What is codominance?

Codominance

Codominance is a type of inheritance where two versions (alleles) of the same gene are expressed separately to yield different traits in an individual. Unlike complete dominance, where one allele masks the expression of the other, or incomplete dominance, where the phenotype is a blend of both alleles, codominance results in both alleles being equally and independently expressed.

Key characteristics of codominance include:

• Both alleles are expressed: Neither allele is recessive or masked. Both contribute to the phenotype.
• Distinct phenotypes: The heterozygous individual displays a phenotype that shows both traits associated with each allele.
• No blending: The phenotype is not an intermediate or blending of the two traits, but rather a display of both.

A classic example of codominance is the ABO blood group system in humans. The A and B alleles are codominant. An individual with both the A and B alleles (genotype AB) will express both A and B antigens on their red blood cells, resulting in blood type AB. Another good example is roan coloration in cattle, where both red and white hairs are expressed, rather than a blended pink color.