Aim. To establish the frequency of the phenotypes of the AB0 system, as well as the calculation of the frequencies of conditional alleles and genotypes (according to F. Bernstein).
Materials and methods. AB0 blood groups were determined according to a standard procedure in 2,107 healthy residents of Odessa, taking into account the age of the patients. Calculations were made according to F. Bernstein and H. Hardy–W. Weinberg.
Results. In the sample studied, the frequency of the phenotype 0 and the frequency of the phenotype AB is lower than reported in studies in population in Ukraine. Analysis of the phenotype frequencies in different age groups showed a significant (p<0.05) increase in the frequency of phenotype 0 in the older age group against the background of a decrease in the frequencies of phenotypes A and AB. The frequency of the allele i increased and the frequency of the IA allele decreased. An increase in the frequency of genotype іі was observed, due to a decrease in the frequencies of the IAIA and IAIВ genotypes.
Conclusion. The frequency of phenotypes 0, A, B, AB was 30.8%, 39.2%, 19.9%, 10.2%, respectively. The dynamics of the genetic structure of the population is determined depending on the age of the group. The selective advantage of phenotype 0 requires further study.