not complete in pigs. Therefore, we cloned and characterized the nucleotide sequence of EAA intron 7, which is critical to understand genetic difference between A and 0 blood groups in pigs, covering complete genomic sequence information of EAA excluding a ~560bp unsequencible gap. We also analyzed genetic polymorphisms within EAA intron 7 and exon 8. We found difference in A0 blood group frequencies among pig breeds. In addition, we designed a new genomic DNA-based A0 blood group typing method and improved the accuracy and simplicity of the typing.

Heterogeneity of O blood group in India: Peeping through the window of molecular biology

BACKGROUND:

Molecular genotyping of ABO blood group system has identified more than 60 “O” group alleles based on the single-nucleotide polymorphisms present in the ABO gene. Heterogeneity of O group alleles has been observed in various countries from South America, Europe, Middle East, and Asia. India is a vast country with more than 1300 million population which is divided into various ethnic and tribal groups. However, very little is known about the heterogeneity of O alleles in Indians.

MATERIALS AND METHODS:

A total of 116 O group individuals from the mixed population of Mumbai, India, were enrolled in the present study. DNA was extracted using the standard phenol–chloroform method. The exons 6 and 7 of the ABO gene were genotyped by polymerase chain reaction-single-strand conformation polymorphism and/or DNA sequencing. The genotyping results were compared with our earlier findings.

RESULTS AND DISCUSSION:

Overall, ten different genotypes were identified. Three rare alleles, namely, O05, O11, and O26 were seen in the mixed group category. These results suggest that there is an internal heterogeneity in the mixed group while Dhodias and Parsis, the groups which were screened earlier, seem to be more homogenous groups. An important piece of information emerges out from this study, that is, O01O02 genotype is expressing some selective force in population groups screened in India as well as many other groups worldwide.

CONCLUSION:

In the future, molecular genotyping of the ABO blood group system among different ethnic and tribal Indian groups would help in generating data to fill up the gaps in the molecular ABO map of the world.

Establishment of an alternative efficiently genotyping strategy for human ABO gene

ABO genotyping is used in several disciplines, including transfusion, transplantation, human evolution, and forensic medicine. Detection of single nucleotide polymorphisms (SNPs) on a locus is a common way to identify different genotypes. In this study we developed a strategy for ABO genotyping, which can rapidly and efficiently detect SNPs. DNA fragments containing 4 SNPs in the ABO gene (c.261delG, c.297A > G, c.1009A > G, and c.1061delC) were amplified using individually and multiplexed polymerase chain reaction (PCR)-based methods and subsequently genotyped by high-resolution melting (HRM) analysis. Human blood ABO genotypes from 92 samples were successfully determined by HRM analysis. A total of 14 genotypes (A/A, A/O01, A/O02, A201/O01, A205/O01, B/B, B/O01, B/O02, A/B, A201/B, A205/B, O01/O01, O02/O02, O01/O02) were identified by analysis of the 4 SNPs of interest in this study. The results suggest that the present HRM assay is a reliable and rapid method for ABO blood type genotyping and it may offer an alternative to traditional genotyping methods.

Allelic variance among ABO blood group genotypes in a population from the western region of Saudi Arabia

Background

Characterization of the ABO blood group at the phenotype and genotype levels is clinically essential for transfusion, forensics, and population studies. This study elucidated ABO phenotypes and genotypes, and performed an evaluation of their distribution in individuals from the western region of Saudi Arabia.

Methods

One-hundred and seven samples underwent standard serological techniques for ABO blood group phenotype analysis. ABO alleles and genotypes were identified using multiplex polymerase chain reaction, and electrophoretic analysis was performed to evaluate the highly polymorphic ABO locus.

Results

A phenotype distribution of 37.4%, 30.8%, 24.3%, and 7.5% was found for blood groups O, A, B, and AB respectively in our study cohort. Genotype analysis identified 10 genotype combinations with the O01/O02 and A102/O02 genotypes being the most frequent with frequencies of 33.6% and 14.95%, respectively. Common genotypes such as A101/A101, A101/A102, A101/B101, B101/B101, and O01/O01 were not detected. Similarly, the rare genotypes, cis-AB01/O02, cis-AB01/O01, and cis-AB01/A102 were not found in our cohort. The most frequently observed allele was O02 (35.98%) followed by the A102 allele (17.76%). Furthermore, our findings are discussed in reference to ABO allele and genotype frequencies found in other ethnic groups.

Conclusion

The study has a significant implication on the management of blood bank and transfusion services in Saudi Arabian patients.

Histo-blood group glycans in the context of personalized medicine

BACKGROUND

A subset of histo-blood group antigens including ABO and Lewis are oligosaccharide structures which may be conjugated to lipids or proteins. They are known to be important recognition motifs not only in the context of blood transfusions, but also in infection and cancer development.

SCOPE OF REVIEW

Current knowledge on the molecular background and the implication of histo-blood group glycans in the prevention and therapy of infectious and non-communicable diseases, such as cancer and cardiovascular disease, is presented.

MAJOR CONCLUSIONS

Glycan-based histo-blood groups are associated with intestinal microbiota composition, the risk of various diseases as well as therapeutic success of, e.g., vaccination. Their potential as prebiotic or anti-microbial agents, as disease biomarkers and vaccine targets should be further investigated in future studies. For this, recent and future technological advancements will be of particular importance, especially with regard to the unambiguous structural characterization of the glycan portion in combination with information on the protein and lipid carriers of histo-blood group-active glycans in large cohorts.

GENERAL SIGNIFICANCE

Histo-blood group glycans have a unique linking position in the complex network of genes, oncodevelopmental biological processes, and disease mechanisms. Thus, they are highly promising targets for novel approaches in the field of personalized medicine. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

The serological and genetic characterization of CisAB blood group in a Chinese family

BACKGROUND

The rare CisAB blood genotype results in the inheritance of both the A and B blood types from a single parent. Several CisAB blood type phenotypes have been characterized that differ in their serological reactions and in the activities of the gene-encoded blood group A and B transferases. In this study, we conducted serological and genetic analyses of a Chinese family with four CisAB-carrying members.

STUDY DESIGN AND METHODS

A 10-year-old girl was suspected to have the CisAB blood type when forward blood typing indicated that she was blood type AB but reverse blood typing indicated that she was blood type A. An examination of this family identified that four of ten family members across three generations had a pattern of AB inheritance that could be explained only by the inheritance of the CisAB genotype. Blood samples from the family were tested serologically and genetically using PCR-SSP for the relevant CisAB alleles. The samples that were suitable for DNA analysis were sequenced for potential mutations.

RESULTS

Of the ten family members included in this study, four members showed mismatched forward and reverse blood grouping results, four members typed as blood group O and the remaining two members typed as blood group B. Among the four mismatched individuals, the propositus and her mother's mother were serologically typed as having the A2B3 phenotype. The propositus' mother and her mother's brother were typed as having the A2B phenotype, and had the genotypes CisAB01/O02 and CisAB01/B101, respectively. Further sequencing analysis of the four samples with the CisAB blood type revealed that a G(261) deletion occurred along with 297A>G, 467C>T, 646T>A, 681G>A, 771C>T, 803G>C and 829G>C substitutions in exons 6 and 7 of CisAB01/O02, while a 297A>G substitution occurred in exon 6 and 467C>T, 803G>C, 526C>G, 657C>T, 703G>A, 796C>A, 930G>A substitutions occurred in exon 7 of CisAB01/B101.

CONCLUSION

A family was identified in which 4/10 family members across three generations had inherited the CisAB blood group. Two of the CisAB genotypes were further identified as CisAB01/O02 and CisAB01/B101. The CisAB heterozygous alleles contributed to the different phenotypes that were observed.

Analysis of circulating cholesterol levels as a mediator of an association between ABO blood group and coronary heart disease

BACKGROUND

Non-O type of ABO blood group has been associated with a predisposition to coronary heart disease. It is thought that this association is partly mediated by increased cholesterol levels in non-O-type individuals. In this study, we sought to estimate the mediation effect size.

METHODS AND RESULTS

In a group of individuals (n=6476) undergoing coronary angiography, we detected associations of non-O type with significant coronary artery disease with >50% stenosis in ≥1 coronary arteries (odds ratio, 1.24; 95% confidence interval, 1.10-1.39; P=2.6×10(-4)) and with prevalent or incident myocardial infarction (odds ratio, 1.22; 95% confidence interval, 1.09-1.37; P=1.2×10(-3)). Subjects of non-O type had higher levels of total cholesterol, low-density lipoprotein cholesterol, and non-high-density lipoprotein cholesterol (mean [SEM] in mmol/L: 4.931[0.021], 3.041 [0.018], and 3.805 [0.020] in non-O type compared with 4.778 [0.026], 2.906 [0.021], and 3.669 [0.024] in O type; P=3.8×10(-7), P=1.5×10(-7), and P=3.1×10(-7), respectively). Mediation analyses indicated that 10% of the effect of non-O type on coronary artery disease susceptibility was mediated by increased low-density lipoprotein cholesterol level (P=7.8×10(-4)) and that 11% of the effect of non-O type on myocardial infarction risk was mediated by raised low-density lipoprotein cholesterol level (P=2.0×10(-3)).

CONCLUSIONS

In a model in which it is presumed that cholesterol is a mediator of the associations of ABO group with coronary artery disease and myocardial infarction, around 10% of the effect of non-O type on coronary artery disease and myocardial infarction susceptibility was mediated by its influence on low-density lipoprotein cholesterol level.

Molecular characterization of weaker variants of A and B in Indian population--the first report

BACKGROUND AND OBJECTIVES

The ABO blood group system is extremely important blood group system in transfusion medicine and weaker variants of A and B are subgroups of the system. From a Country like India with 1.2 billion population sporadic reports detecting weaker variants of A and B serologically are published. Therefore the main objective of the present study is to identify weaker variants of A and B serologically and characterize them at molecular level.

MATERIALS AND METHODS

Eight samples which were referred to us for resolving discrepancies in forward and reverse grouping were first phenotype in our laboratory by standard serologic techniques for ABO blood groups. Molecular genotyping for the ABO locus was done by PCR-SSCP. Altered SSCP patterns were analysed by DNA sequencing. Sequencing of intron 6 and exons 1-5 was done in one sample each.

RESULTS AND CONCLUSION

Nine rare alleles affecting the normal expression of A and B antigens have been identified among Indians. They were two Aw06, one A209, one Ax20, two O05, one O49, one O56 and one O19 alleles. This is the first report demonstrating molecular studies on weaker variants of A and B from India.

ABO blood group and risk of pancreatic cancer: a study in Shanghai and meta-analysis

Studies over 5 decades have examined ABO blood groups and risk of pancreatic cancer in Western, Asian, and other populations, though no systematic review has been published. We studied data from 908 pancreatic cancer cases and 1,067 population controls collected during December 2006-January 2011 in urban Shanghai, China, and reviewed the literature for all studies of this association. Random-effects meta-analysis provided summary odds ratio estimates according to blood group and by populations endemic versus nonendemic for cytotoxin-associated gene A (CagA)-positive Helicobacter pylori. In our Shanghai study, versus group O, only ABO group A was associated with risk (odds ratio (OR) = 1.60, 95% confidence interval (CI): 1.27, 2.03). In 24 pooled studies, group A showed increased risk in both CagA-nonendemic and -endemic populations (ORpooled = 1.40, 95% CI: 1.32, 1.49). In nonendemic populations, groups B and AB were also associated with higher risk (OR = 1.38, 95% CI: 1.16, 1.64; and OR = 1.52, 95% CI: 1.24, 1.85, respectively). However, in CagA-endemic populations, groups B and AB were not associated with risk (OR = 1.05, 95% CI: 0.92, 1.19; and OR = 1.13, 95% CI: 0.92, 1.38, respectively). These population differences were significant. One explanation for contrasts in associations of blood groups B and AB between CagA-endemic and -nonendemic populations could involve gastric epithelial expression of A versus B antigens on colonization behaviors of CagA-positive and CagA-negative H. pylori strains.

Serological characteristic and molecular basis of A2 subgroup in the Chinese population

BACKGROUND

A2 phenotype is a common subgroup of blood group A, but the serological characteristic and genetics basis of A2 phenotype currently was rare reported in the Chinese Han population. Here, a large scale study of the serology and genetics of A2 and A2B phenotypes was performed.

METHODS/MATERIALS

11263 Chinese individuals with group A and AB phenotypes were determined for A2 antigen with the standard serological method. The full coding region of the ABO gene was sequenced in the individuals with A2 and A2B phenotypes. Some samples including each ABO genotypes were chosen for determining the activity of glycosyltransferase A (GTA) in plasma.

RESULTS

134 individuals were assigned as A2 and A2B phenotypes in 11263 individuals. There was imbalance in A2 and A2B phenotypes and the proportion of A2B among AB samples was significantly higher than that of A2 in group A samples. All samples of the A2 and A2B phenotypes were classified into A2-related allele group, A1-related allele group and the other group based on kind of the ABO genotype. Four novel A2-related alleles (A217, A218, A219, A220) were identified. The individuals with same genotype showed different agglutination strength with anti-A1 and anti-H on their RBCs. The plasma from individuals with A2-related allele had almost no GTA activity, while plasma from individuals with A1-related allele had some GTA activity.

CONCLUSION

A2 and A2B phenotypes could derive from different genotypes and the serological characteristic may be heterogeneity in the Chinese Han population.

A novel FUT1 allele was identified in a Chinese individual with para-Bombay phenotype

BACKGROUND

The para-Bombay phenotype is characterised by H-deficient or H partially deficient red blood cells (RBCs) in individuals who secrete ABH antigens in their saliva. Samples from an individual whose RBCs had an apparent para-Bombay phenotype and his family members were investigated and a novel FUT1 allele was identified.

MATERIALS AND METHODS

RBCs' phenotype was characterised by standard serologic technique. Genomic DNA was sequenced with primers that amplified the coding sequence of FUT1 and FUT2, respectively. Routine ABO genotyping analysis was performed. Haplotypes of FUT1 were identified by TOPO cloning sequencing. Recombination expression vectors of FUT1 mutation alleles were constructed and transfected into COS-7 cells. The pα-(1,2)-fucosyltransferase activity of expression protein was determined.

RESULTS

B101/O02 genotype of the proband was correlated with ABH substances in saliva. The proband carried a new FUT1 allele which showed 35C/T, 235G/C and 682A/G heterozygote by directly DNA sequencing. Two haplotypes, 235C and 35T+682G, were identified by TOPO cloning sequencing and COS-7 cells transfected with five recombination vectors including wild-type, 35T, 235C, 682G and 35T+682G alleles were established respectively. The α-(1,2)-fucosyltransferase activities of cell lysates which had transfected with 35T, 235C, 682G and 35T+682G recombination vectors showed 79·45, 16·23, 80·32 and 24·59%, respectively, compared with that of the wild-type FUT1-transfected cell lysates.

CONCLUSION

A novel FUT1 allele 235C was identified, which greatly diminished the activity of α-(1,2)-fucosyltransferase.