Pascal Bailly

Red blood cell immunization in sickle cell disease: evidence of a large responder group and a low rate of anti-Rh linked to partial Rh phenotype

The main side-effect of transfusion is alloimunization against red blood cell (RBC) antigens. Thirteen percent of the general population were shown to be responders and 30% of responders make antibodies indicating a rate of alloimmunization of 3.9%.[1][1] However, alloimmunization is more frequent

A comprehensive survey of both RHD and RHCE allele frequencies in sub‐Saharan Africa

The RH system is one of the most polymorphic blood group systems with numerous allele variants affecting Rh polypeptides expression. This complexity is at the origin of difficulties for transfusion of African patients especially sickle cell disease patients requiring chronic transfusion therapy with high risk of immunization. As a complete survey of RH variants is lacking in African populations, we performed red blood cell genotyping to determine the type and frequency of RHD and RHCE alleles in sub‐Saharan African populations.

Synonymous nucleotide polymorphisms influence Dombrock blood group protein expression in K562 cells.

To gain further insight into ART4 (DO) gene alleles (DO*A, DO*JO1, DO*A‐WL, DO*DOYA, DO*B, DO*B‐WL, DO*B‐SH‐Q149K, DO*B‐(WL)‐I175N, DO*HY1, DO*HY2, DO*DOMR) and evaluate the impact of synonymous nucleotide polymorphisms on protein expression and mRNA accumulation of DO*A‐HA, DO*A‐SH and DO*B‐SH alleles, human erythroleukaemic K562 cells were transducted with variant DO‐lentiviral particles and analysed by flow cytometry and quantitative reverse transcription polymerase chain reaction. Monoclonal antibody (MoAb) detection of DO*A‐HA and DO*JO1 transductants was lower than DO*A transductants, while detection of DO*A‐SH, DO*A‐WL and DO*DOYA transductants was higher. Variant DO*B alleles, i.e. DO*B‐SH, DO*B‐WL, DO*HY1, DO*HY2 and DO*DOMR, showed reduced MoAb binding. The unexpected modifications of protein expression of the DO*A‐HA, DO*A‐SH and DO*B‐SH alleles that differ from the DO*A or DO*B alleles by a single synonymous polymorphism were abolished by reversion, thus implying involvement of these polymorphisms. Depending on the Leu208 codon used, detection level ranged from 1 to 4·14. In the variant alleles resulting from single synonymous polymorphism, mRNA accumulation correlated roughly with MoAbs detection levels, suggesting post‐transcriptional regulation. Other than a few reports involving aberrant splicing, the experiments described herein provide the first evidence that synonymous nucleotide polymorphisms can influence Dombrock blood group expression. Such polymorphisms should be taken into account for molecular screening and potential impact on transfusion.

RH diversity in Mali: characterization of a new haplotype RHD*DIVa/RHCE*ceTI(D2)

Knowledge of RH variants in African populations is critical to improving transfusion safety in countries with populations of African ancestry and to providing valuable information and direction for future development of transfusion in Africa. The purpose of this report is to describe RH diversity in individuals from Mali.

Identification of novel polymorphism restricted to the (C)ces type 1 haplotype avoids risk of transfusion deadlock in SCD patients

Victoria Ling Alan K. Burnett Ken Bradstock John F. Seymour Robert K. Hills Andrew Wei Department of Clinical Haematology, The Alfred Hospital, Melbourne, Victoria, Australia, Department of Haematology, Cardiff University School of Medicine, Cardiff, Wales, Department of Haematology, Westmead Hospital, Westmead, NSW, Australia, Department of Haematology, Peter MacCallum Cancer Centre, East Melbourne; and University of Melbourne, Parkville, Victoria, Australia and Australian Centre for Blood Diseases, Division of Blood Cancers, Monash University, Melbourne, Victoria, Australia E-mail: a.wei@alfred.org.au

Molecular characterization of a new D- - haplotype in a Comorian man

The D‐ ‐ phenotype is a genetic variant of the Rh blood group system. It expresses D antigen but lacks C, c, E and e antigens. In D‐ ‐ phenotype, the RHCE coding region is extensively modified by RHD sequence replacement, nucleotide deletion or splice‐site changes. This article reports the identification of a new D‐ ‐ haplotype in a Comorian man. It exhibits a hybrid gene in which RHCE gene exons 3–8 have been replaced by RHD sequences on the RHCE * C allele background. This allele is associated with no expression of c/C and e/E antigens and overexpression of RhD antigen.

Revisiting the Diego Blood Group System in Amerindians: Evidence for Gene-Culture Comigration

Six decades ago the DI*A allele of the Diego blood group system was instrumental in proving Native American populations originated from Siberia. Since then, it has received scant attention. The present study was undertaken to reappraise distribution of the DI*A allele in 144 Native American populations based on current knowledge. Using analysis of variance tests, frequency distribution was studied according to geographical, environmental, and cultural parameters. Frequencies were highest in Amazonian populations. In contrast, DI*A was undetectable in subarctic, Fuegian, Panamanian, Chaco and Yanomama populations. Closer study revealed a correlation that this unequal distribution was correlated with language, suggesting that linguistic divergence was a driving force in the expansion of DI*A among Native Americans. The absence of DI*A in circumpolar Eskimo-Aleut and Na-Dene speakers was consistent with a late migratory event confined to North America. Distribution of DI*A in subtropical areas indicated that gene and culture exchanges were more intense within than between ecozones. Bolstering the utility of classical genetic markers in biological anthropology, the present study of the expansion of Diego blood group genetic polymorphism in Native Americans shows strong evidence of gene-culture comigration.

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.

Short duplication within the RHCE gene associated with an in cis deleted RHD causing a Rhnull amorph phenotype in an immunized pregnant woman with anti‐Rh29

The rare amorph Rhnull phenotype is caused by silent alleles at the RH locus and usually arises in consanguineous families. To date, only five molecular backgrounds have been identified in five unrelated families. Subjects with Rhnull red blood cells (RBCs) readily produce alloantibodies to high‐prevalence Rh antigens.

Apport du génotypage érythrocytaire à l’immuno-hématologie receveur à travers quatre années d’activité à l’EFS Alpes Méditerranée

AIM OF THE STUDYnCurrent knowledge of the molecular basis of most blood groups enables genetic testing for blood groups to overcome the limitations of agglutination. A retrospective review was carried out on genotyping assays performed between 2011xa0and 2013.nnnMETHODS AND PATIENTSnThe Molecular Hematology Laboratory of the EFS Alpes-Méditerranée implements commercially available tools (BioArray, Gen-Probe) and other techniques (TaqMan, tetra-primer ARMS-PCR, sequencing). It provides a high-level of expertise in molecular biology, complying with regulatory requirements and standards.nnnRESULTSnA total of 2382xa0genotyping assays was performed including 764xa0extended typings and 115xa0large extended typings essentially in cases involving multiple transfusion and suspected rare blood type. Phenotype discrepancies linked to the RH system accounted for 1501xa0genotypings. Discrepancies linked to the D and E were mainly related to an allele coding for weak antigen (weak D type 1, 2, 3xa0and EIV) while those linked to C, c and e antigens were related to an allele coding for a partial antigen (RN, ces(340), ceMo). A high prevalence of (C)ces haplotype in trans of a DAR allele was observed in Afro-Caribbean (54/62).nnnCONCLUSIONnIn transfusion medicine, red-cell genotyping can overcome the limitations of hemagglutination. It must be used only in situations where it provides a benefit either for the patient or resource management. For implementation of appropriate transfusional practices, this technique requires a sound knowledge of the genetic characteristics of blood groups and clinically relevant variants. It also requires competency with molecular biology tools and continuously updated scientific data.