Blood Group Genotyping Research Articles

Age at cancer diagnosis, non-O blood group and asparaginase therapy are independently associated with deep venous thrombosis in pediatric oncology patients: A risk model

IntroductionPediatric oncology patients are at increased risk for deep venous thrombosis (DVT). Determining the sub-population of children at increased DVT risk is critical for optimum clinical management. Therefore, the aim of the current study was to identify clinical risk factors for DVT which are easily identifiable at cancer diagnosis. Materials and methodsA Canadian multicenter case control study in survivors of childhood cancer. Survivors who had DVT (Cases) while being treated for pediatric cancer where matched by center with a minimum of two survivors who did not experience DVT (Controls). Clinical information including age at diagnosis, type of cancer and chemotherapy were collected. Genotyping of blood group was done by single nucleotide polymorphisms analysis. Results218 subjects were recruited at 4 Canadian pediatric centers. Multivariable analysis demonstrated 3 significant variables (reported as Odds Ratio (OR), (95% CI), p value): age at diagnosis p<0.001, non-O blood group OR 2.6 (1.3–5.2) p=0.005 and asparaginase treatment OR 2.4 (1.2–4.8) p=0.011. In order to optimise clinical utility, we reanalysed the study data with age at diagnosis categorised into four subgroups 0–≤2years, >2–≤7years, >7≤10years, >10years. A significant association with DVT were seen in children 0-≤2years (OR 3.1 (1.1–8.3) p=0.026) and >10years (OR 3.8, 1.7–8.5 p=0.001). Significant associations with DVT remained for non-O blood group, OR 2.2 (1.2–4.4) p=0.016 and asparaginase treatment, OR 2.1 (1.1–4.0) p=0.027. The value for the clinical risk model receiver operating characteristics curve was 0.67. ConclusionsWe have shown 3 independent risk factors for DVT in childhood cancer.

Distribution of ABO and Rh (D) allele frequency among the populations of Yilmana Denssa and Mecha, Ethiopia

&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Background:&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-US"&gt; The distributions of ABO blood group and Rh (D) factor is important for population distribution and genetics studies in multi-ethnic countries. Such studies are not completely covered the parts of Ethiopia, a country with multi ethnic groups. Therefore, this study is designed to decipher the population blood group distribution frequency in the population of West Gojam.&lt;/span&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Methods:&lt;/span&gt;&lt;/strong&gt;A total of 200 Volunteer individuals were participated in this study as a study subject to determine blood group in the study population by the antigen-antibody agglutination test. The results of tests were subjected to allelic frequency distribution calculation using Panmictic index.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Results:&lt;/span&gt;&lt;/strong&gt;&lt;span lang="EN-US"&gt; The total of the two sites had O (r=0.624), A (p=0.2299) and B (q=0.1456) of allele frequency and the genotypic frequency were AA (p2=0.05285), AO (2pr=0.287), BB (q2=0.0212), BO (2qr=0.1818), AB (2pq=0.0669) and OO (r2=0.39). Out of the tested samples 91%, was recorded Rh+ in the same population, with frequency of 0.7 for allele D confirming the majority of the population in this area as Rh+. Fixation indices (F) for ABO gene were 17 and 22 Yilmana Denssa and Mecha respectively which was higher in Ylmana Denssa.&lt;/span&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;&lt;span lang="EN-US"&gt;Conclusions:&lt;/span&gt;&lt;/strong&gt;The Panmictic index (P)was 78 lower than Mecha site for ABO gene and the observed heterozygosity (Ho) for ABO gene was 0.53 indicating large genetic variations in populations of the study area. Therefore, the findings of this study can be used as a baseline for the genetic diversity of the study area as a reference for Ethiopian ABO blood group phenotypes and genotypes studies.&lt;/p&gt;

The A0 blood group genotype modifies the jejunal glycomic binding pattern profile of piglets early associated with a simple or complex microbiota.

The intestinal epithelium glycocalyx sugar motif is an important determinant of the bacterial-host interaction and may be affected in pigs by gut microbiota and by blood group genotype. The aim was to study the effect of intestinal association with different microbiota and A0 blood group genotypes on the expressed glycomic pattern in the small intestine. Twelve caesarean-derived pigs previously associated with a simple association (SA) or complex association (CA) microbiota were selected at 26 to 37 d of age. In each subject, different jejunal loops were perfused for 8 h with enterotoxigenic K88 (ETEC), ETEC fimbriae (F4), (LAM), or a saline control. The piglets were genotyped for A0 blood group and the glycomic profile was evaluated by microscopic screening of lectin binding: peanut agglutinin (PNA), which is galactose specific; agglutinin I (UEA), which is fucose specific; lectin II (MALii), which is sialic acid specific; concavalin A, which is mannose specific; soybean agglutinin (SBA), which is -acetyl-galactosamine specific; and wheat germ agglutinin (WGA), which is -acetyl-glucosamine specific. A0 pigs had fewer UEA-positive cells, MALii-positive cells ( < 0.001), and SBA-positive cells ( < 0.10) than 00 pigs. Simple association pigs had more SBA positive cells ( < 0.01) than CA pigs. Enterotoxigenic K88-perfused intestinal loops had fewer UEA-positive cells ( < 0.01) and WGA positive cells ( < 0.001) cells and more PNA positive cells (only in SA pigs, < 0.01). No effects of introduction of F4 and LAM in the intestinal lumen were observed. The porcine A0 blood group genotype and the luminal presence of ETEC strongly affected the jejunal mucosa glycomic pattern profile whereas an early oral simple or complex microbial association had limited effects. Pig genetic background has relevance on the cross talk between intestinal epithelium glycocalyx sugar motif and ETEC and, ultimately, on the gut microbial colonization in later life.

Impact of antigenic exposures and role of molecular blood grouping in enhancing transfusion safety in chronically transfused thalassemics.

Background:Red cell alloimmunization is an acknowledged complication of blood transfusion. Current transfusion practices for thalassemia do not cater to this risk. Serological phenotyping is usually not reliable in these cases unless performed before the first transfusion. Under such circumstances, molecular blood grouping is an effective alternative.Aim:To perform molecular blood group genotyping in chronically transfused thalassemia patients and assess the risk of antigenic exposure and incidence of alloimmunization with current transfusion protocols.Materials and Methods:Molecular blood group genotyping was performed for 47 chronically transfused thalassemia patients. Their 1-year transfusion records were retrieved to assess the antigenic exposure and the frequency thereof.Results:Of 47 patients, 6 were already alloimmunized (3 with anti-E and 3 with anti-K) and were receiving the corresponding antigen negative units. We observed that random selection of ABO and Rh D matched units resulted in 57.7% ±8.26% chance of Rh and Kell phenotype matching also. Forty-four patients had received one or more antigenic exposures at least once. The 6 already alloimmunized patients were further exposed to antigens other than the ones they were immunized to. During the study period, only one patient developed an alloantibody, anti-E with exposure to antigens C (92%) and/or E (32%) at each transfusion.Conclusion:Several factors apart from mere antigen exposure may influence the development of alloimmunization as most of our patients received antigenic exposures but not alloimmunized. Our data provide an impetus for future large-scale studies to understand the development of alloimmunization in such patients.

Allelic variance among ABO blood group genotypes in a population from the western region of Saudi Arabia.

BackgroundCharacterization of the ABO blood group at the phenotype and genotype levels is clinically essential for transfusion, forensics, and population studies. This study elucidated ABO phenotypes and genotypes, and performed an evaluation of their distribution in individuals from the western region of Saudi Arabia.MethodsOne-hundred and seven samples underwent standard serological techniques for ABO blood group phenotype analysis. ABO alleles and genotypes were identified using multiplex polymerase chain reaction, and electrophoretic analysis was performed to evaluate the highly polymorphic ABO locus.ResultsA phenotype distribution of 37.4%, 30.8%, 24.3%, and 7.5% was found for blood groups O, A, B, and AB respectively in our study cohort. Genotype analysis identified 10 genotype combinations with the O01/O02 and A102/O02 genotypes being the most frequent with frequencies of 33.6% and 14.95%, respectively. Common genotypes such as A101/A101, A101/A102, A101/B101, B101/B101, and O01/O01 were not detected. Similarly, the rare genotypes, cis-AB01/O02, cis-AB01/O01, and cis-AB01/A102 were not found in our cohort. The most frequently observed allele was O02 (35.98%) followed by the A102 allele (17.76%). Furthermore, our findings are discussed in reference to ABO allele and genotype frequencies found in other ethnic groups.ConclusionThe study has a significant implication on the management of blood bank and transfusion services in Saudi Arabian patients.

Noninvasive fetal RHD genotyping from maternal plasma

Alloimmunization to antigens of Rh blood group system is of clinical relevance during pregnancy. Despite the use of antenatal anti-D immunoglobulin prophylaxis, some proportion of RhD-negative pregnant women still become immunized. RhD-negative pregnant women with a heterozygous partner can be reassured and managed less intensively if RhD-negative status of the fetus was confirmed. The conventional techniques used for prenatal testing of fetal RhD status are mainly invasive such as chorionic villus sampling, amniocentesis and cordocentesis, and carry risk of transplacental hemorrhage and pregnancy loss. The discovery of cell-free fetal DNA (cffDNA) in maternal plasma in 1997 has opened up new possibilities for noninvasive prenatal diagnosis. With the use of real time polymerase chain reaction technology, circulating fetal DNA has been detected robustly in the plasma of pregnant women, even in the first trimester of pregnancy. Various assays have been developed to confirm the fetal RHD status by targeting the cffDNA using a combination of multiple RHD exons. The commonly used exons are 4, 5, 7, and 10. Common causes leading to discordant results in fetal RHD typing are low fetal DNA concentration due to extraction inefficiency, lack of fetal DNA control, silent maternal RHD alleles, and manual error. False negative results can prove critical in case of alloimmunized pregnancies and hence use of appropriate controls and strict reporting criteria is important to increase the sensitivity of the assay. Owing to the wide genetic variation of the Rh blood group system, the development of fetal genotyping strategies according to ethnic origin of the patients would further increase the sensitivity. Fetal blood group genotyping by noninvasive method is safe, and numerous groups have reported fetal RHD genotyping in D-negative mothers with close to 100% accuracy. Noninvasive fetal RHD typing can be performed in RhD-negative alloimmunized and nonimmunized pregnancies to decide on clinical management and to restrict the anti-D immunoglobulin prophylaxis, respectively. Thus, the introduction of this test for screening all RHD-negative pregnant women is highly desirable.

The treatment of HCV in patients with haemoglobinopathy in Kurdistan Region, Iraq: a single centre experience.

Various variables that might influence the rapid and sustained virological response to recombinant PEG-IFN-α-2a were explored in Iraqi HCV-infected patients with haemoglobinopathy. Forty-three patients were evaluated for the relationship between rapid virological response (RVR), IL-28B polymorphism, viral load, liver enzyme levels, blood group, ultrasound findings, or HCV genotype and the sustained virological response (SVR) achievement. The overall RVR was 55·81% while the overall SVR was 53·49%. SVR in patients that achieved RVR was 82·61% (P = 0·0004). A significant association was found between initial alanine transaminase levels and viral load with SVR achievement (P = 0·025) and (P = 0·004), respectively. Thirty-two (74%) out of 43 of our samples were host genotyped at the IL-28B locus as CC, a significant association was found between CC group and SVR achievement (P = 0·04). Of our samples, 23/43 (53%) were typed as HCV genotype 4, 10/43 (23%) as genotype 1, 9/43 (20·9%) as genotype 3 and 1/43 (2·3%) as genotype 2. A significant association was found between genotype 3 and SVR achievement (P = 0·006). Multivariate analysis showed that only RVR achievement independently associated with SVR in the Iraqi population (P = 0·00). These results can be used to classify the patients requiring the more expensive new direct-acting antiviral drugs.

Development and Validation of a Fully Automated Platform for Extended Blood Group Genotyping

Thirty-five blood group systems, containing >300 antigens, are listed by the International Society of Blood Transfusion. Most of these antigens result from a single nucleotide polymorphism. Blood group typing is conventionally performed by serology. However, this technique has some limitations and cannot respond to the growing demand of blood products typed for a large number of antigens. The knowledge of the molecular basis of these red blood cell systems allowed the implementation of molecular biology methods in immunohematology laboratories. Here, we describe a blood group genotyping assay based on the use of TKL immobilization support and microarray-based HIFI technology that takes approximately 4 hours and 30 minutes from whole-blood samples to results analysis. Targets amplified by multiplex PCR were hybridized on the chip, and a revelation step allowed the simultaneous identification of up to 24 blood group antigens, leading to the determination of extended genotypes. Two panels of multiplex PCR were developed: Panel 1 (KEL1/2, KEL3/4; JK1/2; FY1/2; MNS1/2, MNS3/4, FY*Fy et FY*X) and Panel 2 (YT1/2; CO1/2; DO1/2, HY+, Jo(a+); LU1/2; DI1/2). We present the results of the evaluation of our platform on a panel of 583 and 190 blood donor samples for Panel 1 and 2, respectively. Good correlations (99% to 100%) with reference were obtained.

A model for integrating molecular-based testing in transfusion services.

Molecular-based laboratory tests can predict blood group antigens and supplement serological methods, adding a unique technology to assist in resolving discrepant or incomplete blood group typing or antibody identification. Hospital transfusion services have options for integrating molecular-based methods in their routine operations. We describe here the model of a hospital-reference laboratory partnership. Blood samples for compatibility testing were obtained from patients in a 609-bed hospital serving an urban multiethnic and multiracial population. When results of blood group phenotyping by serological methods were inconclusive, samples were referred for molecular-based testing. The reference laboratory used several methods for genotyping, including polymerase chain reaction followed by restriction enzyme-linked polymorphism analysis, sequence-specific primer polymerase chain reaction and array-based approaches. Human erythrocyte antigen, RHCE and RHD single nucleotide polymorphism arrays were integrated into the laboratory as they became commercially available. The hospital-reference laboratory model made it possible to integrate blood group genotyping promptly by current technology without the expense of new laboratory equipment or adding personnel with technical expertise. We describe ten cases that illustrate the categories of serological problems that were resolved by molecular methods. In-hospital molecular testing for transfusion services has logistical advantages, but is financially impractical for most hospitals. Our model demonstrates the advantages of a hospital-reference laboratory partnership. In conclusion, hospital transfusion services can integrate molecular-based testing in their routine services without delay by establishing a partnership with a molecular blood group reference laboratory. The hospital reference-laboratory model promotes genomic medicine without the expense of new equipment and skilled personnel, while supporting the economy of centralised large-scale laboratory operations.

Duffy blood group genotyping in Thai blood donors.

BackgroundDuffy (FY) blood group genotyping is important in transfusion medicine because Duffy alloantibodies are associated with delayed hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. In this study, FY allele frequencies in Thai blood donors were determined by in-house PCR with sequence-specific primers (PCR-SSP), and the probability of obtaining compatible blood for alloimmunized patients was assessed.MethodsFive hundred blood samples from Thai blood donors of the National Blood Centre, Thai Red Cross Society, were included. Only 200 samples were tested with anti-Fya and anti-Fyb using the gel technique. All 500 samples and four samples from a Guinea family with the Fy(a-b-) phenotype were genotyped by using PCR-SSP. Additionally, the probability of obtaining antigen-negative red blood cells (RBCs) for alloimmunized patients was calculated according to the estimated FY allele frequencies.ResultsThe FY phenotyping and genotyping results were in 100% concordance. The allele frequencies of FY*A and FY*B in 500 central Thais were 0.962 (962/1,000) and 0.038 (38/1,000), respectively. Although the Fy(a-b-) phenotype was not observed in this study, FY*BES/FY*BES was identified by PCR-SSP in the Guinea family and was confirmed by DNA sequencing.ConclusionsOur results confirm the high frequency of the FY*A allele in the Thai population, similar to that of Asian populations. At least 500 Thai blood donors are needed to obtain two units of antigen-negative RBCs for the Fy(a-b+) phenotype.

Determination of ABO blood group genotypes using the real‑time loop‑mediated isothermal amplification method.

ABO genotyping is commonly used in several situations, including blood transfusion, personal identification and disease detection. The present study developed a novel method for ABO genotyping, using loop-mediated isothermal amplification (LAMP). This method allows the simultaneous determination of six ABO genotypes under 40 min at a constant temperature of 62°C. The genotypes of 101 blood samples were determined to be AA (n=6), AO (n=38), BB (n=12), BO (n =29), AB (n=8) and OO (n=8) by the LAMP assay. The results were compared with the phenotypes determined by serological assay and the genotypes determined by direct sequencing, and no discrepancies were observed. This novel and rapid method, with good accuracy and reasonably cost effective, provides a supplement to routine serological ABO typing and may also be useful in other point-of-care testing.

Blood group genotyping: faster and more reliable identification of rare blood for transfusion

Blood group genotyping: faster and more reliable identification of rare blood for transfusion

ABO Blood Type and Personality Traits in Healthy Japanese Subjects.

There is no scientific consensus that a relationship exists between the ABO blood group and personality traits. However, a recent study hypothesized that the dopamine beta-hydroxylase (DBH) gene is in linkage with the ABO gene. The sample population consisted of 1,427 healthy Japanese subjects who completed the Temperament and Character Inventory (TCI). Each subject’s ABO blood type was determined by genotyping the rs8176719 and rs8176746 ABO gene single-nucleotide polymorphisms (SNPs) using a TaqMan genotyping assay. The relationships between the six ABO genotypes or four ABO phenotypes and personality traits were examined using a multivariate analysis of covariance (MANCOVA), controlling for age and sex. The MANCOVA data showed a significant difference in TCI scores among the ABO genotype groups (F [7, 1393] = 3.354, p = 0.001). A subsequent univariate analysis showed a significant difference in the mean scores for Persistence among the genotype groups (F = 2.680, partial η2 = 0.010, p = 0.020). Similarly, dividing the ABO blood type into four phenotypes revealed a significant difference among the phenotype groups (F [7, 1397] = 2.529, p = 0.014). A subsequent univariate analysis showed a significant difference among the phenotype groups in the mean scores for Persistence (F = 2.952, partial η2= 0.006, p = 0.032). We observed a significant association between ABO blood group genotypes and personality traits in a large number of healthy Japanese subjects. However, these results should be regarded as preliminary and should be interpreted with caution because it is possible that the association between ABO blood group genotype and the Persistence trait is relatively weak.

Molecular identification of rare FY*Null and FY*X alleles in Caucasian thalassemic family from Sardinia

Molecular genetic studies on Duffy blood group antigens have identified mutations underlying rare FY*Null and FY*X alleles. FY*Null has a high frequency in Blacks, especially from sub-Saharan Africa, while its frequency is not defined in Caucasians. FY*X allele, associated with Fy(a-b + w) phenotype, has a frequency of 2–3.5% in Caucasian people while it is absent in Blacks. During the project of extensive blood group genotyping in patients affected by hemoglobinopathies, we identified FY*X/FY*Null and FY*A/FY*Null genotypes in a Caucasian thalassemic family from Sardinia. We speculate on the frequency of FY*X and FY*Null alleles in Caucasian and Black people; further, we focused on the association of FY*X allele with weak Fyb antigen expression on red blood cells and its identification performing high sensitivity serological typing methods or genotyping.

A simple genotyping procedure without DNA extraction to identify rare blood donors.

Transfusion-induced alloimmunization has severe clinical consequences including haemolytic transfusion reactions, impaired transfused RBCs longevity and greater difficulty in finding compatible blood. Molecular analysis of genomic DNA now permits prediction of blood group phenotypes based on identification of single nucleotide polymorphisms. Implementation of molecular technologies in donor centres would be helpful in finding RBC units for special patient populations, but DNA extraction remains an obstacle to donor genotyping. We propose a simple method compatible with high throughput that allows blood group genotyping using a multiplex commercial kit without the need for DNA extraction. The principle relies on pre-PCR treatment of whole blood using heating/cooling procedure in association with a recombinant hotstart polymerase. In a prospective analysis, we yielded 5628 alleles identification and designated 63 donors with rare blood, that is either negative for a high-frequency antigen or with a rare combination of common antigens. The procedure was optimized for simplicity of use in genotyping platform and would allow not only to supply antigen-matched products to recipients but also to find rare phenotypes. This methodology could also be useful for establishing a donor repository for human platelet antigens (HPA)-matched platelets since the same issues are involved for patients with neonatal alloimmune thrombocytopenia or post-transfusion purpura.

Next‐generation sequencing: academic overkill or high‐resolution routine blood group genotyping?

Blood group genotyping (BGG) has been in routine clinical practice ever since the molecular determination of blood groups was achieved, during the early to mid 1990s. These early methods were dependent on allele‐specific PCR to detect simple single nucleotide polymorphisms (SNPs) responsible for blood group expression. As our knowledge regarding the molecular background of blood groups advanced, so did the numbers of SNPs requiring detection which necessitated the switch from allele‐specific PCR to array‐based technology, notably slide and bead‐based approaches. All these methods thus described are totally dependent on the predefined genetic basis of each SNP. Hybrid blood group genes (as found in RH, ABO and MNS systems) are difficult to define by all of these aforementioned techniques. With the arrival of cheap next‐generation sequencing (NGS) approaches in the past 5 years, we have conducted long‐range PCR (LR‐PCR) coupled with NGS determination of the major blood group genes. By analysis of these data using an Ion Torrent Personal Genome Machine™ (PGM™), it is readily apparent that NGS can highly effectively be applied with high resolution to blood grouping at costs no more than current array‐based platforms. However, the complexity of the data obtained need careful filtering for effective clinical utilization, but provides useful insight on the evolution of blood groups and their environmental impacts which will be of undoubted value as an academic exercise, but of minimal cost (if any) to the original testing.

Gene conversion events between GYPB and GYPE abolish expression of the S and s blood group antigens.

The locus specifying the MNS blood group system is composed of three highly homologous genes, glycophorin A (GYPA), B (GYPB) and E (GYPE). While more than 20 hybrid genes between GYPA and GYPB have been identified, no hybrid genes between GYPB and GYPE have been reported so far. We serendipitously identified GYPB-E-B hybrid genes by studying three individuals whose rare S-s- blood phenotype failed to be predicted by our genotyping platform. Long-range PCR amplification and extended Sanger sequencing were required to identify and characterize these GYPB-E-B hybrid genes. A PCR assay was developed to detect them in individual or pooled gDNA samples. The first S-s- proband appeared to have two silenced GYPB alleles, one harbouring the so-called P2 mutation and one harbouring GYPE Pseudoexon E4 in place of GYPB Exon B4 (GYPB-E-B hybrid). The two other S-s- probands were homozygous or hemizygous for other GYPB-E-B hybrid alleles, which also lack GYPB Exon B4 and thus do not carry the S/s polymorphism. The three GYPB-E-B hybrid genes reported here constitute the first evidence of recombination events between GYPB and GYPE. As these GYPB-E-B hybrid genes drive the S-s- blood phenotype, it is important to know they are a limitation for the current blood group genotyping methods, including those performed by commercial platforms.

Blood group genotyping: the power and limitations of the Hemo ID Panel and MassARRAY platform

Abstract Matrix-assisted laser desorption/ionization, time-of-flight mass spectrometry (MALDI-TOF MS), is a sensitive analytical method capable of resolving DNA fragments varying in mass by a single nucleotide. MALDI-TOF MS is applicable to blood group genotyping, as the majority of blood group antigens are encoded by single nucleotide polymorphisms. Blood group genotyping by MALDI-TOF MS can be performed using a panel (Hemo ID Blood Group Genotyping Panel, Agena Bioscience Inc., San Diego, CA) that is a set of genotyping assays that predict the phenotype for 101 antigens from 16 blood group systems. These assays involve three fundamental stages: multiplex target-specific polymerase chain reaction amplification, allele-specific single base primer extension, and MALDI-TOFMS analysis using the MassARRAY system. MALDI-TOF MS–based genotyping has many advantages over alternative methods including high throughput, high multiplex capability, flexibility and adaptability, and the high level of accuracy based on the direct detection method. Currently available platforms for MALDI-TOF MS–based genotyping are not without limitations, including high upfront instrumentation costs and the number of non-automated steps. The Hemo ID Blood Group Genotyping Panel, developed and optimized in a collaboration between the vendor and the Blood Transfusion Service of the Swiss Red Cross in Zurich, Switzerland, is not yet widely utilized, although several laboratories are currently evaluating the MassARRAY system for blood group genotyping. Based on the accuracy and other advantages offered by MALDI-TOF MS analysis, in the future, this method is likely to become widely adopted for blood group genotyping, in particular, for population screening. Immunohematology 2015;31:75–80.

Insights into RHCE Molecular Analysis in Samples with Partial D Variants: the Experience of Western France

Background: Although systematic blood group genotyping of patients/donors is virtually possible, serological studies remain the gold standard to identify samples of clinical interest that may be further genotyped. In this context, we sought to identify variant D alleles that are likely to be clinically relevant in terms of other Rh antigens in a subset of population genotyped in Western France. Methods: Samples presenting with the RHD*weak D type 4.2.2 allele (n = 47) were selected for the study. RHCE exons 1-7 were directly sequenced, and expression of Rh antigens was predicted on the basis of the molecular data. Results: Of the 47 samples tested, 19 (40.4%) were predicted to be of potential clinical interest. Moreover, we could show that selecting the samples to be genotyped by the nature of their variant D allele (i.e., RHD*weak D type 4.2.2 allele) rather than by their Duffy-null status appears to increase significantly the likelihood of identifying clinically relevant individuals for Rh status. Conclusion: On the basis of our findings we suggest that all individuals genotyped as weak D type 4.2.2 should be systematically screened for RHCE variants by molecular analysis on a routine basis.

Microarrays in blood group genotyping.

Thirty-five blood group systems, containing more than 300 antigens, are listed by the International Society of Blood Transfusion (ISBT). Most of these antigens result from a single-nucleotide polymorphism (SNP). Blood group typing is conventionally carried out by serology. However, this technique has certain limitations and cannot respond to the growing demand for blood products typed for a large number of antigens. Here we describe a blood group genotyping assay, from genomic DNA extraction from whole-blood samples to results. After DNA extraction, the on-chip test is based on the hybridization of targets beforehand amplified by multiplex polymerase chain reaction, followed by a revelation step allowing the simultaneous identification of up to 24 blood group antigens and leading to the determination of extended genotypes.