Genetic characterization of the RH haplotype in individuals carrying the RHD*46C DEL allele

PRINCIPI, CINTIA; MATTALONI, STELLA MARIS; BIONDI, CLAUDIA; LUJÁN BRAJOVICH, MELINA ELIANA; GARCIA BORRAS, SILVIA; TRUCCO BOGGIONE, CAROLINA; ENSINCK, ALEJANDRA; COTORRUELO, CARLOS

Basilea

Congreso; 29th Regional Congress of the ISBT; 2019

ISBT

Background: The Rh blood group system presents a great clinical interest in Transfusion Medicine due to the participation of itsantibodies in processes of immune destruction of red blood cells. The RH locus consists of two homologous genes, RHD and RHCEthat segregate as haplotypes and in some cases show genetic linkage disequilibrium. The coexistence of aberrant allelic variants in cisin patients who are under therapy with chronic transfusions may be responsible for delayed transfusion hemolytic reactions as a resultof the production of complex alloantibodies. Molecular studies allow the characterization of the alleles responsible for alteredexpression of Rh antigens, optimizing transfusion compatibility.Aims: The aim of this study was to characterize the molecular structure of the RH haplotype in Argentinean donors carrying theRHD*46C allele.Methods: DNA samples from 17 Argentinean donors carrying the RHD*46C DEL allele were investigated. All samples wereassociated to E antigen expression, however, the strength of hemaglutination varied depending on the anti-E clone used, showing avery weak reaction when tested with clones MS-258 and MS-80 and a strong reaction with clone MS-260. In a first step, the c.733Gpolymorphism of the RHCE gene was analyzed using a PCR-SSP strategy. Sequencing of exon 5 of RHCE gene was performed in all733G+ samples.Results: Molecular analysis detected the c.733G SNP in 11 of the 17 samples (64,71%) carrying the RHD*46C DEL allele.Sequencing of exon 5 of RHCE gene allowed the identification of the c.697G, c.712G, c.733G, c.744C SNPs in all 733G+ samples.Summary / Conclusions: The c.46C mutation generates an RHD allele responsible for a DEL phenotype whereas the c.697G,c.712G, c.733G, c.744C polymorphisms in the RHCE gene lead to an aberrant expression of the E antigen. Considering the highprevalence of the RHD*46C DEL allele in some regions of Argentina and that approximately 65% of the samples carrying this alleleare associated to an altered RHCE variant, we propose to genotype c.733G in all RHD*46C samples in order to identify the alleleresponsible for an aberrant expression of the E antigen, sometime mistyped as normal E by serology.