(P-IG-3) Prevalence of the Mia Antigen in a Multi-Ethnic Donor Population

Background/Case Studies: The GYPA and GYPB genes of the MNS blood group are known for gene conversion events leading to hybrid glycophorins. These hybrids express a variety of low prevalence antigens of clinical importance. Most notable, are hybrids expressing Mia with other low prevalence antigens. Though highest in East Asian populations, antibodies to antigens of these hybrids have also been reported in Europe, North America and Australia.

Study

Design/Methods: Donor samples were submitted for genotyping using an in-house selection algorithm. Donor ethnicities were self-reported and included African American, Asian, Caucasian, Hispanic and Other. DNA was extracted on the QIAcube using the QIAamp DNA Blood Mini Kit (Qiagen, Hilden, Germany) and genotyped using the HemoSelect targeted next generation sequencing assay (HaploGNX, San Diego, CA). When available, RBCs were phenotyped to confirm the presence of the Mia antigen (Immucor, Norcross, GA; research use only antisera).

Results/Findings: Of the 15,590 samples genotyped, 2707 (17.4%) were from African American donors; 178 (1.1%) were from Asian donors, 11,560 (74.1%) were from Caucasian donors, 1035 (6.6%) were from Hispanic donors and 110 (0.7%) were from donors self-identified as Other. Sixty-three samples were identified as having an MNS hybrid glycophorin known to express the Mia antigen. Of these, 20 were GYPA*Vw, 17 were GYPA*Hut, two were GP*Mur, 23 were GYP*HF and one bears a novel mutation (see table 1). Forty-nine of the 63 samples were confirmed Mi(a+) by serology. Phenotype confirmation is pending on the remaining 14 samples as RBCs were unavailable for confirmation at the time of genotype testing. No Mi(a+) samples were identified via GYP*Hop or GYP*Bun. Of the GYP*HF, two homozygous examples were identified, one from an Asian donor and one from an African American donor; both of which also possess a variant s antigen. The novel Mia antigen is predicted to include a portion of the GYP*Bun and GP*Mur sequences and reside within GYP*HF.

Conclusions: Numerous reports have been published detailing cases of mild to severe HDFN as well as mild to severe hemolytic transfusion reactions resulting from antibodies to antigens present on these MNS hybrid glycophorins. However, limited data exists identifying ethnic groups shown to possess the antigens. This report demonstrates the prevalence of these antigens as detected in this multi-ethnic donor population.

Importance of research: To date, little data is available identifying ethnic groups positive for the Mia antigen and other antigens associated with these MNS glycophorins hybrids. This study is a comprehensive review of hybrid frequencies in a multi-ethnic population.