epistasis

In genetics, epistasis refers to a phenomenon where one gene masks or suppresses the effect of another non-allelic gene. The gene that masks another is called an epistatic gene, while the gene whose effect is masked is called the hypostatic gene.12

This is distinct from simple dominance, where one allele masks another allele at the same locus. Epistasis involves interactions between genes located at different loci. A classic example is albinism in humans and mice. The gene for albinism can be epistatic to genes that determine skin or hair color, meaning that if an individual has the albino gene, the genes for pigment production will not be expressed, resulting in a lack of pigment regardless of the other genes present. Epistasis can explain variability in the expression of inherited diseases, where some individuals may show no symptoms despite carrying a disease-causing gene.341