A Chinese individual with DEL phenotype caused by a novel RHD allele.

BACKGROUND: RhD variants are categorized into partial D, weak D, and DEL. The detection of DEL can only be achieved through the adsorption and elution method or molecular techniques. Here, we report a case of DEL phenotypes associated with a novel allele in a Chinese individual. STUDY DESIGN AND METHODS: We used serological methods such as saline, indirect anti-human globulin, and adsorption-elution. The RHD genotype was determined by the PCR-sequence specific primer (PCR-SSP) method as well as the Sanger dideoxy sequencing. RESULTS: RBCs of the sample were found to be DEL phenotype by serological testing, with negative reactions in the saline and indirect anti-human globulin tests while positive reactions by the absorption-elution method. The genotyping results revealed a hemizygous (RHDc .1127 T>G/RHD-). The novel allele sequence has been submitted to GenBank (Accession number: OR608456). CONCLUSION: Our study demonstrates a case of a Chinese individual with DEL phenotype caused by a novel allele RHD c .1127 T > G. It expands the database of the DEL variant.

Rh Blood Group Antigens and Alloimmunization Risk of Pregnant Women in South Western, Nigeria.

BACKGROUND: Rh blood group antigens are the second most important blood group antigens in clinical transfusion due to their immunogenicity and prevalence. Childbirth, miscarriage, and other obstetrics events are risk factors for alloimmunization in women which increases the likelihood of haemolytic blood transfusion reaction and hemolytic disease of the fetal/newborn (HDNF/B). Even though there are several data on the RhD status of our populations. However, there is a dearth of data on pregnant women's C, E, c, and e status, their alloimmunization risk, and rates in Nigeria. OBJECTIVES: This study aims to provide information on the distribution of the Rh major antigens and risk factors for alloimmunization in pregnant women in southwestern Nigeria. MATERIALS AND METHODS: This was a descriptive cross-sectional study of 133 pregnant women attending routine ante-natal clinics. Questionnaires were administered to collect biodata and obstetrics history. ABO blood grouping and Rh phenotyping were carried out on their blood samples using RAPID LABS Monoclonal Rhesus Typing Reagent. RESULTS AND DISCUSSION: Rh blood group antigen c was present in 100% of the women, followed by e (98.5%) and D (95.5%). C and E are the least prevalent antigens and probably the ones to which antibodies may be formed. The commonest Rh phenotype was Dce. Of all the pregnant women, alloimmunization was present in 0.8%. Of those who were RhD negative, alloimmunization was present in 16.7%. Pregnant women are more likely to be alloimmunized against C and E antigens than c and e antigens due to their low and high frequencies respectively.

CONTEXTE: Les antigènes du groupe sanguin Rh sont les seconds plus importants en transfusion clinique en raison de leur immunogénicité et de leur prévalence. L'accouchement, la fausse couche et d'autres événements obstétriques sont des facteurs de risque d'alloimmunisation chez les femmes, augmentant ainsi la probabilité de réactions hémolytiques lors de transfusions sanguines et de maladies hémolytiques du fœtus/nouveau-né (HDNF/B). Bien qu'il existe plusieurs données sur le statut RhD de nos populations, il y a un manque de données sur le statut des antigènes C, E, c et e chez les femmes enceintes, leur risque d'alloimmunisation et les taux associés au Nigéria. OBJECTIFS: Cette étude vise à fournir des informations sur la distribution des principaux antigènes Rh et les facteurs de risque d'alloimmunisation chez les femmes enceintes dans le sud-ouest du Nigéria. MÉTHODOLOGIE: Il s'agit d'une étude descriptive transversale de 133 femmes enceintes fréquentant les cliniques prénatales de routine. Des questionnaires ont été administrés pour collecter des données biodémographiques et des antécédents obstétriques. La détermination des groupes sanguins ABO et le phénotypage Rh ont été réalisés sur leurs échantillons de sang à l'aide du réactif de typage Rh monoclonal RAPID LABS. RÉSULTATS ET DISCUSSION: L'antigène c du groupe sanguin Rh était présent chez 100 % des femmes, suivi de e (98,5 %) et D (95,5 %). Les antigènes C et E sont les moins prévalents et probablement ceux contre lesquels des anticorps peuvent être formés. Le phénotype Rh le plus courant était Dce. Parmi toutes les femmes enceintes, l'alloimmunisation était présente chez 0,8 %. Parmi celles qui étaient RhD négatives, 'alloimmunisation était présente chez 16,7 %. Les femmes enceintes sont plus susceptibles de développer une alloimmunisation contre les antigènes C et E que contre les antigènes c et e en raison de leurs fréquences respectives faibles et élevées. MOTS-CLÉS: Antigènes du groupe sanguin Rh, Phénotype, Alloanticorps érythrocytaires, Femmes enceintes.

A patient with anti-f in India identified by extensive immunohematologic workup.

Anti-f is produced by exposure to the compound antigen ce (f) on red blood cells (RBCs), expressed when both c and e are present on the same protein (cis position). Although anti-f was discovered in 1953, there are few cases reported worldwide because the presence of anti-f is often masked by anti-c or anti-e and is not generally found as a single antibody. In the present case, anti-f was identified by using three-cell screening and 11-cell identification panels. The identification of anti-f was further supported by additional testing, including (1) Rh antigen typing; (2) antibody identification panels (enzyme-treated panel [ficin] and an in-house-constructed Rh panel); (3) look-back and phenotyping of donor RBC units, which were responsible for alloimmunization; and (4) molecular testing of the patient's RBCs.

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.

Estimating the serological underrecognition of patients with weak or partial RHD variants.

BACKGROUND: For patients with weak or discrepant RhD RBC phenotypes, RHD genotyping is employed to determine need for RhD-negative management. However, many RHD variants are type D-negative or D-positive. Serological recognition rates (RRs) of weak and partial RHD variants are poorly characterized. STUDY DESIGN AND METHODS: Four US studies employing RHD genotyping for weak or discrepant RhD phenotypes provided data for race/ethnicity-specific serological recognition. Three studies used microplate, and 1 used gel and tube; 2 had anti-D data. We obtained White and Hispanic/Latino allele frequencies (AFs) of weak D types 1, 2, and 3 single-nucleotide variants (SNVs) from the Genome Aggregation Database (gnomAD, v4.0.0) and devised Hardy-Weinberg-based formulas to correct for gnomAD's overcount of hemizygous RHD SNVs as homozygous. We compiled common partial RHD AF from genotyped cohorts of US Black or sickle cell disease subjects. From variant AF, we calculated hemizygous-plus-homozygous genetic prevalences. Serological prevalence: genetic prevalence ratios yielded serological RRs. RESULTS: Overall RRs of weak D types 1-3 were 17% (95% confidence interval 12%-24%) in Whites and 12% (5%-27%) in Hispanics/Latinos. For eight partial RHD variants in Blacks, overall RR was 11% (8%-14%). However, DAR RR was 80% (38%-156%). Compared to microplate, gel-tube recognition was higher for type 2 and DAU5 and lower for type 4.0. Anti-D was present in 6% of recognized partial RHD cases, but only in 0.7% of estimated total genetic cases. DISCUSSION: Based on AF, >80% of patients with weak or partial RHD variants were unrecognized serologically. Although overall anti-D rates were low, better detection of partial RHD variants is desirable.

Molecular dynamics of the human RhD and RhAG blood group proteins.

Introduction: Blood group antigens of the RH system (formerly known as "Rhesus") play an important role in transfusion medicine because of the severe haemolytic consequences of antibodies to these antigens. No crystal structure is available for RhD proteins with its partner RhAG, and the precise stoichiometry of the trimer complex remains unknown. Methods: To analyse their structural properties, the trimers formed by RhD and/or RhAG subunits were generated by protein modelling and molecular dynamics simulations were performed. Results: No major differences in structural behaviour were found between trimers of different compositions. The conformation of the subunits is relatively constant during molecular dynamics simulations, except for three large disordered loops. Discussion: This work makes it possible to propose a reasonable stoichiometry and demonstrates the potential of studying the structural behaviour of these proteins to investigate the hundreds of genetic variants relevant to transfusion medicine.

RH genotypes and red cell alloimmunization rates in chronically transfused patients with sickle cell disease: A multisite study in the USA.

BACKGROUND: Red cell alloimmunization remains a challenge for individuals with sickle cell disease (SCD) and contributes to increased risk of hemolytic transfusion reactions and associated comorbidities. Despite prophylactic serological matching for ABO, Rh, and K, red cell alloimmunization persists, in part, due to a high frequency of variant RH alleles in patients with SCD and Black blood donors. STUDY DESIGN AND METHODS: We compared RH genotypes and rates of alloimmunization in 342 pediatric and young adult patients with SCD on chronic transfusion therapy exposed to >90,000 red cell units at five sites across the USA. Genotyping was performed with RHD and RHCE BeadChip arrays and targeted assays. RESULTS: Prevalence of overall and Rh-specific alloimmunization varied among institutions, ranging from 5% to 41% (p = .0035) and 5%-33% (p = .0002), respectively. RH genotyping demonstrated that 33% RHD and 57% RHCE alleles were variant in this cohort. Patients with RHCE alleles encoding partial e antigens had higher rates of anti-e identified than those encoding at least one conventional e antigen (p = .0007). There was no difference in anti-D, anti-C, or anti-E formation among patients with predicted partial or altered antigen expression compared to those with conventional antigens, suggesting that variant Rh on donor cells may also stimulate alloimmunization to these antigens. DISCUSSION: These results highlight variability in alloimmunization rates and suggest that a molecular approach to Rh antigen matching may be necessary for optimal prevention of alloimmunization given the high prevalence of variant RH alleles among both patients and Black donors.

Successful Heart Transplantation Despite Rhesus Blood Type Mismatch: A Case Report.

Matching for the rhesus (Rh) blood group is currently not taken into account in the organ allocation system. However, in Rh-mismatched transplantation, the primary concern is the potential for RhD-negative recipients to develop sensitization and produce anti-D anti-bodies if they receive a transfusion of RhD-positive blood. It is estimated that over 80% of RhD-negative recipients may experience Rh allosensitization when exposed to RhD-positive blood, although this occurrence is less common in recipients of solid organs. In theory, RhD-negative recipients who receive organs from RhD-positive donors are at risk of alloimmunization and the production of anti-D antibodies, which could complicate future blood product transfusions. However, our understanding of the impact of donor-recipient Rh mismatch on transplant outcomes, particularly in heart transplantation, is limited. We report a case of successful Rh-mismatched heart transplantation, which was effectively managed through the use of preoperative RhD immunoglobulin and plasmapheresis.

Link between human ABO blood groups with diseases influencing blood donors and recipients frequency at RBTC, Delhi, India.

Blood groups had associations with many diseases that affect blood transfusion services by increasing or decreasing the blood demand of particular blood group. The present study was designed to compare the frequency of ABO and Rh blood groups among blood donors and blood component recipients. The ABO and Rh(D) blood groups of donors and recipients were determined using Gel card method. The frequency of blood donors and blood component recipients from January 1, 2020, to December 31, 2023, at regional blood transfusion centre of Delhi, were compared using χ² test. The ABO blood group frequencies of blood donors (n=23025) were: A(23.1%), B(37.53%), AB(10.09%), and O(29.29%). The blood issue (n=20255) was significantly (p=0.0000) higher in A(24.96%), B(39.92%), and lower in AB(9.76%) and O(25.37%). The RDP issue (n=7239) was significantly (p=0.0000) higher in A(24.71%), B(39.34%), and AB(11.53%) and lower in O(24.41%). The FFP issue (n=4164) was significantly (p=0.00024) higher in AB (12.3%) and lower in A (22.05%), B(37.32%), and O(28.14%). The difference between the blood donor frequencies of Rh(D)+Ve(95.19%) and Rh(D)-Ve(4.81%) and the blood issued by Rh(D)+Ve(95.06%) and Rh(D)-Ve(4.94%) was statistically not significant(P=0.52).Blood issues were higher in blood group A and B than in O, platelet issues were higher in A, B and AB than in O, and FFP issues were higher in the AB. Non-O blood groups may have a higher frequency of blood transfusions, while O blood groups may have a protective influence against diseases due to their innate immune response.

Anti-D alloimmunization by Asia type DEL red blood cell units in a D-negative Thai patient.

BACKGROUND: DEL phenotype is a rare Rh variant that cannot be detected by routine serological typing, and DEL individuals are thus typed D-negative (D-). Anti-D alloimmunization has been reported in "true" D- patients receiving DEL red blood cells (RBCs). CASE PRESENTATION: A 17-year-old, D- Thai male patient suffering from immunodeficiency syndrome with negative antibody screening received RBC units from 17 serological D- donors over a period of seven months due to acute respiratory failure with anemia. Before the 12th transfusion, anti-D production was detected. He was later transfused with RBCs from six other apparent D- donors. In order to elucidate anti-D production, all 17 blood donors were investigated by replicative serological testing and molecular analysis to identify potential RHD gene variants. All donors were confirmed D- by routine method, but as many as 12/17 were positive by adsorption-elution testing. Molecular analysis showed that five donors, including four whose blood was transfused before anti-D production occurred, carry the Asia type DEL allele, and are thus predicted to express a DEL phenotype. These data clearly suggest that 1/ the alloimmunized D- patient was exposed to D antigen, 2/ our adsorption-elution test is currently defective to identify DEL RBCs, and 3/ molecular analysis is highly valuable for Asia type DEL allele screening. CONCLUSION: For the first time in Thailand, we report anti-D alloimmunization in a serological D- patient transfused by Asia type DEL RBC units. This work definitely supports the implementation of a dedicated policy for DEL blood management including molecular testing.

[Molecular Mechanism of a Rhesus D Variant Individual with RHD*845A/1227A].

OBJECTIVE: To explore the genetic mutation mechanism of a rare Rhesus D variant individual. METHODS: Regular serological assay was used for determination of Rh type for the sample. Indirect anti-human globulin test (IAT) was used to confirm the RhD antigen and screen the antibodies. D-screen reagent was used to analyze the RhD epitopes of the sample. RHD genotype and RHD zygosity testing of the sample were detected by palymerase chain reaction with sequence-specific primers (PCR-SSP). The full length coding region of RHD gene was sequenced. RHD mRNA was detected using reverse transcription polymerase chain reaction (RT-PCR). The PCR products were cloned and sequenced. RESULTS: The RhD blood group of the sample was determined as weak D, and the Rh phenotype was CcDEe. The antibody screening was negative. The sample tested with all monoclonal anti-Ds in D-screen showed the D epitope profiles as partial D types. The analysis of RHD gene sequence indicated that the individual with RHD c.845G/A and RHD c.1227G/A base heterozygosis. Three kinds of alternative splicing isoforms were obtained by TA cloning and sequencing. CONCLUSION: The object has RHD c.845G/A and RHD c.1227G/A mutation. This heterozygous mutation is responsible for the low expression of RhD antigen on the red blood cells of the sample.

A novel nonsense variant in RHAG underlies a Nordic Rhnull phenotype.

BACKGROUND AND OBJECTIVES: The extremely rare Rhnull phenotype is characterized by the absence of all Rh antigens on erythrocytes. It is divided into the regulator and amorph types based on the underlying genetic background. The more common regulator type depends on critical variants silencing RHAG, which encodes RhAG glycoprotein, necessary for RhD/RhCE expression. Rhnull cells have altered expression of glycophorin B and LW glycoprotein. MATERIALS AND METHODS: Four unrelated Rhnull individuals were investigated. Serological testing was performed according to standard blood bank practice. RHD/RHCE and S/s allele-specific Polymerase chain reaction (PCR) genotyping was done on genomic DNA using in-house PCR assays. RHAG, and in some cases also RHD/RHCE, were sequenced. Initial s phenotyping results triggered additional serological investigation. RESULTS: Anti-Rh29 was identified in all four individuals. Extended typing with anti-S and anti-s showed that the three samples predicted to type as s+ failed to react with 2 of 5 anti-s. Sequence analysis of all 10 RHAG exons and the immediate intron/exon boundaries revealed a single nucleotide variant in the 3'-end of intron 6, c.946 -2a>g in all samples. RHD/RHCE showed no alterations. CONCLUSION: A novel Nordic Rhnull allele was identified. In addition, it was shown that s+ Rhnull red blood cells are not only U- but also have qualitative changes in their s antigen expression.

Infección por SARS-CoV-2 y grupos sanguíneos en pacientes cubanos diagnosticados con la COVID-19 / SARS-Cov-2 Infection and Blood Groups in Cuban Patients Diagnosed with COVID-19

Introducción: Diferentes estudios han propuesto la relación entre los grupos sanguíneos del sistema ABO y la susceptibilidad a la COVID-19 y su importancia en el curso de la enfermedad. Objetivo: Determinar la frecuencia fenotípica de grupos sanguíneos ABO y RhD en un grupo de pacientes con infección activa por SARS-CoV-2. Métodos: Se realizó un estudio descriptivo, transversal y caso control en el Hospital Docente Clínico Quirúrgico Freyre Andrade de La Habana, para determinar la frecuencia fenotípica ABO y RhD en un grupo de pacientes con enfermedad activa por la COVID-19. Se estudiaron 928 muestras de sangre de pacientes con diagnóstico de COVID-19 y 1050 muestras pertenecientes a individuos sanos como grupo control. El grupo sanguíneo ABO y RhD se determinó por método de aglutinación en tubo con sueros hemoclasificadores anti-A, anti-B, anti-A+B, yanti-D. Los resultados fueron expresados en frecuencias absolutas y relativas y se determinó la asociación del grupo sanguíneo con la gravedad de la enfermedad por medio de la prueba no paramétrica de χ2 con un nivel de significación de p ≤ 0,05. Resultados: Se observó predominio del fenotipo O (49,24 por ciento) seguido del A (35,79 por ciento), B (12,68 por ciento) y AB (2,27 por ciento) respectivamente. Los fenotipos O y B presentaron significación estadística para la ocurrencia de la COVID-19, con valores de p < 0,05. No se encontró significación estadística en cuanto al predominio de un fenotipo particular y la necesidad de cuidados intensivos. Conclusiones: La relación del grupo sanguíneo ABO en la infectividad por SARS-CoV-2 y la gravedad de la enfermedad por la COVID-19 requiere estudios adicionales ya que los actuales no son concluyentes(AU)

Introduction: Different studies have proposed the relationship between the blood groups of ABO system and the susceptibility to COVID-19 and its importance in the course of the disease. Objective: To determine the phenotypic frequency of ABO and RhD blood groups in a group of patients with active SARS-CoV-2 infection. Methods: A descriptive, cross-sectional, case-control study was conducted to determine the ABO and RhD phenotypic frequency in a group of patients with COVID-19 active disease. Nine hundred twenty eight blood samples and 1050 samples belonging to healthy individuals as control group were studied. The ABO and RhD blood group was determined by the tube agglutination method with anti-A, anti-B, anti-A+B, and anti-D blood classifying sera. The results were expressed in absolute and relative frequencies and the association of the blood group with the severity of the disease was determined by the non-parametric χ2 test with a significance level of p ≤ 0.05. Results: A predominance of phenotype O (49.24percent) was observed, followed by A (35.79percent), B (12.68percent) and AB (2.27percent) respectively. The O and B phenotypes showed statistical significance for the occurrence of COVID-19, with p values < 0.05. No statistical significance was found regarding the prevalence of a particular phenotype and the need for intensive care. Conclusions: The relationship of the ABO blood group in the infectivity of SARS-CoV-2 and the severity of the disease by COVID-19 requires additional studies, since the current ones are not conclusive(AU)

An Observational Study to Analyse the Association of the ABO and Rh Blood Group Systems With Bronchial Asthma.

Background ABO blood group types are hereditary factors that have been shown to affect the blood levels of many antigens and proteins. Some blood groups have surprisingly been shown to be associated with some specific diseases, probably due to yet unexplained altering effects on the immune system or on the levels of other system-specific proteins. Studies conducted previously attempting to relate bronchial asthma and blood groups have had variable results and such studies on a large scale have not been ventured in India. Hence, the significance of the current study, which aims to search for an increased occurrence of bronchial asthma in any one of the ABO blood group phenotypes and additionally in Rh blood groups. Objective The objective of this study was to analyze the possible association of the ABO and Rh blood group types with bronchial asthma.  Methods This is an observational study with 475 bronchial asthma patients, and 2052 non-asthmatic individuals belonging to the same geographical zone. After obtaining informed consent, ABO and Rh Blood group testing was done on the study subjects using the hemagglutination method. Chi-squared tests were employed for the comparison of proportions. Statistical significance was agreed upon for an error of 5%. Results The O blood group was predominant in both cases (46.9 %) and controls (36.1%). A chi-square analysis revealed a statistically significant higher percentage of O blood group in patients (χ2: 24.537; degrees of freedom (DF): 3; p-value = <0.01). The cases had more Rh -ve individuals (12%) than controls (8%), which too was statistically significant (χ2: 6.711; degrees of freedom (DF): 1; p-value = 0.01). Conclusion The present study shows a positive association between the O blood group and the Rh-negative blood group with bronchial asthma.

[Retrospective Analysis of Irregular Antibodies Causing Hemolytic Disease of the Fetus and Newborn in Jiangxi Province].

OBJECTIVE: To analyze the characteristics of antibody-specific distribution, laboratory detection results of hemolytic disease of the fetus and neonatal(HDFN) caused by irregular blood group antibodies other than ABO, and its correlation with the clinical situation. METHODS: The non-ABO-HDFN cases in our hospital from October 2012 to December 2021 were selected as the research objects, and the cases diagnosed with ABO-HDFN in the same period were randomly selected as the control group, and the data of antibody specific distribution, total bilirubin, direct antibodies, maternal history, age of the children, the presence or absence of combined ABO-HDFN, and whether to exchange/transfuse blood were retrospectively analyzed. The characteristics of non-ABO-HDFN in Jiangxi province were analyzed. RESULTS: The detection rate of non-ABO-HDFN in Jiangxi province increased. Among 187 non ABO-HDFN cases, the highest percentage of Rh-HDFN was detected (94.6%). Compared with the control group of ABO-HDFN, the non-ABO-HDFN had higher mean integral value of direct antibody, higher peak total bilirubin, and longer duration. Anti-M-HDFN may have severe disease but the direct antibody weak positive/negative, it was easy missed in clinical and delayed the treatment. There is no correlation between the specificity of irregular antibodies, the sex of the child, the mother's previous childbirth history, the presence or absence of combined ABO-HDFN and the need for blood exchange/transfusion(P>0.05). CONCLUSION: The irregular antibodies of causing non ABO-HDFN in Jiangxi area are mainly Rh blood group system, followed by MNS blood group system. Understanding the characteristics of HDFN disease, serological features and the correlation with clinical indexes will help to detect and treat non ABO-HDFN in time and reduce the risk of complications.

Molecular basis of RhD-negative phenotype in North Indian blood donor population.

Background & objectives: RHD gene typing is highly complex due to homology with RHCE genes. Molecular polymorphism of the RHCE and RHD genes have been characterized among various populations, but no studies have been undertaken among Indians. This study was undertaken to assess the genetic basis of RHD-negative phenotype in Indian blood donor population. Methods: Sample from a total of 200 phenotypically RhD-negative blood donors were analyzed for presence of RHD gene using polymerase chain reaction (PCR). RHD genotyping was done using three primer sets designed for exons 4 and 10 and one set for identification of pseudo (RHDΨ) gene between introns (int) 3 and 4. Amplified PCR products were analyzed by gel-electrophoresis (XY Loper, Uvitech, Cambridge) and confirmed by nucleotide sequencing (ABI 3730 xl 96 capillary system). Results: No PCR product was found in 195/200 (97.5%) of study samples indicating homozygous gene deletion. Of the 5/200 (2.5%) showing RHD gene polymorphisms, 4/200 (2%) were positive for presence of exon 10 only (RHD-CE-D hybrid). RHDΨ gene was not detected in any of the samples tested. One sample showed presence of all three tested regions and was negative for RHDΨ gene. Interpretation & conclusions: RHD gene deletion was found to be the most common cause of an RHD-negative phenotype while RHDΨ gene was, reported to be present in up to 39 per cent of various ethnic populations, but was not detected. RHD-CE-D hybrid gene (found in 2.5% individuals) is important for predicting the requirement of Rh prophylaxis during the antenatal period.

[Identification of Weak D Type 1 in Rh Blood Group System and Discussion of Transfusion Strategy].

OBJECTIVE: To investigate the molecular mechanism of one patient with abnormal serological phenotype in RhD and discuss the transfusion strategy. METHODS: The RhD variant sample was screened from a patient with IgM type anti-D antibody and further determined by three different sources of anti-D antibodies. Ten exons and the adjacent introns of the RHD gene were amplified, purified and sequenced. RhCE phenotypes and RHCE genotypes were detected. RESULTS: The patient with Rh variant showed abnormal results of serological tests. The RHD gene sequence analysis showed that the RHD*01W.01 with a variation (c.809T>G, p.Val270Gly) in exon 6 of the RHD gene was found in the patient. The RhCE phenotype was CcEe. The genotyping results of RHCE were consistent with the serological typing results. CONCLUSION: The Rh variant of the patient is RHD*01W.01, these findings indicate that RhD variants should be analyzed by molecular assays for the sake of safe transfusion.

Secondary alloanti-D immunization post transfusion of "Asia type" DEL red blood cells.

BACKGROUND: "Asia type" DEL red blood cells (RBCs) express a very weak D antigen and cannot be detected by routine RhD typing. Thus, it is routinely typed as D-negative (D-) blood group and transfused to D- recipients. Here we described a case of secondary alloanti-D immunization that was associated with transfusion of DEL RBCs to D- recipients and was initially considered as primary alloanti-D immunization. CASE PRESENTATION: A 44-year-old D- woman (G2P2) with adenomyosis and anemia underwent transabdominal hysterectomy. She received four units of D- RBCs before operation. Before transfusion, the alloantibody screening test was negative. Four days after the first transfusion, she needed another RBC transfusion. Unexpectedly, the routine pre-transfusion alloantibody screening test became positive and anti-D (titer, 128-fold) was identified, indicating an alloanti-D immunization. The anti-D developed four days after the first transfusion was unexplained, so alloantibody identification was performed on the sample collected before the first transfusion, and weak anti-D combined with anti-E, which was not detectable during the previous routine pre-transfusion alloantibody screening test with non-enzyme-treated screening cells, was identified using bromelain-treated panel cells. The remaining blood samples of first transfusion in bag tails from two donors were collected for RHD genotyping analysis. One donor was later identified as "Asia type" DEL having RHD* 1227 A/01 N.01 genotype. CONCLUSION: Caution should be applied when we conclude that transfusion of "Asia type" DEL RBCs to true D- recipients could induce primary alloanti-D immunization, especially if the short time interval between transfusion and detection of anti-D is observed.

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.