Masking gene interaction is also recognized as dominant epistasis. Here, dominant allele of one gene can mask the effect of either allele of the second gene.

Pleiotropy is the condition where either a single gene has multiple functions in the body or two genes have the same expression of the single character.

When two types of allele have similar functions but different structures, it is called pseudoallele. These genes located in close proximity.

It is a type of phenotypic variation where a single trait of an organism is usually changed due to environmental effects. This is not a hereditary effect when environmental conditions removed it goes back to normal.