What is the phenotypic ratio of F1 progeny in codominance?
The phenomenon of expression of both the alleles in a heterozygote is called codominance. The heterozygous condition has a phenotype different from either of the homozygous genotypes. The joint character may appear to be intermediate between the ones produced by the two homozygous genotypes. The phenotypic ratio of F1 progeny is found to be 1:2:1.
Examples of codominance: AB blood group, MN blood group and sickle-cell haemoglobin.