From The School of Biomedical Sciences Wiki
Jump to: navigation, search

Co-dominance can be considered to be non-mendalian inheritance. In co-dominance there is equal expression of two alleles as the phenotype. If the individual is heterozygous both alleles will be expressed equally[1]. An example of this would be the AB blood group. The genotypes for the A and B antigens are codominant with each other and dominant over the recessive antigen O. This means that the red blood cells will present both A antigens and B antigens on its cell surface membrane.

This is different to incomplete dominance, where the phenotype expressed by an individual is a mixture of both parent alleles. This happens as a result of the dominant allele not being completely expressed over its recessive counterpart. An example of this would be a red flower and white flower producing a progeny pink flower.


  1. Daniel L. Hartl and Elizabeth W. Jones, Genetics Analysis of genes and genomes, 7th Edition, Jones and Bartlett publishers pg 80, pg 712
Personal tools