RUNX1 mutation in a patient with myelodysplastic syndrome and decreased erythrocyte expression of blood group A antigen

Detecting serologically difficult ABO blood groups using single-molecule real-time sequencing technology

BACKGROUND AND OBJECTIVES

Recently, third-generation long-read sequencing technology has been increasingly applied to the detection of various blood group systems. Because of its long read length and use of single-molecule sequencing, it is capable of obtaining the sequences of blood group genes in their entirety as well as of distinguishing haplotypes. Therefore, here, we collected ABO blood group samples that were difficult to classify serologically and analysed the sequences of the coding regions of the ABO genes as well as the sequences upstream and downstream of the coding regions.

MATERIALS AND METHODS

Samples with ABO antigen typing and reverse serum typing discrepancies were screened in a total of 21 patients. All samples were subjected to serological testing and preliminary ABO genotyping (polymerase chain reaction with sequence-specific primers [PCR-SSP]), followed by single-molecule real-time (SMRT) sequencing to obtain complete ABO gene sequences. PCR sequence-based typing (PCR-SBT) was performed to validate the results.

RESULTS

Of the 21 samples, 15 had common ABO types, and 6 had rare ABO subtypes. One new allele, ABO*B.NEW (c.861C>T), and one allelic base recombination event was identified. Forty-two haplotype sequences were obtained via SMRT sequencing with intronic single-nucleotide variants (SNVs) specific to the ABO allele, and all of the exon region sequences were consistent with the PCR-SBT results.

CONCLUSION

SMRT sequencing is capable of accurately obtaining complete ABO gene sequences, distinguishing haplotypes and identifying allelic recombination.

Role of MiRNA in the Regulation of Blood Group Expression

Background

MicroRNAs (miRNAs) are small, endogenous non-coding RNA molecules that inhibit gene expression through either destabilization of the target mRNA or translational repression. MiRNAs recognize target sites, most commonly found in the 3'-untranslated regions of cognate mRNAs. This review aims to provide a state-of-the-art overview of the role of miRNAs in the regulation of major blood group antigens such as ABH as well as cancer-specific glycans.

Summary

Besides their known roles in the control of developmental processes, proliferation, apoptosis, and carcinogenesis, miRNAs have recently been identified to play a regulatory role during erythropoiesis and blood group antigen expression. Since only little is known about the function of the red cell membrane proteins carrying blood group antigens, it is of great interest to shed light on the regulatory mechanisms of blood group gene expression. Some carrier proteins of blood group antigens are not restricted to red blood cells and are widely expressed in other bodily fluids and tissues and quite a few play a crucial role in tumor cells, as either tumor suppressors or promoters.

Key Message

All available data point at a tremendous physiological as well as pathophysiological relevance of miRNAs in context of blood group regulation. Furthermore, miRNAs are involved in the regulation of pleiotropic genetic pathways such as hematopoiesis and tumorigenesis and thus have to be studied in future research on this subject.

Review of ABO Expression and Variations based on Transcriptional Regulation of the ABO Blood Group Gene

Background and Summary

We review the transcriptional regulation of ABO expression and discuss variants in the promoter and erythroid cell-specific regulatory region in individuals with weak ABO phenotypes such as Bm, Am, B3, and A3. We also review the molecular mechanisms responsible for variations in ABO expression in development and disease including the cell type-specific expression of ABO during erythroid cell differentiation, and reduction of A- or B-antigens in cancer cells or on red blood cells in patients with leukemia. Although the relationship between ABO blood group antigens and diseases has been characterized, the physiological significance of the ABO blood group system remains unclear.

Key Messages

This review discusses accumulated knowledge of the ABO gene regulation and potential reasons for conservation of ABO during evolution.

Clinical significance of decreased or loss of ABO blood group expression in acute myeloid leukaemia: A single-centre retrospective study

BACKGROUND AND OBJECTIVES

Decreased or loss of ABO blood group antigen expression has been observed in acute myeloid leukaemia (AML) patients. We studied the clinical significance of this group in AML patients.

MATERIALS AND METHODS

This was a retrospective, single-centre cohort study in which the data were retrieved from April 2009 to December 2019. A total of 1592 AML patients with normal ABO blood group antigen (Group I) and 65 patients of decreased or loss of ABO blood group antigen (Group II) group were enrolled. Data were collected at the time of initial admission for pathological diagnosis. To interrogate the underlying mechanism, publicly available The Cancer Genome Atlas AML data were downloaded.

RESULTS

Group II consisted of 3.9% (65/1657) of AML patients. The 90-day survival (D90) probability was higher for Group II with a mean survival of 86.4 days compared to 80.6 days for Group I (p = 0.047). Group II had higher haematocrit (28.6 vs. 27.4%) and lower d-dimer, fibrinogen degradation production and C-reactive protein. Publicly available data revealed that among 11 CpG methylation sites within the ABO gene, 4 sites with elevated methylation level were associated with improved D90 survival probability and demonstrated an inverse correlation with ABO gene expression. Lower expression of the ABO gene showed improved survival trends for D90 (p = 0.058) and 180-day survival (p = 0.072).

CONCLUSION

AML with decreased expression or loss of ABO blood group showed better early survival during D90. Transfusion support for this subgroup of AML patients should be meticulously performed considering serum typing.

CEBPA double mutations associated with ABO antigen weakness in hematologic diseases

ABSTRACT

ABO antigen weakness is rarely observed in ABO typing for transfusion. Hematologic diseases and associated gene mutations have been suggested as potential causes of this phenomenon, yet the precise etiology has not been elucidated. Through ABO typing and genetic analysis data conducted over 7 years, we have reconfirmed the association between ABO antigen weakness and hematologic diseases, especially acute myeloid leukemia (odds ratio [OR], 2.55; 95% confidence interval [CI], 1.12-5.83) and myelodysplastic syndrome (OR, 6.94; 95% CI, 2.86-16.83), and discovered previously unidentified candidate genes, CEBPA (OR, 43.70; 95% CI, 18.12-105.40), NRAS (OR, 3.37; 95% CI, 1.46-7.79), U2AF1 (OR, 8.12; 95% CI, 2.86-23.03), and PTPN11 (OR, 4.52; 95% CI, 1.51-13.50), seemingly associated with this phenomenon. Among these, CEBPA double mutations displayed a significant association, with ABO antigen weakness being observed in 20 of the 25 individuals (80.0%) possessing these mutations. From this study, new factors associated with ABO antigen weakness have been identified.

Association of Leukemia With ABO Blood Group Distribution and Discrepancy: A Review Article

The ABO system is an essential blood group in clinical transfusion medicine implicated in several human diseases. The ABO system has been investigated for over a century, with various studies exploring potential links to disease susceptibility. The study examines the possible relationship between leukemia and the distribution and the ABO blood group system discrepancy. A comprehensive review was conducted on the recommended databases to review the ABO blood groups, their association with leukemia, and the expected changes in blood groups among leukemia patients. The study highlights different kinds of leukemia, such as acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL), their characteristics, and their relationship with ABO blood groups. The document concludes that studying ABO blood group distributions among leukemia patients showed that the most common blood group in acute leukemia is the A group, while in chronic leukemia, the O group is predominant; more studies are required. This study also confirmed an association between leukemia and ABO blood group discrepancy.

Novel evidence that the ABO blood group shapes erythropoiesis and results in higher hematocrit for blood group B carriers

The ABO blood group (BG) system is of great importance for blood transfusion and organ transplantation. Since the same transcription factors (TFs) and microRNAs (miRNAs) govern the expression of ABO BG antigens and regulate erythropoiesis, we hypothesized functional connections between both processes. We found significantly higher hemoglobin and hematocrit values in BG B blood donors compared to BG A. Furthermore, we observed that erythropoiesis in BG B hematopoietic stem/progenitor cells (HSPCs) was accelerated compared to BG A HSPCs. Specifically, BG B HSPCs yielded more lineage-specific progenitors in a shorter time (B: 31.3 ± 2.2% vs. A: 22.5 ± 3.0%). Moreover, non-BG A individuals exhibited more terminally differentiated RBCs with higher enucleation rates containing more hemoglobin compared to BG A. Additionally, we detected increased levels of miRNA-215-5p and -182-5p and decreased expression of their target TFs RUNX1 and HES-1 mRNAs in erythroid BG B precursor cells compared to BG A. This highlights the important roles of these factors for the disappearance of differentiation-specific glycan antigens and the appearance of cancer-specific glycan antigens. Our work contributes to a deeper understanding of erythropoiesis gene regulatory networks and identifies its interference with BG-specific gene expression regulations particularly in diseases, where ABO BGs determine treatment susceptibility and disease progression.

ABO Blood Group and the Risk and Prognosis of Lymphoma

ABO blood group antigens exhibit alternative phenotypes and genetically derived structures that are located on the red cell surface. The role of ABO blood group in cancer biology has been intensely reported by several studies, and it is now widely recognized that ABO antigens are associated with the risk and prognosis of several types of tumors, namely gastric cancer and pancreatic cancer. However, there have been contentious limited issues with the association between the ABO blood group and lymphoma. In this narrative review, based on literature data, we discuss the role of ABO blood group in the risk and prognosis of lymphoma and summarize the current knowledge of the underlying pathogenic mechanisms of the association. The possible association of ABO blood group with racial disparities and pathological classification in lymphoma patients is also discussed.

Analysis of the Genomic Sequence of ABO Allele Using Next-Generation Sequencing Method

Background

Although many molecular diagnostic methods have been used for ABO genotyping, there are few reports on the full-length genomic sequence analysis of the ABO gene. Recently, next-generation sequencing (NGS) has been shown to provide fast and high-throughput results and is widely used in the clinical laboratory. Here, we established an NGS method for analyzing the sequence of the start codon to the stop codon in the ABO gene.

Study Design and Methods

Two pairs of primers covering the partial 5’-untranslated region (UTR) to 3’-UTR of the ABO gene were designed. The sequences covering from the start codon to the stop codon of the ABO gene were amplified using these primers, and an NGS method based on the overlap amplicon was developed. A total of 110 individuals, including 88 blood donors with normal phenotypes and 22 ABO subtypes, were recruited and analyzed. All these specimens were first detected by serological tests and then determined by polymerase chain reaction sequence-based typing (PCR-SBT) and NGS. The sequences, including all the intron regions for the specimens, were analyzed by bioinformatics software.

Results

Among the 88 blood donors with a normal phenotype, 48 homozygous individuals, 39 heterozygous individuals, and one individual with a novel O allele were found according to the results of the PCR-SBT method. Some single-nucleotide variants (SNV) in intronic regions were found to be specific for different ABO alleles from 48 homozygous individuals using the NGS method. Sequences in the coding region of all specimens using the NGS method were the same as those of the PCR-SBT method. Three intronic SNVs were found to be associated with the ABO subtypes, including one novel intronic SNV (c.28+5956T>A). Moreover, six specimens were found to exhibit DNA recombination.

Conclusion

An NGS method was established to analyze the sequence from the start codon to the stop codon of the ABO gene. Two novel ABO alleles were identified, and DNA recombination was found to exist in the ABO alleles.

Reduction of blood group A antigen on erythrocytes in a patient with myelodysplastic syndrome harboring somatic mutations in RUNX1 and GATA2

BACKGROUND

Reduction of blood group ABO antigens on red blood cells (RBCs) is well known in patients with leukemias, and this reduction of ABO expression is strongly associated with DNA methylation of the ABO promoter. Previously, we reported a two-nucleotide deletion in RUNX1 encoding an abnormally elongated protein lacking the trans-activation domain in a patient with myelodysplastic syndrome (MDS) showing A-antigen loss on RBCs. This prompted us to investigate the underlying mechanism responsible for A-antigen reduction on RBCs in another patient with MDS.

STUDY DESIGN AND METHODS

Screening of somatic mutations was carried out using a targeted sequencing panel with genomic DNA from peripheral blood mononuclear cells from the patient and eleven MDS controls without A- or B-antigen loss. DNA methylation of the ABO promoter was examined by bisulfite genomic sequencing. Transient transfection assays were performed for functional evaluation of mutations.

RESULTS

Screening of somatic mutations showed missense mutations in RUNX1 and GATA2 in the patient, while no mutation was found in exons of those genes in the controls. There was no significant difference in ABO promoter methylation between the patient and the controls. Transient transfection experiments into COS-7 and K562 cells suggested that the amino acid substitutions encoded by those mutations reduced or lost the trans-activation potential of the ABO expression.

CONCLUSION

Considering the discrepancy between the variant frequencies of these mutations and the ratios of the RBCs with A-antigens loss, the antigen reduction might be associated with these somatic mutations and hypermethylation of the ABO promoter.

A cell-specific regulatory region of the human ABO blood group gene regulates the neighborhood gene encoding odorant binding protein 2B

The human ABO blood group system is of great importance in blood transfusion and organ transplantation. ABO transcription is known to be regulated by a constitutive promoter in a CpG island and regions for regulation of cell-specific expression such as the downstream + 22.6-kb site for epithelial cells and a site in intron 1 for erythroid cells. Here we investigated whether the + 22.6-kb site might play a role in transcriptional regulation of the gene encoding odorant binding protein 2B (OBP2B), which is located on the centromere side 43.4 kb from the + 22.6-kb site. In the gastric cancer cell line KATOIII, quantitative PCR analysis demonstrated significantly reduced amounts of OBP2B and ABO transcripts in mutant cells with biallelic deletions of the site created using the CRISPR/Cas9 system, relative to those in the wild-type cells, and Western blotting demonstrated a corresponding reduction of OBP2B protein in the mutant cells. Moreover, single-molecule fluorescence in situ hybridization assays indicated that the amounts of both transcripts were correlated in individual cells. These findings suggest that OBP2B could be co-regulated by the + 22.6-kb site of ABO.