A gene showing codominance has: Both alleles independently expressed in the heterozygote; One allele dominant on the other; Alleles tightly linked on the same chromosome; Alleles that are recessive to each other

Codominance is a condition in which the alleles of a gene pair in a heterozygote are fully expressed thereby resulting in offspring with a phenotype that is neither dominant nor recessive. In codominance, the phenotypes produced by both alleles are clearly expressed. A typical example showing codominance is the ABO blood group system. For instance, a person having A allele and B allele will have a blood type AB because both the A and B alleles are codominant with each other.