Skip to Content


Pronunciation: e-pis'ta-sis


  1. The formation of a pellicle or scum on the surface of a liquid, especially as on standing urine.
  2. Phenotypic interaction of nonallelic genes.
  3. A form of gene interaction whereby one gene masks or interferes with the phenotypic expression of one or more genes at other loci; the gene the express phenotype of which is said to be “epistatic,” whereas the phenotype altered or suppressed is then said to be “hypostatic.”

Synonym(s): epistasy

[G. scum; epi- + G. stasis, a standing]

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.