The word "epistatic" refers to a genetic phenomenon where one gene has the ability to suppress or mask the effects of another gene. In simpler terms, it means that one gene can control or override the expression of another gene. Full definition
Our knowledge concerning epistatic relationships between these genes implies the existence of a poorly understood biochemical maintenance of twist expression during mesoderm invagination by the snail gene. (science.institut-curie.org)
[20] It removes the possible influence of dominance and epistatic effects which, if present, will tend to make monozygotic twins more similar than dizygotic twins and mask the influence of shared environmental effects. (en.wikipedia.org)
A considerable genetic heterogeneity is expected within and among studies, as different combinations of the various alleles of the multiple genes and epistatic gene interactions may produce similar phenotypes. (capmh.biomedcentral.com)