{"id":2753,"date":"2016-06-13T17:05:11","date_gmt":"2016-06-13T17:05:11","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/biologyxwaymakerxmaster\/?post_type=chapter&#038;p=2753"},"modified":"2024-04-29T16:32:57","modified_gmt":"2024-04-29T16:32:57","slug":"reading-penetrance-and-expressivity","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology1\/chapter\/reading-penetrance-and-expressivity\/","title":{"raw":"Penetrance and Expressivity","rendered":"Penetrance and Expressivity"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Describe the impacts of penetrance and expressivity on a trait's expression in a population<\/li>\r\n<\/ul>\r\n<\/div>\r\nPenetrance refers to the probability of a gene or trait being expressed. In some cases, despite the presence of a dominant allele, a phenotype may not be present. One example of this is polydactyly in humans (extra fingers and\/or toes). A dominant allele produces polydactyly in humans but not all humans with the allele display the extra digits. \u201cComplete\u201d penetrance means the gene or genes for a trait are expressed in all the population who have the genes. \u201cIncomplete\u201d or \u2018reduced\u2019 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. 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\u2019s family medical history and predict the risk of passing a genetic condition to future generations.\r\n\r\n[caption id=\"attachment_2935\" align=\"aligncenter\" width=\"1024\"]<img class=\"wp-image-2935 size-large\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/110\/2016\/06\/15205138\/penetrance-1024x282.png\" alt=\" Complete penetrance: all six squares are dark green. Incomplete penetrance: three of the squares are dark green, and three of the squares are white. The squares in each example are intended to represent individuals of the same genotype for the gene of interest.\" width=\"1024\" height=\"282\" \/> Illustration modeled after similar image by Steven M. Carr,\u00a0<a href=\"https:\/\/www.mun.ca\/biology\/scarr\/Penetrance_vs_Expressivity.html\" target=\"_blank\" rel=\"noopener\">Penetrance versus expressivity<\/a>.[\/caption]\r\n\r\nExpressivity on the other hand refers to variation in phenotypic expression when an allele is penetrant. Back to the polydactyly example, an extra digit may occur on one or more appendages. The digit can be full size or just a stub. Hence, this allele has reduced penetrance as well as variable expressivity. Variable expressivity refers to the range of signs and symptoms that can occur in different people with the same genetic condition. 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.\r\n\r\n[caption id=\"attachment_2934\" align=\"aligncenter\" width=\"1024\"]<img class=\"wp-image-2934 size-large\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/110\/2016\/06\/15205107\/expressivity-1024x281.png\" alt=\" Narrow expressivity: all six squares are dark green. Variable expressivity: the six squares are various shades of green. The squares in each example are intended to represent individuals of the same genotype for the gene of interest.\" width=\"1024\" height=\"281\" \/> Illustration modeled after similar image by Steven M. Carr, <a href=\"https:\/\/www.mun.ca\/biology\/scarr\/Penetrance_vs_Expressivity.html\" target=\"_blank\" rel=\"noopener\">Penetrance versus expressivity<\/a>.[\/caption]\r\n\r\n<div class=\"textbox shaded\">For more information about reduced penetrance and variable expressivity take a look at the\u00a0<a href=\"http:\/\/www.phgfoundation.org\/tutorials\/penetrance\/index.html\" target=\"_blank\" rel=\"noopener\">interactive tutorial on penetrance<\/a>\u00a0the PHG Foundation offers. The tutorial\u00a0explains the differences between reduced penetrance and variable expressivity.<\/div>\r\n<h2>Variable Expressivity and Incomplete Penetrance<\/h2>\r\n<iframe src=\"\/\/plugin.3playmedia.com\/show?mf=4409401&amp;p3sdk_version=1.10.1&amp;p=20361&amp;pt=573&amp;video_id=1XW-j3VQGRY&amp;video_target=tpm-plugin-m9dihad6-1XW-j3VQGRY\" width=\"800px\" height=\"500px\" frameborder=\"0\" marginwidth=\"0px\" marginheight=\"0px\"><\/iframe>\r\n\r\nYou can <a href=\"https:\/\/course-building.s3-us-west-2.amazonaws.com\/Biology+for+Majors+I\/Transcriptions\/VariableExpressivityandIncompletePenetrance_Transcript.txt\" target=\"_blank\" rel=\"noopener\">view the transcript for \"Variable Expressivity and Incomplete Penetrance\" here (link opens in new window)<\/a>.\r\n\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/fb0e58bb-4e9d-40eb-9fd9-9ead78fc5ac2\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Describe the impacts of penetrance and expressivity on a trait&#8217;s expression in a population<\/li>\n<\/ul>\n<\/div>\n<p>Penetrance refers to the probability of a gene or trait being expressed. In some cases, despite the presence of a dominant allele, a phenotype may not be present. One example of this is polydactyly in humans (extra fingers and\/or toes). A dominant allele produces polydactyly in humans but not all humans with the allele display the extra digits. \u201cComplete\u201d penetrance means the gene or genes for a trait are expressed in all the population who have the genes. \u201cIncomplete\u201d or \u2018reduced\u2019 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. 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\u2019s family medical history and predict the risk of passing a genetic condition to future generations.<\/p>\n<div id=\"attachment_2935\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2935\" class=\"wp-image-2935 size-large\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/110\/2016\/06\/15205138\/penetrance-1024x282.png\" alt=\"Complete penetrance: all six squares are dark green. Incomplete penetrance: three of the squares are dark green, and three of the squares are white. The squares in each example are intended to represent individuals of the same genotype for the gene of interest.\" width=\"1024\" height=\"282\" \/><\/p>\n<p id=\"caption-attachment-2935\" class=\"wp-caption-text\">Illustration modeled after similar image by Steven M. Carr,\u00a0<a href=\"https:\/\/www.mun.ca\/biology\/scarr\/Penetrance_vs_Expressivity.html\" target=\"_blank\" rel=\"noopener\">Penetrance versus expressivity<\/a>.<\/p>\n<\/div>\n<p>Expressivity on the other hand refers to variation in phenotypic expression when an allele is penetrant. Back to the polydactyly example, an extra digit may occur on one or more appendages. The digit can be full size or just a stub. Hence, this allele has reduced penetrance as well as variable expressivity. Variable expressivity refers to the range of signs and symptoms that can occur in different people with the same genetic condition. 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.<\/p>\n<div id=\"attachment_2934\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2934\" class=\"wp-image-2934 size-large\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/110\/2016\/06\/15205107\/expressivity-1024x281.png\" alt=\"Narrow expressivity: all six squares are dark green. Variable expressivity: the six squares are various shades of green. The squares in each example are intended to represent individuals of the same genotype for the gene of interest.\" width=\"1024\" height=\"281\" \/><\/p>\n<p id=\"caption-attachment-2934\" class=\"wp-caption-text\">Illustration modeled after similar image by Steven M. Carr, <a href=\"https:\/\/www.mun.ca\/biology\/scarr\/Penetrance_vs_Expressivity.html\" target=\"_blank\" rel=\"noopener\">Penetrance versus expressivity<\/a>.<\/p>\n<\/div>\n<div class=\"textbox shaded\">For more information about reduced penetrance and variable expressivity take a look at the\u00a0<a href=\"http:\/\/www.phgfoundation.org\/tutorials\/penetrance\/index.html\" target=\"_blank\" rel=\"noopener\">interactive tutorial on penetrance<\/a>\u00a0the PHG Foundation offers. The tutorial\u00a0explains the differences between reduced penetrance and variable expressivity.<\/div>\n<h2>Variable Expressivity and Incomplete Penetrance<\/h2>\n<p><iframe loading=\"lazy\" src=\"\/\/plugin.3playmedia.com\/show?mf=4409401&amp;p3sdk_version=1.10.1&amp;p=20361&amp;pt=573&amp;video_id=1XW-j3VQGRY&amp;video_target=tpm-plugin-m9dihad6-1XW-j3VQGRY\" width=\"800px\" height=\"500px\" frameborder=\"0\" marginwidth=\"0px\" marginheight=\"0px\"><\/iframe><\/p>\n<p>You can <a href=\"https:\/\/course-building.s3-us-west-2.amazonaws.com\/Biology+for+Majors+I\/Transcriptions\/VariableExpressivityandIncompletePenetrance_Transcript.txt\" target=\"_blank\" rel=\"noopener\">view the transcript for &#8220;Variable Expressivity and Incomplete Penetrance&#8221; here (link opens in new window)<\/a>.<\/p>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_fb0e58bb-4e9d-40eb-9fd9-9ead78fc5ac2\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/fb0e58bb-4e9d-40eb-9fd9-9ead78fc5ac2?iframe_resize_id=assessment_practice_id_fb0e58bb-4e9d-40eb-9fd9-9ead78fc5ac2\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-2753\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">All rights reserved content<\/div><ul class=\"citation-list\"><li>Variable Expressivity and Incomplete Penetrance. <strong>Authored by<\/strong>: Learning Simply. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/1XW-j3VQGRY\">https:\/\/youtu.be\/1XW-j3VQGRY<\/a>. <strong>License<\/strong>: <em>All Rights Reserved<\/em>. <strong>License Terms<\/strong>: Standard YouTube License<\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">Public domain content<\/div><ul class=\"citation-list\"><li>What are reduced penetrance and variable expressivity?. <strong>Provided by<\/strong>: National Institutes of Health. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/ghr.nlm.nih.gov\/handbook\/inheritance\/penetranceexpressivity\">http:\/\/ghr.nlm.nih.gov\/handbook\/inheritance\/penetranceexpressivity<\/a>. <strong>Project<\/strong>: Genetics Home Reference. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/about\/pdm\">Public Domain: No Known Copyright<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":11,"template":"","meta":{"_candela_citation":"[{\"type\":\"pd\",\"description\":\"What are reduced penetrance and variable expressivity?\",\"author\":\"\",\"organization\":\"National Institutes of Health\",\"url\":\"http:\/\/ghr.nlm.nih.gov\/handbook\/inheritance\/penetranceexpressivity\",\"project\":\"Genetics Home Reference\",\"license\":\"pd\",\"license_terms\":\"\"},{\"type\":\"copyrighted_video\",\"description\":\"Variable Expressivity and Incomplete Penetrance\",\"author\":\"Learning Simply\",\"organization\":\"\",\"url\":\"https:\/\/youtu.be\/1XW-j3VQGRY\",\"project\":\"\",\"license\":\"arr\",\"license_terms\":\"Standard YouTube License\"}]","CANDELA_OUTCOMES_GUID":"f89c49c8-b9d0-4a0a-bafa-6d50770a79bd, f211ed6a-70e6-49bd-805b-ed8cf759e24c","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-2753","chapter","type-chapter","status-publish","hentry"],"part":258,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2753","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":12,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2753\/revisions"}],"predecessor-version":[{"id":6011,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2753\/revisions\/6011"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/parts\/258"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapters\/2753\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/media?parent=2753"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/pressbooks\/v2\/chapter-type?post=2753"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/contributor?post=2753"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology1\/wp-json\/wp\/v2\/license?post=2753"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}