Genes interact with one other and control the phenotypes. Some of the genes not only control their own expression but also mask or regulate the expression of other genes. These genes, known as epistatic genes, mask the activity of the other genes. The epistatic genes create certain modifications in other genes. The genes getting masked or altered by the other genes do not express themselves due to the activity of masking. Hence, they are known as hypostatic genes. Epistasis also results due to the presence of a single dominant allele in a pair. We intend to discuss the recessive epistasis, dominant epistasis, and epistasis involving duplicate genes. Mostly the F2 generations show the phenotypic ratio of 9:3:3:1.

Image: Examples of Epistasis (Coat color in the mice depicting the recessive epistasis with a phenotypic ratio of 9:3:4; Color of summer squash depicting the dominant epistasis with a phenotypic ratio of 12:3:1; and flower color depicting the epistasis involving duplicate genes…