Rh Phenotype Research Articles

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

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. 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. 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.

Relation of Immune Thrombocytopenia and Blood Group: A Retrospective Single Center Study

Aim: Although blood group antigens were initially identified as erythrocyte surface antigens and their significance was mainly ascribed to serology, it soon became evident that these antigens are widely distributed in human tissues such as platelets. Immunthrombocytopenia (ITP) is a common autoimmune disorder characterized by a low platelet count. In our study, we investigated the relationship between ABO and Rhesus (Rh) blood groups and primary ITP.
 Material and Methods: A retrospective study was conducted at our center with 304 patients diagnosed with primary ITP and 491 blood donors.
 Results: ABO phenotype in patients group A, B, O, AB were 42.8%, 14.1%, 34.9%, 8.2%, respectively and 51.6%, 8.1%, 27.9%, 12.4% in the control group, respectively. Rh phenotype in patients group positive or negative 87.5%, 12.5 % respectively and 88.8%, 11.2% in the control group, respectively. A total of 304 patients with primary ITP, consisting of 203 (66.8%) females, and 101(33,2%) males were included in this study. The mean age was 49,5 ±18 years. There was no significant difference in the distribution of ABO blood types and Rh factor by gender (respectively p=0.176, p= 0.195).
 Conclusion: In our study, no significant difference was found between the blood group distribution in the population and the blood group distribution of patients diagnosed with primary ITP.

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

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. 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. 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. 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.

Impact of ABO/Rhesus (D, C, c, E, e) blood type on development of vascular complications in type 2 diabetes

Introduction: Many studies on type 2 diabetes had conflicting results about the prognostic importance of the ABO or Rhesus (Rh) D expression, and in this context, the other important types of Rh were never studied. Objective: The purpose of this study was to investigate whether ABO and Rh phenotype has an association with vascular complications in type 2 diabetes. Methods: 390 individuals were included in this study (194 were type 2 diabetic patients and 196 were healthy persons). 159 of diabetic patients were classified into two groups: group DC which included 98 diabetic patients with vascular complications, and group D which included 61 diabetic patients without vascular complications. A slide agglutination test was done to determine the ABO and Rh types. Results: While no difference was observed between the frequency of any ABO or Rh types between patients and healthy people, the frequency of A-type and each Rh+ type was higher in the DC group compared to the D group. In addition, the prevalence of the Rh DCceand Rh DcEphenotypes was higher in the DC group. Conclusion: Determining the phenotype of the Rhesus blood group may be a cheap and easy prognostic test for vascular complications development in type 2 diabetes.

ABO, Rh, and Kell Blood Group Antigen Frequencies among Pregnant Women in Sokoto, Nigeria.

Background: Blood group antigens have been used to evaluate ethnic diversity of human populations and they also play most important roles in pregnancy and blood transfusion. Knowledge of antigen frequencies is important to assess the risk of alloimmunization and to guide the probability of finding antigen-negative donor blood. This study was aimed at determining the frequencies of ABO, Rh and Kell blood group antigens phenotype among pregnant women. Materials and Methods: The study was cross sectional in nature conducted among 1,250 consecutively recruited pregnant women in the department of Obstetrics and Gynaecology, antenatal clinic in Sokoto from January 2020 to September 2020. The blood grouping were determined using standard tube techniques for ABO while column agglutination card was used for Rh C, E, c, e and Kell blood groups. The data were collected, and calculations were done to determine the frequencies of ABO, Rh, and Kell blood group antigens and chi square was used to determine statistical significance . Results: The distribution of the ABO blood group revealed that 48.5% were group O, 27.3% were group B, 19.4% were group A and 4.8% were group AB. Out the subjects investigated, 93.1%, 30.2%, 24.6% , 90.2% and 97.6%were RhD, RhC, RhE, Rhc and Rhe positive respectively while 2.4% were Kell positive while 97.6% were Kell negative. ABO antigens has statistically significant correlation with Kell antigens. Conclusion: There is phenotypic variability of ABO and Rh blood group antigens with low prevalence of Kell antigen that has statistical relationship with ABO antigen. Incorporation of blood group phenotyping as premarital screening may reduce the prevalence of alloantibody formation.

Clinically significant minor blood group antigens amongst South Indian donor population

Background and objectives: Distribution of blood group antigen varies among different races. It is important to know the distribution of these antigens so as to provide a donor database that aid in providing compatible blood units for patients with multiple alloantibodies. The present study was conducted to determine the distribution of clinically significant minor blood group antigens amongst the South Indian blood donors. Materials and methods: Blood samples were collected from healthy regular repeat voluntary blood donors of same ethnicity attending a tertiary care hospital in South Kerala. Clinically significant blood antigens of the ABO, Rh (D, C, c, E, and e), Kell, Duffy and Kidd blood group systems were determined. The ABO and Rh(D) grouping were performed by tube technique using monoclonal antisera. Column agglutination technique was used to phenotype Rh, Kell, Duffy and Kidd antigens. Results: Total 200 healthy repeat voluntary blood donors were enrolled in the study. Out of 200 donors, 92% were RhD positive. Among the Rh antigens, the e antigen was positive in 97.8 % and 100% among the Rh(D) positive and Rh(D) negative donors respectively. No E antigen was detected in RhD negative donors. Total 6 and 2 Rh phenotypes were observed among the Rh(D) positive and negative donors respectively. R1R1 and Rr were the most frequent phenotypes among the RhD positive and negative donors (47.28% and 93.75%) respectively. Among the Kell blood group antigens, K and Kpb antigens were present in 100% of our donors while in Duffy and Kidd system Fya and Jka were most predominant (89% and 87%) respectively. Conclusions: The findings of the present study would be helpful in developing in-house panel cells. Moreover, a rare donor registry of donors typed negative for a high-frequency antigen can be formulated. IMC J Med Sci. 2024; 18(1):004. DOI: https://doi.org/10.55010/imcjms.18.004 *Correspondence: Soonam John, Department of Transfusion Medicine, Government Medical College, Parippally, Kollam, Kerala,India. Email: johnsoonam@gmail.com

Polyagglutinability phenomenon: a case report and review of the literature

BackgroundPolyagglutinability of red blood cells is a rare immunological phenomenon, it is due to a cryptic antigen that is abnormally present on the surface of red blood cells. The aim of our work is to shed light on polyagglutinability, which is still poorly understood cause of discordance between the cell and serum tests and can sometimes have harmful transfusion consequences.Case presentationWe report the case of a 70-year-old African patient admitted for management of hemolytic anemia.ResultsDuring the erythrocyte grouping, a discordance between the cell and serum tests was observed, with polyagglutinability for the RH phenotype, a positive AB control, and even a positive control. The direct antiglobulin test and the Coombs test were also positive. The same results were obtained even after washing the red blood cells and incubating them at 37 °C for 30 min. For transfusion purposes, erythrocyte genotyping was performed, and the patient was transfused with an A+ red blood cell unit with an RH Kell-compatible phenotype.ConclusionPolyagglutinability should always be taken into account when grouping anomalies are encountered. Although it may not show any symptoms, hemolysis is frequently observed during transfusions.

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

To explore the genetic mutation mechanism of a rare Rhesus D variant individual. 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. 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. 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.

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.

The Pattern of Rh Phenotype among Voluntary Blood Donors – A Single-Center Observation from North India

Background: Human blood is precious and its availability and requirement are important elements of a comprehensive health-care delivery. Healthy voluntary donors are key sources to maintain the supply of human blood, and due care is warranted to ensure that the right blood reaches the right patient. Blood donor screening is standard practice, and the knowledge of ABO and Rh phenotype study is important. Prevalence and pattern of Rh phenotypes in a particular area may be important for various functioning of any blood bank. Materials and Method: Various centers frequently showcase prevalence pattern of Rh phenotype at a specified centre or region. A similar study was undertaken from collected data of voluntary blood donors in our tertiary care center. Results: Out of 2000 donor samples, B, A, O, and AB were in the decreasing order of frequency with 33.3%, 29.6%, 25.7%, and 11.4%, respectively. The most common Rh antigens observed were e (97.1%), followed by D (93.8%), C (88.45%), c (51.05%), and E (18.45%). Out of eight phenotypes in D-positive donors, R1R1 (DCCee), R1r (DCcee), and R1R2 (DCcEe) were most frequently observed. In D-negative donors, rr (ddccee), r’r (ddCcee), and r’r’ (CCddee) were the most common. Conclusion: The Rh phenotype pattern in our centre had diverse pattern and knowledge of this would guide further studies.

RHD Gene Analysis of A Blood Donor with Del Phenotype

To analyze the RHD genotype of a blood donor with Del phenotype in Yunnan. Rh serological phenotype was identified. RHD gene was detected by PCR-SSP typing, and its 10 exons were sequenced. Exon 9 was amplified for sequencing and analysis. RHD zygosity was detected. The Rh phenotype of this specimen was CcDelee. Genomic DNA exhibited a 1 003 bp deletion spanning from intron 8, across exon 9 into intron 9. The deletion breakpoints occurred between two 7-bp short tandem repeat sequences. There was no variation in the sequences of the remaining exons. The Rh hybridization box test showed that there was one RHD negative allele. This specimen is Del type caused by deletion of RHD exon 9.

Primary Aldosteronism and Drug Resistant Hypertension: A "Chicken-Egg" Story.

Drug-resistant arterial hypertension (RH) is a major risk factor for cardiovascular disease, often due to overlooked underlying causes. Identification of such causes poses significant clinical challenges. In this setting, primary aldosteronism (PA) is a frequent cause of RH and its prevalence in RH patients is likely higher than 20%.The pathophysiological link between PA and the development and maintenance of RH involves target organ damage and the cellular and extracellular effects of aldosterone excess that promote pro-inflammatory and pro-fibrotic changes in the kidney and vasculature.The feasibility of adrenal vein sampling in PA patients with RH, and the clinical benefit achieved by adrenalectomy, further emphasize the need to implement systematic screening for this common form of secondary hypertension in the management of a high-risk population as RH patients.: We herein review the current knowledge of the factors that contribute to the RH phenotype with a focus on PA and discuss the issues regarding the screening for PA in this setting and the therapeutic approaches (surgical and medical) aimed at resolving RH caused by PA.

Extended red blood cell antigens and phenotypes in Burkina Faso: potential issues to design local population-sourced red blood cell reagent panels.

To date, 43 blood group systems with 349 red blood cell (RBC) antigens have been recognized. The study of their distribution is useful for blood services to improve their supply strategies for providing blood of rare phenotypes, but also to design indigenous RBC panels for alloantibody screening and identification. In Burkina Faso, the distribution of extended blood group antigens is not known. This study aimed to investigate the extended profiles of blood group antigens and phenotypes of this population and to raise limitations and potential strategies for the design of local RBC panels. We conducted a cross-sectional study that included group O blood donors. Extended phenotyping for antigens in the Rh, Kell, Kidd, Duffy, Lewis, MNS, and P1PK systems was performed using the conventional serologic tube technique. The prevalence of each antigen and phenotype combination was determined. A total of 763 blood donors were included. The majority were positive for D, c, e, and k and negative for Fya and Fyb. The prevalence of K, Fya, Fyb, and Cw was less than 5 percent. The most frequent Rh phenotype was Dce, and the most common probable haplotype was R0R0 (69.5%). For the other blood group systems, the K-k+ (99.4%), M+N+S+s- (43.4%), and Fy(a-b-) (98.8%) phenotypes were the most frequent. Antigenic polymorphism of blood group systems by ethnicity and geography argues for the design and evaluation of population-sourced RBC panels to meet specific antibody profiles. However, some of the specificities identified in our study, such as the rarity of double-dose antigen profiles for certain antigens and the cost of antigen phenotyping tests, are major challenges to overcome.

Hybrids and microconversions in RH genes: investigation and implication in transfusion therapy

: The discovery and characterization of the RH genes, i.e., RHD and RHCE, in the early 90s have been milestones in the field of blood group genetics. In addition to the single nucleotide variants (SNVs), which are commonly considered as the predominant molecular actors resulting in the variability of antigen expression, genetic exchange between both RH genes has been shown to be a frequent mutational mechanism. Indeed, dozens of hybrid alleles and microconversions associated with variant RH phenotype have been reported so far. Interestingly, these alleles display population-specific patterns of distribution. Also, they are directly involved in the qualitative and quantitative alteration of RH antigen expression, which has immediate consequences for diagnostics and transfusion management. Overall, hybrid alleles and microconversions contribute largely to the complexity of the RH blood group system. In the current state of knowledge, this narrative review: (I) defines and introduces the molecular determinants of the genetic exchange in the RH genes; (II) describes how these variant alleles may alter the expression of polymorphic and high-frequency antigens (HFAs) and/or result in the expression of low-frequency antigens (LFAs); (III) reports on their distribution at a low-resolution population scale; and (IV) discusses their relevance and identification in routine clinical practice for transfusion management at the laboratory level.

Evaluation of the immuno-hematological qualification of the blood donation at the Avicenne military hospital in Marrakech

Blood transfusion is a therapeutic act that consists of administering blood, or one of its cellular or plasma components, from one or more healthy subjects called "donors" to a sick subject called "recipient. Transfusion safety is ensured by controlling all stages of the transfusion chain, from the collection of blood, its preparation and biological qualification, to the performance of the transfusion act and even the follow-up of the recipients. The basis of immunohematological safety is the compatibility between the erythrocyte characteristics of the donor and those of the recipient. Donation Biological Qualification (DQ) laboratories have a duty and an obligation to ensure maximum reliability and sensitivity of results. They must therefore put in place the human, technical, material, computer and organizational resources, method validation, traceability of operations and risk analysis of all stages of the analysis process, to guarantee reliable results obtained in a timeframe compatible with the optimal use of the blood products. Thus, the work methodology within the immunohematology laboratory must be structured in procedures and operating modes in order to respect the standards of the reference system and to reduce the causes of errors to a minimum. Our work focused on the evaluation of the immunohematological qualification of blood donations within the blood transfusion center (CTS) at the Avicenne military hospital (HMA) in Marrakech, including the state of the premises, personnel and techniques used in the QBD service with the following goals · Review the level of qualification within the CTS of HMA. · To highlight the techniques of immunohematological qualification of blood donation per-formed at the CTS at the Avicenne Military Hospital in Marrakech compared to what is done nationally and internationally. · To draw the phenotypic profile of ABO, RHD and Kell blood groups in a representative population of donors from the city of Marrakech and regions, recruited over a period of 5 years. · The study of the prevalence of phenotypic markers, blood donations collected in the blood transfusion center of the HMA in Marrakech between the years 2016-2017-2017-2018-2019-2020, led to the following results: · For the ABO system, group O is the most frequent (50.47%), followed by group A (30.14%), then group B (15.45%) and lastly group AB (3.93%). · The standard Rhesus system (D); the Rh positive phenotype (D+) predominates largely (89.21%) while the Rh negative (D-) is about 10.79%. · Of the 7713 donations studied, only 3130 were used to study the prevalence of Rh phenotypes. For the remaining 4583 donations, phenotyping was not performed because of a stockout of gel cards. The Ccee phenotype is the most frequent (40.31%). · For the Kell system, the prevalence of K anti-gen was 8.17%. · For the IAT: no IAT was positive in the donors. · In our series, there was no return of the incident report form (IRF) and no traceability of the number of adverse transfusion reactions (ADR). This study allowed us to highlight several shortcomings concerning · The lack of trained personnel · Insufficient techniques in terms of precision, sensitivity and specificity · The lack of high level technical automatons · Occasional reagent stockouts due to supply delays. However, the transfusion system of the Avicenne Military Hospital of Marrakech (HMA) is still lacking in new techniques that have proven their worth in the development of this field; namely · HLA histocompatibility typing. · The research of antiplatelet antibodies: HPA; · Molecular biology: by gene amplification (PCR) from genomic DNA, in particular when hemagglutination shows its limits in the con-text of transfusion medicine. In the light of this work, a list of recommendations has been proposed in order to overcome these dysfunctions and to ensure a better immunohematological safety, in front of the various situations envisaged during the daily practice by reinforcing the operational and technical capacities of the blood transfusion service. Furthermore, the improvement of automation and computerization will reduce the risk of human error, by automatically handling certain phases of the process. However, whatever the degree of automation safety, its quality is strictly linked to the pre-analytical phase of sample collection, sample acceptability and collection information entry, for which particular attention should be paid.

Association between ABO blood group and COVID-19-positive patients in institutional-based hospital, Coimbatore – A cross-sectional study

Objective: The novel coronavirus disease (COVID-19) has spread globally and caused 6.5 million death as of October 2022. Risk factors for COVID-19 morbidity and mortality include age, sex, smoking, hypertension, cardiovascular disorders, respiratory disease, and diabetes mellitus. Association between ABO blood groups and number of other infections or disease severity following infections such as SARS-COV-1 and hepatitis B virus has been reported. Rh(D) phenotype (positive and negative Rh blood types) is associated with very few diseases compared to ABO blood group. Various articles have reported the association of ABO blood group and COVID-19. Our aim was to investigate if any association exists in between ABO blood group with Rh phenotype and COVID-19 infection in Coimbatore and with the result an awareness among the public should be created to hasten the preventive measure from further encounter of the infection and help the government in taking a proactive approach to fight COVID-19 in the area. Thus, we conducted a study to find out the association between ABO blood group and COVID-19-positive (SARS-COV-2) patients in institutional-based hospital – Coimbatore which was one of the most affected districts in Tamil Nadu. Materials and Methods: This is a single-center, retrospective, observational, and cross-sectional study conducted in a private institutional-based hospital in Coimbatore. The data were collected from around 437 patients’ medical records, who were tested COVID-19-positive between October 2020 and November 2021 whose blood grouping was available as part of investigation. Data were analyzed statistically to correlate the association of ABO blood group, Rh phenotype, and COVID-19 infection. Results: In 437 COVID-19-infected patients, the ABO blood group displayed a percentage distribution for A, B, AB, and O at 19% (83), 35% (153), 8.5% (37), and 37.5% (164), respectively and 409 (93.6%) were Rh +ve. Among the patients, blood group O 164 (37.5%), followed by blood group B153 (35%) is observed to be significantly associated with COVID-19 susceptibility, whereas blood group A83 (19%) and AB 37(8.5%) showed lower susceptibility for COVID-19 infection. Conclusion: This study did not show any statistically significant association of ABO blood group and Rh phenotype seen in relation to COVID-19 infection.

Extended red blood cell phenotyping among regular donors in Fayoum, Egypt. Red Blood Cell Inventory Plan

Abstract Background Antibodies to clinically significant red cell antigens contribute to hemolytic transfusion reactions and hemolytic disease of fetus and newborn. The aim of the study was to estimate the prevalence of extended red cell antigen phenotypes among regular donors in Fayoum, Egypt, and to create an emergency model database for chronic transfusion patients. Similar data in Egypt is rare to find in the literature. Patients and methods The study was carried out over 1 year from December 2020 until November 2021in Fayoum University Hospital Blood Bank. In all, 1834 healthy known blood donor samples were analyzed for major Rh phenotypes (D, C, c, E, e) and for other clinically significant systems including Kell, Kidd, MNS, and Duffy. Results Phenotypic frequencies of Rh system were D+ (84.4%), e+ (79.6%), and C+ (63.9%). The K antigen frequency was 4.3%, Jka 79.4%, Jkb 62.37%, Fy a 33.2%, Fy b 44.4%, M antigen 88%, N antigen 38.6%, and the S and s antigens 48.2 and 85.3%, respectively. Conclusion Determination of red cell antigen phenotyping in Fayoum, Egypt, plays an important role in setting a routine phenotyping strategy for multiple transfused patients by keeping the donor database for rare phenotypes to prevent hemolytic transfusion reaction.

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

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. 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). 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. 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.

Rare Blood Groups in ABO, Rh, Kell Systems - Biological and Clinical Significance.

Background: The frequency of ABO, Rh and Kell blood group antigens differs among populations of different ethnic ancestry. There are low-frequency antigens (<1%) and high-frequency antigens (>90%). A rare blood group is defined as the absence of a high-frequency antigen in the general population, as well as absence of multiple frequent antigens within a single or multiple blood group systems. Aim: To perform red blood cell typing and to calculate the antigen and phenotype frequencies, in order to identify rare blood group donors within the clinically most important АВО, Rh and Kell systems. Material and Methods: АВО, Rh (D, C, E, c, e) and Kell (K) antigen typing was performed using specific monoclonal sera and microplate technique, while Cellano (k) typing was performed with a monoclonal anti-k, antihuman globulin and column agglutination technique. Weak ABO subgroups were determined using the absorption elution method or molecular genotyping (PCR-SSP). Results: ABO antigen frequency is: A (40.89%), O (34.22%), B (16.97%), AB (7.92%) and weak ABO subgroups (0, 009 %). The established genotypes were AxO1 (0, 0026%) and AxB (0, 001%). Rh antigen frequency is: D (85.79%), C (71.7%), c (76.0%), E (26.0%) and е (97.95%). The most common Rh pheno-type is the DCcee (32.7%) while the rarest phenotype is the DCCEE phenotype (0. 003%). The prevalence of K and k antigen is 7.5% and 99.94%, respectively. The frequency of the rare phenotype K+k- is 0.06%. Conclusion: Large scale phenotyping of blood group antigens enables the identification of blood donors with rare blood groups for patients with rare phenotypes or with antibodies to high-frequency antigens and to frequent antigens within one or more blood group systems.

Is the Development of Gestational Diabetes Associated With the ABO Blood Group/Rhesus Phenotype?

AimsThere are few published data on the putative association between the ABO blood group/rhesus (Rh) factor and the risk of developing gestational diabetes mellitus (GDM). Our aim was to explore the link between each one factor and GDM development.MethodsAll women having given birth at Lille University Medical Center (Lille, France) between August 1st, 2017, and February 28th, 2018, were tested for GDM, using the method recommended in the French national guidelines. The risk of GDM was assessed for each ABO blood group, each Rh phenotype and combinations thereof, using logistic regression models.Results1194 women had at least one GDM risk factor. The percentage of GDM varied with the ABO group (p=0.013). Relative to group O women, group AB women were more likely to develop GDM (OR = 2.50, 95% CI [1.43 to 4.36], p=0.001). Compared with the Rh-positive O group, only the Rh-positive AB group had an elevated risk of developing GDM (OR = 3.02, 95% CI [1.69 to 5.39], p < 0.001).ConclusionsOur results showed that Rh-positive group AB women have a greater risk of GDM. With a view to preventing GDM, at-risk individuals could be identified by considering the ABO blood group phenotype either as a single risk factor or in combination with other risk factors.