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Background: Among the alleles of the ABO system, cisAB and B(A) are the most intriguing due to their ability to encode a glycosyltransferase that can synthesize both A and B antigens. This dual activity leads to the formation of the AB phenotype, even in the presence of the O allele; resolution is achieved by molecular analyses., Case Presentation and Methods: We describe herein a Brazilian family in which the mother (M42.1) of group AB and the father (M42.2) of group O have two children of group AB (M42.3 and M42.4). Serological characterization involved ABO and H phenotyping tests and serial dilution of ABO monoclonal antibodies. Characterization of ABO genotypes and alleles were performed by PCR-RFLP and sequencing., Results and Discussion: In serological tests, red blood cells from M42.1, M42.3, and M42.4 showed an intermediate reactivity pattern between A 1 B and A 2 B. Molecular analyses revealed the presence of the ABO*O.01.01/O.01.01 genotype in M42.2 and the ABO*cisAB.05/O.01.01 genotype in M42.1, M42.3, and M42.4. The ABO*cisAB.05 allele encodes a glycosyltransferase able to synthesize A and B antigens in quantities sufficient to cause an agglutination reaction higher than that observed in A 2 B phenotypes., Conclusion: The combination of serological and molecular methods used in this study allowed us to determine the serological pattern, identify the ABO alleles, and explain the inheritance of the AB phenotype in this family., (© 2024 AABB.)

Background and Objectives: Missense variants in exon 7 of the ABO gene can lead to the formation of cisAB alleles. These alleles encode glycosyltransferases (GTs) capable of synthesizing both A and B antigens. In this study, we report the discovery of a novel cisAB allele and characterize it at molecular, protein and serological levels., Materials and Methods: Blood and DNA samples from the proband and seven relatives were examined using standard and modified ABO phenotyping, polymerase chain reaction-restriction fragment length polymorphism and ABO gene sequencing. We assessed the impact of the p.Leu324Ser variant on the protein structure of the mutant GT using bioinformatics tools., Results: Molecular tests revealed a c.971T>C (p.Leu324Ser) variant in the ABO gene in five of the eight individuals. This variant results in a GT that produces more A antigens and fewer B antigens. Bioinformatics analysis suggests that the amino acid substitution (p.Leu324Ser) could potentially affect enzymatic activity and specificity of the GT., Conclusion: We identified a novel cisAB allele resulting from a c.971T>C variant in the ABO gene. This variant led to the expression of an AB weak phenotype., (© 2024 International Society of Blood Transfusion.)

Background: Toxoplasmosis is one of the most common parasitic infections worldwide with varying prevalence between human populations. These variations are mainly associated with human exposure to risk factors. In this article, the seroprevalence of Toxoplasma gondii infection and the risk factors associated with infection in 1729 blood donors from São José do Rio Preto, São Paulo, Brazil were analysed., Methods: The serological tests for detecting immunoglobulin M (IgM) and immunoglobulin G (IgG) anti-T. gondii were used. The risk factors associated with the infection were identified through the application of an epidemiological questionnaire., Results: The prevalence of T. gondii infection was 48.0%. The following factors were identified in the final model after multiple logistic regression analysis: drinking raw milk (p=0.003; odds ratio [OR] 1.364 [confidence interval {CI} 1.1 to 1.7]), residing in a rural area (p<0.0001; OR 2.764 [CI 1.7 to 4.6]) and receiving a blood transfusion (p=0.015; OR 1.856 [CI 1.1 to 3.0])., Conclusions: The data obtained in this study showed that the blood donor population is exposed to risk factors related to infection by T. gondii. These data allow the establishment of control programs to contribute to public health in northwestern São Paulo state., (© The Author(s) 2023. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Competing Interests: Conflicts of interest All authors have read the journal's policy on conflicts of interest and have none to declare.

Objectives: This study aimed to evaluate the reactivity and the titers of commercial anti-A and anti-A,B antisera in the detection of A weak antigen expression in human red blood cells., Background: Commercial monoclonal antisera for ABO phenotyping are useful reagents allowing the identification of the four main ABO phenotypes (A, B, AB, and O). However, the reactivity of these commercial reagents can not be evident when the A or B antigens are weakly expressed, and these antisera have low titers., Methods/materials: Six samples from blood donors and five samples from patients with ABO forward and reverse discrepant phenotyping were evaluated. The ABO phenotyping was carried out with different commercial monoclonal anti-A and anti-A,B antisera under different temperatures, using test tubes and gel column agglutination., Results: Monoclonal anti-A antisera with titers less than 256 and anti-A,B with titers less than 128 failed to detect the weak expression of A antigen in 73% and 67% of the A weak phenotypes, respectively. Titres equal to or higher than 2048 (anti-A) and 1024 (anti-A,B) showed better reactivity, independent of the cell clone., Conclusion: Our data indicate that anti-A and anti-A,B antisera with high titers give better reactivity with red blood cells carrying A weak antigen expression., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Twin hematopoietic chimera in humans is a phenomenon that was discovered accidentally and the prevalence of which remains unclear. The resolution of chimera cases requires studying family medical records, data analysis, and investigations of hematopoietic cells and cells from other tissues. The interactions among ABO, Lewis, and secretor histo-blood group systems are explored to resolve cases of hematopoietic chimera. Here we report a rare case of hematopoietic chimera where twins present a mixed field reaction in the ABO, Rh, and Kidd red blood cell phenotyping. Using red blood cells separated from the mixed field as well as molecular approaches and investigations of family members, we identify inconsistent genotypes with the Mendelian inheritance pattern when comparing the peripheral blood with the buccal epithelium of the male twin and his twin sister. Analysis of the ABO, Lewis, and secretor phenotypes, and genomic DNA from buccal epithelium showed the genotypes ABO * A1.01 /ABO* B.01 and FUT2 * 01N.02 / FUT2 * 01N.02 in the male twin and the genotypes ABO * O.01.01 / ABO * O.01.02 and FUT2 * 01 / FUT2 * 01 in the female twin. The results of the HLA-DRB1 genotyping showed inconsistency between the male and his twin sister. We conclude that the serological analyses combined with molecular approaches used in this study are good tools to resolve cases of hematopoietic chimera., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2019 by S. Karger AG, Basel.)

It is well documented that Hb S and iron affect blood cells, and trigger oxidative processes and generation of free radicals with potential for lipid peroxidation. We evaluated the frequency of polymorphisms in the HFE gene in Hb AS blood donors and how these polymorphisms influenced lipid peroxidation and antioxidant capacity. Blood samples were collected from 211 Hb AS blood donors, 119 Hb AA blood donors as a control group, and 28 sickle cell disease patients (Hb SS). The H63D allele was found at a frequency of 10.5% in the Hb AS samples, and the C282Y allele frequency was 0.7%. In the control group, the frequencies of the H63D and C282Y alleles were 13.4 and 2.1%, respectively. In the sickle-cell disease patients, the H63D and the C282Y allele frequencies were 10.7 and 3.5%, respectively. The frequencies of the C282Y and H63D polymorphisms in Hb AS blood donors are similar to those reported for the Brazilian population. Serum malondialdehyde values, indicative of lipid peroxidation, were highest in sickle cell patients, independent of the polymorphisms in the HFE gene, with significant differences, showing the influence of Hb S allele in the levels of lipid peroxidation. However, the trolox equivalent antioxidant capacity average levels, indicative of the antioxidant capacity, were reduced with significant differences, indicating that in spite of a lipid peroxidation raise, this is not followed by the increased of the antioxidant capacity, leading to oxidative stress.