Editing Penetrance (section)

=== Reduced penetrance ===
The penetrance is said to be reduced if less than 100% of individuals carrying a particular genotype express associated traits, and is likely to be caused by a combination of genetic, environmental and lifestyle factors.<ref name=":0" /><ref name=":1" /> ''[[BRCA1]]'' is an example of a genotype with reduced penetrance. By age 70, the mutation is estimated to have a breast cancer penetrance of around 65% in women. Meaning that about 65% of women carrying the gene will develop breast cancer by the time they turn 70.<ref>{{Cite journal |last1=Chen |first1=Jinbo |last2=Bae |first2=Eunchan |last3=Zhang |first3=Lingjiao |last4=Hughes |first4=Kevin |last5=Parmigiani |first5=Giovanni |last6=Braun |first6=Danielle |last7=Rebbeck |first7=Timothy R |date=23 April 2020 |title=Penetrance of Breast and Ovarian Cancer in Women Who Carry a BRCA1/2 Mutation and Do Not Use Risk-Reducing Salpingo-Oophorectomy: An Updated Meta-Analysis |url=https://doi.org/10.1093/jncics/pkaa029 |journal=JNCI Cancer Spectrum |volume=4 |issue=4 |pages=pkaa029 |doi=10.1093/jncics/pkaa029 |issn=2515-5091 |pmc=7353955 |pmid=32676552 }}</ref>

* '''Non-penetrance:''' Within the category of ''reduced penetrance,'' individuals carrying the mutation without displaying any signs or symptoms, are said to have a genotype that is non-penetrant. For the BRCA1 example above, the remaining 35% which never develop breast cancer, are therefore carrying the mutation, but it is non-penetrant. This can lead to healthy, unaffected parents carrying the mutation on to future generations that might be affected.<ref name=":3">{{Citation |last1=Korf |first1=Bruce R. |title=Chapter 19 - Introduction to Human Genetics |date=1 January 2009 |work=Clinical and Translational Science |pages=265–287 |editor-last=Robertson |editor-first=David |url=https://www.sciencedirect.com/science/article/pii/B9780123736390000194 |access-date=13 February 2024 |place=San Diego |publisher=Academic Press |doi=10.1016/b978-0-12-373639-0.00019-4 |isbn=978-0-12-373639-0 |last2=Sathienkijkanchai |first2=Achara |editor2-last=Williams |editor2-first=Gordon H. |url-access=subscription |archive-date=17 February 2023 |archive-url=https://web.archive.org/web/20230217203012/https://www.sciencedirect.com/science/article/pii/B9780123736390000194 |url-status=live }}</ref>