[Objective] To study the molecular biological mechanism for a case of ABO blood group B subtype, and perform three-dimensional modeling of the mutant enzyme. [Methods] The ABO phenotype was identified by the tube method and microcolumn gel method; the ABO gene of the proband was detected by sequence-specific primer polymerase chain reaction (PCR-SSP), and the exon 6 and 7 of the ABO gene were sequenced and analyzed. Homologous modeling of Bw.03 glycosyltransferase (GT) was carried out by Modeller and analyzed by PyMOL2.5.0 software. [Results] The weakening B antigen was detected in the proband sample by forward typing, and anti-B antibody was detected by reverse typing. PCR-SSP detection showed B, O gene, and the sequencing results showed c.721 C>T mutation in exon 7 of the B gene, resulting in p. Arg 241 Trp. Compared with the wild type, the structure of Bw.03GT was partially changed, and the intermolecular force analysis showed that the original three hydrogen bonds at 241 position disappeared. [Conclusion] Blood group molecular biology examination is helpful for the accurate identification of ambiguous blood group. Homologous modeling more intuitively shows the key site for the weakening of Bw.03 GT activity. The intermolecular force analysis can explain the root cause of enzyme activity weakening.

Objective: To reveal the molecular basis of the cisAB (p. Met266Leu) glycosyltransferase by studying a proband with cisAB subtype and his family. Methods: A male newborn was selected as the research subject. Tube methods were used to identify ABO blood types of the proband and his family members. PCR-SSP detection, ABO gene sequencing, and cloning analysis were performed on the proband and some family members. The inheritance pattern of the subtype gene in the family was determined through pedigree analysis. Homology modeling was used to analyze the impact of amino acid variations on the structure of the transferase, and molecular docking was used to demonstrate the bifunctional activity of the transferase and the donor-receptor binding conformation. Results: Serological tests showed that the proband and his father had enhanced anti-H agglutination, and the grandmother had a forward and reverse discrepancy. Sequencing of the proband revealed heterozygous variations of c. 297A>G, c. 526C>G, c. 657C>T, c. 703G>A, c. 803G>C, and c. 930G>A compared with A1. 01 (compared with B. 01, lacking the c. 796C>A variation, namely harboring the c. 796A>C variation) and c. 261delG. Combined with cloning analysis, the proband's genotype was determined to be ABO cisAB (c. 796A>C)/ABO O. 01. 01, the father's genotype was ABO cisAB (c. 796A>C)/ABO O. 01. 02, and the grandmother's genotype was ABO cisAB (c. 796A>C)/ABO B102. Pedigree analysis indicated that the cisAB allele in this newborn was inherited from his father and grandmother rather than a natural mutation. Homology modeling showed that the side chain orientation and intermolecular forces of Leu266 in the cisAB (p. Met266Leu) transferase changed, and molecular docking demonstrated that the "binding pocket" of the active center of the variant enzyme could accommodate both UDP-GalNAc and UDP-Gal, indicating that the cisAB enzyme structure has bifunctional activity. Conclusion: The bifunctional activity of this cisAB (p. Met266Leu) enzyme is related to the nucleotide variation of c. 796A>C, and molecular docking indicates that the enzyme has dual affinity for A/B sugar donors.

Objective: To perform serological and molecular biological identification of a proband with ABO blood group identified as AwB subtype, and to investigate and analyze the proband's family. Methods: Serological identification of ABO blood groups was performed for the proband and family members using the microcolumn gel assay and saline tube method. Subsequently, PacBio third-generation sequencing was employed to perform full-length sequencing of the ABO gene and haplotype analysis on the proband and her son to accurately determine their genotypes. Results: Serological testing revealed that the proband and her son exhibited the A B subtype phenotype, while the proband's husband had a normal AB type. The results of third-generation sequencing showed that one allele of the ABO blood group in the proband and her son was ABO B.01; the other allele, when compared with the reference sequence ABO A1.01, exhibited a heterozygous mutation of c.297A>G in exon 6, and heterozygous mutations of c.526C>G, c.657C>T, c.703G>A, c.796C>G, c.803G>C, and c.930G>A in exon 7. The c.796C>G mutation resulted in an amino acid substitution of p. Leu266Val in the polypeptide chain, matching the characteristics of the ABO cisAB.09 allele. Therefore, the genotype of the proband and her son was ABO cisAB.09/ABO B.01, with a blood group phenotype of cisAB09 subtype. Conclusion: The combination of serological testing and molecular biological techniques can accurately identify the blood group of patients with ABO subtypes. Family investigation identified two cases of the cisAB09 subtype, demonstrating that the cisAB09 allele can be stably inherited by offspring and remains stable within the family lineage.

Objective To statistically analyze the perioperative results of patients with ABO-incompatible kidney trans-plantation(ABOi-KT),in order to explore the changes in blood group antibody of type-A/B recipients.Methods A total of 33 cases of blood group A/B ABOi-KT recipients in our hospital from January 2021 to October 2023 were recruited and divided into two groups of group A(n=18)and group B(n=15)according to the different blood types of recipient.The effects of preoperative plasmapheresis on antibody titer,antibody rebound and renal function after operation(serum urea ni-trogen,creatinine and estimated glomerular filtration rate on the 1st,3rd,7th and 14th day)were analyzed between the two groups.According to the postoperative rebound of blood type antibodies,33 recipients were divided into antibody rebound group(n=7)and non rebound group(n=26),and the differences in initial blood type antibody titers between the two groups were analyzed.Results There was no significant difference in the clearance rate of IgM with preoperative plasma ex-change between the two groups(Z=-0.26,P＞0.05);Levels of serum urea nitrogen and creatinine on the 1st,3rd,7th and 14th day after operation between group A and group B were not statistically significant(P＞0.05),the same as eGFR.Group B was more prone to rebound antibody compared with group A(P＜0.05).There was a significant difference in the in-itial IgM antibody titer between the blood type antibody rebound group and the non rebound group(Z=-2.127,P＜0.05),but no statistically significant difference in the initial IgG antibody titer(Z=-1.835,P＞0.05)between the two groups was found.Conclusion The patients type B receiving type AB kidney donors are more prone to rebound antibody after ABOi-KT operation compared to the the patients type A receiving type AB.

Objective:To explore the molecular basis for an individual with Bel subtype of the ABO blood type due to a novel c. 620T>C variant gene, and assess its impact on the structure of GTB transferase.Methods:An individual who had visited the First Affiliated Hospital of Zhengzhou University on February 11, 2023 was selected as the study subject. ABO phenotyping was initially conducted with serological methods, which was followed by direct sequencing of 7 exons of the ABO gene. Subsequently, single-strand sequencing was carried out by using allele-specific primers, and the variant in the B transferase was homology-modeled using the Modeller software. The impact of the variant on the transferase′s spatial structure was analyzed with the PyMOL software. Results:The serological phenotype of the patient was identified as the Bel subtype. Direct sequencing revealed that she has harbored a novel c. 620T>C variant, resulting in a p. Leu207Pro substitution in the polypeptide chain. Combined with single-strand sequencing, her genotype was ultimately determined as ABO* BELnew/ ABO* O.01.02. Three-dimensional protein structure modeling showed that, compared with the wild type, the distance of one hydrogen bond between Proline and Glycine at position 272 has increased, along with disappearance of another hydrogen bond. Conclusion:The novel c. 620T>C (p.Leu207Pro) variant of B allele may affect the structural stability of the glycosyltransferase. The weakened enzyme activity in turn may lead to reduced B antigen expression, manifesting as the Bel subtype by serological analysis.

Objective:To study the molecular basis for a proband with A subtype B of the ABO blood group and explore the influence of amino acid variant on the activity of glycosyltransferase (GT).Methods:A proband who had presented at the First Affiliated Hospital of Zhengzhou University on July 2, 2020 was selected as the study subject. Serological identification of the ABO blood groups of the proband and her family members were performed by gel card and test tube methods. The ABO gene of the proband was identified by PCR-sequence specific primers (PCR-SSP) and DNA sequencing. A 3D molecular homologous model was constructed to predict the impact of the variant on the stability of α-(1→3)-D-N-acetylgalactosamine transferase (GTA). Results:The red blood cells of the proband, her mother and two younger brothers showed weak agglutination with anti-A and strong agglutination with anti-B. The sera showed 1~2+ agglutination with Ac and no agglutination with Bc. Based on the serological characteristics, the proband was identified as AwB subtype. Pedigree analysis suggested that the variant was inherited from her mother. The blood group of the proband was identified as A223B type by PCR-SSP. ABO gene sequencing analysis showed that the proband has harbored heterozygous variants of c. 297A>G, c. 467C>T, c. 526C>G, c. 657C>T, c. 703G>A, c. 796C>A, c. 803G>C, c. 930G>A and c. 1055insA. Based on the results of clone sequencing, it was speculated that the genotype was ABO* A223/ ABO* B.01. There were c. 467C>T and c. 1055insA variants compared with ABO* A1.01, and c. 1055insA variant compared with ABO* A1.02. Homologous modeling showed that the C-terminal of A223 GT was significantly prolonged, and the local amino acids and hydrogen bond network have changed. Conclusion:Above results revealed the molecular genetics mechanism of A223B subtype. The c. 1055insA variant carried by the proband may affect the enzymatic activity of GTA and ultimately lead to weakening of A antigen.

Objective:To explore the RH genotype for a female with RhD(-) blood type and its molecular basis. Methods:A 26-year-old female who had attended the outpatient clinic of the First Affiliated Hospital of Zhengzhou University in August 2019 was selected as the study subject. Peripheral blood samples were collected from the proband and her parents for Rh phenotyping with gel card method. PCR-sequence-based typing (PCR-SBT) and DNA sequencing were used to determine the RHD zygosity and RH genotype of the proband and her parents. Homology modeling of Rh proteins was performed with bioinformatic software, and protein structural alterations caused by the variant was simulated by molecular dynamics. This study was approved by the Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University (Ethics No. 2023-KY-0870-003). Results:Serological tests showed that the proband and her father both had weakened e antigen of the Rh phenotype. PCR-SBT and DNA sequencing showed that the genotypes of the proband and her parents were dce/ dCE, dce/ DcE and dCE/ DcE, respectively. And the genotypes of the RHD and RHCE of the proband were RHD*01N.01/ RHD*01N.16, RHCE*01.01/RHCE*04, respectively. Protein simulation and molecular dynamics analysis revealed that the ce_16C variant resulted from RHCE* ce (c.48G>C) may alter the structure of intracellular and extracellular loops, mainly affecting the mobility of extracellular loops 2, 6 and intracellular loops 3, 4. Conclusion:Variant of the RHCE* ce allele c. 48G>C probably underlay the weakened e antigen in this proband.

Objective:To serologically and genotypically analyze the pedigree of a case with a new allele c.175_176insGA of B el subtype and preliminarily explore the molecular mechanism of weak expression of glycosyltransferase B. Method:In the descriptive study,a 23-year-old male voluntary blood donor and his family members were selected for the study. The ABO and Le blood types of the proband and his family members was identified by the test tube method. The agglutination inhibition test was applied to detect the B and H antigens in saliva, and the Sanger sequencing and PacBio (Pacific Bioscience) third-generation haplotype sequencing were performed on the study subjects to identify genotypes. Finally, Expasy software were applied to amino acid translation of DNA sequences and prediction of protein length after gene alteration. ORF finder was applied to predict alternative start codons as well as open reading frames of mRNA, and protein expression mechanisms were analyzed.Results:The proband and her sister were B el subtype, her mother was AB el subtype, her father was normal O type, and all members of the family were Le(a+b+) phenotype. Sanger sequencing results showed that a new allele of c.175_176insGA was found in exon 4 of the proband, her mother, and her sister. Third-generation haplotype sequencing detected the haplotypes of the family members, which revealed that the proband was ABO*O.01.02/ABO*BEL.NEW (c.175_176insGA), the father was ABO*O.01.02/ABO*O.01.02, the mother was ABO*A1.02/ABO*BEL.NEW (c.175_176insGA), and the sister was ABO*O.01.02/ABO*BEL.NEW (c.175_176insGA). Analysis of the protein expression mechanism indicated that although the new allele of ABO*BEL.NEW was presumed to cause a frameshift mutation and result in a premature stop codon p.Asp59Glu*fs20 in exon 5, encoding an inactive glycosyltransferase, an alternative start codon could be utilized to initiate translation of B el subtype functional glycosyltransferase. Conclusion:Expression of the new allele of B el subtype is associated with the translation of B el subtype glycosyltransferase initiated by alternative start codons.

Objective:To investigate the molecular biological mechanism of Bw07 allele and its transferase alteration carried by a proband of ABw07 subtype.Methods:A 2-year-old male child was selected as the research object. The peripheral blood of the proband and his parents was identified for ABO blood type by the test tube method, and the ABO subgroup PCR-SSP detection and ABO gene sequencing were performed on the three individuals to determine their blood type genotypes. Finally, the effect of the p.Arg352Gln mutation on Bw07 transferase was verified by virtual mutation, DUET structure prediction, molecular dynamics analysis, and in vitro cellular experiments.Results:The serological phenotypes of the proband and his mother were ABw and Bw, respectively, while his father was normal A. The ABO subgroup PCR-SSP assay identified the three genotypes as Bw07/A, Bw07/O, and A/A, respectively.Sanger sequencing further verified that the proband and his mother carried the Bw07 gene, and virtual mutation showed that the intermolecular forces were weakened by the R352Q mutation. DUET predicted that this p.Arg352Gln mutation could affect the thermodynamic stability of Bw07 transferase. Molecular dynamics analysis confirmed that the alteration of thermodynamic stability was mainly related to the appearance of large fluctuations in the amino acid backbone atoms in the 125-133, 193-198 and 336-354 regions, and in vitro cellular experiments further verified the weakened antigen synthesis of Bw07 transferase.Conclusion:The formation of the ABw07 phenotype is associated with the mutation of the highly conserved Arg352 to Gln in Bw07 transferase.

【Objective】 To explore the impact of monoclonal anti-CD47(IBI188) on clinical pre-transfusion testing and its solutions, then compare it with monoclonal anti-CD38, so as to develop safe and rational transfusion strategies. 【Methods】 The blood typing, direct antiglobulin testing(DAT) and antibody screening were conducted by standard methods. Red blood cells(RBCs) were treated with fig protease, papain, trypsin and dithiothreitol(DTT) to observe whether the effect of monoclonal anti-CD47 could be eliminated. Cord RBCs and RBCs with different Rh phenotypes were cross-matched; Plasma samples were adsorbed with papain-treated O allogeneic RBCs. 【Results】 ABO reverse typing were affected by monoclonal anti-CD47 treatment, and all serum antibody screening were positive, and their DAT were negative or weakly positive. Neither enzyme nor DTT could weaken the effect of monoclonal anti-CD47 on antibody screening. In saline cross-matching, differences in agglutination intensity were corresponded to differences in CD47 expression on RBCs, but all RBCs agglutinated 2+ to 4+ by polybrene method and anti-human globulin method. Papain treated allogeneic RBCs can remove the monoclonal anti-CD47 in the serum through 3 to 4 rounds of absorption. 【Conclusion】 Monoclonal anti-CD47 interferes with pre-transfusion testing, which can be removed by allogeneic RBCs absorption(not suitable for antibody screening or cross-matching), but not by enzyme or DTT. Blood typing and antibody screening should be conducted before monoclonal anti-CD47 treatment and patients should be transfused with homozygous matched RBCs.