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Introduction: DEL is known to be one of the weakest D variants, which can be detected by the adsorption-elution technique or by molecular study. Currently, in Thailand, we do not routinely test for DEL variants serologically or genetically among serologic RhD-negative blood donors. Case Presentation: We reported 2 cases of alloimmunization after transfused with Rh DEL, RHD*DEL1 allele, in the Thai population. The first case was a 73-year-old male with anemia who presented with post-cardiac arrest and septic shock. The patient was group B, RhD-negative, and was transfused with RhD-negative red blood cells (RBCs). Antibody screening and identification found that the patient developed anti-D and anti-Mia during the admission course. The second case was a 38-year-old woman with pseudomyxoma peritonei who developed anti-D after receiving four units of RhD-negative RBCs during cytoreductive surgery with hyperthermic intraperitoneal chemotherapy. Both patients did not receive anti-D immunoglobulin and had no previous history of anti-D detection. We retrospectively investigated and found two units of RHD*DEL1 among the RBCs transfused to these patients. Discussion: Previous reports of several cases of anti-D alloimmunization in RhD-negative recipients transfused by RHD*DEL1, an Asian-type DEL, are limited only to East Asia. We first identified 2 patients with anti-D alloimmunization after receiving the RHD*DEL1 RBCs in the Thai population. This raises concern about Rh DEL screening among D-negative Thai blood donors and whether to remove DEL units from the D-negative inventory to improve patient safety. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: Exposure to normal or variably expressed RhD antigens in an antigen‐negative individual can elicit an immune response and lead to the formation of clinically significant anti‐D alloantibodies. We present the case of anti‐D alloimmunization by DEL variant missed in routine blood donor screening. Material and Methods: Blood donors were typed for D antigen using the direct serologic micromethod. Nonreactive samples were confirmed in the indirect antiglobulin method with an IgM/IgG anti‐D monoclonal reagent. Genomic DNA was extracted using a commercial QIAamp DNA Blood Mini kit on the QIAcube device (Qiaqen, Germany). RHD genotyping was performed using the PCR‐SSP genotyping kits‐ Ready Gene D weak, Ready Gene D weak screen, Ready Gene CDE, and Ready Gene D AddOn (Inno‐Train, Germany). Unidentified alleles were sent for DNA genome sequencing. Results: After identifying DEL positive blood units in RhD negative blood donor pool, a look‐back study was performed to determine if their previous donations caused alloimmunization in recipients. Out of 40 D negative recipients, one developed anti‐D alloantibody after 45 days. The patient did not receive other RhD positive blood products. Blood donor typed D negative in direct and indirect agglutination method. RHD screening was positive, but RHD genotyping and DNA sequencing showed no mutation indicating the normal genotype. Conclusion: Currently used methods in RHD genotyping are insufficient to identify many variant alleles, especially intronic variations. We suggest additional gene investigation including yet unexplored regions of regulation and intron regions to justify our serological finding. [ABSTRACT FROM AUTHOR]

Background: We evaluated different technological approaches and anti-D clones to propose the most appropriate serologic strategy in detecting the largest numbers of D variants in blood donors. Methods: We selected 101 samples from Brazilian blood donors with different expressions of D in our donor routine. The tests were performed in immediate spin (IS) with eleven commercially available anti-D reagents in a tube and microplate. The D confirmatory tests for the presence of weak D included the indirect antiglobulin test (IAT) in a tube, gel and solid-phase red blood cell adherence (SPRCA). All DNA samples were extracted from peripheral blood and the D variants were classified using different molecular assays. Results: The RHD variants identified by molecular analysis included weak D types (1, 2, 3, 11 and 38) and partial Ds (DAR1.2, DAR1, DAR3.1, DAU0, DAU2, DAU4, DAU5, DAU6, DMH and DVII). The monoclonal-monoclonal blend RUM-1/MS26 was the best anti-D reagent used in detecting the D antigen in the IS phase in a tube, reacting with 83.2% of the D variants, while the anti-D blend D175 + 415 was the best monoclonal antibody (MoAb) used in a microplate to minimize the need for an IAT, reacting with 83.2% of the D variants. The D confirmatory tests using SPRCA showed a reactivity (3 - 4+) with 100% of the D variant samples tested. Conclusion: Our results show that, even using sensitive methods and MoAbs to ensure the accurate assignment of the D antigen, at least 17% of our donor samples need a confirmatory D test in order to avoid alloimmunization in D-negative patients.

Background: The D antigen is a subset of Rh blood group antigens involved in the hemolytic disease of the newborn [HDFN] and hemolytic transfusion reaction [HTR]. The hybrid Rhesus box that was created after RH gene deletion, was known as a mechanism of the Rh-negative phenotype. Hybrid marker identification is used to confirm the deletion of the RHD gene and to determine zygosity. This study aims to detect this marker in Rh-negative and weak D phenotype blood donors of the southeast of Iran. Materials and Methods: The molecular analysis of the hybrid Rhesus box was performed on the 200 Rh-negative blood donors in Sistan and Baluchestan province, southeast Iran. The presence of alleles responsible for the D variants was assessed by DNA sequencing in 26 weak D phenotype donors. Results: Of the 200 Rh-negative blood samples, 198 samples were homozygous (99%), and two samples were heterozygous (1%). Heterozygous samples had RHD*01N.73 allele and the RHD*01N.18 allele. Of the 26 samples with weak D phenotype, 16 partial DLO (61%), 4 partial DBT1 (15.3%), 2 partial DV type 2 (7.7%), 1 weak D type 1, 1 weak D type 4.2.3, 1weak D type 105 and 1 RHD (S103P) (4%) were determined. Conclusion: Since RHD gene deletion is the main mechanism of the Rh-negativity in Sistan and Baluchestan provinces, a hybrid Rhesus box marker can be used in resolving RhD typing discrepancies by RHD genotyping methods.

Objectives: The aim of this study was to determine RHESUS D GENE (RHD) allelic variants among Croatian D‐negative blood donors and compare our results with respective data from other European countries. Background: Altered or reduced D antigen expression can result in D variants, which can be mistyped and can lead to the alloimmunisation of the blood recipient. RHD genotyping can distinguish D variants: weak D, partial D and DEL, thus preventing alloimmunisation. Material/methods: A total of 6523 samples obtained from D‐negative Croatian donors were screened for the presence of RHD using the real‐time polymerase chain reaction (PCR) method. PCR‐SSP was performed for D variant genotyping by using commercial genotyping kits (Inno‐Train, Kronberg, Germany). Genomic DNA sequencing for all 10 exons of the RHD was performed when the genotyping kits failed to assign a D variant. Results: RHD molecular screening revealed 23 (0.35%) RHD‐PCR positive samples, all C/E positive, in decreasing frequency: 11 hybrid RHD‐CE (2‐9) D‐CE variants, 4 weak partial D type 11 and 2 weak D type 2. Six samples remained unresolved and were sequenced. For 12 of 23 samples (excluding large hybrids), an adsorption/elution of anti‐D serum was performed, confirming that all 12 were RhD+. The calculated frequency of clinically significant D alleles in RhD‐negative blood donors was 1:543 (0.18%) or 1:53 (1.89%) in C/E blood donors. Conclusion: Data on the significant frequency of D variants among serologically D‐negative blood donors in the north‐eastern region of Croatia could help in introducing RHD molecular screening of blood donors in a routine workflow. [ABSTRACT FROM AUTHOR]

Objective: To explore the molecular biology of D variant blood group with RHD*95A genotype and the genetic mechanism of its generation., Methods: A total of 6 samples from 3 generations of a family were analyzed. RHD blood group was identified by saline test tube and microcolumn gel card method. 10 exons of RHD gene were amplified by Polymerase Chain Reaction-Sequence Specific Primer (PCR-SSP) and analyzed by direct sequencing. Homology modeling was used to compare the structural differences between mutant RHD protein and wild-type RHD protein., Results: The proband was identified as D variant by serological identification, RHD gene sequencing directly detected a c. 95 c > A mutation in exon 1 that leads to encoding the 32-bit amino acids by threonine Thr (T) into aspartic acid Asn (N), the rest of the exon sequences were normal compared with the normal RHD*01 gene. In the family, the proband's father, grandmather and uncle were all carried the same RHD*95A allele. Protein modeling results suggested that the hydrogen chain connected to the 32nd amino acid residue was changed after p.T32N mutation, which affected the structural stability of RHD protein., Conclusion: The first genetic lineage of the RHD*95A gene was identified in a Chinese population. The c.95C>A mutation in RHD gene was found in the family, which resulted in reduced expression of RHD antigen and showed D variant, the mutation could be stably inheritable. Gene identification and protein structure analysis of D variant population is helpful to explore the molecular mechanism of its formation and ensure the safety of blood transfusion.

Anti-D (- RH1) of the Rh blood group system is clinically important as it causes haemolytic transfusion reactions and haemolytic disease of the fetus and newborn. Although most people are either D+ or D−, there is a plethora of D variants, often categorized as either weak D or partial D. These two types are inadequately defined and the dichotomy is potentially misleading. DVI is the D variant most commonly associated with anti-D production and UK guidelines recommend that patients are tested with anti-D reagents that do not react with DVI. Weak D types 1, 2, and 3 are seldom, if ever, associated with alloanti-D production, so a policy recommendation would be to treat patients with those D variants as D+, to preserve D− stocks, whereas patients with all other D variants would be treated as D−. All donors with D variant red cells, including DVI, should be treated as D+. [ABSTRACT FROM AUTHOR]

The D variant of encephalomyocarditis virus (EMCV-D) induces a diabetes mellitus-like disease in male SJL/J mice. Other inbred strains, while resistant to the diabetogenic effect, exhibit strikingly different responses to this virus. In these studies, infection of diabetes resistant C3H mice with the D variant produces massive acute pancreatitis with little apparent direct islet cell involvement. This exocrine tropism is not altered when C3H mice with an inherent macrophage defect are infected, and appears to be a gender-specific phenomenon, with female C3H mice resistant to this exocrine involvement. Long-term infection of both male and female C3H mice does not change their response to the virus. Castration of male C3H mice, using a protocol that has been reported to block the diabetogenic effect of this virus, does not alter the development of this acinar lesion. The B variant of EMCV does not induce acinar destruction, nor is it diabetogenic. However, preinfection with the B variant 3 days prior to infection with the D variant does protect against the development of the exocrine lesion. Coinfection with equal doses of the two variants also protects against this lesion, as does coinfection with a lower dose of B variant. Therefore, the host response that is generated against the B variant appears to be responsible for this protection from D variant exocrine destruction. Due to the short time frame, it is unlikely that this protection is the result of an antibody response. Rather, this data is more consistent with an interferon response generated against the B variant that would inhibit replication of the D variant. [ABSTRACT FROM AUTHOR]

Background: The D antigen is a subset of Rh blood group antigens involved in the hemolytic disease of the newborn [HDFN] and hemolytic transfusion reaction [HTR]. The hybrid Rhesus box that was created after RH gene deletion, was known as a mechanism of the Rh-negative phenotype. Hybrid marker identification is used to confirm the deletion of the RHD gene and to determine zygosity. This study aims to detect this marker in Rh-negative and weak D phenotype blood donors of the southeast of Iran. Materials and Methods: The molecular analysis of the hybrid Rhesus box was performed on the 200 Rh-negative blood donors in Sistan and Baluchestan province, southeast Iran. The presence of alleles responsible for the D variants was assessed by DNA sequencing in 26 weak D phenotype donors. Results: Of the 200 Rh-negative blood samples, 198 samples were homozygous (99%), and two samples were heterozygous (1%). Heterozygous samples had RHD*01N.73 allele and the RHD*01N.18 allele. Of the 26 samples with weak D phenotype, 16 partial DLO (61%), 4 partial DBT1 (15.3%), 2 partial DV type 2 (7.7%), 1 weak D type 1, 1 weak D type 4.2.3, 1weak D type 105 and 1 RHD (S103P) (4%) were determined. Conclusion: Since RHD gene deletion is the main mechanism of the Rh-negativity in Sistan and Baluchestan provinces, a hybrid Rhesus box marker can be used in resolving RhD typing discrepancies by RHD genotyping methods., (Copyright © 2021 Tehran University of Medical Sciences.)

Background: We evaluated different technological approaches and anti-D clones to propose the most appropriate serologic strategy in detecting the largest numbers of D variants in blood donors., Methods: We selected 101 samples from Brazilian blood donors with different expressions of D in our donor routine. The tests were performed in immediate spin (IS) with eleven commercially available anti-D reagents in a tube and microplate. The D confirmatory tests for the presence of weak D included the indirect antiglobulin test (IAT) in a tube, gel and solid-phase red blood cell adherence (SPRCA). All DNA samples were extracted from peripheral blood and the D variants were classified using different molecular assays., Results: The RHD variants identified by molecular analysis included weak D types (1, 2, 3, 11 and 38) and partial Ds (DAR1.2, DAR1, DAR3.1, DAU0, DAU2, DAU4, DAU5, DAU6, DMH and DVII). The monoclonal-monoclonal blend RUM-1/MS26 was the best anti-D reagent used in detecting the D antigen in the IS phase in a tube, reacting with 83.2% of the D variants, while the anti-D blend D175 + 415 was the best monoclonal antibody (MoAb) used in a microplate to minimize the need for an IAT, reacting with 83.2% of the D variants. The D confirmatory tests using SPRCA showed a reactivity (3 - 4+) with 100% of the D variant samples tested., Conclusion: Our results show that, even using sensitive methods and MoAbs to ensure the accurate assignment of the D antigen, at least 17% of our donor samples need a confirmatory D test in order to avoid alloimmunization in D-negative patients., (Copyright © 2019 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier Editora Ltda. All rights reserved.)