Molecular serological characteristics of ABO system A antigen

Abstract

Background. One of the polymorphic antigens in the ABO system is antigen A, which includes many allelic variants with different expression. Immunological methods for determining the blood group of the ABO system have limitations in their use, including due to the presence of weekly expressed antigens in humans. For the correct determination of blood group according to the ABO system, genetic typing is becoming increasingly important. 89 alleles of the ABO*A gene are known. Knowledge of ABO*A gene polymorphisms and their prevalence contributes to the prevention of errors in determining the blood group of donors and recipients.Objective: to describe variants of ABO*A gene alleles in Russians and serological characteristics of the antigens encoded by them.Materials and methods. The blood of 14,000 people was examined. The blood group was determined using anti-A, anti- Aweak, anti-B, lectin (anti-A1) and gel cards. A molecular study of ABO*A gene polymorphisms was conducted in 151 people. Polymerase chain reaction with sequence-specific primers and direct Sanger sequencing were used.Results. 7 different ABO*A alleles were detected, including the ABO*A1.01 and ABO*A1.02 alleles. In 118 individuals with a weak A antigen, the ABO*A2.01 allele was the most frequent (87.29 %). Rare alleles ABO*A2.06 (5.93 %), ABO*AW.06 (4.23 %), ABO*A2.09 (0.85 %) and ABO*Ax (1.70 %) were found. Serological characteristics of A antigens variants depending on genotypes are described, variants A1, A2, A3 and very weak A were detected. Extraagglutinins α1 were absent in all persons with weakened A antigen.Conclusion. Small or mixed agglutination with Coliclones or red blood cell stratification in the gel suggest the presence of antigen A with weakened expression. Modern molecular methods make it possible to identify rare gene alleles and genotypes. Erythrocyte genomics helps to resolve the ambiguity of the serological results allows understanding the true mechanisms of particular phenotype formation and makes a contribution to ensuring the immunological safety of blood components transfusions.