Serologic strategy in detecting RHD altered alleles in Brazilian blood donors.

Background: We evaluated different technological approaches and anti-D clones to propose the most appropriate serologic strategy in detecting the largest numbers of D variants in blood donors.

Methods: We selected 101 samples from Brazilian blood donors with different expressions of D in our donor routine. The tests were performed in immediate spin (IS) with eleven commercially available anti-D reagents in a tube and microplate.

Characterization of RHD alleles present in serologically RHD-negative donors determined by a sensitive microplate technique.

Background And Objectives: Weak D phenotypes with very low antigen densities and DEL phenotype may not be detected in RhD typing routine and could be typed as D-negative, leading to D alloimmunization of D-negative recipients. The present study aimed to investigate the presence of RHD-positive genotypes in blood donors typed as D-negative by an automated system using the solid-phase methodology as a confirmatory test.

Methods: Two screenings were performed in different selected donor populations.

Correlation among automated scores of agglutination, antigen density by flow cytometry and genetics of D variants.

Background: Laboratory testing to identify the molecular basis of serologic weak D phenotypes is recommended to determine whether a pregnant woman or potential transfusion recipient should be managed as RhD-positive or RhD-negative. The variation in D antigen expression on RBCs, different potencies of anti-D typing reagents, lack of standardized test methods, and the subjectivity of interpreting agglutination reactions complicate the detection of D variants. We evaluated the correlation of agglutination scores by an automated immunoassay analyzer with D antigen densities determined by flow cytometry, and D variant types identified by molecular analysis.

Novel RHAG allele encoding the Rh(null) phenotype in Brazil.

Rhnull is a rare phenotype characterized by the loss of Rh antigen expression. This phenotype can be related to several molecular backgrounds. In this study, we show a novel allele in a Brazilian pregnant woman encoding the Rhnull phenotype due to a change in RHAG exon2 c.

How do we identify RHD variants using a practical molecular approach?

Serologic resolution of Rh discrepancies due to partial D or weak D phenotypes is a frequent problem encountered during routine typing that can be solved by RHD genotyping because it provides better characterization of these variants. The objective of the current study was to develop algorithms for identification of D variants in multiethnic populations based on a logic sequence of molecular tests using a large number of atypical RhD specimens. Thus, a total of 360 blood samples with atypical D antigen expression were analyzed.