Cloning and characterization of DNA complementary to human UDP-GalNAc: Fuc alpha 1----2Gal alpha 1----3GalNAc transferase (histo-blood group A transferase) mRNA

Identification of five novel ABO blood group alleles

BACKGROUND

Today we know more than 200 ABO variant alleles. Most ABO subtypes are caused by single nucleotide substitutions in exons 6 or 7, which encode for the catalytic domain of ABO glycosyltransferases. Understanding the molecular basis of these variants provides insights into the mechanisms responsible for the different phenotypes. We investigated the molecular background causing inconclusive ABO serology of five samples referred to our laboratory.

METHODS

The ABO phenotypes were determined by standard gel column agglutination and tube technique as well as flow cytometry. Molecular investigation included sequence-specific primer (SSP)-PCR and sequencing of all seven ABO exons containing the adjacent flanking intron regions (including the ABO regulatory regions) using published and in-house primers.

RESULTS

Serological and molecular analysis of five probands revealed diverse ABO blood group variations. Four probands showed weak A antigen expression and one proband weak B antigen expression. Proband 1 exhibited a c.952G>A (p.Val318Met) variant linked to the ABO*A1.01 background, while proband 2 carried a c.973T>C (p.Trp325Arg) and proband 3 a c.28+5G>A splice site variant associated with the same allele. Proband 4 revealed the c.407C>A (p.Thr136Lys) variant on an ABO*A2.01 background, and proband 5 had the c.860C>T (p.Ala287Val) variant associated with the ABO*B.01 background.

DISCUSSION

Here we show the serological and molecular analysis of five samples with serologic ABO blood grouping attenuations and/or discrepancies revealing novel A and B subgroup alleles. We report five novel variant alleles: ABO*A1.952A, ABO*A1.973C, ABO*A1.28+5A, ABO*A2.01.407A, and ABO*B1.860T.

ABO Blood Type and Urinary Bladder Cancer: Phenotype, Genotype, Allelic Association with a Clinical or Histological Stage and Recurrence Rate

Background  Previous research on connection between the ABO blood group and bladder cancer has been based on determining the ABO phenotype. This specific research is extended to the molecular level, providing more information about particular ABO alleles. Aim  To investigate the impact of the ABO blood group genotype or phenotype as a risk factor for urinary bladder cancer. Materials and Methods  In the case-control study, we included 74 patients who underwent surgery for a urinary bladder tumor at the Urology Clinic, Clinical Hospital Centre Zagreb, in 2021 and 2022. The control group comprised 142 asymptomatic and healthy blood donors. ABO genotyping to five basic alleles was done using a polymerase chain reaction with sequence-specific primers. We compared ABO phenotypes, genotypes, and alleles between patients and the healthy controls and investigated their distribution according to the clinical and histological stage and recurrence rate. Results  No statistically significant difference was found among the groups, nor for the observed disease stages in terms of the phenotype and genotype. At the allele level, the results show a significantly lower proportion of malignancy in O1 ( p  < 0.001), A1 ( p  < 0.001), and B ( p  = 0.013), and a lower proportion of metastatic disease in A2 (0%, p  = 0.024). We also found significantly higher proportions of high-grade tumors in patients with O1 (71.4%, p  < 0.001), A1 (70.1%, p  = 0.019), of nonmuscle invasive tumors in patients with O1 (55.1%, p  < 0.001), O2 (100%, p  = 0.045), and recurrent tumors in patients with O1 (70.2%, p  < 0.001) and A1 (74.2%, p  = 0.007) alleles. Conclusion  We did not find an association between the ABO blood group genotype or phenotype as a genetic risk factor for urinary bladder cancer. However, an analysis at the allelic level revealed a statistically significant association between certain alleles of the ABO blood group system and urinary bladder tumors, clinical or histological stage, and recurrence rate, respectively.

Rapid Identification of Seven Common ABO Alleles by Two-Dimensional Polymerase Chain Reaction Technology

INTRODUCTION

The molecular biology detection technology of the human ABO blood group system makes up for the limitations in many aspects compared with conventional serological typing technology. This study aimed to establish a new method to identify seven common ABO alleles (ABO*A1.01, ABO*A1.02, ABO*A2.01, ABO*B.01, ABO*O.01.01, ABO*O.01.02, and ABO*O.02.01) by two-dimensional polymerase chain reaction (2D PCR). 2D PCR can identify multiple target genes in a closed test tube by labeling specific primers with tags homologous to the sequence of fluorescently labeled probes, and melting curve analysis is performed after the fluorescent probes are hybridized with tag complementary sequences in PCR-specific products. In this study, 2D PCR and PCR sequence-specific primer (PCR-SSP) were combined to discriminate different alleles in a single reaction, which has the characteristics of high throughput, and compared with other typing techniques; the typing results can be obtained without additional operations.

METHODS

The ABO*A1.01 allele genetic sequence was used as the reference sequence. The specific sense and antisense primers for seven common ABO alleles were designed on exons 6 and 7 according to the principle of 2D PCR and PCR-SSP. Single nucleotide polymorphism sites for identifying seven alleles were detected in FAM and HEX channels, respectively. Two hundred sixty DNA samples were enrolled for rapid ABO genotyping by 2D PCR, and 95 of them were selected for Sanger sequencing. The Kappa test was used to analyze the agreement of the methodologies.

RESULTS

These 7 alleles each had four characteristic melting valleys at different single nucleotide polymorphism loci. A total of 15 genotypes were detected, including ABO*A1.01/A1.02, ABO*A1.01/O.01.01, ABO*A1.01/O.01.02, ABO*A1.02/A1.02, ABO*A1.02/O.01.01, ABO*A1.02/O.01.02, ABO*B.01/B.01, ABO*B.01/O.01.01, ABO*B.01/O.01.02, ABO*O.01.01/O.01.01, ABO*O.01.01/O.01.02, ABO*O.01.02/O.01.02, ABO*A1.01/B.01, ABO*A1.02/B.01, and ABO*B.01/O.01. v (containing a rare ABO*O allele, based on the sequencing results). The Kappa test showed completely consistent results for 2D PCR and Sanger sequencing (Kappa = 1).

CONCLUSION

The 2D PCR technique could be used for molecular typing of the ABO blood group, which was efficient, rapid, accurate, and economical.

Truncated glycosyltransferase coding regions in novel ABO alleles give rise to weak A or B blood group expression and discrepant typing results

BACKGROUND

Correct ABO blood-group matching between donor and patient is crucial for safe transfusions. We investigated the underlying reason causing inconclusive ABO serology in samples referred to our laboratory.

STUDY DESIGN AND METHODS

Flow cytometric analysis, ABO genotyping, and sequencing were used to characterize ABO-discrepant blood samples (n = 13). ABO gene variants were inserted in a GFP-containing bicistronic vector to assess A/B expression following overexpression in HeLa cells.

RESULTS

Seven novel alleles with nonsense mutations predicted to truncate the encoded ABO glycosyltransferases were identified. While these variants could represent O alleles, serology showed signs of ABO glycosyltransferase activity. ABO*A1.01-related alleles displayed remarkably characteristic percentages of A-positive cells for samples with the same variant: c.42C>A (p.Cys14*; 10%), c.102C>A (p.Tyr34*; 31%-32%, n = 2), c.106dup (p.Val36Glyfs*21; 16%-17%, n = 3) or c.181_182ins (p.Leu61Argfs*21; 12%-13%, n = 2). Transfection studies confirmed significantly decreased A expression compared to wild type. The remaining variants were found on ABO*B.01 background: c.1_5dup (pGly3Trpfs*20), c.15dup (p.Arg6Alafs*51) or c.496del (p.Thr166Profs*26). Although the absence of plasma anti-B was noted overall, B antigen expression was barely detected on erythrocytes. Overexpression confirmed decreased B in two variants compared to wildtype while c.1_5dup only showed a non-significant downward trend.

CONCLUSION

Samples displaying aberrant ABO serology revealed seven principally interesting alleles. Despite the presence of truncating mutations, normally resulting in null alleles, low levels of ABO antigens were detectable where alterations affected ABO exons 1-4 but not exon 7. This is compatible with the previously proposed concept that alternative start codons in early exons can be used to initiate the translation of functional ABO glycosyltransferase.

Emergence of an erythroid cell-specific regulatory region in ABO intron 1 attributable to A- or B-antigen expression on erythrocytes in Hominoidea

A- and B-antigens are present on red blood cells (RBCs) as well as other cells and secretions in Hominoidea including humans and apes such as chimpanzees and gibbons, whereas expression of these antigens on RBCs is subtle in monkeys such as Japanese macaques. Previous studies have indicated that H-antigen expression has not completely developed on RBCs in monkeys. Such antigen expression requires the presence of H-antigen and A- or B-transferase expression in cells of erythroid lineage, although whether or not ABO gene regulation is associated with the difference of A- or B-antigen expression between Hominoidea and monkeys has not been examined. Since it has been suggested that ABO expression on human erythrocytes is dependent upon an erythroid cell-specific regulatory region or the + 5.8-kb site in intron 1, we compared the sequences of ABO intron 1 among non-human primates, and demonstrated the presence of sites orthologous to the + 5.8-kb site in chimpanzees and gibbons, and their absence in Japanese macaques. In addition, luciferase assays revealed that the former orthologues enhanced promoter activity, whereas the corresponding site in the latter did not. These results suggested that the A- or B-antigens on RBCs might be ascribed to emergence of the + 5.8-kb site or the corresponding regions in ABO through genetic evolution.

A historical overview of advances in molecular genetic/genomic studies of the ABO blood group system

In 1990, 90 years after the discovery of ABO blood groups by Karl Landsteiner, my research team at the Molecular Biology Laboratory of the now-defunct Biomembrane Institute elucidated the molecular genetic basis of the ABO polymorphism. Henrik Clausen, Head of the Immunology Laboratory, initiated the project by isolating human group A transferase (AT), whose partial amino acid sequence was key to its success. Sen-itiroh Hakomori, the Scientific Director, provided all the institutional support. The characterization started from the 3 major alleles (A1, B, and O), and proceeded to the alleles of A2, A3, Ax and B3 subgroups and also to the cis-AB and B(A) alleles, which specify the expression of A and B antigens by single alleles. In addition to the identification of allele-specific single nucleotide polymorphism (SNP) variations, we also experimentally demonstrated their functional significance in glycosyltransferase activity and sugar specificity of the encoded proteins. Other scientists interested in blood group genes later characterized more than 250 ABO alleles. However, recent developments in next-generation sequencing have enabled the sequencing of millions of human genomes, transitioning from the era of genetics to the era of genomics. As a result, numerous SNP variations have been identified in the coding and noncoding regions of the ABO gene, making ABO one of the most studied loci for human polymorphism. As a tribute to Dr. Hakomori's scientific legacy, a historical overview in molecular genetic/genomic studies of the human ABO gene polymorphism is presented, with an emphasis on early discoveries made at his institute.

Detection of five common variants of ABO gene by a triplex probe-based fluorescence-melting-curve-analysis

Current studies have suggested that the ABO blood group system is associated with several clinical conditions. For large-scale genotyping of ABO alleles, we developed a triplex fluorescence melting curve analysis (FMCA) to determine five single nucleotide variants (SNVs), c.261delG, c.796C>A, c.802G>A and c.803G>C and c.1061delC, responsible for common ABO phenotypes using dual-labeled self-quenched (TaqMan) probes in a single tube. We accurately determined c.796C>A, c.802G>A, and c.803G>C genotypes using a FAM-labeled probe, c.261delG using a CAL Fluor Orange 560- labeled probe, and c.1061delC using a Cy5-labeled probe. The present genotyping results of five SNVs in 214 subjects of the 1000 Genomes Project were in full agreement with those of the database sequence. The predicted ABO phenotypes using combinations of these five SNVs by this method in 288 Japanese subjects were in complete agreement with those by hemagglutination assay, although we did not find any A2 (alleles containing c.1061delC) or O.02 (alleles containing c.802G>A) alleles. The present triplex probe-based FMCA is a valid and credible method for a considerably accurate large-scale determination of ABO allele genotypes and estimation of phenotypes.

Molecular basis of weak A subgroups in the Korean population: Identification of three novel subgroup-causing variants in the ABO regulatory regions

BACKGROUND

Recent studies on Chinese and Japanese populations have shown that weak ABO subgroups could be caused by variants in the major regulatory regions of ABO, the proximal promoter, +5.8-kb site, and CCAAT-binding factor/NF-Y binding site. We investigated the molecular basis of weak A subgroups in the Korean population.

STUDY DESIGN AND METHODS

This study included 11 samples suspected to have a weak A subgroup. These samples were subjected to sequencing analysis of ABO exons 6 and 7. If no subgroup-causing variants were detected in this region, exons 1-5 and three major regulatory regions were sequenced.

RESULTS

Sequencing analysis of exons 6 and 7 detected two known subgroup alleles (ABO*AW.10, n = 5; ABO*AEL.02, n = 2). The remaining four samples contained a sequence variant in the proximal promoter (g.4944C>T, n = 1; g.4954G>T, n = 1) or +5.8-kb site (g.10843T>C, n = 1; g.10935C>T, n = 1). Notably, three of the four variants (g.4944C>T, g.4954G>T, and g.10843T>C) have not been reported previously in weak ABO subgroups.

CONCLUSION

This study provides the first evidence that alterations in the proximal promoter and + 5.8-kb site could account for a substantial proportion of weak A subgroups in the Korean population.

Mixed-Up Sugars: Glycosyltransferase Cross-Reactivity in Cancerous Tissues and Their Therapeutic Targeting

The main categories of glycan changes in cancer are: (1) decreased expression of histo-blood group A and/or B antigens and increased Lewis-related antigens, (2) appearance of cryptic antigens, such as Tn and T, (3) emergence of genetically incompatible glycans, such as A antigen expressed in tumors of individuals of group B or O and heterophilic expression of Forssman antigen (FORS1), and (4) appearance of neoglycans. This review focuses on the expression of genetically incompatible A/B/FORS1 antigens in cancer. Several possible molecular mechanisms are exemplified, including missense mutations that alter the sugar specificity of A and B glycosyltransferases (AT and BT, respectively), restoration of the correct codon reading frame of O alleles, and modification of acceptor specificity of AT to synthesize the FORS1 antigen by missense mutations and/or altered splicing. Taking advantage of pre-existing natural immunity, the potential uses of these glycans for immunotherapeutic targeting will also be discussed.

Allelic distribution of ABO gene in Chinese centenarians

Objective

Human ABO blood groups are determined by the alleles A, B, and O (O01 and O02) of the ABO gene and have been linked to the risks for cardiovascular diseases and cancers that affect lifespan.

We examined the genetic associations of the ABO gene and blood groups with longevity.

Methods

We inspected the frequencies of the A, B, O, and O02 alleles in a large Chinese centenarian population (n = 2201) and in middle‐aged controls (n = 2330). The single nucleotide polymorphisms were selected as allele A (rs507666), B (rs8176743, rs8176746, and rs8176749), O (rs687289), and O02 (rs688976, rs549446, and rs512770).

Results

Supported by allelic and genotypic association studies, the frequencies of blood types A, B, O, and AB in centenarian versus control participants were not statistically different: 0.2821 versus 0.2781 (χ² = 0.09, P = 0.76), 0.2867 versus 0.3060 (χ² = 2.03, P = 0.15), 0.3380 versus 0.3159 (χ² = 2.52, P = 0.11), and 0.0859 versus 0.0910 (χ² = 0.37, P = 0.54), respectively. Sex had little effect on these distributions.

Conclusion

Integrated with other previous reports, we conclude from this large Chinese cohort that genetic variants of the ABO gene and blood groups are not associated with longevity.

ABO genotyping of various hematopoietic cell lines to select model cells for research purposes

Various cells from humans and animals have been established as cell lines, and their features, characteristics, and origins have been reported. Many laboratories use cell lines as model cells, which are selected to suit research purposes. We attempted to identify the ABO genotypes of 31 human leukemia and lymphoma cell lines stored in our laboratory using three methods: the PCR amplification of specific alleles (PASA), PCR-restriction fragment length polymorphism (RFLP), and the direct DNA sequencing of PCR products. We distinguished 31 human leukemia and lymphoma cell lines examined into six major ABO genotypes: A/O (A101/O01: n = 1, A101/O12: n = 4, A101/O26: n = 1, A101/O49: n = 1, A102/O01: n = 3), A/A (A101/A101: n = 1, A102/A102: n = 2), B/O (Bw29/O01: n = 1), B/B (B101/B101: n = 2), O/O (O01/O01: n = 9, O01/O02: n = 1, O01/O26: n = 1, O02/O03: n = 1), and A/B (A102/B101: n = 3). To the best of our knowledge, this is the first study to identify the ABO genotypes of various cell lines. The ABO genotypes of cell lines are important when selecting an experimental model cell for an ABO blood group study, and are essential information for cell lines. These results may be employed by research and clinical laboratories as well as in the forensic field.

ABO blood group A transferase and its codon 69 substitution enzymes synthesize FORS1 antigen of FORS blood group system

Human histo-blood group A transferase (AT) catalyzes the biosynthesis of oligosaccharide A antigen important in blood transfusion and cell/tissue/organ transplantation. This enzyme may synthesize Forssman antigen (FORS1) of the FORS blood group system when exon 3 or 4 of the AT mRNA is deleted and/or the LeuGlyGly tripeptide at codons 266–268 of AT is replaced by GlyGlyAla. The Met69Ser/Thr substitutions also confer weak Forssman glycolipid synthase (FS) activity. In this study, we prepared the human AT derivative constructs containing any of the 20 amino acids at codon 69 with and without the GlyGlyAla substitution, transfected DNA to newly generated COS1(B3GALNT1 + A4GALT) cells expressing an enhanced level of globoside (Gb4), the FS acceptor substrate, and immunologically examined the FORS1 expression. Our results showed that all those substitution constructs at codon 69 exhibited FS activity. The combination with GlyGlyAla significantly increased the activity. The conserved methionine residue in the ABO, but not GBGT1, gene-encoded proteins may implicate its contribution to the separation of these genes in genetic evolution. Surprisingly, with increased Gb4 availability, the original human AT with the methionine residue at codon 69 was also demonstrated to synthesize FORS1, providing another molecular mechanism of FORS1 appearance in cancer of ordinary FORS1-negative individuals.

Amino acid substitutions at sugar-recognizing codons confer ABO blood group system-related α1,3 Gal(NAc) transferases with differential enzymatic activity

Functional paralogous ABO, GBGT1, A3GALT2, and GGTA1 genes encode blood group A and B transferases (AT and BT), Forssman glycolipid synthase (FS), isoglobotriaosylceramide synthase (iGb3S), and α1,3-galactosyltransferase (GT), respectively. These glycosyltransferases transfer N-acetyl-d-galactosamine (GalNAc) or d-galactose forming an α1,3-glycosidic linkage. However, their acceptor substrates are diverse. Previously, we demonstrated that the amino acids at codons 266 and 268 of human AT/BT are crucial to their distinct sugar specificities, elucidating the molecular genetic basis of the ABO glycosylation polymorphism of clinical importance in transfusion and transplantation medicine. We also prepared in vitro mutagenized ATs/BTs having any of 20 possible amino acids at those codons, and showed that those codons determine the transferase activity and sugar specificity. We have expanded structural analysis to include evolutionarily related α1,3-Gal(NAc) transferases. Eukaryotic expression constructs were prepared of AT, FS, iGb3S, and GT, possessing selected tripeptides of AT-specific AlaGlyGly or LeuGlyGly, BT-specific MetGlyAla, FS-specific GlyGlyAla, or iGb3S and GT-specific HisAlaAla, at the codons corresponding to 266–268 of human AT/BT. DNA transfection was performed using appropriate recipient cells existing and newly created, and the appearance of cell surface oligosaccharide antigens was immunologically examined. The results have shown that several tripeptides other than the originals also bestowed transferase activity. However, the repertoire of functional amino acids varied among those transferases, suggesting that structures around those codons differentially affected the interactions between donor nucleotide-sugar and acceptor substrates. It was concluded that different tripeptide sequences at the substrate-binding pocket have contributed to the generation of α1,3-Gal(NAc) transferases with diversified specificities.

Blood group ABO gene-encoded A transferase catalyzes the biosynthesis of FORS1 antigen of FORS system upon Met69Thr/Ser substitution

Blood group A/B glycosyltransferases (AT/BTs) and Forssman glycolipid synthase (FS) are encoded by the evolutionarily related ABO (A/B alleles) and GBGT1 genes, respectively. AT/BT and FS catalyze the biosynthesis of A/B and Forssman (FORS1) oligosaccharide antigens that are responsible for the distinct blood group systems of ABO and FORS. Using genetic engineering, DNA transfection, and immunocytochemistry and immunocytometry, we have previously shown that the eukaryotic expression construct encoding human AT, whose LeuGlyGly tripeptide at codons 266 to 268 was replaced with FS-specific GlyGlyAla tripeptide, induced weak appearance of FORS1 antigen. Recently, we have shown that the human AT complementary DNA constructs deleting exons 3 or 4, but not exons 2 or 5, induced moderate expression of FORS1 antigen. The constructs containing both the GlyGlyAla substitution and the exon 3 or 4 deletion exhibited an increased FS activity. Here, we report another molecular mechanism in which an amino acid substitution at codon 69 from methionine to threonine or serine (Met69Thr/Ser) also modified enzymatic specificity and permitted FORS1 biosynthesis. Considering that codon 69 is the first amino acid of exon 5 and that the cointroduction of Met69Thr and GlyGlyAla substitutions also enhanced FS activity, the methionine substitutions may affect enzyme structure in a mode similar to the exon 3 or 4 deletion but distinct from the GlyGlyAla substitution.

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.

ABO blood group A transferases catalyze the biosynthesis of FORS blood group FORS1 antigen upon deletion of exon 3 or 4

Evolutionarily related ABO and GBGT1 genes encode, respectively, A and B glycosyltransferases (AT and BT) and Forssman glycolipid synthase (FS), which catalyze the biosynthesis of A and B, and Forssman (FORS1) oligosaccharide antigens responsible for the ABO and FORS blood group systems. Humans are a Forssman antigen-negative species; however, rare individuals with A_pae phenotype express FORS1 on their red blood cells. We previously demonstrated that the replacement of the LeuGlyGly tripeptide sequence at codons 266 to 268 of human AT with GBGT1-encoded FS-specific GlyGlyAla enabled the enzyme to produce FORS1 antigen, although the FS activity was weak. We searched for additional molecular mechanisms that might allow human AT to express FORS1. A variety of derivative expression constructs of human AT were prepared. DNA was transfected into COS1 (B3GALNT1) cells, and cell-surface expression of FORS1 was immunologically monitored. To our surprise, the deletion of exon 3 or 4, but not of exon 2 or 5, of human AT transcripts bestowed moderate FS activity, indicating that the A allele is inherently capable of producing a protein with FS activity. Because RNA splicing is frequently altered in cancer, this mechanism may explain, at least partially, the appearance of FORS1 in human cancer. Furthermore, strong FS activity was attained, in addition to AT and BT activities, by cointroducing 1 of those deletions and the GlyGlyAla substitution, possibly by the synergistic effects of altered intra-Golgi localization/conformation by the former and modified enzyme specificity by the latter.

Evolutionary divergence of the ABO and GBGT1 genes specifying the ABO and FORS blood group systems through chromosomal rearrangements

Human alleles at the ABO and GBGT1 genetic loci specify glycosylation polymorphism of ABO and FORS blood group systems, respectively, and their allelic basis has been elucidated. These genes are also present in other species, but presence/absence, as well as functionality/non-functionality are species-dependent. Molecular mechanisms and forces that created this species divergence were unknown. Utilizing genomic information available from GenBank and Ensembl databases, gene order maps were constructed of a chromosomal region surrounding the ABO and GBGT1 genes from a variety of vertebrate species. Both similarities and differences were observed in their chromosomal organization. Interestingly, the ABO and GBGT1 genes were found located at the boundaries of chromosomal fragments that seem to have been inverted/translocated during species evolution. Genetic alterations, such as deletions and duplications, are prevalent at the ends of rearranged chromosomal fragments, which may partially explain the species-dependent divergence of those clinically important glycosyltransferase genes.

ABO blood groups in relation to breast carcinoma incidence and associated prognostic factors in Moroccan women

The association between blood groups ABO and different types of diseases was established in several previous studies. Our aim was to seek the possible association between the ABO blood group and breast cancer-associated prognostic factors. The Chi-squared analytic test was used to compare phenotypic ABO distribution among Moroccan blood donors and 442 cases of women suffering from breast carcinoma with archived files in Maternity Ward of University Hospital C.H.U Ibn Rochd between 2008 and 2011. High incidence of breast carcinoma was observed in blood type B patients (p < 0.05). Blood type B was associated with breast carcinomas overexpressing human epidermal growth factor receptor HER2 (p < 0.05) and high risk of cancer at age over 70 years (p < 0.001). Blood type A was associated with high risk of cancer among women younger than 35 years old. Blood type A and AB were associated with high incidence of lymph node metastasis (p < 0.05). Multivariate analysis has shown correlation between O blood type and estrogen receptor-positive tumor. Patients with blood group A, B, and AB were more likely to develop aggressive breast carcinoma. Further follow-up studies are necessary to clarify the role of ABH antigens in the progression of breast carcinoma.

No Association of Blood Type O With Neuroendocrine Tumors in Multiple Endocrine Neoplasia Type 1

CONTEXT

An association between ABO blood type and the development of cancer, in particular, pancreatic cancer, has been reported in the literature. An association between blood type O and neuroendocrine tumors in multiple endocrine neoplasia type 1 (MEN1) patients was recently suggested. Therefore, blood type O was proposed as an additional factor to personalize screening criteria for neuroendocrine tumors in MEN1 patients.

OBJECTIVE

The aim of this study was to assess the association between blood type O and the occurrence of neuroendocrine tumors in the national Dutch MEN1 cohort.

DESIGN

This is a cohort study using the Dutch National MEN1 database, which includes more than 90% of the Dutch MEN1 population. Demographic and clinical data were analyzed by blood type. Chi-square tests and Fisher exact tests were used to determine the association between blood type O and occurrence of neuroendocrine tumors. A cumulative incidence analysis (Gray's test) was performed to assess the equality of cumulative incidence of neuroendocrine tumors in blood type groups, taking death into account as a competing risk.

RESULTS

The ABO blood type of 200 of 322 MEN1 patients was known. Demographic and clinical characteristics were similar among blood type O and non-O type cohorts. The occurrence of neuroendocrine tumors of the lung, thymus, pancreas, and gastrointestinal tract was equally distributed across the blood type O and non-O type cohorts (Grays's test for equality; P = 0.72). Furthermore, we found no association between blood type O and the occurrence of metastatic disease or survival.

CONCLUSIONS

An association between blood type O and the occurrence of neuroendocrine tumors in MEN1 patients was not confirmed. For this reason, the addition of the blood type to screening and surveillance practice seems not to be of additional value for identifying MEN1 patients at risk for the development of neuroendocrine tumors, metastatic disease, or a shortened survival.

A new method for ABO genotyping using fluorescence melting curve analysis based on peptide nucleic acid probes

ABO genotyping has been routinely used to identify suspects or unknown remains in crime investigations. Probe-based fluorescence melting curve analysis (FMCA) is a powerful tool for mutation detection and is based on melting temperature shifts due to thermal denaturation. In the present study, we developed a new method for ABO genotyping using peptide nucleic acid (PNA) probe-based FMCA. This method allowed for the simultaneous detection of three single nucleotide polymorphism (SNP) sites in the ABO gene (nucleotide positions 261, 526, and 803) and the determination of 14 ABO genotypes (A/A, A/O01 or A/O02, A/O03, B/B, B/O01 or B/O02, B/O03, O01/O01 or O01/O02 or O02/O02, O01/O03 or O02/O03, O03/O03, A/B, cis-AB01/A, cis-AB01/B, cis-AB01/O01 or cis-AB01/O02, and cis-AB01/cis-AB01). Using this method, we analyzed 80 samples and successfully identified ABO genotypes (A/A [n=5], A/O01 or A/O02 [n=23], B/B [n=3], B/O01 or B/O02 [n=18], A/B [n=9], O01/O01 or O01/O02 or O02/O02 [n=20], cis-AB01/A [n=1], and cis-AB01/O01 or cis-AB01/O02 [n=1]). In addition, all steps in the method, including polymerase chain reaction, PNA probe hybridization, and FMCA, could be performed in one single closed tube in less than 3h. Since no processing or separation steps were required during analysis, this method was more convenient and rapid than traditional methods and reduced the risk of contamination. Thus, this method may be an effective and helpful tool in forensic investigations.

An integrative evolution theory of histo-blood group ABO and related genes

The ABO system is one of the most important blood group systems in transfusion/transplantation medicine. However, the evolutionary significance of the ABO gene and its polymorphism remained unknown. We took an integrative approach to gain insights into the significance of the evolutionary process of ABO genes, including those related not only phylogenetically but also functionally. We experimentally created a code table correlating amino acid sequence motifs of the ABO gene-encoded glycosyltransferases with GalNAc (A)/galactose (B) specificity, and assigned A/B specificity to individual ABO genes from various species thus going beyond the simple sequence comparison. Together with genome information and phylogenetic analyses, this assignment revealed early appearance of A and B gene sequences in evolution and potentially non-allelic presence of both gene sequences in some animal species. We argue: Evolution may have suppressed the establishment of two independent, functional A and B genes in most vertebrates and promoted A/B conversion through amino acid substitutions and/or recombination; A/B allelism should have existed in common ancestors of primates; and bacterial ABO genes evolved through horizontal and vertical gene transmission into 2 separate groups encoding glycosyltransferases with distinct sugar specificities.

Next-generation sequencing is a credible strategy for blood group genotyping

Although several medium/high-throughput tools have been engineered for molecular analysis of blood group genes, they usually rely on the targeting of single nucleotide polymorphisms, while other variants remain unidentified. To circumvent this limitation a strategy for genotyping blood group genes by next-generation sequencing (NGS) was set up. Libraries consisting of exons, flanking introns and untranslated regions of 18 genes involved in 15 blood systems were generated by the Ion AmpliSeq(™) Library Kit 2.0 and by fragmenting polymerase chain reaction products, normalized by two different approaches, mixed and sequenced by the Ion Torrent Personal Genome Machine (PGM(™) ) Sequencer. In our conditions, defined to limit both intra- and inter-sample variability, sequences from mixed libraries were read in a single run for a total coverage of 86·03% of the coding DNA sequences, including all loci defining the most clinically relevant antigens in all genes, except ABO. Importantly, the challenging attempt to generate gene-specific data for the homologous genes was successful. This work, which combines two complementary approaches to generate libraries, defines technical conditions for genotyping blood group genes, illustrates that NGS is suitable for such an application and suggests that, after automation, this novel tool could be used for molecular typing at the laboratory level.

A simple ABO genotyping by PCR using sequence-specific primers with mismatched nucleotides

In forensics, the specific ABO blood group is often determined by analyzing the ABO gene. Among various methods used, PCR employing sequence-specific primers (PCR-SSP) is simpler than other methods for ABO typing. When performing the PCR-SSP, the pseudo-positive signals often lead to errors in ABO typing. We introduced mismatched nucleotides at the second and the third positions from the 3'-end of the primers for the PCR-SSP method and examined whether reliable typing could be achieved by suppressing pseudo-positive signals. Genomic DNA was extracted from nail clippings of 27 volunteers, and the ABO gene was examined with PCR-SSP employing primers with and without mismatched nucleotides. The ABO blood group of the nail clippings was also analyzed serologically, and these results were compared with those obtained using PCR-SSP. When mismatched primers were employed for amplification, the results of the ABO typing matched with those obtained by the serological method. When primers without mismatched nucleotides were used for PCR-SSP, pseudo-positive signals were observed. Thus our method may be used for achieving more reliable ABO typing.

In-vitro stem cell derived red blood cells for transfusion: are we there yet?

To date, the use of red blood cells (RBCs) produced from stem cells in vitro has not proved practical for routine transfusion. However, the perpetual and widespread shortage of blood products, problems related to transfusion-transmitted infections, and new emerging pathogens elicit an increasing demand for artificial blood. Worldwide efforts to achieve the goal of RBC production through stem cell research have received vast attention; however, problems with large-scale production and cost effectiveness have yet to prove practical usefulness. Some progress has been made, though, as cord blood stem cells and embryonic stem cells have shown an ability to differentiate and proliferate, and induced pluripotent stem cells have been shown to be an unlimited source for RBC production. However, transfusion of stem cell-derived RBCs still presents a number of challenges to overcome. This paper will summarize an up to date account of research and advances in stem cell-derived RBCs, delineate our laboratory protocol in producing RBCs from cord blood, and introduce the technological developments and limitations to current RBC production practices.

Evaluation of a blood group genotyping platform (BLOODchip(®) Reference) in Japanese samples

BACKGROUND

Blood-group genotyping arrays have been widely used in Caucasian and African American populations, but have not been thoroughly tested in Japanese subjects.

AIM

To evaluate, using the BLOODchip(®) Reference genotyping system, the concordance of previously typed samples with expected phenotypes and the coverage of the Japanese variants.

METHODS

Blood samples from 100 Japanese donors were obtained. DNA was extracted with QIAsymphony (Qiagen, Hilden, Germany). Samples were typed by serological methods and processed with the BLOODchip(®) . When a non-concordant result was identified, further sequencing by polymerase chain reaction-single specific primer (PCR-SSP) was performed.

RESULTS

Concordance between systems was 98% (736/751), and 98.8% (742/751) if only non-software-related non-concordances were considered. In the ABO group, 6 'No Call' (NC, inability of the BLOODchip(®) to assign a result) were ascribed to a variant of blood subtype A1 (A102; 467C>T), a common subtype in Asian populations, whereas three NC presented additional polymorphisms not contained in the BLOODchip(®) (A102/A205, A102/O06 and A204/O02). In the RhD group, one discrepancy was correctly genotyped as RHD*1227A (Del phenotype) by the BLOODchip(®) (phenotyped as partial D, RHD*DIVb). Another was phenotyped as D+ by the BLOODchip(®) (phenotyped weak D by serology) and confirmed as RHD*D-CE(2)-D heterozygous by sequencing. The 3 RhD NC can be solved by further software update. For RhCE, one discrepancy was correctly genotyped for both systems; however, only the BLOODchip(®) was able to detect RHCE*CX allele.

CONCLUSIONS

By programming the A102 ABO variant into the system software with the new allele combinations, the BLOODchip(®) Reference is a suitable genotyping tool to be applied to Asian samples.

Molecular genetic basis of the human Forssman glycolipid antigen negativity

Forssman heterophilic glycolipid antigen has structural similarity to the histo-blood group A antigen, and the GBGT1 gene encoding the Forssman glycolipid synthetase (FS) is evolutionarily related to the ABO gene. The antigen is present in various species, but not in others including humans. We have elucidated the molecular genetic basis of the Forssman antigen negativity in humans. In the human GBGT1 gene, we identified two common inactivating missense mutations (c.688G>A [p.Gly230Ser] and c.887A>G [p.Gln296Arg]). The reversion of the two mutations fully restored the glycosyltransferase activity to synthesize the Forssman antigen in vitro. These glycine and glutamine residues are conserved among functional GBGT1 genes in Forssman-positive species. Furthermore, the glycine and serine residues represent those at the corresponding position of the human blood group A and B transferases with GalNAc and galactose specificity, respectively, implicating the crucial role the glycine residue may play in the FS α1,3-GalNAc transferase activity.

ABO genotyping by TaqMan assay and allele frequencies in a Japanese population

ABO genotyping have become common tools for forensic casework. We developed a new rapid ABO genotyping method using a fast real-time PCR system with the TaqMan® Sample-to-SNP™ Kit. Eight single nucleotide polymorphism (SNP) sites in the ABO gene (nt 261, 297, 467, 657, 703, 829, 930 and 1061) were selected to determine the ABO genotypes. ABO genotypes were easily determined by examining allelic discrimination patterns. This method enabled analyses to be completed in about 1h per plate with no postmortem change influences. The detection limit in each SNP site was examined as 100pg per reaction. ABO genotyping from 1000 Japanese individuals was also examined to determine the distribution of ABO genotypes and allele frequencies. Thus, 31 genotypes were clearly identified, and these were controlled by four common and seven rare alleles. The power of discrimination, heterozygosity and polymorphism information contents were 0.913, 0.775 and 0.812, respectively. Therefore, selecting these eight SNP sites could be useful for high specific ABO genotyping. This rapid, sensitive and accurate genotyping method is useful for forensic casework.

ABO blood group genotyping by quenching probe method

We developed a multiplex ABO genotyping method with quenching probes (Q-probe). In this method, it is possible to discriminate the mutations, not only frequently used positions 261 and 796 but also position 703 in a single PCR. Each probe was designed to have cytosine residue at 5' or 3' end and labeled with three different fluorescence dyes, enabling the triplex detections of these polymorphisms. All polymorphisms were successfully detected by using fluorescence labeled Q-probe in a specifically amplified PCR product. Each Q-probe showed unique dissociation patterns depending on the polymorphism types. All of the results obtained with Q-probe were compared with standard serotyping and TaqMan PCR method and resulted in complete match with each other. Consequently, these results indicated that multiplex ABO genotyping method is quite accurate and convenient method for the determination of ABO genotype.

Genetic and mechanistic evaluation for the mixed-field agglutination in B3 blood type with IVS3+5G>A ABO gene mutation

BACKGROUND

The ABO blood type B(3) is the most common B subtype in the Chinese population with a frequency of 1/900. Although IVS3+5G>A (rs55852701) mutation of B gene has been shown to associate with the development of B(3) blood type, genetic and mechanistic evaluation for the unique mixed-field agglutination phenotype has not yet been completely addressed.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we analyzed 16 cases of confirmed B(3) individuals and found that IVS3+5G>A attributes to all cases of B(3). RT-PCR analyses revealed the presence of at least 7 types of aberrant B(3) splicing transcripts with most of the transcripts causing early termination and producing non-functional protein during translation. The splicing transcript without exon 3 that was predicted to generate functional B(3) glycosyltransferase lacking 19 amino acids at the N-terminal segment constituted only 0.9% of the splicing transcripts. Expression of the B(3) cDNA with exon 3 deletion in the K562 erythroleukemia cells revealed that the B(3) glycosyltransferase had only 40% of B(1) activity in converting H antigen to B antigen. Notably, the typical mixed-field agglutination of B(3)-RBCs can be mimicked by adding anti-B antibody to the K562-B(3) cells.

CONCLUSIONS/SIGNIFICANCE

This study thereby demonstrates that both aberrant splicing of B transcripts and the reduced B(3) glycosyltransferase activity contribute to weak B expression and the mixed-field agglutination of B(3), adding to the complexity for the regulatory mechanisms of ABO gene expression.

An integrated system of ABO typing and multiplex STR testing for forensic DNA analysis

A new amplification system for ABO and STR genotyping in a single reaction has been successfully developed. Two types of information can be obtained from a biological sample at one time. One is the classical information of ABO blood group typing for screening suspects and the other is STR information for individual identification. The system allows for the simultaneous detection of 15 autosomal STR loci (containing all CODIS STR loci as well as Penta D and Penta E), six ABO genotypes (O/O, B/B, A/A, A/O, A/B, and B/O) and the gender-determining locus Amelogenin. Primers are designed so that the amplicons are distributed ranging from 75bp to 500bp within a four-dye fluorescent design, leaving a fourth dye for the internal size standard. With 30 cycles, the results showed that the optimal amount of DNA template for this multiplex ranges from 250pg to 2ng and the lowest detection threshold is 125pg (as low as 63pg for ABO loci). For the DNA template outside the optimal detection range, we could adjust the number of cycles to obtain the robust profiles. Mixture studies showed that over 83% of minor alleles were detected at 1:9 ratios. The full profiles were still observed when 4ng of degraded DNA was digested by DNase I and 1ng undegraded DNA was added to 40μM haematin. Polymerase chain reaction (PCR)-based conditions including the concentrations of primers, magnesium and the Taq polymerase as well as volume, cycle numbers and annealing temperature were examined and optimised. In addition, the system was validated by 364 bloodstain samples and 32 common casework samples. According to the Chinese National Standards and Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines, our system demonstrates good detection performance and is an ideal tool for forensic DNA typing with potential application.

ABO research in the modern era of genomics

Research on ABO has advanced significantly in recent years. A database was established to manage the sequence information of an increasing number of novel alleles. Genome sequencings have identified ABO orthologues and paralogues in various organisms and enhanced the knowledge on the evolution of the ABO and related genes. The most prominent advancements include clarification of the association between ABO and different disease processes. For instance, ABO status affects the infectivity of certain strains of Helicobacter pylori and Noroviruses as well as the sequestration and rosetting of red blood cells infected with Plasmodium falciparum. Genome-wide association studies have conclusively linked the ABO locus to pancreatic cancer, venous thromboembolism, and myocardial infarction in the presence of coronary atherosclerosis. These findings suggest ABO's important role in determining an individual's susceptibility to such diseases. Furthermore, our understanding of the structures of A and B transferases and their enzymology has been dramatically improved. ABO has also become a research subject in neurobiology and the preparation of artificial/universal blood and became a topic in the pseudoscience of "blood type diets." With such new progress, it has become evident that ABO is a critical player in the modern era of genomic medicine. This article provides the most up-to-date information regarding ABO genomics.

Molecular basis of blood group expression

Antigen diversity arises from changes at the gene level that range from single nucleotide polymorphisms (SNPs) to intra- and inter-genic exchanges, inversions, insertions, and deletions. Nucleotide changes often result in amino acid difference from the wild-type gene product and with those changes new blood group antigens arise. Alternatively, there is loss of expression altogether, which is deemed the 'null' phenotype. Near complete knowledge of the genetic changes underlying the expression of blood group antigens will lead to the reality that red cell genotyping as a test-of-record. The importance of molecular testing in immunohematology necessitates appropriate training and competency programs to ensure that the highly skilled staff has the appropriate knowledge background. This review summarizes the core mechanisms for gene expression and provides a compilation of the molecular basis for blood group expression.

A novel method for ABO genotyping using a DNA chip

ABO genotyping is often performed to identify the blood type of decomposed samples, which is difficult to be determined by a serological test. In this study, we developed a simple method for ABO genotyping using a DNA chip. In this method, polymerase chain reaction-amplified and fluorescent-labeled fragments in the ABO gene and primate-specific D17Z1 were hybridized with DNA probes on a chip designed to detect single nucleotide polymorphisms (SNPs) in the ABO gene and part of the D17Z1 sequence. Using blood samples from 42 volunteers and 10 animal species, we investigated whether the chip could be used to detect SNPs in the ABO gene and the D17Z1 sequence. This method was then applied to various forensic samples, and it was confirmed that this method was suitable for the simultaneous analyses of ABO genotyping and species identification. This method fulfills the recent need for the development of rapid and convenient methods for criminal investigations.

Variant ABO blood group alleles, secretor status, and risk of pancreatic cancer: results from the pancreatic cancer cohort consortium

BACKGROUND

Subjects with non-O ABO blood group alleles have increased risk of pancreatic cancer. Glycosyltransferase activity is greater for the A(1) versus A(2) variant, whereas O01 and O02 variants are nonfunctioning. We hypothesized: 1) A(1) allele would confer greater risk than A(2) allele, 2) protective effect of the O allele would be equivalent for O01 and O02 variants, 3) secretor phenotype would modify the association with risk.

METHODS

We determined ABO variants and secretor phenotype from single nucleotide polymorphisms in ABO and FUT2 genes in 1,533 cases and 1,582 controls from 12 prospective cohort studies. Adjusted odds ratios (OR) for pancreatic cancer were calculated using logistic regression.

RESULTS

An increased risk was observed in participants with A(1) but not A(2) alleles. Compared with subjects with genotype O/O, genotypes A(2)/O, A(2)/A(1), A(1)/O, and A(1)/A(1) had ORs of 0.96 (95% CI, 0.72-1.26), 1.46 (95% CI, 0.98-2.17), 1.48 (95% CI, 1.23-1.78), and 1.71 (95% CI, 1.18-2.47). Risk was similar for O01 and O02 variant O alleles. Compared with O01/O01, the ORs for each additional allele of O02, A(1), and A(2) were 1.00 (95% CI, 0.87-1.14), 1.38 (95% CI, 1.20-1.58), and 0.96 (95% CI, 0.77-1.20); P, O01 versus O02 = 0.94, A(1) versus A(2) = 0.004. Secretor phenotype was not an effect modifier (P-interaction = 0.63).

CONCLUSIONS

Among participants in a large prospective cohort consortium, ABO allele subtypes corresponding to increased glycosyltransferase activity were associated with increased pancreatic cancer risk.

IMPACT

These data support the hypothesis that ABO glycosyltransferase activity influences pancreatic cancer risk rather than actions of other nearby genes on chromosome 9q34.

Rapid direct PCR for ABO blood typing

Many different molecular typing methods have been reported to complement routine serological ABO blood typing in forensics. However, these ABO genotyping methods are often time-consuming and call for an initial DNA isolation step that requires the use of expensive kits or reagents. We report here a rapid direct ABO genotyping method that eliminates the need for DNA extraction from fresh blood, hair, and body fluid stains before PCR. Using a fast PCR instrument and an optimized polymerase, the genotyping method-which employs a multiplex allele-specific primer set for the simultaneous detection of three single-nucleotide polymorphism (SNP) sites (nucleotides 261, 526, and 803)-identifies A, B, O01/O02, O03, and cis-AB01 alleles in around 70 min from sample collection to electropherogram. Not only will this ABO genotyping method be efficiently used in forensic practice for rapid screening of samples before full-blown multilocus short tandem repeat profiling, but it will also demonstrate an example of rapid direct genotyping of SNPs that offers the advantages of time- and cost-efficiency, convenience, and reduced contamination during DNA analysis.

The structural basis of blood group A-related glycolipids in an A3 red cell phenotype and a potential explanation to a serological phenomenon

Glycolipids from the red cells of a rare blood group A subgroup individual, expressing the blood group A(3) phenotype with the classical mixed-field agglutination phenomenon, A(2(539G>A))/O(1) genotype, and an unusual blood group A glycolipid profile, were submitted to a comprehensive biochemical and structural analysis. To determine the nature of blood group A glycolipids in this A(3) phenotype, structural determination was carried out with complementary techniques including proton nuclear magnetic resonance (1D and 2D), mass spectrometry (MS) (nano-electrospray ionization/quadrupole time-of-flight and tandem mass spectrometry) and thin layer chromatography with immunostaining detection. As expected, total blood group A structures were of low abundance, but contrary to expectations extended-A type 2 and A type 3 glycolipids were more dominant than A hexaglycosylceramides based on type 2 chain (A-6-2 glycolipids), which normally is the major A glycolipid. Several para-Forssman (GalNAcβ3GbO(4)) structures, including extended forms, were identified but surmised not to contribute to the classic mixed-field agglutination of the A(3) phenotype. It is proposed that the low level of A antigen combined with an absence of extended branched glycolipids may be the factor determining the mixed-field agglutination phenomenon in this individual.

The M142T mutation causes B3 phenotype: three cases and an in vitro expression study

The B3 phenotype is the most common B subtype in Korea. The B305 allele (425 T>C, M142T) was first reported in 2 Chinese individuals; however, it has not yet been reported in the Koreans, and the impact of the M142T mutation on the expression of the B3 phenotype has also not been studied. To resolve an ABO discrepancy between a group O neonate and her group O father and A(1)B(3) mother, blood samples from these individuals and other family members were referred to our laboratory for ABO gene analysis. The B305 allele was discovered in the neonate (B305/O01), her mother (A102/ B305), and her maternal aunt (B305/O02), while her father was typed as O01/O02. Transient transfection experiments were performed in HeLa cells using the B305 allele synthesized by site-directed mutagenesis; flow cytometric analysis revealed that this transfect expressed 35.5% of the total B antigen produced by the B101 allele transfect. For comparison, Bx01 allele transfects were also created, and they expressed 11.4% of the total B antigen expressed on the surface of B101 transfects. These experiments demonstrate that the M142T (425 T>C) mutation is responsible for the B subtype phenotype produced by the B305 allele.