Impact of a confirmatory RhD test on the correct serologic typing of blood donors

BACKGROUND: The RHD gene is highly polymorphic, which results in a large number of RhD variant phenotypes. Discrepancies in RhD typing are still a problem in blood banks and increase the risk of alloimmunization. In this study, the RhD typing strategy at a blood bank in Brazil was evaluated.METHODS: One-hundred and fifty-two samples typed as RhD negative and C or E positive by routine tests (automated system and indirect antiglobulin test using the tube technique) were reevaluated for RhD status by three methods. The method with the best performance was implemented and evaluated for a period of one year (n = 4897 samples). Samples that were D positive exclusively in the confirmatory test were submitted to molecular analysis.RESULTS: The gel test for indirect antiglobulin testing with anti-D immunoglobulin G (clone ESD1) presented the best results. Seventy samples (1.43%) previously typed as RhD negative showed reactivity in the gel test for indirect antiglobulin testing and were reclassified as D positive. D variants that may cause alloimmunization, such as weak D type 2 and partial DVI, were detected.CONCLUSION: The confirmatory RhD test using the gel test for indirect antiglobulin testing represents a breakthrough in transfusion safety in this blood center. Our results emphasize the importance of assessing the blood group typing strategy in blood banks.

Molecular analysis of the GYPB gene to infer S, s, and U phenotypes in an admixed population of Minas Gerais, Brazil

OBJECTIVE: To implement genotyping for S, s and U antigens of the MNS blood group system at the Fundação Hemominas and to evaluate the occurrence of GYPB gene polymorphisms associated with the U- and U+var phenotypes and deletion of the GYPB gene for the first time in an admixed population of Minas Gerais, Brazil. The S, s and U antigens can cause transfusion reactions and perinatal hemolytic disease. Genotyping is a useful tool in immunohematology, especially when phenotyping cannot be performed. METHODS: Ninety-six samples from blood donors and patients with sickle cell disease previously phenotyped for the S, s and U antigens were selected. Allele-specific primer polymerase chain reaction (ASP-PCR) and polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) assays were employed to identify the GYPB*S and GYPB*s alleles and the GYPB(P2) and GYPB(NY) variants, as well as deletion of the GYPB gene. RESULTS: The results of allele-specific genotyping (GYPB*S and GYPB*s) were totally in agreement with the phenotyping of S+ (n = 56), s+ (n = 60) and s- (n = 35) samples. However, the GYPB*S allele, in association with the GYPB(P2) variant, was detected in 17.5% of the S- samples (n = 40), which shows the importance of assessing this variant in the Brazilian population. Of the S-s- samples (n = 10), 60% had the deletion of the GYPB gene and 40% were homozygous or hemizygous for the GYPB(P2) variant. CONCLUSION: Genotyping was an effective strategy to infer the S, s, and U phenotypes in the admixed population from Minas Gerais (Brazil) and may contribute to transfusion safety.