Determining the frequency of colton blood group antigens Coa and Cob in the Maltese population

Abstract

This study aimed at identifying the frequency of two blood group antigens of interest within the Colton (Co) blood group system, Coa and Cob , the higher and lower prevalence antigens respectively. The antigenic frequency was determined using the polymerase chain reaction-allele specific primer extension (PCR-ASPE) technique on a sample size of 68 adult Maltese blood donor samples and 351 neonatal cord blood samples. The aforementioned methodology enabled the molecular typing of the missense variant in the aquaporin 1 (AQP1) gene (NM_198098:c.134C>T; rs28362692), responsible for the single amino acid change of Ala45Val (alanine for Coa and valine for Cob at position 45) (NP_932766:p.Ala45Val) within the AQP1 protein chain. As a result of the missense variant, the Colton phenotypes Co(a+b-), Co(a+b+) and Co(a-b+) could be identified through the stipulated PCR-ASPE technique, and the rare phenotype, Co(a-b+), if detected, would also be subjected to DNA sequencing. Analysis of raw data unveiled that the Co(a+b-) phenotype was the most prevalent in both the donor pool (88.23%) and the cord blood pool (86.04%), whilst the Co(a+b+) phenotype revealed a lower occurrence in the donor pool (5.88%) and the cord blood pool (6.98%). The Co(a-b+) was not encountered in the donor and cord blood samples tested, negating the need for DNA sequencing. The novelty of this study can be seen in the unprecedented determination of the frequency of the Coa and Cob antigens within the Maltese population. Outlining the Colton blood group antigen frequencies is a significant step to understand any susceptibilities to the development of the pertinent antibodies, thus aiding in the reduction of Haemolytic Transfusion Reactions (HTRs) and Haemolytic Disease of the Foetus and Newborn (HDFN). Moreover, research of this calibre would expand the local database of molecular typing of blood group antigens, improving transfusion.