Examples of Mendelian deviations:
1. Codominance
In one of the Mendelian law (the third) it is described that there is a dominant and recessive allele of the gene and if these two are inherited together and form heterozygote (one from mother one from father) only the trait of the dominant allele will be expressed.
Codominance is one of the examples that there are exceptions. If the dominant and recessive alleles are in the heterozygote, both will be expressed equally. Example of codominance is blood types. If there is allele Ia and allele Ib the blood type (expressed trait) will be AB.
2. Incomplete dominance
This is also the deviation of Mendel’s laws. It happens when the dominant allele does not mask the phenotypic expression of the recessive allele in a heterozygote. The expressed phenotype will be between the phenotypes of its homozygous. For example, if allele a is for the red color of the flower and A for the white, heterozygous Aa will give pink color.
