Epistasis is the control of a phenotype by two or more genes. This genetic interaction often involves the masking of the phenotypic effects of one gene by the effects of a second gene. A gene is epistatic when its presence suppresses the effect of the other gene. Epistatic genes are also known as inhibiting genes due to their effects on other genes which are described as hypostatic.
The inverse of epistasis is pleiotropy, whereby a single gene controls more than one phenotypic trait.
