What does epistasis mean?
Epistasis is a genetics term for an interaction between genes in which one gene masks or modifies the phenotypic effect of another. For example, one gene may determine whether a second gene's effect is visible, changing the observable trait and the way it is inherited. The term is especially important in studies of inheritance, plant breeding, developmental biology, and quantitative genetics, where interactions among multiple genes can produce patterns that do not follow simple Mendelian ratios. Epistasis is also used more broadly for situations in which one influence conceals or alters the effect of another. Its usefulness lies in showing that biological traits often arise not from isolated genes but from interactions among them. The concept is therefore central to understanding how genetic variation is expressed and how complex traits develop.
nounIn genetics, epistasis is the interaction between genes in which the expression of one gene masks or modifies the phenotypic effect of another.
- The interaction between genes in which the expression of one gene masks or modifies the phenotypic effect of another.
"The mutation illustrates epistasis by masking the effect normally produced by the other gene."
"The researchers identified a form of genetic epistasis that masks the lethal effect of a mutation in another gene."
"In plant breeding, epistasis can make the inheritance pattern of a trait appear more complex than a simple Mendelian ratio would predict."
The plural is possible but uncommon in ordinary writing.
"The study compared several forms of epistases affecting pigmentation."
One gene can act like a dimmer switch for another: epistasis is when the switch's setting changes how the second gene is expressed.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does epistasis come from?
Epistasis comes from Greek ἐπίστασις (epistasis), a formation from epi, meaning “upon,” and stasis, meaning “standing” or “position,” with stasis ultimately related to histan, “to stand.” The term was later adopted in genetics for the masking or modification of one gene's phenotypic effect by another. Its Greek relatives include apostasy and apostate, while static and status belong to a wider family of words connected with the same root idea of standing.
Related word forms
How epistasis is actually used
This is primarily a technical term in genetics, used in studies of inheritance, gene function, quantitative traits, plant breeding, and genomics. In general contexts, it may be understood figuratively as one influence concealing or altering the effect of another.
Easily confused with epistasis
Epistasis concerns how one gene masks or modifies the effect of another, whereas epistemic relates to knowledge or the conditions for acquiring it.
Apoptosis is programmed cell death, while epistasis is a form of interaction between genes affecting the expression of traits.