Frequency of Mia (MNS7) and Classification of Mia-Positive Hybrid Glycophorins in an Australian Blood Donor Population

Abstract

Background: MNS blood group system genes GYPA and GYPB share a high degree of sequence homology and gene structure. Homologous exchanges between GYPA and GYPB form hybrid genes encoding hybrid glycophorins GP(A-B-A) and GP(B-A-B). Over 20 hybrid glycophorins have been characterised. Each has a distinct phenotype defined by the profile of antigens expressed including Mia. Seven hybrid glycophorins carry Mia and have been reported in Caucasian and Asian population groups. In Australia, the population is diverse; however, the prevalence of hybrid glycophorins in the population has never been determined. The aims of this study were to determine the frequency of Mia and to classify Mia-positive hybrid glycophorins in an Australian blood donor population. Method: Blood samples from 5,098 Australian blood donors were randomly selected and screened for Mia using anti-Mia monoclonal antibody (CBC-172) by standard haemagglutination technique. Mia-positive red blood cells (RBCs) were further characterised using a panel of phenotyping reagents. Genotyping by high-resolution melting analysis and DNA sequencing were used to confirm serology. Result: RBCs from 11/5,098 samples were Mia-positive, representing a frequency of 0.22%. Serological and molecular typing identified four types of Mia-positive hybrid glycophorins: GP.Hut (n = 2), GP.Vw (n = 3), GP.Mur (n = 5), and 1 GP.Bun (n = 1). GP.Mur was the most common. Conclusion: This is the first comprehensive study on the frequency of Mia and types of hybrid glycophorins present in an Australian blood donor population. The demographics of Australia are diverse and ever-changing. Knowing the blood group profile in a population is essential to manage transfusion needs.