What is the type of genetic inheritance that determines the ABO blood group system? What are the relations of dominance among the involved alleles?
The inheritance of the ABO blood system is a multiple alleles inheritance. There are three involved alleles, IA, IB and i that combine in pairs to form the genotypes.
Concerning dominance, the allele i is recessive in relation to the alleles IA and IB. Among IA and IB however lack of dominance is established with the heterozygous (IAIB) manifesting distinct phenotype.