Non-invasive prenatal rhesus D genotyping using cell-free foetal DNA.

Background & objectives: Non-invasive prenatal diagnosis (NIPD) of rhesus D (RHD) genotype using cell-free foetal DNA is extensively used in many developed countries. Studies on NIPD from India are scarce. The aim of the present study was to evaluate the performance of non-invasive foetal RHD genotyping by targeting exon 10 of the RHD gene using cell-free DNA. Methods: DNA was extracted from the maternal plasma of alloimmunized and non-alloimmunized women between 7 and 34 wk of gestation. RHD sequence was determined by quantitative real time polymerase chain reaction (PCR). Results were compared with RhD phenotype obtained from cord blood samples of neonates. Results: A total of 135 samples from RhD-negative pregnant women were collected. The foetal RHD status was conclusive in all 135 (100%) cases. The highest number of cases reported for RHD genotyping were from Punjab (38.5%) followed by Haryana (24.4%), Himachal Pradesh (17.0%) and Chandigarh Union Territory (13.3%). The non-invasive test correctly predicted the foetal RhD phenotype in 133 of 135 cases, making the accuracy of the test as 98.51 per cent [95% confidence interval (CI): 97.90-99.50%]. The overall sensitivity and specificity of the test were 99.18 per cent (95% CI: 95.52-99.98%) and 92.31 per cent (95% CI: 63.97-99.81%), respectively, with negative and positive predictive values of 99.80 per cent (95% CI: 94.85-99.87%) and 96.31 per cent (95% CI: 62.87-98.84%), respectively. Interpretation & conclusions: Non-invasive foetal RHD determination by single-exon quantitative PCR exhibited high accuracy and could be used in routine clinical practice after confirmatory studies are done.

Rh blood phenotyping (D, E, e, C, c) microarrays using multichannel surface plasmon resonance imaging.

The application of Surface Plasmon Resonance Imaging (SPRi) for the detection of transmembrane antigen of the Rhesus (Rh) blood group system is demonstrated. Clinically significant Rh blood group system antigens, including D, C, E, c, and e, can be simultaneously identified via solid phase immobilization assay, which offers significant time savings and assay simplification. Red blood cells (RBCs) flowed through the micro-channel, where a suitable condition for Rh blood group detection was an RBC dilution of 1:10 with a stop-flow condition. Stop flow showed an improvement in specific binding compared to continuous flow. Rh antigens required a longer incubation time to react with the immobilized antibody than A and B antigens due to the difference in antigen type and their location on the RBC. The interaction between the immobilized antibodies and their specific antigenic counterpart on the RBC showed a significant difference in RBC removal behavior using shear flow, measured from the decay of the SPR signal. The strength of the interaction between the immobilized antibody and RBC antigen was determined from the minimum wall shear stress required to start the decay process in the SPR signal. For a given range of immobilized antibody surface densities, the Rh antigen possesses a stronger interaction than A, B, and AB antigens. Identification of 82 samples of ABO and Rh blood groups using SPRi showed good agreement with the standard micro-column agglutination technique. A wider coverage of antigenic recognition for RBC when using the solid phase immobilization assay was demonstrated for the RBC with the antigenic site located on the transmembrane protein of the clinically significant Rh antigen. Given the level of accuracy and precision, the technique showed potential for the detection of the Rh minor blood group system.

[From the discovery of microbial Mep-Amt ammonium transporters to human Rhesus factors]. / De la découverte des transporteurs d'ammonium Mep-Amt microbiens aux facteurs Rhésus humains.

Ammonium, ubiquitous on Earth, plays major and distinct roles in most organisms. While it can be a nitrogen source for many microorganisms and plants, it is a cytotoxic metabolic product actively detoxified by the liver in animals. Furthermore, in the latter, ammonium synthesis in the kidney is involved in acid/base homeostasis. Ammonium transport is ensured by a family of proteins, called Mep-Amt-Rh. This family is conserved in all domains of life and comprises the human Rh factors, notably known in transfusional medicine. While the study of bacterial, fungal and vegetal Mep-Amt transporters reveals a fine-tuned and rapid regulation of these proteins in function of environmental changes, the regulation of animal Rh proteins has been poorly addressed. This review notably highlights the importance of the yeast model in the study of the regulation of these proteins as well as in the functional characterization of Mep-Amt-Rh members of diverse origins.

A novel paper-based assay for the simultaneous determination of Rh typing and forward and reverse ABO blood groups.

We propose a new, paper-based analytical device (PAD) for blood typing that allows for the simultaneous determination of ABO and Rh blood groups on the same device. The device was successfully fabricated by using a combination of wax printing and wax dipping methods. A 1:2 blood dilution was used for forward grouping, whereas whole blood could be used for reverse grouping. A 30% cell suspension of A-cells or B-cells was used for haemagglutination on the reverse grouping side. The total assay time was 10 min. The ratio between the distance of red blood cell movement and plasma separation is the criterion for agglutination and indicates the presence of the corresponding antigen or antibody. The proposed PAD has excellent reproducibility in that the same blood groups, namely A, AB, and O, were reported by using different PADs that were fabricated on the same day (n=10). The accuracy for detecting blood group A (n=12), B (n=13), AB (n=9), O (n=14), and Rh (n=48) typing were 92%, 85%, 89%, 93%, and 96%, respectively, in comparison with the conventional slide test method. The haematocrit of the sample affects the accuracy of the results, and appropriate dilution is suggested before typing. In conclusion, this study proposes a novel method that is straightforward, time-saving, and inexpensive for the simultaneous determination of ABO and Rh blood groups, which is promising for use in developing countries.

Identifying D-positive donors using a second automated testing platform.

Because of the variability of D expression, one method may be inadequate to correctly classify donors with variant RHD alleles. We evaluated the use of a solid -phase automated platform (ImmucorGamma Galileo) to confirm D- test results obtained on first-time donors on the Beckman Coulter PK7300 automated microplate test system. Samples with discordant results were analyzed by serologic tube methods, RHD genotyping using the BLOODchip platform (Progenika) and, if necessary, sequencing. We estimated the number of cases of alloimmunization in women younger than 50 years likelyto be prevented by the addition of Galileo testing. From May 2011 to May 2012, 910,220 donor samples were tested; 15,441 were first-time donors with concordant D- results. Five donors tested D- on the PK7300 and weak D+ on the Galileo; one was found to be a false positive on further testing. On manual testing, the other four donors had positive indirect antiglobulin test results with one to three of the antisera used and were C+. On BLOODchip testing, two donors were classified as D+, and two were assigned a "no call". D variants included weak D type 67, weak D type 9, and two novel variants. Approximately 10 percent of D- units are transfused to women younger that 50 years. Assuming an alloimmunization rate of 30 percent, use of the Galileo would prevent approximately one alloimmunization every 5 to 6 years in this patient group. We conclude that the yield of preventing alloimmunization in this population by adding a second automated seologic testing platform is very low.

Prevalence of Rh, Duffy, Kell, Kidd & MNSs blood group antigens in the Indian blood donor population.

BACKGROUND & OBJECTIVES: Little data are available regarding the frequencies of the blood group antigens other than ABO and RhD in the Indian population. Knowledge of the antigen frequencies is important to assess risk of antibody formation and to guide the probability of finding antigen-negative donor blood, which is especially useful when blood is required for a patient who has multiple red cell alloantibodies. This study was carried out to determine the frequencies of the D, C, c, E, e, K, k, Fy(a), Fy(b), Jk(a), Jk(b), M, N, S and s antigens in over 3,000 blood donors. METHODS: Samples from randomly selected blood donors from Delhi and nearby areas (both voluntary and replacement) were collected for extended antigen typing during the period January 2009 to January 2010. Antigens were typed via automated testing on the Galileo instrument using commercial antisera. RESULTS: A total of 3073 blood samples from donors were phenotyped. The prevalence of these antigens was found to be as follows in %: D: 93.6, C: 87, c: 58, E: 20, e: 98, K: 3.5, k: 99.97, F(a) : 87.4, Fy(b) : 57.6, Jk(a) : 81.5, Jk(b) : 67.4, M: 88.7, N: 65.4, S: 54.8 and s: 88.7. INTERPRETATION & CONCLUSIONS: This study found the prevalence of the typed antigens among Indian blood donors to be statistically different to those in the Caucasian, Black and Chinese populations, but more similar to Caucasians than to the other racial groups.

Comparison of different blood sample processing methods for sensitive detection of low level chimerism by RHD real-time PCR assay.

The rhesus D blood group, which is expressed on the red blood cells (RBC) of 85% of the Caucasian population, is one of the most immunogenic RBC antigens, inducing D antibody formation in up to 20-80% of D-negative transfusion recipients and about 10% of pregnancies at risk. Pregnancy-induced D-antibodies can persist for many years, but the mechanisms underlying this persistence are unclear. The LOTUS study, a long-term follow-up study of mothers from severely affected children with hemolytic disease of the fetus and newborn investigates, among other endpoints, whether persistent feto-maternal chimerism is associated with long-term maternal anti-D persistence. We questioned which blood sample processing method should be used to detect low levels of RHD chimerism with the highest sensitivity and specificity using qPCR. After optimization of primer and probe concentrations for singleplex RHD exon 5 and 7 qPCR, sensitivity, specificity and efficiency of RHD and DYS1 qPCR were investigated in artificial chimeric samples. Sensitivity of DYS1 was one log higher (0.0001%) in enriched mononuclear cell fractions as compared with whole blood. Comparable linear sensitivity (0.007%) and mean efficiency (84-99%) for RHD qPCR were observed in all samples regardless whether whole blood or pre- or post-mixing of cellular fractions had been used. We conclude that RHD chimerism using singleplex exon 5 and 7 qPCR is linearly detectable down to 1.0 GE, without an advantage of fraction enrichment.

High throughput non-invasive determination of foetal Rhesus D status using automated extraction of cell-free foetal DNA in maternal plasma and mass spectrometry.

PURPOSE: To examine the potential high throughput capability and efficiency of an automated DNA extraction system in combination with mass spectrometry for the non-invasive determination of the foetal Rhesus D status. METHODS: A total of 178 maternal plasma samples from RHD-negative pregnant women were examined, from which DNA was extracted using the automated Roche MagNA Pure system. Presence of the foetal RHD gene was detected by PCR for RHD exon 7 and subsequent analysis using the Sequenom MassArray mass spectrometric system. RESULTS: We determined that as little as 15 pg of RHD-positive genomic DNA could be detected in a background of 585 pg of RHD-negative genomic DNA. The analysis of the clinical samples yielded a sensitivity and specificity of 96.1 and 96.1%, respectively. CONCLUSION: Our study indicated that automated DNA extraction in combination with mass spectrometry permits the determination of foetal Rhesus D genotype with an accuracy comparable to the current approaches using real-time PCR.

[Contribution of the genetic fingerprintings compared to grouping ABO/Rhesus technique in the expertise of filiation]. / Apport des empreintes génétiques par rapport à la technique de groupage ABO/Rhésus dans l'expertise de filiation.

Paternity is based on biological analyzes that have drastically developed during the past 20 years. According to scientific developments, paternity testing was based on red blood groups studies, the analysis of red cell enzymes and plasma proteins polymorphisms, the typing of the HLA antigens, and the DNA polymorphism in its various forms. This study aims at comparing two analyses: red blood groups and DNA polymorphism. The performance of each test is analyzed in this report, based on a study of 142 cases. Indeed, the numbers of case of paternity exclusion are respectively 6 and 45 by the classic method and the genetic one. Thanks to studies based on the gene amplification of microsatellites, the efficiency of this reference technique has been proved, however, the classic one makes it possible in the cases of exclusion to lead to a certain decision without recourse to other systems. Of these facts, beyond the most efficient biological analysis, it is very important to think about paternity testing as a process in which biological tests are only one step.

Poblaciones costeras de Chile: marcadores genéticos en cuatro localidades / Coastal Chilean populations: genetic markers in 4 locations

Background: Historical and anthropological data suggest the presence of descendents of Changos, Cuncos, Chonos and Yamanas, South American indian populations, in certain Chilean coastal villages. Aim: To assess the degree of South American indian admixture in Chilean coastal villages using protein markers, to complete the assessment of human biological diversity in Chile. Subjects and methods: AB0, Rh, MNS, Duffy and Kidd blood group systems were assessed in 47, 48, 55 and 24 individuals from Paposo, Carelmapu, Laitec and Ukika respectively. Phenotypic and gene frequencies were calculated. The degree of South American indian admixture was estimated from the AB0*0 allele and Rh*dce haplotypes. Results: High frequencies of AB0*0, Fy*a, Jk*b alleles, Dce and Ms haplotypes were found in all villages, consistent with the pattern expected for South AmericanAboriginal populations. The highest presence of South American indian admixture was present in Laitec with 80 per cent and in Ukika with 74 per cent. The figures for Paposo and Carelmapu were 60 and 65 per cent respectively. Conclusions: Accordin g to South American indian admixture estimates, the genetic isolation of coastal populations is lower than that of inland subjects, suggesting thatsea proximity facilitates gene flow

Identification of two new D variants, DHMi and DHMii using monoclonal anti-D.

Fifteen examples of red cells are described which showed discrepant reactivity on routine grouping with two monoclonal anti-D typing reagents, HAM-A being negative and MAD-2 strongly positive. The reaction profile of these cells with a number of monoclonal anti-D characterised the samples into two new variant groups, DHMi and DHMii. DHMi was characterised by a negative reaction with BRAD-8 and DHMii by a negative reaction with BRAD-5. DHMi cells were found to have a papain-sensitive site, identified by Mab 21 G6, which was not detectable in DHMii. The presence of allo-anti-D in one case of DHMi suggests a partial D in these individuals. The positive reaction of HAM-A with sialidase- and endo-F-treated DHMii cells suggests that sialic acid and/or N-glycans could possibly be involved in blocking the reaction with untreated cells. All samples typed as C-E+. One was e negative while the rest had variable depression of the e and f antigens. Marginal depression of E was seen with those DHMi cells tested, but not with DHMii cells. Data from family studies suggest that the variant D in both DHMi and DHMii is inherited as a cDE gene complex and is controlled by the RH locus.

Composición genética de la población chilena: los atacameños de la comuna de San Pedro de Atacama / Genetic composition of chilean population: the atacameños from San Pedro de Atacama

This work describes the genetic composition of atacameños from San Pedro de Atacama. The results show that a) the contribution of non-indigenous genes is relatively low, in relation to the spanish inmigration period. b) the Hardy-Weinberg genetics disequilibrium for MNSs system should have biological implications. c) the variant for esterasa D enzyme may be the same found in other chilean populations

Rh(D) antigen expression and isolation of a new Rh(D) cDNA isoform in human erythroleukemic K562 cells.

Human erythroleukemic K562 cells are known to have several erythroid properties. K562 cells possess Rh mRNAs, but expression of Rh proteins has not previously been reported. We immunoprecipitated Rh protein from K562 cell lysate using rabbit anti-Rh and detected Rh(D) antigens on K562 cells using fluorescence-activated cell sorting (FACS). These results suggest that K562 cells will be useful as an expression model for most Rh antigens. We also cloned a new Rh(D) cDNA isoform (RhK562-II), from a K562 cDNA library using polymerase chain reaction (PCR) with 5' and 3' end oligonucleotides of the published Rh(e/E) antigen encoding cDNA sequence as primers. Sequence analysis showed that RhK562-II is composed of 951 nucleotides (316 amino acids), identical to the first 939 nucleotides (exons 1 to 6) of one of the Rh(D) cDNAs (RhXIII), except for nucleotide 654 (C-->G exchange). However, this exchange is the same as that of another published Rh(D) cDNA (RhPII cDNA). RhK562-II is deprived of exons 7 and 8 (nucleotides 940 to 1,153), followed by an identical sequence up to the 3' end of the open-reading frame of the RhXIII cDNA, which causes a frame-shift mutation and produces a premature stop codon. In vitro expression of RhK562-II using the transcription and translation rabbit reticulocyte lysate system produced two major Rh-related proteins (30 kD and 25 kD), which were immunoprecipitated by rabbit polyclonal anti-Rh and separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

Studies on the glycoprotein associated with Rh (rhesus) blood group antigen expression in the human red blood cell membrane.

The blood group Rh antigens are associated with non-glycosylated 30-kDa erythrocyte membrane proteins (the Rh30 polypeptides) and the Rh glycoprotein. We used antipeptide antibodies to study the Rh glycoprotein in human erythrocyte membranes. The Rh glycoprotein was present in Rhnull U+ve cells. However, the N-glycan chain of the Rh glycoprotein in Rhnull U+ve cells was smaller than in normal cells. In contrast, the N-glycan chain of the Rh glycoprotein was larger than normal in glycophorin B-deficient red cells. We suggest that this observation reflects a lower rate of movement of newly synthesized Rh glycoprotein through intracellular membranes to the cell surface in the absence of glycophorin B, and that in normal red cells glycophorin B facilitates the movement of the Rh protein complex to the cell surface. Our results provide evidence for the intracellular interaction of at least three proteins, the Rh glycoprotein, Rh30 polypeptides, and glycophorin B during the biosynthesis and cell surface expression of the Rh complex. These observations are likely to be important for the successful design of expression systems for the blood group Rh antigens.

Evidence for a structurally homologous Rh-like polypeptide in Rhnull erythrocytes.

Human Rhnull red blood cells fail to react with Rh antibodies, indicating that these cells are either devoid of Rh protein or, like other species, possess antigenically distinct variants. To determine whether Rhnull cells possess an Rh-like polypeptide, 32-kDa proteins from D--, rr, and Rhnull cells were labeled with the cysteine-specific probe, 125I-labeled pyridyldithioethylamine. Size comparisons of labeled proteins in Triton X-100-solubilized membranes from Rh-bearing and Rhnull cells showed similar sedimentation coefficients and Stoke's radii. Immunoprecipitated Rh(D) from D-- cells, Rh(c) from rr cells, and purified 32-kDa proteins from Rhnull cells were digested with alpha-chymotrypsin and examined by high-performance liquid chromatography and by two-dimensional iodopeptide mapping. Analysis of 125I-labeled chymotryptic fragments from immunoprecipitated Rh(D) and Rh(c) showed the labeled peptides from both phenotypes to be virtually identical. High-performance liquid chromatography profiles and iodopeptide maps of 32-kDa Rhnull proteins yielded patterns identical to 32-kDa proteins isolated from D-- cells and rr cells with the exception of one missing 125I-labeled peptide. Further analysis of the Rh-related fragments from Rhnull cells showed significant homology with immunoprecipitated Rh(D) and Rh(c). DNA sequence analysis of cysteine-encoding regions from Rh-bearing and Rhnull cells showed complete identity. These data suggest that Rhnull red blood cells, although serologically distinct, possess an Rh-like protein that is structurally very similar to Rh(D) and Rh(c).

Typing and screening of blood from intraosseous access.

STUDY OBJECTIVE: To determine if intramedullary aspirate from intraosseous needle placement can be used as a source for evaluating blood compatibility. DESIGN: A prospective, nonrandomized, crossover study. SETTING/PARTICIPANTS: Patients admitted to the hematology/oncology service undergoing bone marrow aspiration for medical purposes. INTERVENTIONS: Patients had simultaneous samples of bone marrow aspiration from the posterior iliac crest and peripheral venous blood drawn and sent for typing and screening. MEASUREMENTS AND MAIN RESULTS: The paired samples were evaluated for ABO and Rh typing as well as the presence of human leukocyte activity by evaluating the reaction strength between the marrow and venous samples. RESULTS: No differences were seen in the reaction strength between the paired samples in any subjects for ABO and Rh typing (P = .90, yielding beta = .0523). In addition, human leukocyte activity was detected in both the marrow and venous samples in one patient. CONCLUSION: Bone marrow aspirates following intraosseous infusion can be used for accurate and reliable typing and screening of blood.

Two-dimensional iodopeptide mapping demonstrates that erythrocyte Rh D, c, and E polypeptides are structurally homologous but nonidentical.

The 32,000 molecular weight (mol wt) erythrocyte Rh D, c, and E polypeptides were separately purified from cDE/cDE erythrocytes by monoclonal immunoprecipitations and compared by two-dimensional iodopeptide mapping. Digestions of the isolated Rh polypeptides with alpha-chymotrypsin revealed a high degree of structural homology between c and E (13/14 iodopeptides were identical) and less striking homology between D and c or E (8/19 identical). The iodopeptide maps of Rh proteins purified by a nonimmunologic protocol from cDE/cDE erythrocytes were virtually identical to the composite pattern (D + c + E) deduced from the individual maps of Rh D, c, and E iodopeptides. Digestions of the isolated Rh polypeptides with trypsin revealed an overall homology of approximately 50% between iodopeptides derived from D, c, and E. These data indicate that the erythrocyte Rh D, c, and E antigens are carried by homologous but distinct molecular species; c and E appear more closely related to each other than to D.

Human monoclonal antibody against Rh(D) antigen: partial characterization of the Rh(D) polypeptide from human erythrocytes.

A human monoclonal anti-Rh(D) antibody produced by an Epstein-Barr virus (EBV)-transformed B-cell line (IgG1(lambda), clone H2D5D2) has been purified on protein A-Sepharose column and used for binding studies and immune precipitation of the blood group rhesus (Rh) antigens. Scatchard plot analyses show that the 125I-labeled antibody (iodo-gen procedure), binds to 1.09 X 10(5), 0.43 X 10(5), and 0.32 X 10(5) antigen sites on each D--/D--, R2R2 and R1R1 RBC, respectively, with an association constant of approximately 0.6 X 10(8) mol/L-1. Immune precipitation studies indicate also that the Rh(D) antigen of the Rh(D)-positive RBCs is carried by a 29 kd polypeptide as deduced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). No material could be precipitated from Rh(D)-negative or Rhnull RBCs. These results indicate that the monoclonal and the polyclonal human anti-Rh(D) behave similarly. A sample (Blo., presumed genotype R2r or R0R2) showing an increased number of antigen sites (0.76 X 10(5)/cell) and a high binding constant (5.7 X 10(8) mol/L-1) was used, as well as D--/D-- RBCs, for further purification of the 29-kd component. Extraction by Triton X-100 (0.1% to 5%) of the immune complexes formed between the membrane-bound Rh(D) antigens and the monoclonal antibody as well as a direct quantitative estimate of the 29-kd component, suggest that the Rh(D) polypeptide is loosely bound to the skeleton, since less than or equal to 80% can be solubilized from the membrane. In similar conditions, glycophorin A showed a slight association with the Triton-insoluble residue, whereas glycophorin B was easily and completely extracted. In contrast, both the minor RBC sialoglycoproteins, glycophorin C and glycoprotein gamma, remained predominantly bound to the membrane skeleton. The purified Rh(D) polypeptide obtained from Blo. and D--/D-- RBCs by immunoprecipitation and preparative gel electrophoresis was homogenous as judged by SDS-PAGE. Amino acid composition indicated that the Rh(D) protein contained sulfhydryl groups which are essential for biological activity.