penetrance


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Related to penetrance: expressivity, Incomplete penetrance

penetrance

 [pen´ĕ-trans]
the frequency with which a heritable trait is manifested by individuals carrying the principal gene or genes conditioning it.

pen·e·trance

(pen'ĕ-trans),
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.

penetrance

/pen·e·trance/ (pen´ĭ-trins) the frequency with which a heritable trait is manifested by individuals carrying the principal gene or genes conditioning it.

penetrance

(pĕn′ĭ-trəns)
n.
The frequency, under given environmental conditions, with which a specific phenotype is expressed by those individuals with a specific genotype.

penetrance

[pen′ətrəns]
Etymology: L, penetrare, to penetrate
the regularity with which an allele is expressed in a person who carries it. If an allele always produces its effect on the phenotype, it is fully penetrant. Achondroplasia is caused by a fully penetrant allele; if the allele is present, achondroplasia results. If an allele produces its effect less frequently than 100% of the time, it is not fully penetrant. Retinoblastoma develops in 90% of the children carrying the allele for the disease; in 10% of children the allele is nonpenetrant. penetrant, adj.

penetrance

Penetration The disruption of a surface, as in penetrating–eg, gunshot wounds, hospital-acquired penetration contact due to infected 'sharps', or forcible penetration in rape

pen·e·trance

(pen'ĕ-trăns)
The frequency, expressed as a fraction or percentage, of people who are phenotypically affected, among people of an appropriate genotype; factors affecting expression may be environmental, or due to purely random variation; contrasted with hypostasis where the condition has a genetic origin and therefore tends to cause correlation in relatives.

penetrance

The frequency with which a GENE manifests its effect. Failure to do so may result from the modifying effect of other genes or from environmental influences. A single hereditable dominant or recessive characteristic is either penetrant or not. Penetrance is measured as the proportion of individuals in a population with a particular genotype who show the corresponding PHENOTYPE.

penetrance

the percentage of individuals with a particular GENOTYPE that display the genotype in the PHENOTYPE. For example, a dominant gene for baldness is 100% penetrant in males and 0% penetrant in most females, because the gene requires high levels of the male hormone for expression, an example of SEX LIMITATION. Once a gene shows penetrance it may show a range of EXPRESSIVITY of phenotype.

penetrance 

The frequency with which the characteristics transmitted by a gene appear in individuals possessing it. Penetrance is represented as the ratio of individuals who carry the gene and express its effects, over the total number of carriers of the gene in a population. Few of the genes in the genome show a high penetrance because environmental factors play a role in development. Examples: familial exudative vitreoretinopathy and neurofibromatosis (type 1 and type 2), which are both inherited as autosomal dominant, have 100% penetrance; about 90% of the children who carry the retinoblastoma gene develop the disease while the gene remains non-penetrant in the remaining 10% of the children. See expressivity; familial exudative vitreoretinopathy.

penetrance

the frequency with which a heritable trait is manifested by individuals carrying the principal gene or genes conditioning it.

incomplete penetrance
when penetrance is less than 100%.
References in periodicals archive ?
While classical Mendelian genetic disorders result from mutations in single genes that have relatively high penetrance and are therefore readily recognizable clinically, many common clinical disorders known to have hereditary transmission are associated with genetic mutations that do not produce a clinically recognizable phenotype due to poor penetrance yet are far more prevalent in the general population.
Furthermore, because H63D and C282Y are known to have different penetrance rates (Burke et al.
Primary HOA is rare and often familial, transmitted as autosomal dominant with variable penetrance.
Acute intermittent porphyria (AIP) is a hereditary hepatic porphyria inherited as autosomal dominant with low penetrance resulting from mutation in the gene encoding the enzyme, porphobilinogen deaminase (PBG-D) [hydroxymethylbilane synthase, uroporphyrinogen I synthase].
Prevalence and penetrance of BRCA1 and BRCA2 mutations in a population-based series of breast cancer cases.
Munro CS: The phenotype of Darier's disease: penetrance and expressivity in adults and children.
12) The penetrance of the C282Y/C282Y genotype, or proportion of persons with the genotype who develop clinical disease, is thought to be considerably less than 100%.
This certainty is described as 100 percent penetrance.
Penetrance is the likelihood a genetic trait will be expressed; in complete penetrance, all persons with the gene express the trait, but in incomplete penetrance, only a portion of the population with the gene expresses the genetic trait.