Evaluation of the applicability and effectiveness of a molecular strategy for identifying weak D and DEL phenotype among D– blood donors of mixed origin exhibiting high frequency of RHD*Ψ

BACKGROUND Molecular tests designed to detect the presence of active RHD gene among D– donors have been successfully applied in people of European ancestry, but not in admixed populations with a considerable frequency of RHD*Ψ . Our goal was to evaluate the performance of a molecular screening tool for identifying active RHD alleles among Brazilian blood donors classified as D– C+ and/or E+. STUDY DESIGN AND METHODS Pools of five DNA samples of serologically D– C+ and/or E+ donors were checked by a RHD polymerase chain reaction (PCR) assay specific for RHD Intron 4 and Exon 7. When a pool result was positive, samples were genotyped individually for RHD Intron 4 and Exon 7, RHD*Ψ , RHCE*Cc , and RHD zygosity. Donors suspected of active RHD gene were further evaluated by whole‐coding region and flanking intron direct sequencing. RESULTS A total of 405 donors were included. Two percent exhibited active RHD gene, codifying D‐weak (38 and 45) or DEL phenotype. The most prevalent DEL allele was RHD*DEL1 (c.1227G>A), which is proven to be immunogenic. A high frequency of RHD*Ψ was detected in the donors with nondeleted RHD alleles (31%), far superior to the frequency of RHD variant alleles (15.5%). The proposed approach presented sensitivity of 100% and specificity of 85.7% for identifying active RHD gene. CONCLUSION The strategy of checking D– donors with RHD PCR followed by exclusion of RHD*Ψ allele has proved efficient in identifying weak‐D and DEL phenotype in the Brazilian population.