<unk>  is a term used in genetics that describes the extent to which the properties controlled by a gene, its phenotype, will be expressed. For example Huntingtons disease has 95%<unk>  whereby 5% of those with the dominant allele for Huntingtons don't acquire the disease and 95% do.<unk>  is the percentage of individuals with a specific genotype which possess an associated phenotype. For example, if 50% of the individuals carrying the "blue" gene are blue, the "blue" gene has 50%<unk> .
If a gene is highly penetrant, the trait it produces will always or almost always be apparent in an individual carrying the gene. A gene with low<unk>  will only sometimes produce the symptom or trait with which it has been associated at a detectable level. In the case of low<unk>  it is difficult to distinguish environmental from genetic factors.
Common examples used to show degrees of<unk>  are often highly penetrant. There are several reasons for this:
However, relatively few of the genes in the genome show high<unk> . Traits such as height or intelligence are modified by multiple genes as well as by environmental factors. Distribution of polygenic traits often falls along a bell curve.
The<unk>  of some diseases is age-related.  An example is multiple endocrine neoplasia 1 (MEN 1), a disorder characterized by parathyroid hyperplasia and pancreatic islet-cell and pituitary adenomas.   It is due to a mutation in the menin gene on chromosome 11q13.  In one study the age-related<unk>  of MEN1 was 7 percent by age 10 years and nearly 100 percent by age 60 years.
Penetrance
Mixture
Association 
Anise
Derivative 
Amplification 
Providencia
Sublimation 