Determination of fetal RHD type in plasma of RhD negative pregnant women.

Alloimmunization against the RhD antigen is the most common cause of hemolytic disease of the fetus and newborn. Antenatal anti-D prophylaxis in addition to postnatal anti-D prophylaxis reduces the number of RhD-immunizations compared to only postnatal administration. Cell-free fetal DNA released from the apoptotic trophoblastic placental cells into the maternal circulation can be used to determine the fetal RHD type in a blood sample from an RhD negative mother. Based on this typing, antenatal anti-D prophylaxis can be recommended only to RhD negative women carrying an RhD positive fetus, since only these women are at risk of developing anti-D. The objective was to establish and validate a method for non-invasive fetal RHD typing. The fetal RHD genotype was studied in 373 samples from RhD negative pregnant women (median gestational week 24). DNA extracted from plasma was analyzed for the presence/absence of RHD exon 7 and 10 in a real-time PCR. The RHD genotype of the fetus was compared with the serological RhD type of the newborn. In 234 samples, the fetal RHD test was positive and in 127 samples negative. There was one false positive and no false negative results. In 12 samples, the fetal RHD type could not be determined, in all of them due to a maternal RHD gene. This method gives a reliable detection of fetal RHD positivity in plasma from RhD negative pregnant women. Antenatal anti-D prophylaxis based on the predicted fetal RhD type will avoid unnecessary treatment of pregnant women carrying an RhD negative fetus.

Novel RHD alleles with weak hemagglutination and genetic Exon 9 diversity: weak D Types 45.1, 75, and 76.

BACKGROUND: Molecular variant RHD allele analysis is best complemented by detailed characterization of the associated D phenotype. STUDY DESIGN AND METHODS: Variant D types were characterized using molecular typing, RHD sequencing, extended serologic D antigen investigations, and flow cytometric D antigen quantification. RESULTS: We discovered three novel weak D types termed weak D Types 45.1, 75, and 76 with RHD nucleotide substitutions coding for amino acid exchanges in predicted intracellular RhD polypeptide stretches; antigen densities of approximately 1.990, 900, and 240 D sites per red blood cell were found, respectively. Adsorption-elution technique-supported D epitope mapping of these three weak D types demonstrated the expression of all tested D epitopes. Initial molecular typing of the three investigated samples by RHD gene exon scanning polymerase chain reaction using sequence-specific priming yielded a negative reaction for A1193 located in RHD Exon 9 and could be explained by specific mutations for weak D Types 45.1 (C818T, G1195A), 75 (G1194C), and 76 (A1215C). CONCLUSION: All novel weak D types expressed all tested D epitopes. It is of interest that for weak D Types 45.1, 75, and 76, similar alleles with a maximal divergence of one amino acid only, that is, weak D Types 45, 41, and 68, respectively, have been reported so far.

Higher frequency of secretor phenotype in O blood group - its benefits in prevention and/or treatment of some diseases.

ABO blood groups and secretor status are important in clinical and forensic medicine and in relation to some diseases. There are geographic and racial differences in their frequencies, but the frequency of secretor status in different ABO blood group systems has not been determined yet. Therefore, the aim of this study was mainly to determine this point. Blood and saliva from 762 randomly selected apparently healthy adult individuals (480 men and 282 women) were examined to determine their ABO and Rhesus blood groups by standard conventional methods, and their secretor status by using Lewis blood grouping and/or hemagglutination inhibition test of saliva. Results showed that 76.1% of the study population were ABH blood group antigens secretors and 23.9% were nonsecretors. The frequencies of secretor status in different ABO blood groups were 70.1% in group A, 67.8% in group B, 67.9% in group AB, and 88.3% in group O. In conclusion, blood group O individuals have significantly higher frequency of secretor status than non-O blood group individuals. This finding would be beneficial to them, protecting them, at least partially, from certain malignancies or allowing them to have less aggressive disease, and this finding might be useful in enhancing further studies and research in this direction.

[Identification strategy of RHCE gene variants at the National Blood Group Reference Laboratory: impact on transfusion safety]. / Stratégie d'identification des variants du gène RHCE au Centre national de référence pour les groupes sanguins: impact sur la sécurité transfusionnelle.

The RH blood group is the most polymorphic and immunogenic blood group system. The RH locus is composed of 2 highly homologous genes: the RHD gene encoding the D polypeptide; and the RHCE gene, encoding C or c together with either E or e polypeptides. Numerous variants exist for both RHD and RHCE genes. Among them we were interested in the serological and molecular definition of numerous pre-published RHCE variants encountered in different populations. The identification of these variants is crucial to ensure the transfusion safety for patients expressing these variants. Here we propose a procedure to identify some of them and discuss the adequate transfusion strategy. This procedure has enable us to identify new variants to be presented at the symposium.

Novel weak D types 31 and 32: adsorption-elution-supported D antigen analysis and comparison to prevalent weak D types.

BACKGROUND: Weak D types are thought to express rather quantitative than qualitative D antigen variants. Distinct type-specific phenotypes and weak D cases with anti-D alloimmunization, however, suggest a variable degree of D antigen alteration. STUDY DESIGN AND METHODS: Variant D types were investigated by use of molecular typing, RHD sequencing, extended serologic D antigen investigations, and flow cytometric D antigen density determination. RESULTS: Two novel weak D types were discovered, termed weak D type 31 and 32 with single RHD nucleotide substitutions coding for amino acid exchanges in predicted intracellular RhD polypeptide stretches, with antigen densities of approximately 130 and 50 D sites per red blood cell, respectively. Adsorption-elution technique-supported D epitope mapping of these two weak D types, the recently described weak D type 26, and of the most common Central European weak D types (weak D types 1, 2, 3, 4.0, and 4.1) demonstrated the expression of all tested D epitopes. In contrast, a distinct D epitope loss was detected in weak D type 15 and partial D control samples. CONCLUSION: All novel and prevalent weak D types expressed all tested D epitopes. Our results indicate that adsorption-elution techniques may be of advantage whenever D epitope loss is suspected in extremely weak D variants.

Analysis of RHD genes in Taiwanese RhD-negative donors by the multiplex PCR method.

The determination of the RhD phenotype is important in transfusion medicine. However, due to the complexity of D antigen expression, the routine serological method cannot differentiate all RhD variants. In addition, the induction of the anti-D antibody is still the major cause of severe hemolytic disease of the newborn (HDN). Therefore, it is important to understand RHD gene profiles. To analyze the RHD gene profiles of Taiwanese RhD-negative donors, the multiplex PCR method was applied to amplify RHD specific exons 3, 4, 5, 7, and 9. Based on the PCR results, the 156 RhD-negative donors were divided into 12 groups according to the different expression patterns of the RHD gene. These 12 groups were further divided into three categories: type I=Rh D(el) (21.8%); type II = partial D, containing some exons (9.0%); and type III = true RhD-negative (69.2%). The results indicated that 21.8% of RhD-negative donors in Taiwan were RhD(el), and 9% carried a part of the RHD gene. Six defined RhD variants were found in this study: four R(O) (Har), one D(Va), and two D(IVb). However, no true RhD-negative or RhD(el) donor with the CcdEe phenotype was found in this analysis.

Risk estimation of ABO and Rho(D) incompatibility in persons with mono- and polyphyletic surnames in Monterrey, Mexico: comparison with other Mexican population

ABO and Rho(D) blood groups were determined in 3813 males and females affiliated with the Instituto Mexicano del Seguro Social (IMSS) who are residents of the Monterrey Metropolitan Area (MMA) in northeastern Mexico. They were selected by their monophyletic or polyphyletic surnames. The ABO and Rho(D) blood group phenotypes and gene frequencies were determined and based upon these, the risk of incompatibilities was estimated for both marriages (MI) and maternal-fetal incompatibility (MFI). These were compared with those estimated for other populations of residents in the MMA, and in other locations in Mexico, as well as with the two most important ancestral populations, Spanish and Tlaxcaltecan Mexican Indians, with the hypothesis that the percent of risk ABO and Rho(D) MI and MFI are greater in the population with monophyletic surnames than those with polyphyletic surnames. It was found that for persons with nomophyletic and polyphyletic surnames, as well as for the other populations in the MMA and other places in Mexico, their ABO and Rho(D) MI and MFI percent of risk are intermediate to the ones estimated for their ancestry. The percentages of MI and MFI are higher for the persons with monophyletic than for the ones with polyphyletic surnames, other populations from the MMA and those from other locations in Mexico. The risks are higher when the similarity with Spanish increases and are lower when their similarities with the mexican Indians increase

Inferencia de parametros estadisticos de los grupos sanguineos O A B y el factor Rh en el departamento de Cochabamba / Statistical parameters of blood groups O, A, B and factor Rh in Cochabamba

Se determinaron los grupos sanguineos O, A, B y el FactorRh en 20.611 personas del departamento de Cochabamba. Se tomaron muestras dirigidas de diversas areas geograficas habitadas por grupos poblacionales de distinta influencia racial y de areas autoctonas. Se hicieron comparaciones e inferencias de los datos obtenidos entre la poblacion de la ciudad de Cochabamba,las provincias, las poblaciones autoctonas (tribus de los Yuracares) y los datos proporcionados por el Autor A. Guyton en el libro Fisiologia Medica y el autor B., Houssay en el libro Fisiologia Humana. La distribucion de los datos finales es: Grupos sanguineos ( por ciento ): O:74.6; A:19.3; B:5,2; AB:0,9. Factor Rh: Positivo 98,9; Negativos: 1,1

Grupos sanguineos y el factor Rh en el Departamento de Cochabamba / Blood groups and the Rh factor in the Departament of Cochabamba

Se denominan los grupos sanguineos y factor Rh en 9.817 personas del Departamento de Cochabamba. El estudio que se constituye en la primera parte de uno mas amplio, tomo en cuenta diversas areas geograficas y de distinta influencia racial dentro del mencionado departamento. Los datos obtenidos senalan la siguiente distribucion para los grupos sanguineos 72,6// el O, 20,6// para el A, 5,8// para el B y 1// para el AB. En cuanto al factor RH positivo 98,3// y negativo 1,7//. Los resultados muestran significativas diferencias con la informacion referida a paises europeos y del norte del Continente Americano.