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Pronunciation: pen'e-trans

Definition: The frequency, expressed as a fraction or percentage, of people who are phenotypically affected, among those of an appropriate genotype (i.e., homozygous or hemizygous for recessives, heterozygous or hemizygous for dominants); for an autosomal dominant disorder, if only a proportion of people carrying the mutant allele display the abnormal phenotype, the trait is said to show incomplete penetrance. If all with the mutant allele show the abnormal phenotype, the trait is said to have complete or full penetrance.

See: penetration

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