codominant A heterozygote that shows fully the phenotypic effects of both alleles at a gene locus. For example, humans of the AB blood group show the phenotypic effect of both I^A and I^B codominant genes.

codominant A heterozygote that shows fully the phenotypic effects of both alleles at a gene locus. For example, humans of the AB blood group show the phenotypic effect of both I^A and I^B codominant genes.

codominance The condition that arises when both alleles in a heterozygous organism are dominant and are fully expressed in the phenotype. For example, the human blood group AB is the result of two alleles, A and B, both being expressed. A is not dominant to B, nor vice versa. Compare incomplete dominance.