What is incomplete expressivity?
“Complete” penetrance means the gene or genes for a trait are expressed in all the population who have the genes. “Incomplete” or ‘reduced’ penetrance means the genetic trait is expressed in only part of the population. The penetrance of expression may also change in different age groups of a population.
How does incomplete penetrance occur?
Incomplete penetrance may be due to the effect of the type of mutation. Some mutations of a given disease may exhibit complete penetrance, where as others in the same gene show incomplete or very low penetrance.
What is meant by variable expressivity?
Variable expressivity refers to the range of signs and symptoms that can occur in different people with the same genetic condition.
Is Huntington disease variable expressivity?
Some diseases, such as Huntington’s disease, may have an earlier onset with more severe symptoms in subsequent generations. This type of variable expressivity is called anticipation.
What makes variable expressivity different from reduced penetrance?
As with reduced penetrance, variable expressivity is probably caused by a combination of genetic, environmental, and lifestyle factors, most of which have not been identified. If a genetic condition has highly variable signs and symptoms, it may be challenging to diagnose. What does it mean if a disorder seems to run in my family?
Is there such a thing as incomplete penetrance?
Incomplete penetrance, variable expressivity, or dosage insensitivity in four families with directly transmitted unbalanced chromosome abnormalities Am J Med Genet A. 2018 Feb;176(2):319-329.doi: 10.1002/ajmg.a.38564. Epub 2017 Dec 1. Authors
When does incomplete penetrance, variable expressivity or dosage insensitivity occur?
Incomplete penetrance, variable expressivity, or dosage insensitivity in four families with directly transmitted unbalanced chromosome abnormalities The direct transmission of microscopically visible unbalanced chromosome abnormalities (UBCAs) is rare and usually has phenotypic consequences.
Is there a microRNA connection to incomplete penetrance?
Incomplete penetrance and variable expressivity: is there a microRNA connection? Incomplete penetrance and variable expressivity are non-Mendelian phenomena resulting in the lack of correlation between genotype and phenotype.