Monique Silvy

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

Weak D and DEL alleles detected by routine SNaPshot genotyping: identification of four novel RHD alleles

BACKGROUND: Molecular RHD blood group typing is very efficient for managing donors and patients carrying any of the various molecular types of weak D and DEL. The purpose of the work was to develop a multiplex polymerase chain reaction (PCR) SNaPshot assay for simultaneous detection of weak D and DEL alleles that are prevalent in Europeans, Africans, and Asians.

Identification of RHCE and KEL alleles in large cohorts of Afro-Caribbean and Comorian donors by multiplex SNaPshot and fragment assays: a transfusion support for sickle cell disease patients

To lower the alloimmunization risk following transfusion in blacks, we developed two genotyping assays for large‐scale screening of Comorian and Afro‐Caribbean donors. One was a multiplex SNaPshot assay designed to identify ces(340), ceMO/AR/EK/BI/SM, ces, ces(1006) and KEL*6/*7 alleles. The other was a multiplex fragment assay designed to detect RHD, RHDψ and RHCE*C and 455A>C transversion consistent with (C)ces Type 1 and DIII Type5 ces. Variant RHCE*ce alleles or RH haplotypes were detected in 58·69% of Comorians and 41·23% of Afro‐Caribbeans. The ces allele, (C)ces Type 1, and DIII Type 5 ces haplotypes were identified respectively in 39·13%, 14·67% and 4·88% of Comorians and 32·23%, 5·28% and 1·76% of Afro‐Caribbeans. Genotypes consistent with partial D, C, c and/or e antigen expression were observed in 26·08% of Comorians and 14·69% of Afro‐Caribbeans. No homozygous genotype corresponding to the RH:‐18, ‐34, and ‐46 phenotypes were found. However, over 50% of genotypes produced low‐prevalence antigens at risk for negative recipients, i.e., V, VS, JAL, and/or KEL6. One new variant RHCE*ces(712) allele was identified. This is the first determination of variant RHCE and KEL allele frequencies. Results indicate the most suitable targets for molecular assay screening to optimize use of compatible blood units and lower immunization risk.

Characterization of novel RHD alleles: relationship between phenotype, genotype, and trimeric architecture

BACKGROUND: RH1 is one of the most clinically important blood group antigens in the field of transfusion and prevention of fetomaternal incompatibilities. New variant RHD alleles are regularly identified and their characterization is essential to ensuring patient safety.

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.

Molecular background of D‐negative phenotype in the Tunisian population

Background: Most studies of the molecular basis of Rhesus D‐negative phenotype have been conducted in Caucasian and African populations. A comprehensive survey of RHD alleles was lacking in people from North Africa (Tunisians, Moroccans and Algerians) which could be very efficient for managing donors and patients carrying an RHD molecular variant. We analyse the molecular background of D‐negative population in Tunisia in the present study.

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.