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- Known as incomplete penetrance, this term can be broadly defined as any absence of clinical disease in individuals harboring a known disease-causing genotype.
Jul 25, 2022 · A genotype-based definition of the causes of rare diseases incorporating information from population cohorts and clinical studies is critical for our understanding of incomplete penetrance and variable expressivity.
- Rebecca Kingdom, Caroline F. Wright
- Front Genet. 2022; 13: 920390.
- 10.3389/fgene.2022.920390
- 2022
People also ask
What is the difference between complete and incomplete penetrance?
What is incomplete penetrance in genetics?
What causes incomplete penetrance?
What is an example of incomplete penetrance?
- Overview
- Reduced penetrance
- Variable expressivity
- For more information about reduced penetrance and variable expressivity:
- Topics in the Inheriting Genetic Conditions chapter
Reduced penetrance and variable expressivity are factors that influence the effects of particular genetic changes. These factors usually affect disorders that have an autosomal dominant pattern of inheritance, although they are occasionally seen in disorders with an autosomal recessive inheritance pattern.
Penetrance refers to the proportion of people with a particular genetic variant (or gene mutation) who exhibit signs and symptoms of a genetic disorder. If some people with the variant do not develop features of the disorder, the condition is said to have reduced (or incomplete) penetrance. Reduced penetrance often occurs with familial cancer syndromes. For example, many people with a variant in the BRCA1 or BRCA2 gene associated with an increased cancer risk will develop cancer during their lifetime, but some people will not. Doctors cannot predict which people with these variants will develop cancer or when the tumors will develop.
Reduced penetrance probably results from a combination of genetic, environmental, and lifestyle factors, many of which are unknown. This phenomenon can make it challenging for genetics professionals to interpret a person’s family medical history and predict the risk of passing a genetic condition to future generations.
Although some genetic disorders exhibit little variation, most have signs and symptoms that differ among affected individuals. Variable expressivity refers to the range of signs and symptoms that can occur in different people with the same genetic condition. For example, the features of Marfan syndrome vary widely— some people have only mild symptoms (such as being tall and thin with long, slender fingers), while others also experience life-threatening complications involving the heart and blood vessels. Although the features are highly variable, most people with this disorder have a variant in the same gene (FBN1).
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.
Additional information about penetrance and expressivity is available from the Merck Manual Consumer Version.
Feb 28, 2021 · “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.
Incomplete penetrance examples such as OI demonstrate that even monogenic diseases do not have predictable expression patterns in a population. Is there a way to explain this unpredictability?
Penetrance refers to the likelihood that a clinical condition will occur when a particular genotype is present. A condition is said to show incomplete penetrance when some individuals who carry the pathogenic variant express the associated trait while others do not. Also called reduced penetrance.
Jan 4, 2019 · Incomplete penetrance is a phenomenon of interest to many geneticists, with particular emphasis on disease expression. It occurs in genes of many animals, including humans, and is common with autosomal dominant diseases.
Genetic background and environment contribute to incomplete penetrance, in which not all individuals with a genotype display a corresponding phenotype, and variable expressivity, in which individuals of a particular genotype may have stronger or weaker versions of a phenotype.
