Molecular genetic analysis of Mia‐positive hybrid glycophorins revealed two novel alleles of GP.Vw and multiple variant transcripts of GYPB existing in both the homozygous GP.Mur and wild‐type GPB individuals

Background The hybrid glycophorins of MNS blood group system express a series of low incidence antigens including Mia, which are commonly found in Southeast Asian populations. In this study, the molecular basis of Mia‐positive hybrid glycophorins was firstly clarified in the Chinese Southern Han population. RNA transcripts of GYPB gene in the homozygous GP.Mur individuals were also analyzed. Study design and methods DNAs were extracted from the whole blood samples of 111 Mia‐positive donors. Then, high‐resolution melting (HRM) analysis for GYP(B‐A‐B) was used to analyze the genotypes. Sequencing of GYPB pseudoexon 3 was conducted in the samples with variant melting curves. TA‐cloning and subsequent sequencing of GYPA exons 2–4 were performed in the Mia‐positive samples with normal GYPB/GYPB genotype by HRM. The transcript analysis of GYPB was conducted in homozygous GP.Mur and wild‐type glycophorin B (GPB) individuals using RNA extracted from the cultured erythroblast. Results The heterozygous GYP*Mur/GYPB (n = 101), homozygous GYP*Mur/GYP*Mur (n = 7) including one novel GYP*Mur allele with an extra GYPA/GYPE specific nucleotide substitution (c.229+110A>T), heterozygous GYP*Bun/GYPB (n = 1) and GYP*Vw/GYPA (n = 2) with two novel GYP*Vw alleles were identified. RNA transcript analysis revealed multiple transcripts of GYPB existing in both homozygous GP.Mur and normal GPB individuals. Conclusion The results showed the genetic diversity of hybrid glycophorins in the Chinese population. Besides, the successful analysis of GYPB transcripts indicates that the cultured erythroblast is a good source for RNA transcript analysis for the protein only expressed on the red blood cells.