unilateral suppression unilateral suppression (partial) 2013-06-05T21:39:32Z An effect in which the perturbation of one gene, which has no effect on the phenotype in question, is combined with the perturbation of another gene, which causes the mutant phenotype in question, and results in the amelioration or lessening of the severity/penetrance of the mutant phenotype, in effect making the organism more, but not completely, "wild type" in character with regards to the phenotype in question. With respect to any single quantifiable phenotype, this may be expressed as an inequality as: a < ab < b = wt [E = a] OR wt = b < ab < a [E = a] where 'a' and 'b' are the observed phenotype values of the individual perturbations, 'ab' is the observed phenotype value of the double perturbation, 'E' is the expected phenotype value of the double perturbation, and 'wt' is the wild type phenotype value. MI:1294 PSI-MI orchard