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The authors reflect on the complexities of incompatibility of fetal blood group and human platelet antigen (HPA)-1a genotyping between a pregnant woman and her fetus. They inform that such incompatibility can result in maternal alloimmunization and could cause hemolytic disease of the fetus and newborn, and fetal neonatal alloimmune thrombocytopenia. They inform that the severe fetal neonatal alloimmune thrombocytopenia cases are caused by antibodies against the HPA.

Background: Alloimmunization against the high-frequency Vel blood group antigen may result in transfusion reactions or hemolytic disease of fetus and newborn. Patients with anti-Vel alloantibodies require Vel-negative blood but Vel-negative individuals are rare (1:4000). Identification of Vel-negative donors ensures availability of Vel-negative blood; however, accurate Vel blood group typing is difficult due to variable Vel antigen expression and limited availability of anti-Vel typing sera. We report the production of a recombinant anti-Vel that also identifies weak Vel expression., Study Design and Methods: A recombinant anti-Vel monoclonal antibody was produced by cloning the variable regions from an anti-Vel-specific B cell isolated from an alloimmunized patient into a vector harboring the constant regions of immunoglobulin (Ig)G1-kappa or IgM-kappa. Antibody Vel specificity was tested by reactivity to SMIM1-transfected HEK293T cells and by testing various red blood cells (RBCs) of donors with normal, weak, or no Vel expression. High-throughput donor screening applicability was tested using an automated blood group analyzer., Results: A Vel-specific IgM class antibody was produced. The antibody was able to distinguish between Vel-negative and very weak Vel antigen-expressing RBCs by direct agglutination and in high-throughput settings using a fully automated blood group analyzer and performed better than currently used human anti-Vel sera. High-throughput screening of 13,288 blood donations identified three new Vel-negative donors., Conclusion: We generated a directly agglutinating recombinant anti-Vel IgM, M3F5S-IgM, functional in manual, automated agglutination assays and flow cytometry settings. This IgM anti-Vel will improve diagnostics by facilitating the identification of Vel-negative blood donors., (© 2019 AABB.)

Individual variations in erythrocyte parameters are influenced by factors like sex, age, diet and season. Genetic variations have also been associated with erythrocyte parameters. The aim of this systematic review is to provide an overview of associations between single nucleotide polymorphisms (SNPs) and erythrocyte parameters in humans. A systematic review protocol was published at the international prospective register of systematic reviews (registration number CRD42016053052). Literature searches were conducted in Medline and Embase. Studies were included if: investigating a(n) causality/association/correlation; population-based; investigating a human population of Caucasian/mixed-ethnic descent; and written in English, Dutch or German. Study quality was assessed using the quality of genetic association studies tool. In total, 4385 studies were screened on title/abstract and 194 studies were screened on full text. Inclusion criteria were met by 13 candidate gene studies (n = 126-49,488) and eight genome-wide association studies (GWASes, n = 1664-116,666). One moderate and six good quality GWAS(es) identified 1237 SNPs located in/near 241 genes. SNPs in/near ten genes were found to be associated with one or more erythrocyte parameter(s) by multiple GWASes, namely HIST1H2AC, MPST, SLC17A1 and SLC17A3 with mean cell hemoglobin (MCH), HIST1H1T and KCTD17 with MCH and mean cell volume (MCV), HBS1L and MYB with MCH, MCV and red cell count (RCC), HFE with MCH, MCV and hemoglobin, and TMPRSS6 with MCH, MCV, hemoglobin and mean cell hemoglobin concentration (MCHC). Four genes were found across multiple erythrocyte parameters by one study in each parameter. Fourteen SNPs were associated with one or more erythrocyte parameter(s) in multiple cohorts, namely rs129128, rs17342717, rs228129 and rs5756504 (MCH), rs4895441, rs7775698, rs9376092 and rs9494145 (MCH, MCV, RCC), rs6569992 (MCH, RCC), rs1800562 (hemoglobin, MCH, MCV), rs130624 and rs198846 (MCH, MCV), rs4820268 and rs855791 (MCH, MCV, MCHC). Further research on these fourteen genes in erythropoiesis is recommended, especially eight whose role in erythropoiesis is unclear., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Traditionally, red blood cell antigens have been identified using serological methods, but recent advances in molecular biology have made the implementation of methods for genetic testing of most blood group antigens possible. The goal of this study was to validate the performance of the ID CORE XT blood group typing assay., Materials and Methods: One thousand independent samples from donors, patients and neonates were collected from three research institutes in Spain and the Netherlands. DNA was extracted from EDTA-anticoagulated blood. The data were processed with the ID CORE XT to obtain the genotypes and the predicted blood group phenotypes, and results were compared to those obtained with well-established serological and molecular methods. All 1,000 samples were typed for major blood group antigens (C, c, E, e, K) and 371-830 samples were typed for other antigens depending on the rarity and availability of serology comparators., Results: The incorrect call rate was 0%. Four "no calls" (rate: 0.014%) were resolved after repetition. The sensitivity of ID CORE XT for all phenotypes was 100% regarding serology. There was one discrepancy in E- antigen and 33 discrepancies in Fy b - antigen. After bidirectional sequencing, all discrepancies were resolved in favour of ID CORE XT (100% specificity). ID CORE XT detected infrequent antigens of Caucasians in the sample as well as rare allelic variants., Discussion: In this evaluation performed in an extensive sample following the European Directive, the ID CORE XT blood genotyping assay performed as a reliable and accurate method for correctly predicting the genotype and phenotype of clinically relevant blood group antigens.

The blood group multiplex ligation-dependent probe amplification (MLPA) is a comprehensive assay, developed for genotyping the majority of clinically relevant blood group antigens in both patients and donors. The MLPA is an easy method to apply and only requires a thermal cycler and capillary electrophoresis equipment. Because the molecular basis of blood group antigens can be a single nucleotide polymorphism, an insertion/deletion polymorphism, or genetic recombination, a single assay such as the MLPA to facilitate these different types of genetic variation is a prerequisite in blood group typing. An MLPA assay allows the simultaneous detection of up to 50 polymorphisms in a single tube. The blood group MLPA currently consists of three separate probe pools targeting 104 different blood group alleles of 18 blood group systems. The assay is performed in a 96-well plate; therefore, a maximum of 32 genomic DNA samples can be processed simultaneously. Results are available within 24 hours,and software for analysis of the MLPA results is available free of charge. In addition to the analysis of genetic variation in blood group genes, a major advantage of the test is the ability to detect aberrations in gene copy numbers, which is especially useful for the determination of homo- or hemizygous status of RHD or other blood group genes and for detection of blood chimerism. A relatively large number of RH wild-type and mutation-specific probes are included in the assay, allowing an extensive analysis of RHD variants. In our reference lab in the Netherlands, the MLPA was validated to detect RH variants in patients, donors, and pregnant women. Furthermore, we have used the MLPA to provide comprehensive typing after blood transfusion of 52 blood group antigens simultaneously, in patients with red cell autoantibodies or patients with rare phenotypes.