The Rh blood group system: a review

Molecular genotyping versus serological diagnosis for RH blood group typing in sickle cell patients

OBJECTIVES

High rate of alloimmunization in sickle cell disease (SCD) patients poses a significant challenge in finding compatible blood unit. Accurate determination of the blood group genotype of them can help reduce the alloimmunization risk. Tetra ARMS PCR is a novel method that has been utilized recently to investigate SNPs in diseases in a fast and reliable way.

METHODS

Our study included 104 SCD and sickle thalassemia (Sβ) patients referred to Baghaei-2-Hospital of Ahvaz in 2019 using a nonrandom sampling method. Blood samples were collected for serological and molecular tests. Rh genotyping was performed using Tetra ARMS PCR and compared with the serological results.

RESULTS

Based on the Tetra ARMS PCR method, out of 104 patients, 7 (6.7%) were d/d, 40 (38.5%) were D/d, 57 (54.8%) were D/D, 25 (24%) were C/C, 59 (56.7%) were C/c, 20 (19.3%) were c/c, 4 (3.8%) were E/E, 25 (24%) were E/e, and patients 75 (72.2%) were e/e. There were discrepancies in the serological and molecular results for 11 patients.

CONCLUSION

Use of Tetra ARMS PCR in combination with serological methods for determining the Rh blood group system in donors and transfusion-dependent patients represents a remarkable transformation in the field of immunohematology.

Identification of a novel RHCE*Ce (829G > A) allele associated with absence of C and e antigens expression

BACKGROUND

The Rh blood group antigens are encoded by the RHD and RHCE genes, which possess a remarkable degree of polymorphism owing to their high homologous structures. These variants of the RH genes can lead to absence or weak expression of antigens.

METHODS

Analysis of RHCE genotyping by Polymerase Chain Reaction (PCR-SSP) method specific to detect c.48G, c.48C, 109 bp insertion of IVS2, c.201A and c.307C and RhCE phenotyping, were conducted in 316 Chinese patients in previous study. One patient with discrepancy typing result was collected for further RhCE serologic typing using microcolumn gel method and tube method in saline using monoclonal antibodies. PacBio sequencing was performed for RHCE, RHD and RHAG complete sequence analysis. 3D molecular models of the protein with the wild-type and mutant residue were generated using the DynaMut web server. The effect of the mutation on the protein function was predicted by PolyPhen-2 software.

RESULTS

One male patient of Chinese Han was detected with RHCE*C allele showed by PCR-SSP method but ccEE phenotype. Further PacBio sequencing identified one normal RHCE*cE allele and one RHCE*Ce allele carried a novel c.829G > A (p.Gly277Arg) variant, which the encoded amino acid located in the ninth transmembrane segment of RhCE protein. Crystallisation analysis of 3D molecular models revealed that the substitution at Arg277 leads to the formation of additional hydrogen bonds, including weak hydrogen bonds between multiple atoms. It also results in hydrophobic ion interactions between Arg277 and Ala244. This mutation is predicted to have a damaging effect on protein function.

CONCLUSION

One novel RHCE*Ce allele with c.829G > A (p.Gly277Arg) variant was identified to resulting in the absence or weak expression of C and e antigens.

Guide to Rho(D) Immune Globulin in Women With Molecularly Defined Asian-type DEL (c.1227G>A)

Rh hemolytic disease of the fetus and newborn is a potential risk for D-negative mothers who produce anti-D during pregnancy, which can lead to morbidity and mortality in subsequent pregnancies. To prevent this hemolytic disease, Rho(D) immune globulin (RhIG) is generally administered to D-negative mothers without anti-D at 28 weeks of gestation and shortly after delivery. However, current guidelines suggest that pregnant mothers with molecularly defined weak D types 1, 2, 3, 4.0, and 4.1 do not need RhIG as they are unlikely to produce alloanti-D when exposed to fetuses with D-positive red cells. This issue and the necessity of RHD genotyping have been extensively discussed in Western countries, where these variants are relatively common. Recent evidence indicates that women with Asian-type DEL (c.1227G>A) also do not form alloanti-D when exposed to D-positive red cells. We report that mothers with molecularly defined Asian-type DEL, similar to those with weak D types 1, 2, 3, 4.0, and 4.1, do not require RhIG before and after delivery. Collectively, this review could pave the way for the revision of international guidelines to include the selective use of RhIG based on specific genotypes, particularly in women with the Asian-type DEL.

The RHCE gene encodes the chicken blood system I

BACKGROUND

There are 13 known chicken blood systems, which were originally detected by agglutination of red blood cells by specific alloantisera. The genomic region or specific gene responsible has been identified for four of these systems (A, B, D and E). We determined the identity of the gene responsible for the chicken blood system I, using DNA from multiple birds with known chicken I blood system serology, 600K and 54K single nucleotide polymorphism (SNP) data, and lowpass sequence information.

RESULTS

The gene responsible for the chicken I blood system was identified as RHCE, which is also one of the genes responsible for the highly polymorphic human Rh blood group locus, for which maternal/fetal antigenic differences can result in fetal hemolytic anemia with fetal mortality. We identified 17 unique RHCE haplotypes in the chicken, with six haplotypes corresponding to known I system serological alleles. We also detected deletions in the RHCE gene that encompass more than 6000 bp and that are predicted to remove its last seven exons.

CONCLUSIONS

RHCE is the gene responsible for the chicken I blood system. This is the fifth chicken blood system for which the responsible gene and gene variants are known. With rapid DNA-based testing now available, the impact of I blood system variation on response against disease, general immune function, and animal production can be investigated in greater detail.

More evidence for widespread antagonistic pleiotropy in polymorphic disease alleles

Introduction

Many loci segregate alleles classified as "genetic diseases" due to their deleterious effects on health. However, some disease alleles have been reported to show beneficial effects under certain conditions or in certain populations. The beneficial effects of these antagonistically pleiotropic alleles may explain their continued prevalence, but the degree to which antagonistic pleiotropy is common or rare is unresolved. We surveyed the medical literature to identify examples of antagonistic pleiotropy to help determine whether antagonistic pleiotropy appears to be rare or common.

Results

We identified ten examples of loci with polymorphisms for which the presence of antagonistic pleiotropy is well supported by detailed genetic or epidemiological information in humans. One additional locus was identified for which the supporting evidence comes from animal studies. These examples complement over 20 others reported in other reviews.

Discussion

The existence of more than 30 identified antagonistically pleiotropic human disease alleles suggests that this phenomenon may be widespread. This poses important implications for both our understanding of human evolutionary genetics and our approaches to clinical treatment and disease prevention, especially therapies based on genetic modification.

Mobile calculator application for estimating human erythrocyte antigen frequency in Korea

OBJECTIVES

This study aimed to establish a comprehensive human erythrocyte antigen (HEA) frequency data set for Koreans. It also sought to develop a mobile app that facilitates the calculation of the frequencies of specific antigen-negative red blood cell units and the average number of units required for antigen typing.

METHODS

Human erythrocyte antigen frequencies were compiled from large-scale blood donor data and 5 previous papers. Based on the collected data, we developed a mobile calculator app for HEA frequency and evaluated its usability.

RESULTS

Human erythrocyte antigen frequency data for 20 blood group systems, including the ABO, Rh, MNS, Duffy, Kidd, and Diego systems, were established. The app was designed to enable users to select the desired phenotype from a drop-down menu and display the calculated frequency at the bottom. The number of units required for antigen typing to find 1 compatible red blood cell unit was also displayed. Five users participated in app evaluation and rated the functionality and information categories highly. In quizzes prompting users to calculate frequencies using the app, all participants provided correct answers, confirming the app's user-friendly functionality.

CONCLUSIONS

This app, which encompasses comprehensive HEA frequency data, is expected to find multiple uses in transfusion medicine, including optimizing blood bank workflow and defining rare blood groups in Korea.

A cold case of hemolytic disease of the fetus and newborn resolved by genomic sequencing and population studies to define a new antigen in the Rh system

BACKGROUND

We report an obstetric case involving an RhD-positive woman who had developed a red blood cell (RBC) antibody that was not detected until after delivery of a newborn, who presented with a positive direct antiglobulin test result. Immunohematology studies suggested that the maternal antibody was directed against a low-prevalence antigen on the paternal and newborn RBCs.

RESULTS

Comprehensive blood group profiling by targeted exome sequencing revealed a novel nonsynonymous single nucleotide variant (SNV) RHCE c.486C>G (GenBank MZ326705) on the RHCE*Ce allele, for both the father and newborn. A subsequent genomic-based study to profile blood groups in an Indigenous Australian population revealed the same SNV in 2 of 247 individuals. Serology testing showed that the maternal antibody reacted specifically with RBCs from these two individuals.

DISCUSSION

The maternal antibody was directed against a novel antigen in the Rh blood group system arising from an RHCE c.486C>G variant on the RHCE*Ce allele linked to RHD*01. The variant predicts a p.Asn162Lys change on the RhCE protein and has been registered as the 56th antigen in the Rh system, ISBT RH 004063.

CONCLUSION

This antibody was of clinical significance, resulting in a mild to moderate hemolytic disease of the fetus and newborn (HDFN). In the past, the cause of such HDFN cases may have remained unresolved. Genomic sequencing combined with population studies now assists in resolving such cases. Further population studies have potential to inform the need to design population-specific red cell antibody typing panels for antibody screening in the Australian population.

The Distribution Patterns of Rhesus (Rh) Antigens

INTRODUCTION

The determination of one's blood group is dictated by the inheritance-based diversity in the presence or absence of RBC antigens on the surface. Extended Rhesus (Rh) antigens are the most clinically relevant antigens of blood group systems after the ABO blood group system in transfusion medicine. The aim of this study was to serologically assess the prevalence of extended Rh antigens across diverse blood group systems.

METHODS

A total of 2043 samples were tested for the ABO blood group and Rh typing with monoclonal antisera. The Rh phenotyping (C, c, E, e ) was performed on all the samples.

RESULTS

The most frequently observed ABO blood group was O (36.5%), while AB (13.6%) was identified as the least prevalent. Positive Rh D antigen was found in 91.6% of tested samples, while 8.4% were Rh D-negative. The most frequently encountered antigen was e, followed by D, while the least prevalent was E.

DISCUSSION

Establishing a Rh phenotype repository for blood donors and conducting Rh phenotype assessments as part of pretransfusion testing before initiating the initial blood transfusion for each patient could significantly lower the patients' incidence of alloimmunization.

Serologic profiling of D variants in donor routine: unveiling the impact on false-negative results and alloimmunization

The high number of D variants can lead to the unnecessary use of Rh immune globulin, overuse of D- RBC units, and anti-D allommunization. D variant prevalence varies among ethnic groups, and knowledge of the main variants present in a specific population, their behavior in serologic tests, and their impact on clinical practice is crucial to define the best serologic tests for routine use. The present study aimed to explore the serologic profile of D variants and to determine which variants are most associated with false-negative D typing results and alloimmunization. Donor samples were selected in two study periods. During the first period, D typing was performed on a semi-automated instrument in microplates, and weak D tests were conducted in tube or gel tests. In the second period, D typing was carried out using an automated instrument with microplates, and weak D tests were performed in solid phase. Samples from patients typed as D+ with anti-D were also selected. All samples were characterized by molecular testing. A total of 37 RHD variants were identified. Discrepancies and atypical reactivity without anti-D formation were observed in 83.4 percent of the samples, discrepant D typing results between donations were seen in 12.3 percent, and D+ patients with anti-D comprised 4.3 percent. DAR1.2 was the most prevalent variant. Weak D type 38 was responsible for 75 percent of discrepant samples, followed by weak D type 11, predominantly detected by solid phase. Among the D variants related to alloimmunization, DIVa was the most prevalent, which was not recognized by serologic testing; the same was true for DIIIc. The results highlight the importance of selecting tests for donor screening capable of detecting weak D types 38 and 11, especially in populations where these variants are more prevalent. In pre-transfusion testing, it is crucial that D typing reagents demonstrate weak reactivity with DAR variants; having a serologic strategy to recognize DIVa and DIIIc is also valuable.

ABO and Rhesus blood groups and multiple health outcomes: an umbrella review of systematic reviews with meta-analyses of observational studies

BACKGROUND

Numerous studies have been conducted to investigate the relationship between ABO and Rhesus (Rh) blood groups and various health outcomes. However, a comprehensive evaluation of the robustness of these associations is still lacking.

METHODS

We searched PubMed, Web of Science, Embase, Scopus, Cochrane, and several regional databases from their inception until Feb 16, 2024, with the aim of identifying systematic reviews with meta-analyses of observational studies exploring associations between ABO and Rh blood groups and diverse health outcomes. For each association, we calculated the summary effect sizes, corresponding 95% confidence intervals, 95% prediction interval, heterogeneity, small-study effect, and evaluation of excess significance bias. The evidence was evaluated on a grading scale that ranged from convincing (Class I) to weak (Class IV). We assessed the certainty of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation criteria (GRADE). We also evaluated the methodological quality of included studies using the A Measurement Tool to Assess Systematic Reviews (AMSTAR). AMSTAR contains 11 items, which were scored as high (8-11), moderate (4-7), and low (0-3) quality. We have gotten the registration for protocol on the PROSPERO database (CRD42023409547).

RESULTS

The current umbrella review included 51 systematic reviews with meta-analysis articles with 270 associations. We re-calculated each association and found only one convincing evidence (Class I) for an association between blood group B and type 2 diabetes mellitus risk compared with the non-B blood group. It had a summary odds ratio of 1.28 (95% confidence interval: 1.17, 1.40), was supported by 6870 cases with small heterogeneity (I2 = 13%) and 95% prediction intervals excluding the null value, and without hints of small-study effects (P for Egger's test > 0.10, but the largest study effect was not more conservative than the summary effect size) or excess of significance (P < 0.10, but the value of observed less than expected). And the article was demonstrated with high methodological quality using AMSTAR (score = 9). According to AMSTAR, 18, 32, and 11 studies were categorized as high, moderate, and low quality, respectively. Nine statistically significant associations reached moderate quality based on GRADE.

CONCLUSIONS

Our findings suggest a potential relationship between ABO and Rh blood groups and adverse health outcomes. Particularly the association between blood group B and type 2 diabetes mellitus risk.

A novel pyrosequencing strategy for RHD zygosity for predicting risk of hemolytic disease of the fetus and newborn

OBJECTIVE

The aim of this study was the development of an accurate and quantitative pyrosequence (PSQ) method for paternal RHD zygosity detection to help risk management of hemolytic disease of the fetus and newborn (HDFN).

METHODS

Blood samples from 96 individuals were genotyped for RHD zygosity using pyrosequencing assay. To validate the accuracy of pyrosequencing results, all the samples were then detected by the mismatch polymerase chain reaction with sequence-specific primers (PCR-SSP) method and Sanger DNA sequencing. Serological tests were performed to assess RhD phenotypes.

RESULTS

Serological results revealed that 36 cases were RhD-positive and 60 cases were RhD-negative. The concordance rate between pyrosequencing assay and mismatch PCR-SSP assay was 94.8% (91/96). There were 5 discordant results between pyrosequencing and the mismatch PCR-SSP assay. Sanger sequencing confirmed that the pyrosequencing assay correctly assigned zygosity for the 5 samples.

CONCLUSION

This DNA pyrosequencing method accurately detect RHD zygosity and will help risk management of pregnancies that are at risk of HDFN.

Homologous blood transfusion and doping: Where are we now?

Homologous blood transfusion (HBT) is used for doping in endurance sports since the 1960s. The blood comes from a compatible donor, that is, someone with a compatible ABO and rhesus blood group. Despite been prohibited by the IOC in 1985, no detection method was available until 2003. Then came the idea to use red blood cells (RBC) minor blood groups antigens that constitute an "identity" card of someone's RBC to detect the presence of a second RBC population. The method validated for doping control samples uses flow cytometry after incubation of isolated RBC with eight to 12 primary antibodies against specific minor blood groups antigens. The presence of double populations of RBC is revealed by a major and a minor peak in a fluorescence histogram. The sensitivity was estimated sufficient to detect HBT for a few weeks. Despite the complexity and cost of the method, right after its application in 2004, several cases of HBT were identified but the number of cases dropped rapidly over the years. In the 2010s, other ways to detect HBT were developed and evaluated: indirect detection using the Athlete Biological Passport approach, and a few years later forensic DNA analysis to establish the presence of two different DNA in a blood sample after HBT. Despite the high specificity of the latter, the sensitivity was recently questioned in vivo. Nowadays, the flow cytometry method remains the method of choice for HBT detection and recent investigations helped to simplify the method and increase its specificity and sensitivity.

Recurrent pregnancy loss in a patient with anti-Rh17

BACKGROUND

Rh is one of the most important blood group systems in transfusion medicine. The two homologous genes RHD and RHCE are located on chromosome 1p36.11 and encode for RhD and RhCE proteins, respectively. Complex genetic polymorphisms result in a variety of antigenic expression of D, C, E, c, and e. Here, we describe a case of a young female with D-- who developed anti-Rh17 secondary to blood transfusion and had signs of haemolytic disease of the fetus and fetal death in five consecutive pregnancies.

CASE DESCRIPTION

EDTA-whole blood samples were collected from the patient, husband and eight siblings for blood grouping, phenotyping, and red cell antibody screening. Extracted DNA was genotyped by SNP-microarray and massively parallel sequencing (MPS) with targeted blood group exome sequencing. Copy number variation analysis was performed to identify structural variants in the RHD and RHCE. Routine phenotyping showed all family members were D+. The patient's red blood cells were C-E-c-e-, Rh17- and Rh46- and had anti-Rh17 and anti-e antibodies. MPS showed the patient carried a wildtype RHD sequence and homozygous for RHCE (1)-D (2-9)-CE (10) hybrid gene predicted to express a D-- phenotype.

CONCLUSIONS

Our patient had a rare D-- phenotype and confirmed to have RHCE/RHD hybrid gene with replacement of 2-9 exons of RHCE by RHD sequences. Unfortunately, our patient developed anti-Rh17 and anti-e antibodies due to blood transfusion and suffered fetal demise in her very first pregnancy. The adverse outcomes could have been prevented by active prenatal management.

Biological ammonium transporters: evolution and diversification

Although ammonium is the preferred nitrogen source for microbes and plants, in animal cells it is a toxic product of nitrogen metabolism that needs to be excreted. Thus, ammonium movement across biological membranes, whether for uptake or excretion, is a fundamental and ubiquitous biological process catalysed by the superfamily of the Amt/Mep/Rh transporters. A remarkable feature of the Amt/Mep/Rh family is that they are ubiquitous and, despite sharing low amino acid sequence identity, are highly structurally conserved. Despite sharing a common structure, these proteins have become involved in a diverse range of physiological process spanning all domains of life, with reports describing their involvement in diverse biological processes being published regularly. In this context, we exhaustively present their range of biological roles across the domains of life and after explore current hypotheses concerning their evolution to help to understand how and why the conserved structure fulfils diverse physiological functions.

Genetic polymorphisms and expression of Rhesus blood group RHCE are associated with 2,3-bisphosphoglycerate in humans at high altitude

Red blood cell (RBC) metabolic reprogramming upon exposure to high altitude contributes to physiological human adaptations to hypoxia, a multifaceted process critical to health and disease. To delve into the molecular underpinnings of this phenomenon, first, we performed a multi-omics analysis of RBCs from six lowlanders after exposure to high-altitude hypoxia, with longitudinal sampling at baseline, upon ascent to 5,100 m and descent to sea level. Results highlighted an association between erythrocyte levels of 2,3-bisphosphoglycerate (BPG), an allosteric regulator of hemoglobin that favors oxygen off-loading in the face of hypoxia, and expression levels of the Rhesus blood group RHCE protein. We then expanded on these findings by measuring BPG in RBCs from 13,091 blood donors from the Recipient Epidemiology and Donor Evaluation Study. These data informed a genome-wide association study using BPG levels as a quantitative trait, which identified genetic polymorphisms in the region coding for the Rhesus blood group RHCE as critical determinants of BPG levels in erythrocytes from healthy human volunteers. Mechanistically, we suggest that the Rh group complex, which participates in the exchange of ammonium with the extracellular compartment, may contribute to intracellular alkalinization, thus favoring BPG mutase activity.

Analysis of Rhesus (Rh) Antigen Distributions in Donors and Multi-transfused Patients for Phenotype-Matched Transfusion

Knowledge about the frequency of Rh blood group systems in the local population help build a donor pool for multi-transfused patients and provide antigen-negative compatible blood for patients with alloantibodies. ABO and Rh antigens were identified for blood donors and patients before transfusion. The antiglobulin test based on the micro-column gel method was used to perform unexpected antibody screening and identification for patients in pre-transfusion testing. The incidence of the adverse transfusion reactions and the accordance rate of Rh phenotype-matched transfusion were analyzed retrospectively. A total of 246,340 specimens were detected with Rh blood group antigens D, C, E, c, and e. Rh D antigen was the most common phenotype with a frequency of 99.40%, followed by e antigen, C antigen, c antigen, and E antigen. In Rh D positive specimens, DCe was the most common phenotype, while DCE was the least common. At the same time, in Rh D negative specimens, ce was the most common phenotype with CE and CcE unobserved. Rh phenotype-matched transfusion has been conducted in our department since 2012. The accordance rate of Rh phenotype-matched transfusion has been kept above 95% and the resulting incidence of adverse transfusion reactions has been decreasing year by year, from 19.95‰ in 2011 to 2.21‰ in 2021. Blood transfusion with matched Rh phenotypes was able to avoid the generation of unexpected antibodies, reduce the incidence of adverse transfusion reactions, and enhance precise diagnosis and treatment.

ABO and Rh (D) blood group phenotype distribution pattern among blood donors at the Nekemte Blood Bank, Oromia, West Ethiopia: a retrospective cross-sectional study

OBJECTIVE

To determine the distribution of ABO and Rh (D) blood group phenotypes among blood donors.

METHODS

This retrospective cross-sectional study enrolled blood donors whose socio-demographic and blood group phenotype data were collected from blood bank donor records. Descriptive statistics were used to summarise the number and percentage distribution of categorical variables. To determine if the distributions of the ABO and Rh phenotypes differed, a chi-square test was employed.

RESULTS

Of 14,887 blood donors with a median age of 20 years (interquartile range = 18-30 years), 72.8% were males, and young donors (age range = 18-24 years) accounted for 61.7%. Group O (45.6%) was the most prevalent ABO blood phenotype, followed by A (29.5%), B (20.2%), and AB (4.7%). The dominant blood group was O positive (42.4%), followed by A positive (27.4%), B positive (18.9%), AB positive (4.3%), O negative (3.2%), A negative (2.1%), B negative (1.3%), and AB negative (0.4%). The overall Rh (D)-negative distribution rate was 7.0%.

CONCLUSION

This study showed that blood group O was the most common ABO phenotype, followed by A, B, and AB. Overall, 93.0% of the donors were Rh (D)-positive. These findings may help guide blood transfusion programmes.

Genotype analysis to clarify RhD variants in discrepant samples of Chilean population

Introduction

The D antigen variants are classified as weak, partial, and extremely weak (DEL) and can be differentiated using molecular tests. In Chile, the laboratories of local blood centers do not identify variants of the D antigen, referring them for study to the Reference Laboratory of the Public Health Institute of Chile. So, our aim was to talk about the results of the molecular analysis of variants of the D antigen in samples that had different results in the serological classification.

Methods

In the D antigen classification of the Rh system, 479 samples with serological discrepant results were sent for molecular analysis. The Rh phenotype was performed with monoclonal anti-C, anti-c, anti-E, and anti-e antisera by direct agglutination. To find the D antigen, researchers used direct agglutination with monoclonal antisera and indirect antiglobulin testing with the column (gel) agglutination method. Molecular analysis was performed with a polymerase chain reaction with sequence-specific primers (SSP-PCR) and sequencing.

Results and discussion

The presence of D antigen variants was confirmed in 332 samples (69.3%), with an initial discrepancy in serological classification. In this group of discrepant samples, the frequency of weak RhD variants was 66% (219/332), that of extremely weak RhD was 28% (93/332), and that of partial RhD was 6% (20/332). The weak variants type 2 (27.4%), type 3 (8.4%), type 48 (8.4%), and type 1 (8.1%) were the next most prevalent variants after RHD*DEL43 (28%). The ccEe (R2r) phenotype was the most frequently detected (38.4%) and is present in 87% of the RHD*DEL43 samples. The E antigen is associated with the presence of this variant. Our analyses give the first description of D antigen variants in Chile. The most common variants are DEL type (RHD*DEL43) and weak (weak type 2), which are linked to the ccDEe (R2r) phenotype. These findings allow us to characterize the variants of the D antigen in Chile and, according to the obtained data, to design strategies for the management of donors, patients, and pregnant women.

Novel GH109 enzymes for bioconversion of group A red blood cells to the universal donor group O

Glycoside hydrolases (GHs) have been employed for industrial and biotechnological purposes and often play an important role in new applications. The red blood cell (RBC) antigen system depends on the composition of oligosaccharides on the surface of erythrocytes, thus defining the ABO blood type classification. Incorrect blood transfusions may lead to fatal consequences, making the availability of the correct blood group critical. In this regard, it has been demonstrated that some GHs may be helpful in the conversion of groups A and B blood types to produce group O universal donor blood. GHs belonging to the GH109 family are of particular interest for this application due to their ability to convert blood from group A to group O. This work describes the biochemical characterisation of three novel GH109 enzymes (NAg68, NAg69 and NAg71) and the exploration of their ability to produce enzymatically converted RBCs (ECO-RBC). The three enzymes showed superior specificity on pNP-α-N-acetylgalactosamine compared to previously reported GH109 enzymes. These novel enzymes were able to act on purified antigen-A trisaccharides and produce ECO-RBC from human donor blood. NAg71 converted type A RBC to group O with increased efficiency in the presence of dextran compared to a commercially available GH109, previously used for this application.

Generation of Rh D-negative blood using CRISPR/Cas9

Blood supply shortages, especially the shortage of rare blood types, threaten the current medical system. Research on stem cells has shed light on in vitro blood cell manufacturing. The in vitro production of universal red blood cells (RBCs) from induced pluripotent stem cells (iPSCs) has become the focus of transfusion medicine. To obtain O-type Rh D-negative blood, we developed O-type Rh D-negative human (h)iPSCs using homology-directed repair (HDR)-based CRISPR/Cas9. HuAiPSCs derived from human umbilical arterial endothelial cells and showing haematopoietic differentiation preferences were selected for gene modification. Guide RNAs (gRNAs) were selected, and a donor template flanked by gRNA-directed homologous arms was set to introduce a premature stop code to RHD exon 2. CRISPR/Cas9 gene editing has resulted in the successful generation of an RHD knockout cell line. The HuAiPSC-A1-RHD-/- cell line was differentiated into haematopoietic stem/progenitor cells and subsequently into erythrocytes in the oxygen concentration-optimized differentiation scheme. HuAiPSC-A1-RHD-/- derived erythrocytes remained positive for the RBC markers CD71 and CD235a. These erythrocytes did not express D antigen and did not agglutinate in the presence of anti-Rh D reagents. In conclusion, taking the priority of haematopoietic preference hiPSCs, the HDR-based CRISPR/Cas9 system and optimizing the erythroid-lineage differentiation protocol, we first generated O-type Rh D-negative universal erythrocytes from RHD knockout HuAiPSCs. Its production is highly efficient and shows great potential for clinical applications.

Polymorphisms in the promoter regions of RHD and RHCE genes in the Chinese Han population

BACKGROUND AND OBJECTIVES

The Rh blood group system is the most polymorphic human blood group system. Previous studies have investigated variants in the RHD and RHCE promoter. The relevance of these variants to the Chinese Han population is further clarified in this study.

MATERIALS AND METHODS

In total, 317 donors (223 Rh D-positive [D+], including 20 Del and 94 Rh D-negative [D-]) were randomly selected. The promoter regions and exon 1 of RHD and RHCE were amplified through polymerase chain reaction (PCR) whose products were directly sequenced using forward and reverse primers.

RESULTS

Expected PCR products of the RHD promoter and exon 1 were amplified in 223 D+ individuals, including 20 Del individuals, and were absent in 81 of 94 D- individuals. Expected PCR products of RHCE were observed in all donors. Two single nucleotide variants (SNVs) were observed in the RHD promoter region. Moreover, 11 SNVs were observed in the promoter and exon 1 of RHCE. rs4649082, rs2375313, rs2281179, rs2072933, rs2072932, rs2072931 and rs586178 with strong linkage disequilibria were significantly different between the D+ and D- groups. [A;C] was the most common haplotype in the RHD promoter (NC_000001.11:g.[-1033A>G;-831C>T]). [G;T;T;A;T;A;C;G;A;C;G] was the most predominant haplotype in both total and D- groups. In D+ individuals, [A;C;T;G;C;G;C;G;C;C;C] was the most frequent haplotype in the RHCE promoter (NC_000001.11:g.[-1080A>G;-958C>T;-390T>C;-378G>A;-369C>T;-296G>A;-144C>G;-132G>A;-122C>A;28C>T;48C>G]).

CONCLUSION

We speculate that the SNVs/haplotypes found in this article cannot significantly affect gene expression. The present study findings should help elucidate the molecular basis of the polymorphic expression of RHD and RHCE promoter regions.

O-negative blood shortage management in a university hospital: Impact of transfusing RhD-positive red blood cells to RhD-negative patients

BACKGROUND

Shortages of O-negative red blood cells are becoming increasingly common, forcing hospitals' blood transfusion services to find solutions to conserve this blood group for patients who need it most. The present study aimed to retrospectively evaluate the practice of transfusing selected RhD-negative patients with RhD-positive red blood cells and to assess the impact of this measure on patients and blood transfusion service management.

METHODOLOGY

Transfusion data of 1199 RhD-negative patients hospitalised at Cliniques Universitaires Saint-Luc between 2019 and 2022 were analysed. For patients who received RhD-positive red blood cells, age, gender, reason for hospital admission, indication for transfusion, and immunohematology analyses were recorded. These data enabled an assessment of transfusion practices over the years, characterisation of patients who received RhD-mismatched transfusions, determination of the alloimmunisation rate, and calculation of the total number of RhD-negative red blood cells saved.

RESULTS

During the study period, 141 RhD-negative patients received 604 RhD-positive red blood cells. A change in transfusion practices was observed over the years, with a greater proportion of RhD-negative patients being transfused with RhD-positive red blood cells in 2022 (28%) compared to 2019 (2%). The overall alloimmunisation rate was at least 20%, and 416 red blood cells were saved without any consequences. Patients undergoing cardiovascular surgery received the highest number of RhD-positive red blood cells.

CONCLUSION

The transfusion of selected RhD-negative patients with RhD-positive red blood cells is a low-risk practice that helps conserve RhD-negative red blood cells. However, there is a minimum 20% risk of alloimmunisation, which could have clinical and transfusion-related consequences in the future.

Rh flow cytometry: An updated methodology for D antigen density applied to weak D types 164 and 165

BACKGROUND

An original methodology for determining the D antigen density on red cells was published in 2000 and has been applied in many publications since. This flow cytometry-based assay remained largely unrevised utilizing monoclonal anti-Ds that are not readily available anymore. We updated the methodology to quantify erythrocyte D antigen sites using microspheres and monoclonal anti-Ds that are commercially available today.

METHODS

The absolute D antigen density of a frozen standard CcDEe cell, drawn in 2003, a fresh blood donation from the same individual, drawn in 2022, and an internal control CcDEe cell, was quantified by flow cytometry using fluorescence-labeled microspheres. The internal control CcDEe cell was used in conjunction with 9 commercial anti-Ds to determine D antigen densities of 7 normal D, 4 partial D, and 11 weak D type samples, including 2 novel alleles.

RESULTS

The reproducibility of the updated assay was evaluated with red cells of published D antigen densities. The current results matched the known ones closely. The new weak D types 164 and 165 carried 4500 and 1505 D antigens/red cell, respectively. The absolute D antigen density decreased from 27,231 to 26,037 in an individual over 19 years.

DISCUSSION

The updated assay gave highly reproducible results for the D antigen densities of Rh phenotypes. Readily available anti-Ds allowed for the determination of the D antigen densities of 7 weak D types. The assay is suitable to evaluate the effects of distinct amino acid substitutions on the RhD phenotype.

Assessment of the Relation Between Patterns of Third-Molar Impaction and Blood Group: A Retrospective Study

Background The prevalence of impacted third molars is high in the global general population. The etiology of impacted third molars is not fully understood, but it is thought to result from combined genetic and environmental factors. Some studies have suggested a link between the blood group and the risk of impacted third molars. This study aimed to investigate the association between the blood group and the presence of impacted third molars and its pattern. Method A total of 856 panoramic radiographs were included in the study. The third molars were evaluated for the pattern of third-molar impaction and blood characteristics recorded as ABO group and presence or absence of Rhesus antigen. Results The results showed no significant association between the blood group and the presence of impacted third molars. The prevalence of at least one impacted the third molar was 34.6%. The most common angulation of impacted third molars was vertical (V) (45.1%), followed by mesioangular (MA) (33.7%), distoangular (DA) (13.8%), and horizontal (H) (7.4%). There was no significant association between the blood group and the number of impacted third molars nor between the blood group and the angulation of the impacted third molars. Conclusion This study suggests that the blood group is not a major factor in the development of impacted third molars. However, further studies with larger sample sizes are needed to confirm these findings.

Serological and molecular characterisation of the most prevalent weak D variants in Croatian population

INTRODUCTION

Existence of hundreds of RHD gene variants contributes to variable D antigen expression and inconsistencies in reporting the RHD results. The aim of the study was to determine the serological and molecular characteristics of the most prevalent RHD alleles encoding serologically weak D variants.

MATERIAL AND METHODS

Blood donors (n = 145 924) were typed for D antigen using the direct serologic micromethod. Nonreactive samples were analysed in IAT method with the IgM/IgG anti-D monoclonal blend, and 0,2% (n = 263) confirmed weak D antigen expression. After genomic DNA extraction (Qiaqen, Germany), RHD genotyping was performed using in house reagents and PCR-SSP kits (Inno-Train, Germany).

RESULTS

The prevalence of serologically weak D in blood donor population was 0.2% (n = 263). RHD genotyping confirmed weak D allele in 92.4% and partial D allele in 7.6%. The most common was weak D type 1 (49.7%) followed by weak D type 3 (24.7%) and type 2 (9.5%). Relatively high frequency was detected for weak D type 14 (4.6%) and type 64 (2.3%). In the category of partial D phenotypes, only DVI variant was found. Direct typing has shown great variability in the strength of reactions with different clones of anti-D reagents.

CONCLUSION

Weak D type 1 is the most common weak D variant in Croatian blood donor population. The frequency of D variants and distribution of Rh phenotypes in our study was in concordance with other studies. It has been shown that serological methods and the combination of clones used, cannot distinguish variant D types, which justifies the use of molecular methods.

Association of Plasma Metabolites and Lipoproteins with Rh and ABO Blood Systems in Healthy Subjects

This study investigated the associations between the levels of 27 plasma metabolites, 114 lipoprotein parameters, determined using nuclear magnetic resonance spectroscopy, and the ABO blood groups and the Rhesus (Rh) blood system in a cohort of n = 840 Italian healthy blood donors of both sexes. We observed good multivariate discrimination between the metabolomic and lipoproteomic profiles of subjects with positive and negative Rh. In contrast, we did not observe significant discrimination for the ABO blood group pairwise comparisons, suggesting only slight metabolic differences between these group-specific metabolic profiles. We report univariate associations (P-value < 0.05) between the subfraction HDL1 related to Apo A1, the subfraction HDL2 related to cholesterol and phospholipids, and the particle number of LDL2 related to free cholesterol, cholesterol, phospholipids, and Apo B and the ABO blood groups; we observed association of the lipid main fraction LDL4 related to free cholesterol, triglycerides, and Apo B; creatine; the particle number of LDL5; the subfraction LDL5 related to Apo B; the particle number of LDL4; and the subfraction LDL4 related to Apo B with Rh blood factors. These results suggest blood group-dependent (re)shaping of lipoprotein metabolism in healthy subjects, which may provide relevant information to explain the differential susceptibility to certain diseases observed in different blood groups.

Rh Blood Group D Antigen Genotyping Using a Portable Nanopore-based Sequencing Device: Proof of Principle

BACKGROUND

Nanopore sequencing is direct sequencing of a single-stranded DNA molecule using biological pores. A portable nanopore-based sequencing device from Oxford Nanopore Technologies (MinION) depends on driving a DNA molecule through nanopores embedded in a membrane using a voltage. Changes in current are then measured by a sensor, thousands of times per second and translated to nucleobases.

METHODS

Genomic DNA (gDNA) samples (n = 13) were tested for Rh blood group D antigen (RHD) gene zygosity using droplet digital PCR. The RHD gene was amplified in 6 overlapping amplicons using long-range PCR. Amplicons were purified, and the sequencing library was prepared following the 1D Native barcoding gDNA protocol. Sequencing was carried out with 1D flow cells R9 version. Data analysis included basecalling, aligning to the RHD reference sequence, and calling variants. Variants detected were compared to the results acquired previously by the Ion Personal Genome Machine (Ion PGM).

RESULTS

Up to 500× sequence coverage across the RHD gene allowed accurate variant calling. Exonic changes in the RHD gene allowed RHD allele determination for all samples sequenced except 1 RHD homozygous sample, where 2 heterozygous RHD variant alleles are suspected. There were 3 known variant RHD alleles (RHD*01W.02, RHD*11, and RHD*15) and 6 novel RHD variant alleles, as previously seen in Ion PGM sequencing data for these samples.

CONCLUSIONS

MinION was effective in blood group genotyping, provided enough sequencing data to achieve high coverage of the RHD gene, and enabled confident calling of variants and RHD allele determination.

Distribution and frequency of principal Rh blood group antigens (D, C, c, E, and e) and their phenotypes in the blood donors attending blood bank in a tertiary care hospital in Barpeta district of Assam

BACKGROUND

The ABO and Rhesus grouping system antigens have been found to have the highest immunogenicity and propensity to produce alloantibodies that cause most of the transfusion reactions. The Rhesus antigens that produce most of the immunogenic transfusion reactions are D, C, c, E, and e. Knowledge of the distribution of these Rh antigens in a population helps to render compatible blood in alloimmunized patients.

AIM

The aim was to study the distribution and frequency of principal Rh blood group antigens (D, C, c, E, and e) and their phenotypes in the blood donors attending blood bank in a tertiary care hospital in Barpeta district of Assam.

MATERIALS AND METHODS

The study was conducted in 315 voluntary blood donors in the blood bank of a tertiary care center. Rh-D typing was done by conventional tube method. Specific monoclonal antisera, i.e., anti-C, anti-c, anti-E, and anti-e, were used and tests were performed by conventional tube method for detection of the presence of rest of the major Rh antigens.

RESULTS

The samples were analyzed for the five major Rhesus antigens. "D" antigen was found to be the most common antigen (99.05%), followed by e (97.14%), C (92.38%), c (51.43%), and E (20.95%). In order of descending frequency, the most common phenotypes were DCCee - 45.71%, DCcee - 30.48%, DCcEe - 11.43%, DccEe - 4.76%, DCcEE - 1.90%, DCCEe - 1.90%, Dccee - 1.90%, DCCEE - 0.95%, and dccee - 0.95%.

CONCLUSION

D antigen is the most common antigen in our study population, whereas "e" antigen is the most common in most of the studies done from other parts of India. Data on frequencies of major Rh antigens in the local donor population will help in transfusing alloimmunized patients with corresponding antibody-negative blood ensuring blood safety.

Prevalence of Rh and K phenotypes among blood donors from different ethnicities in Samtah (Southwestern Region) Saudi Arabia

INTRODUCTION

Rh and Kell blood group systems are amongst the most important blood group systems; being highly immunogenic after ABO system. The aim of this study was to evaluate the frequencies of Rh antigens, haplotypes and K antigen among blood donors belonging to various ethnicities in Samtah, Jazan, Saudi Arabia.

METHODS

This study was conducted during January 2019 and August 2020 at Samtah General Hospital, Samtah. Records of all blood donors recruited during this period were included for data acquisition. A total of 4977 blood donors' records were reviewed and data were analysed. A total of 3863 donors' results were considered in the final analysis.

RESULTS

In comparison to Saudi blood donors, C antigen was less frequent in Sudanese donors (69.7% and 34.0%), the c antigen was less frequent in Indian (79.2% and 59.3%) and Philippine (79.2% and 40.0%) donors and more frequent in Sudanese (79.2% and 97.9%) donors, the E antigen was less frequent in Yemini (27.0% and 19.5%) and the e antigen was more frequent in Yemini (96.7% and 99.2%) donors. The DcE haplotype was less frequent (3.1% and 0.7%) and the ce haplotype was more frequent (4.3% and 7.6%) in Yemini donors. The K antigen was less frequent in Pakistani (11.9% and 4.1%; p = .041) and Indian (11.9% and 1.9%; p = .023) donors.

CONCLUSION

Rh and K antigens showed marked variations in their frequencies among blood donors of different ethnicities. Utilization of blood from various ethnicities warrant extended phenotyping of Rh and K antigens to avoid the risk of alloimmunization in multiply transfused patients.

The crawford variant as a cause of rhd typing discrepancies in blood banks: a case report

We present the case of a 55-year-old Colombian male who showed a discrepancy in the serological typing of the RhD antigen in his first platelet donation. The discrepancy persisted after a serological investigation with multiple Anti-D monoclonal reagents (IgG and IgM) under different conditions (22°C and 37°C, saline, and LISS/Coombs). Furthermore, partial RhD typing was performed, obtaining negative results with a commercially available panel of six Anti-D reagents. Molecular analysis showed a homozygous deletion of RHD and heterozygosity for the Crawford variant (RHCE*ce, RHCE*ceCF), with a predicted phenotype of C-, c+, E-, e+, Vs+, V+. Following the investigation of this case, this man has made 14 platelet donations showing variable reactivity, with agglutinations ranging from - to 2+. Since Crawford red blood cells express some RhD antigen epitopes, they could cause alloimmunization in RhD negative receptors. Likewise, Anti-D alloantibodies have been documented in Crawford variant carriers. Therefore, it is recommended that carriers of this variant be classified as RhD positive if they are blood donors and RhD negative if they are transfusion recipients. Also, in pregnant women carrying a Crawford variant, Anti-D immunoprophylaxis is recommended.

The individual and global impact of copy-number variants on complex human traits

The impact of copy-number variations (CNVs) on complex human traits remains understudied. We called CNVs in 331,522 UK Biobank participants and performed genome-wide association studies (GWASs) between the copy number of CNV-proxy probes and 57 continuous traits, revealing 131 signals spanning 47 phenotypes. Our analysis recapitulated well-known associations (e.g., 1q21 and height), revealed the pleiotropy of recurrent CNVs (e.g., 26 and 16 traits for 16p11.2-BP4-BP5 and 22q11.21, respectively), and suggested gene functionalities (e.g., MARF1 in female reproduction). Forty-eight CNV signals (38%) overlapped with single-nucleotide polymorphism (SNP)-GWASs signals for the same trait. For instance, deletion of PDZK1, which encodes a urate transporter scaffold protein, decreased serum urate levels, while deletion of RHD, which encodes the Rhesus blood group D antigen, associated with hematological traits. Other signals overlapped Mendelian disorder regions, suggesting variable expressivity and broad impact of these loci, as illustrated by signals mapping to Rotor syndrome (SLCO1B1/3), renal cysts and diabetes syndrome (HNF1B), or Charcot-Marie-Tooth (PMP22) loci. Total CNV burden negatively impacted 35 traits, leading to increased adiposity, liver/kidney damage, and decreased intelligence and physical capacity. Thirty traits remained burden associated after correcting for CNV-GWAS signals, pointing to a polygenic CNV architecture. The burden negatively correlated with socio-economic indicators, parental lifespan, and age (survivorship proxy), suggesting a contribution to decreased longevity. Together, our results showcase how studying CNVs can expand biological insights, emphasizing the critical role of this mutational class in shaping human traits and arguing in favor of a continuum between Mendelian and complex diseases.

Rhesus negative males have an enhanced IFNγ-mediated immune response to influenza A virus

The Rhesus D antigen (RhD) has been associated with susceptibility to several viral infections. Reports suggest that RhD-negative individuals are better protected against infectious diseases and have overall better health. However, potential mechanisms contributing to these associations have not yet been defined. Here, we used transcriptomic and genomic data from the Milieu Interieur cohort of 1000 healthy individuals to explore the effect of Rhesus status on the immune response. We used the rs590787 SNP in the RHD gene to classify the 1000 donors as either RhD-positive or -negative. Whole blood was stimulated with LPS, polyIC, and the live influenza A virus and the NanoString human immunology panel of 560 genes used to assess donor immune response and to investigate sex-specific effects. Using regression analysis, we observed no significant differences in responses to polyIC or LPS between RhD-positive and -negative individuals. However, upon sex-specific analysis, we observed over 40 differentially expressed genes (DEGs) between RhD-positive (n = 384) and RhD-negative males (n = 75) after influenza virus stimulation. Interestingly these Rhesus-associated differences were not seen in females. Further investigation, using gene set enrichment analysis, revealed enhanced IFNγ signalling in RhD-negative males. This amplified IFNγ signalling axis may explain the increased viral resistance previously described in RhD-negative individuals.

Weak D type 42: Antigen density and risk of alloimmunization in the province of Québec

BACKGROUND AND OBJECTIVES

A high proportion of suspected weak D patients referred to Héma-Québec were genotyped as weak D type 42 (368/2105, 17.5%). These patients are currently considered D with regard to RhD immunoprophylaxis in pregnancy and transfusion. The goal of this study was to retrospectively evaluate the risk of alloimmunization in weak D type 42 patients and to characterize their RhD surface molecule expression on red blood cells (RBCs) in comparison to other weak D types (1, 2 and 3).

MATERIALS AND METHODS

A retrospective analysis using the weak D type 42 patients' medical data to verify potential anti-D alloimmunization events was conducted. Quantitative analyses using flow cytometry were also performed on RBCs to quantify the cell surface density of the D antigen.

RESULTS

Data on 215 subjects with weak D type 42 were reviewed. None developed immune allo-anti-D; three had definite exposure to D+ red cells and 41 had possible exposure through pregnancy. Flow cytometry analysis showed that weak D types 1, 2, 3 and 42 had relative antigen densities of 2.7%, 2.2%, 8.1% and 3.6%, respectively, with R1R2 red cells referencing 100% density. The estimated antigen density range of weak D type 42 was 819-1104 sites per RBC.

CONCLUSION

Our retrospective alloimmunization data analysis and antigen density study establish a basis for the consideration of a weak D type 42 individual as D+. This consideration would allow for a targeted reduction of RhD immunoprophylaxis in pregnancy and the unjustified use of D- units for transfusion.

Patient blood management in a neurosurgical patient with anti-e antibody

The successful application of patient blood management approach in a 48-year-old neurosurgery patient planned for meningioma excision and requiring transfusion is described. The patient had multiple past immunizing events and developed antibody against a high-frequency antigen “e” of the Rh blood group system. With the joint effort from transfusion medicine specialist, anesthesiologist, and surgeon, the patient was successfully managed using the preoperative autologous blood donation program.

The Correlation between Impacted Third Molar and Blood Group

Background

Blood type is among the most important genetical characteristics of any individual and is shown to be correlated with the development of a variety of illnesses including dental diseases. Finding the association of ABO and Rh blood groups and impacted tooth is important in order to predict which population is more vulnerable to grow impacted third molars that could lead to making better intervention. The present investigation tried to take a small step in that regard, by evaluating the correlation between ABO and Rh blood groups and the most commonly impacted tooth, bony impacted third molars among Iranian individuals.

Methods

The investigation was done retrospectively on patients who were referred to the Department of Oral Radiology, Shiraz University of Medical Science, Shiraz, Iran. The patients were classified according to their blood groups, and 40 patients were randomly selected for each blood type. Therefore, the impaction of their third molars was evaluated, and statistical analyses were done in order to find any association.

Results

A total of 320 participants contributed to the study; 136 (42%) were males and 184 (57%) were females. The mean age was 29 ± 6 years. Among all participants, 205 (64%) had no impacted third molar, 26 (8%) had one impacted third molar, 43 (13%) had 2 impacted third molars, 5 (1%) had 3 impacted third molars, and 41 (12%) had 4 impacted molars.

Conclusion

According to the results of the present study, nearly one out of three individuals has at least an impacted third molar in the Iranian population, being more prevalent in individuals between 20 and 30 years old. The evaluation of the relationship between the blood group and impacted third molar revealed that blood groups have no association with the impacted third molars. However, more studies with higher and diversified participants should be done to find comprehensive results.

DEL in China: the D antigen among serologic RhD-negative individuals

BACKGROUND

Providing RhD-negative red cell transfusions is a challenge in East Asia, represented by China, Korea, and Japan, where the frequency of RhD-negative is the lowest in the world.

FINDINGS

Among 56 ethnic groups in China, the RhD-negative frequency in Han, the prevalent ethnicity, is 0.5% or less, similar to most other ethnic groups. The Uyghur ethnic group has the highest reported RhD-negative frequency of up to 4.7%, as compared to 13.9% in the US. However, an estimated 7.15 million RhD-negative people live in China. The RhD-negative phenotype typically results from a loss of the entire RHD gene, causing the lack of the RhD protein and D antigen. The DEL phenotype carries a low amount of the D antigen and types as RhD-negative in routine serology. The DEL prevalence in RhD-negative individuals averages 23.3% in the Han, 17% in the Hui and 2.4% in the Uyghur ethnicities. The Asian type DEL, also known as RHD*DEL1 and RHD:c.1227G > A allele, is by far the most prevalent among the 13 DEL alleles observed in China.

CONCLUSION

The purpose of this review is to summarize the data on DEL and to provide a basis for practical strategy decisions in managing patients and donors with DEL alleles in East Asia using molecular assays.

Major and minor blood group phenotyping and database generation for recruits : A pilot study

Background

Alloimmunization to minor blood group antigens is a problem that has for long befuddled the blood bankers, requiring blood group phenotyping of target populations worldwide. However, the same exercise had been lacking in our Armed Forces population necessitating this pilot study.

Methods

A total of 2000 recruits of a regimental center in northern India were phenotyped for major and minor blood group antigens including ABO, Rhesus (D, C, c, E, and e antigens), Kell (K), MNSs (S and s antigens), Kidd (Jka and Jkb), and Duffy (Fya and Fyb) using commercially prepared polyclonal antisera on a fully automated system based on electromagnetic technology. Typing for M and N antigens (MNSs system) was performed using the tube method using company provided specific polyclonal antisera. The results were also compared with that of Indian and other populations of the world.

Results

Blood group antigen frequencies observed in our study population were mostly in sync with the prevalence rates of major and minor blood group antigens reported in other studies; however, in certain cases, they were also at variance. In our study, Rh D-negative antigen, JKa-Jkb- phenotype frequency were comparatively much higher than those reported in other Indian studies.

Conclusion

To conclude, ours was a pilot study to establish the database of major and minor antigens of Armed Forces combatants. However, it is recommended that if the same effort can be replicated at the other transfusion centers and major hospitals of Armed Forces, it will vastly benefit their alloimmunized patient clientele needing lifesaving transfusions.

A rapid and simple procedure for the isolation and cultivation of fibroblast-like cells from medaka and zebrafish embryos and fin clip biopsies

In many human diseases, the molecular pathophysiological mechanisms are not understood, which makes the development and testing of new therapeutic approaches difficult. The generation and characterization of animal models such as mice, rats, fruit flies, worms or fish offers the possibility for in detail studies of a disease's development, its course and potential therapies in an organismal context, which considerably minimizes the risk of therapeutic side effects for patients. Nevertheless, due to the high numbers of experimental animals used in research worldwide, attempts to develop alternative test systems will help in reducing their count. In this regard, the cell culture system displays a suitable option due to its potential of delivering nearly unlimited material and the good opportunities for high-throughput studies such as drug testing. Here, we describe a quick and simple method to isolate and cultivate vital fibroblast-like cells from embryos and adults of two popular teleost model organisms, the Japanese rice fish medaka (Oryzias latipes) and the zebrafish (Danio rerio).

A Rare Cohort of Two Rhnull Individuals

OBJECTIVE

A 77 year old female was admitted with a subdural hematoma requiring 1 unit of apheresis platelets. She was a study subject in the 1960s and was found to be Rhnull, along with another individual who previously served as a directed donor for her.

METHODS

Serologic testing performed by the immunohematology reference laboratory (IRL) confirmed that the patient was Rhnull and expressed anti-Rh29 antibodies. While searching for red blood cells (RBCs) for possible transfusion, it was discovered that the individual from the original study had recently donated an autologous unit.

RESULTS

The IRL discovered that the donor's antigen typing was r'r'. Testing had been performed using a molecular human erythrocyte antigen BeadChip (HBC). Due to the discrepancy between current and historical testing results, a donor segment was thawed and by tube testing confirmed to be Rhnull. A limitation of HBC is that many null phenotypes will be missed.

CONCLUSION

This case demonstrated that Rhnull evaluation of the donor required both serological and molecular methods.

Blood Pharming – eine realistische Option?

Die Bluttransfusion ist ein wesentlicher und unersetzlicher Teil der modernen Medizin. Jedoch stellt vor allem bei Patienten mit sehr seltenen Blutgruppenkonstellationen der Mangel an Blutprodukten auch heute noch ein wichtiges Gesundheitsproblem weltweit dar. Um diesem Problem entgegenzutreten, versucht man seit einiger Zeit künstlich rote Blutzellen zu generieren. Diese haben potenzielle Vorteile gegenüber Spenderblut, wie z. B. ein verringertes Risiko für die Übertragung von Infektionskrankheiten. Diese Übersicht fasst die aktuellen Entwicklungen über den Prozess der Erythropoese, die Expansionsstrategien der erythrozytären Zellen, der verschiedenen Quellen für ex vivo expandierte Erythrozyten, die Hürden für die klinische Anwendung und die zukünftigen Möglichkeiten der Anwendung zusammen.

Safety assessment of RhD-positive red cell transfusion in RhD-negative liver-transplant recipients: Single-centre report from India

Background & objectives:

The number of blood components required during a liver-transplant surgery is significant. It is challenging for blood transfusion services to provide the required RhD-negative red blood cells (RBCs) for recipients during the peri-operative period. This retrospective study presents safety data of transfusing RhD-positive RBCs in RhD-negative living donor liver-transplant (LDLT) recipients during the peri-operative period with six-month follow up for risk of developing alloantibodies.

Methods:

All RhD-negative patients who underwent LDLT and were transfused ABO-compatible but RhD-positive RBC units between January 2012 and May 2018 were included in the study. Twenty one RhD-negative patients who received a total of 167 RhD-positive RBCs peri-operatively were chosen for alloantibody screening. All the patients were started on triple immunosuppression drugs as per the standard hospital protocol. Blood grouping, cross-match and antibody screening were done by column agglutination technique.

Results:

Post-transplant antibody screen (weekly for 12 wk) was negative, and none of the patients developed anti-D alloantibodies till their last follow up (mean 21 months).

Interpretation & conclusions:

Our observations suggest that it may be safe to use RhD-positive RBCs peri-operatively in RhD-negative LDLT recipients with low risk of alloimmunization.

How a Paleogenomic Approach Can Provide Details on Bioarchaeological Reconstruction: A Case Study from the Globular Amphorae Culture

Ancient human remains have the potential to explain a great deal about the prehistory of humankind. Due to recent technological and bioinformatics advances, their study, at the palaeogenomic level, can provide important information about population dynamics, culture changes, and the lifestyles of our ancestors. In this study, mitochondrial and nuclear genome data obtained from human bone remains associated with the Neolithic Globular Amphorae culture, which were recovered in the Megalithic barrow of Kierzkowo (Poland), were reanalysed to gain insight into the social organisation and use of the archaeological site and to provide information at the individual level. We were able to successfully estimate the minimum number of individuals, sex, kin relationships, and phenotypic traits of the buried individuals, despite the low level of preservation of the bone samples and the intricate taphonomic conditions. In addition, the evaluation of damage patterns allowed us to highlight the presence of “intruders”—that is, of more recent skeletal remains that did not belong to the original burial. Due to its characteristics, the study of the Kierzkowo barrow represented a challenge for the reconstruction of the biological profile of the human community who exploited it and an excellent example of the contribution that ancient genomic analysis can provide to archaeological reconstruction.

Design, implementation, and assessment of an interactive simulation to teach undergraduate immunology students hemolytic disease of the newborn

Hemolytic disease of the newborn (HDN) is a potentially fatal condition caused by a Rhesus (Rh) antigen incompatibility between a mother and fetus. As a result, determining the Rh status of expectant parents is a routine clinical assessment. Both the physiological and immunological basis of this condition are taught to undergraduate students. At the University of South Australia, some undergraduate immunology students find this topic challenging. The author designed, implemented, and assessed the impact of an interactive simulation to facilitate student learning of HDN. The students were actively engaged in determining the blood grouping and Rh status of an expectant mother and father and then determining the possibility of developing HDN. The simulation was found to take only 15 min to complete yet led to a significant increase in student performance in an end of semester exam question. Student perceived understanding was found to significantly improve following the introduction of the simulation, even though the content had been covered in a formal lecture. Student feedback was highly positive of this learning approach. In conclusion, short, interactive simulations can be used effectively to enhance student learning of challenging concepts.

Serological screening and genetic analysis of RhCE variants in the Chinese Southern Han donors

OBJECTIVES

To screen RhCE variants in the Chinese Southern Han donors for molecular genetic analysis.

BACKGROUND

More than hundreds of RhCE variant alleles have been described to resulting in weak and/or partial expression of RhCE antigens, generation of low-prevalence antigens and/or absence of a high-prevalence antigen of Rh system, which mainly reported in the people of African origin. In this study, the serological screening and molecular genetic analysis of RhCE variants were performed in the Chinese Southern Han donors.

METHODS

The blood samples of E(+) donors were preliminarily collected. Then, RhCE antigens of the E(+) samples were further typed by using two sets of monoclonal anti-C, anti-c, anti-e and another anti-E. When weak expression of RhCE antigens was found, direct sequencing for 10 exons of RHCE gene, RH genotyping analysis by using multiplex ligation-dependent probe amplification, flow cytometric analysis and even cDNA sequencing were performed.

RESULTS

A total of 4487 E(+) samples were collected and four samples with weak expression of antigens were detected. RHCE*Ce375G and RHCE*Ce667T variant alleles were identified in two samples with weak expression of e antigen, respectively. But no variant alleles were found in another two samples with weak expression of C antigen.

CONCLUSION

The variant RHCE*Ce375G validated by mRNA sequencing and the deduced RHCE*Ce667T alleles were firstly identified in the Chinese population. The DCE haplotype might account for the weak expression of C antigen in two donors.