Polymorphism of ABO*O alleles and its clinical significance

Abstract

Background. 62 ABO*O alleles of the ABO system are known. Some ABO*O alleles may be accompanied by the presence of residual A-glycosyltransferase activity in people of group O, which may lead to errors in determining the blood group. This confirms the important clinical significance of the ABO*O allele polymorphism. Knowledge of ABO*O gene polymorphisms and their prevalence contributes to the prevention of errors in determining the blood group of the ABO system.Objective: to study allele variants of the ABO*O gene in Russians.Materials and methods. The blood samples of 14,000 people were examined. The blood group was determined using anti-A, anti-Aweak, anti-B, lectin (anti-A1) and gel cards, as well as by cross-sectional method using standard red blood cells of O, A, and B groups. In one patient, the method of adsorption-elution with cold elution was used to identify a weak variant of antigen A, and the method of thermal elution was used to eliminate antigen- blocking plasma factors. Molecular determination of ABO*O alleles was performed in 130 individuals by polymerase chain reaction with sequence- specific primers and Sanger direct sequencing.Results. 13 allelic variants of the ABO*O gene were identified (10 with a typical deletion of c.261delG / N and 3 nondeletional alleles with polymorphism c.802G>A). Deletion alleles of ABO*O.01 were found in 92.85 % of the examined patients, nondeletion alleles of АВО*О.02 group – in 7.15 % of cases. The ABO*O.01.01 allele was detected with a frequency of 67.14 %, other deletion alleles – much less frequently: ABO*O.01.02 and ABO*O.01.11 – 5.71 %, ABO*O.01.26 – 5.00 %, ABO*O.01.12 – 4.30 %, ABO*O.01.13 and ABO*O.01.44 – 1.43 %, ABO*O.01.05, ABO*O.01.46, ABO*O.01.68 – 0.71 % each. Non-deletional alleles were found with the following frequencies: ABO*O.02.01 – 4.3 %, ABO*O.02.03 allele – 2.14 %, ABO*O.02.02 – 0.71 %. All individuals with the O group with the nondeletional allele had the Oαβ group, except for one patient (with the ABO*O.01.02 O.02.02 genotype), who had the Oβ group.Conclusion. For the first time, the immunogenetic characteristics of Russians are given according to ABO*O genes. Erythrocyte genomics helps to resolve the ambiguity of serological methods results and allows understanding mechanisms of different phenotypes formation. For the correct definition of natural isohemagglutinins and weak antigens variants should be used at least two different serological methods.