Experimental Study And Two Family Survey On RhD-deletion Phenotype

RhD-- deletion is a very rare variant in Rh blood group system.It is characterized with the completely absence of C/c,E/e antigen and(or) elevated expression of D antigen.RhD--deletion individuals are easily immunized by transfusion or pregnancy.The high titer alloantibody produced,may cause severe hemolytic disease of fetus or newborn. However,the mechanism of RhD-- deletion is still unclear.We found two suspicious RhD-- cases in clinic and made a preliminarily investigation about the two RhD-- individuals and their family members in serological and molecular aspects.The First Section Serological detection on RhD--individuals and genealogical blood group investigationRh deletion D-- is defined on the serological aspect at present.We made all-round serological tests to the two RhD-- individuals,including identification of blood group,Coombs test,antibody screening and identification,antibody titer and HDN test,together with investigation of genealogical blood group to all family members by classic hemagglutination methods.It indicated:no RhC/c,E/e antigen was detected on the surface of the red cells and there existed an antibody aim directly at the antigens.In the family survey,we found the two individuals come from cognate and non-cognate families and the parental phenotypes were homozygous.Therefore,we confirmed the two individuals to be RhD-- phenotype.RhD--can occur in cognate and non-cognate families. The Second Section Rh blood group genotyping and sequence analysis on RhD-- individuals and family membersIn order to preliminarily approach the molecular mechanisms of the RhD--,we amplified many exons and introns of RHD and RHCE gene with polymerase chain reaction-sequence specific primers.Then,we sequenced the abnormal amplified segment disagreed with its phenotype based on the PCR results.We detected from the PCR-SSP that D,e related gene fragments existed in the two RhD--.By sequencing with the abnormal fragments related with e antigen,we found:the 251886th nucleotide of exons 5 was absent and Point mutations were found at the 251922nd and 251954th nucleotide in the 1st individual.The 251953rd nucleotide of exon 5 was found mutation in the 2nd individual.So we confirmed that the exon deletion,together with deletion and mutation of single nucleotide were important reasons resulting in RhD--.