Hybrid glycophorin and red blood cell antigen genotyping in Asian American type O blood donors with Mi phenotype.

BACKGROUND

The GP.Mur glycophorin with Mi phenotype is relatively common and clinically significant in the Southeast Asian populations. The aim of this study is to genotype Mi -positive Asian American type O blood donors. Red blood cell (RBC) minor antigens were also determined in the same cohort.

STUDY DESIGN AND METHODS

Asian American blood donors of the Gulf Coast Regional Blood Center (Houston, TX) were screened using a typing reagent (NOVACLONE Anti-Mi Monoclonal IgG Typing Reagent, Dominion Biologicals Ltd) from March 2016 to July 2018. Aliquots of Mi -positive blood from type O donors were subjected to serologic confirmation using Mi - and/or Mur-specific GAMA210 and 64D6 monoclonal antibodies, and two human antisera. Extracted genomic DNA was amplified by polymerase chain reaction (PCR) using GYP hybrid gene/allele-specific primers followed by bidirectional Sanger sequencing. Zygosity for GYPMur and GYPBun was determined using TaqMan real-time PCR assay. Phenotypes of 35 RBC antigens and three phenotypic variants were determined with use of an in vitro diagnostic test, PreciseType HEA Molecular BeadChip Test (Immucor).

RESULTS

By screening 4600 blood donations in the Houston metropolitan area, 209 samples from 103 unique donors were identified to be Mi -positive. By PCR and sequencing analysis, 97 of the 103 Mi -positive donors carried hybrid genes GYPMur (89.7% including two homozygotes), GYPBun (6.2%), GYPVw (3.1%) and GYPHut (1.0%). Concordance between serology and DNA analysis was 98%, 99%, and 100% for the GAMA210, 64D6, and human antisera, respectively. Genotyping of RBC antigens showed that the Mi -positive donors were predominantly associated M+ N- S- s+ (48.5%) and M+ N+ S- s+ (38.1%) phenotypes.

CONCLUSIONS

The GP.Mur glycophorin is most prevalent in the Mi -positive Asian American type O blood donors.