Penetrance

Penetrance is a term used in genetics describing the proportion of individuals carrying a particular variation of a gene that also express a particular trait . For example, Huntingtons disease has 95% penetrance, whereby 5% of those with the dominant allele for Huntingtons don't acquire the disease and 95% do. In other word, penetrance is the percentage of individuals with a specific genotype that possess an associated phenotype. For example, if 50% of the individuals carrying the "blue" allele are blue, the "blue" allele has 50% penetrance. Penetrance only considers whether individuals express the trait or not — for variation in the degree of expression of a given trait, see expressivity.If a allele is highly penetrant, the trait it produces will always or almost always be apparent in an individual carrying the allele. Reduced or incomplete penetrance occurs when some individuals fail to express the trait, even though they carry the allele. An allele with low penetrance will only sometimes produce the symptom or trait with which it has been associated at a detectable level. In the case of low penetrance it is difficult to distinguish environmental from genetic factors.Common examples used to show degrees of penetrance are often highly penetrant. There are several reasons for this:#Highly penetrant alleles, and highly heritable symptoms, are easier to demonstrate – if the allele is present, the phenotype is expressed ;#Alleles which are highly penetrant are more easily noticed by geneticists, and alleles for symptoms which are highly heritable are more easily inferred to exist, and then more easily tracked down.However, relatively few of the alleles in the genome show high penetrance. Traits such as height or intelligence are influenced by multiple genes as well as by environmental factors. Distribution of polygenic traits often falls along a bell curve.The penetrance of some diseases is age-related. An example is multiple endocrine neoplasia 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 penetrance of MEN1 was 7 percent by age 10 years and nearly 100 percent by age 60 years. (From the Wikpedia article Penetrance.)

Download PDF containing detailed information.

Recent Publications on Penetrance:
General lessons from large-scale studies to identify human cancer predisposition genes. There are now about 100 genes known to cause Mendelian inherited cancer...	21st November, 2009	Molecular and Population Genetics Laboratory, Wellcome Trust Centre for	J Pathol. 2009 Nov 19. DOI Direct Link
The challenge of detecting epistasis (GxG Interactions): Genetic Analysis Workshop 16. Interest is increasing in epistasis as a possible source of the...	20th November, 2009	Division of Statistical Genomics and Department of Genetics, Washington	Genet Epidemiol. 2009 Nov 18;33(S1):S58-S67. DOI Direct Link
Longitudinal Evaluation of an N-Ethyl-N-Nitrosourea-Created Murine Model with Normal Pressure Hydrocephalus. BACKGROUND: Normal-pressure hydrocephalus (NPH) is a neurodegenerative...	20th November, 2009	Department of Neurology, National Taiwan University Hospital, College of	PLoS One. 2009 Nov 17;4(11):e7868. DOI Direct Link
A rare Asian founder polymorphism of Raptor may explain the high prevalence of Moyamoya disease among East Asians and its low prevalence among Caucasians. BACKGROUND: In an earlier study, we identified a locus for Moyamoya...	19th November, 2009	Department of Health and Environmental Sciences, Kyoto University Graduate	Environ Health Prev Med. 2009 Nov 19. DOI Direct Link
COGENT (COlorectal cancer GENeTics): an international consortium to study the role of polymorphic variation on the risk of colorectal cancer. It is now recognised that a part of the inherited risk of colorectal...	19th November, 2009	Molecular and Population Genetics, Nuffield Department of Medicine,	Br J Cancer. 2009 Nov 17. DOI Direct Link
→View more research publications.

Penetrance Patents:
US Patent No.	Title
7495102	Azaindole inhibitors of aurora kinases
7514594	Transgenic animal model of bone mass modulation
7517522	ADAMTS13 genes and proteins and variants and therapeutic compositions and methods utilizing the same
7517648	NPHP nucleic acids and proteins
7528093	SCN3A locus for idiopathic generalized epilepsy, mutations thereof and method using same
→View more patents.

BioPortfolio Ltd. offers e-mail and postal lists for Penetrance scientists - we have details of around 588 individuals working on Penetrance .