penetrance The proportion of individuals of a specified genotype who manifest that genotype in the phenotype under a defined set of environmental conditions. If all individuals carrying a lethal mutation die prematurely, then the mutant gene is said to show complete penetrance. An organism may not express the phenotype normally associated with its genotype because of the presence of modifiers, epistatic genes (see EPISTASIS), or suppressors in the rest of the genome; or because of a modifying effect of the environment. Expressivity describes the degree or extent to which a given genotype is expressed phenotypically in an individual.

penetrance The proportion of individuals of a specified genotype who manifest that genotype in the phenotype under a defined set of environmental conditions. If all individuals carrying a lethal mutation die prematurely, then the mutant gene is said to show complete penetrance. An organism may not express the phenotype normally associated with its genotype because of the presence of modifiers, epistatic genes (see EPISTASIS), or suppressors in the rest of the genome; or because of a modifying effect of the environment. Expressivity describes the degree or extent to which a given genotype is expressed phenotypically in an individual.

penetrance The proportion of individuals of a specified genotype who manifest that genotype in the phenotype under a defined set of environmental conditions. If all individuals carrying a lethal mutation die prematurely, then the mutant gene is said to show complete penetrance. An organism may not express the phenotype normally associated with its genotype because of the presence of modifiers, epistatic genes (see epistasis), or suppressors in the rest of the genome; or because of a modifying effect of the environment. Expressivity describes the degree or extent to which a given genotype is expressed phenotypically in an individual.