Genotyping of the rare Para-Bombay blood group in southern Thailand

INTRODUCTION

The para-Bombay phenotype, or H-deficient secretor, results from different mutations of the FUT1, with or without the FUT2 mutation. Consequently, there is an absent or weak expression of the H antigen on red blood cells (RBCs). Routine ABO blood grouping for two siblings with blood group O showed discrepant results with their parental blood group AB. Fragments encompassing the entire coding region of the FUT1 and FUT2 genes were investigated.

METHODS

Blood and saliva specimens were collected to verify the correct ABO grouping by cell grouping, serum grouping and the hemagglutination inhibition (HI) test, respectively. The FUT1 and FUT2 genomes were identified using the whole-exome sequencing (WES) in two children's DNA blood specimens and may have caused, or been relative to, their blood group. Genetic variations of the FUT1 and FUT2 genes have been investigated in the other family members using the Sanger sequencing.

RESULTS

The serologic reaction results of the proband revealed that A, B and H antigens were absent on RBCs, and that the serum contained anti-H. However, ABH and AH antigens were present in the saliva PB1 and PB2, respectively. The probands PB1 and PB2 were assigned as AB and A blood groups, respectively. Blood genotyping confirmed that heterozygous mutations of the FUT1 gene, c.551_552delAG, were identified. Three family members, PB3, PB, and PB8, also showed normal ABO blood groups, but their genotypes were also the FUT1 mutation c.551_552delAG.

CONCLUSIONS

The FUT1 mutation c.551_552delAG may result in the reduced or absent H antigen production on RBCs, which characterizes the para-Bombay phenotypes. Blood genotyping is essential if these individuals need a blood transfusion or are planning to donate blood.

"Auto-anti-A1" in a healthy young blood donor: A rare cause of ABO discrepancy

”Auto-anti-A1” has been sparsely discussed in the literature. Only few workers in the past depicted such antibody in transfused and nontransfused patients. The current case is probably the first example of auto-anti-A1 in a healthy young blood donor who was typed as ABO Group “A1B.” The cold reacting autoantibody in the donor was serologically characterized in details and was found to be nonhemolytic. ABO discrepancy was resolved and the donor was finally typed as “A1B Negative.” Therefore, we concluded that auto-anti-A1 may be a rare cause of ABO discrepancy and its resolution is essential to confirm blood group and subsequent blood transfusion management.

Analysis of ABO grouping discrepancies among patients from a tertiary hospital in Korea

BACKGROUND

Accurate ABO typing is essential for preventing ABO incompatibility reactions. However, the causes of ABO grouping discrepancy has not been sufficiently studied, and it may vary among different ethnic populations. Thus, the aim of this retrospective study was to investigate the causes of ABO discrepancy in the East Asian population.

MATERIALS AND METHODS

A retrospective observational study on ABO typing discrepancy among patients in a tertiary hospital was carried out using the electronic medical record database of Samsung Medical Center (Seoul, Korea) between July 2016 and May 2019.

RESULTS

ABO grouping was performed on 551,959 blood samples during the study period; 1468 events of serologic ABO discrepancy were determined from 1334 (0.24 %) samples. A total of 134 samples (0.02 %) presented multiple causes of ABO discrepancy. Weak/missing serum reactivity (594, 40.5 %) was the most frequent reason for ABO discrepancy, followed by extra serum reactivity (370, 25.2 %), weak/missing red cell reactivity (267, 18.2 %), mixed-field red cell reactivity (176, 12.0 %), and extra red cell reactivity (61, 4.2 %). In the category of weak/missing red cell reactivity, ABO subgroup was the most common reason, and using ABO genotyping, 26.2 % of the cases genotyped were found to be related to the cis-AB allele.

CONCLUSIONS

Our results suggest that the incidence and cause of ABO typing discrepancies vary among institutes and ethnic groups. Our data helps to better understand and facilitate the resolution of ABO typing discrepancies in patients.

Genomic analysis of blood samples with serologic ABO discrepancy identifies 12 novel alleles in a Chinese Han population

OBJECTIVES

This study aimed at identifying new ABO alleles from155 unrelated blood samples with potential ABO discrepancy in a Chinese Han population of 835 144 donors.

BACKGROUND

Serological strategies and genotyping are crucial for the precise determination of ABO discrepancy.

METHODS

Their ABO phenotypes and plasma glycosyltransferase activity were determined by standard forward and reverse typing and dilution tests. The genomic DNA of the ABO gene was amplified by polymerase chain reaction and sequenced. The frequency of ABO subgroup alleles associated with ABO discrepancy was analysed.

RESULTS

Serological analysis indicated that 53, 96 and 6 samples with ABO discrepancy were identified in the A, B and O subgroups, respectively. Genetic analysis revealed 12 novel alleles among the 46 associated with serologic ABO discrepancy. The majority of novel alleles was obtained from point mutations or single base insertion in Exons 6 to 7 of the ABO gene. The most frequent alleles were ABO*cisAB.01 (14/53, 26.42%) and ABO*A2.05 (7/53, 13.2%) in the A subgroup and ABO*BA.02 (34/96, 35.42%) and ABO*BEL.11 (15/96, 15.62%) in the B subgroup. Samples with the same ABO subgroup allele displayed different phenotypes, such as ABO*AX.13, ABO*BW.03, ABO*BW.12, ABO*BW.15, ABO*BEL.03, ABO*BEL.10 and ABO*BEL.11.

CONCLUSION

This study identified 12 novel alleles among the 46 associated with serologic ABO discrepancies. ABO genotyping is needed for the accurate evaluation of blood phenotype to improve the safety of blood transfusion.

Unexpectedly Weak Anti-B in 2 Group O Pediatric Patients on Parenteral Nutrition and Disease Specific Supplemental Enteral Feeds

Anti-A and anti-B antibodies are naturally occurring and develop from exposure to intestinal bacteria after age 4 to 6 months. In the laboratory, strong agglutination with A1 and B cells, or B cells only and A1 cells only, on reverse typing in a healthy person with immunocompetence is expected for patients with ABO types O, A, and B, respectively. However, absent or weak anti-A and anti-B antibodies can be observed in some clinical scenarios, such as patients with immunodeficiencies, newborns, elderly patients, and patients who have recently received bone marrow transplants. In this article, we report the cases of 2 pediatric patients with group O blood type who were receiving total parenteral nutrition (TPN) and disease-specific enteral feeds and who have strong anti-A and absent/weak anti-B.

Establishing Blood Group Genotyping to Resolve ABO Discrepancies in Iran

ABO discrepancies are recognized when the reactions obtained in the forward type do not "match" the reactions obtained in the reverse type. Discrepant results are often caused by a variant ABO gene. Molecular analysis is required to confirm the type of subgroups and discrepancy. In this study ABO genotyping was performed on a series of blood donors and patients to determine their definite blood groups. We examined 100 samples with ABO discrepancies from blood donors and patients referred to Tehran Blood Transfusion Center between October 2015 and August 2016. ABO genotyping was performed on all samples with allele specific PCR for differentiation of A, B and O alleles. Exon 6 and 7 of ABO gene were sequenced to confirm the results. The genotyping of donor/patients samples with discrepant results of ABO blood typing consisted of 61 cases of A₂ and A₂B, 3 cases of B 302 and 4 cases of Aw06. Genotyping of 6 samples that had extra antibody in their serum (AB blood group) confirmed the cell type reaction results. 6 samples that had shown a very weak reaction with anti-AB (similar to O blood group) and had no anti-A in their serum were genotyped as O ₁ O ₂. Blood group genotyping laboratory provides an efficient service for evaluation of ABO discrepancies and resolve the problems encountered in serology reactions.

A novel Bruton tyrosine kinase gene variation was found in an adult with X-linked agammaglobulinemia during blood cross-matching prior to surgical operation

AIMS/OBJECTIVES

To investigate the underlying molecular mechanism of the patient's ABO typing discrepancy.

BACKGROUND

ABO typing discrepancy was frequently seen in patients due to different causes. In this study, ABO typing discrepancy was found in a 24-year-old man with arthralgia, whose forward ABO grouping was O and reverse ABO grouping was AB. Primary immunodeficiency disease was speculated in this patient, especially X-linked agammaglobulinemia (XLA).

METHODS

Immunoglobulins of all isotypes were detected using a specific protein analyser. Lymphocyte subgroups were analysed by flow cytometry. All 19 exons and boundaries of BTK gene were amplified by polymerase chain reaction (PCR), and all PCR products were sequenced by a DNA analyser. BTK protein in the leukocytes and platelets was detected by Western blot.

RESULTS

No B lymphocytes could be detected in the peripheral blood of the patient. A novel BTK gene variation, c.817G>T, in the exon 9 of BTK gene was discovered. No BTK protein expression could be detected in the leukocytes and platelets of the patient.

CONCLUSIONS

XLA could be occasionally discovered by ABO typing discrepancy in some cases because of the deficiency of reciprocal IgM anti-A and/or anti-B antibodies in the serum of the patient. Humoral immunodeficiency is one of the causes of ABO typing discrepancy.

The Mechanism of Allelic Competition in the ABO 547G>A Mutant is Associated with Decreased Activity of Glycosyltransferase B

The 547G>A polymorphism demonstrates significant allelic competition in people who harbor the B306 allele. We have performed the full sequencing of ABO gene in family members and measured their serum glycosyltransferase activity for demonstrating the cause of allelic competition. Genetic study including two regulatory regions and exon 1, and exons 2-7 of ABO gene demonstrated c.547G>A in exon 7 of the proband and her second son. The ABO genotype of the proband, husband, first son, and other son was ABO*A102/ABO*B306, ABO*A105/ABO*O02, ABO*A102/ABO*O02, and ABO*B306/ABO*O02 respectively. Serum glycosyltransferse B activity in the proband and her second son was lower than in normal B controls. We infer that allelic competition in the the 547G>A carrying individuals is associated with reduced activity of glycosyltransferase B.

Anti-m antibody in solid tumors-two case reports

Anti-M antibodies are usually of IgM, appear as cold agglutinins and are clinically insignificant. We are reporting two cases of anti-M in cases of solid tumors where the anti-M caused discrepancy in blood grouping, reacted in coombs phase of crossmatching. Anti-M in first case showed dosage effect. These antibodies can be clinical significant when detected in coombs phase, making M antigen negative coombs compatible unit transfusion imperative.

Molecular genetic analysis and structure model of a rare B(A)02 subgroup of the ABO blood group system

BACKGROUND

Serological analysis of ABO blood group has been widely applied in transfusion medicine. However, ABO subgroups with different expression of blood group antigens sometimes cannot be determined by serological methods. Therefore, genotyping is useful to understand the variant ABO phenotypes.

MATERIAL AND METHODS

Exon 6 to exon 7 and adjacent introns of the ABO gene from a donor with ABO typing discrepancy were amplified and sequenced. Cloning sequencing was also performed to identify the allele. To explore the effect of mutation, three dimensional model of mutant p.Pro234Ala was built and optimized.

RESULTS

The variant B (c. 700C > G) allele expressed an AweakB phenotype with anti-A in his serum with a ABO*B(A)02/O02 heterozygote genotype. Cloning sequencing confirmed that the c.700C > G single nucleotide polymorphism was associated with a B101 allele. Three dimensional molecular modeling suggested that p.Pro234Ala might affect the conformation of His233, Met266 and Ala268, which were known as critical residues for donor recognition.

CONCLUSION

ABO genotyping is needed for correct identification subgroups to improve accuracy evaluation of blood typing and increase the safety of blood transfusion. Alteration of DNA sequence in the ABO gene resulted in amino acid substitutions and led to a weak or missing expression of ABO antigens.

A rare case report of chronic variable immunodeficiency divulged by ABO discrepancy

ABO discrepancy refers to incongruence between the results of red cell and serum groupings. One such case is described here; the discrepant results of whose routine ABO grouping led to the diagnosis of common variable immunodeficiency. There was no reaction in the reverse grouping of a young patient presenting with recurrent bacterial infections, pointing towards an absence of antibodies in the serum. Diagnosis was made on the basis of markedly decreased serum immunoglobulin levels and by serum protein electrophoresis showing scanty gamma regions.

Acute Hemolytic Transfusion Reaction in a Patient with Bombay Phenotype: Implications for ABO Grouping

Bombay blood group is a rare phenotype that is characterized serologically by absence of H, A and B antigens on red cell surface and presence of corresponding antibodies in the serum. We report a case of 45-year old patient having Bombay blood group phenotype who experienced an acute reaction due to transfusion of mismatched blood unit.

A case of IgM deficiency with B cell deficiency detected by ABO discrepancy in a patient with acute osteomyelitis

ABO discrepancy refers to an inconsistency between red cell and serum typings and has various causes, including hypogammaglobulinemia. IgM deficiency is a rare disorder that may accompany several conditions such as infection and autoimmune disorders. Here, we describe a case of IgM deficiency discovered during the evaluation of an ABO discrepancy in a 16-yr-old Korean boy. ABO blood grouping showed that while his cell type was O+, serum typing detected only anti-A (3+). Anti-B was not detectable at room temperature but was graded at 1+ at 4℃. ABO genotyping revealed an O/O genotype. His serum IgG, IgA, and IgM concentrations were 770 mg/dL (reference range: 800-1,700 mg/dL), 244 mg/dL (reference range: 100-490 mg/dL), and 13.5 mg/dL (reference range: 50-320 mg/dL), respectively. He was diagnosed with acute osteomyelitis on the basis of clinical presentation and imaging studies. The symptoms gradually improved within 3 weeks of treatment. However, the ABO discrepancy and IgM deficiency persisted even 6 months after recovery and lymphocyte subset analysis revealed CD19+ B cell deficiency. To the best of our knowledge, IgM deficiency detected by ABO discrepancy in a patient with acute osteomyelitis has not been reported before.