{"id":830,"date":"2015-11-28T00:05:32","date_gmt":"2015-11-28T00:05:32","guid":{"rendered":"http:\/\/stg-blogs.bmj.com\/jmg\/?p=830"},"modified":"2015-11-28T00:05:32","modified_gmt":"2015-11-28T00:05:32","slug":"low-level-apc-mutational-mosaicism-is-the-underlying-cause-in-a-substantial-fraction-of-unexplained-colorectal-adenomatous-polyposis-cases","status":"publish","type":"post","link":"https:\/\/stg-blogs.bmj.com\/jmg\/2015\/11\/28\/low-level-apc-mutational-mosaicism-is-the-underlying-cause-in-a-substantial-fraction-of-unexplained-colorectal-adenomatous-polyposis-cases\/","title":{"rendered":"Low-level APC mutational mosaicism is the underlying cause in a substantial fraction of unexplained colorectal adenomatous polyposis cases"},"content":{"rendered":"<p>Familial Adenomatous Polyposis (FAP), caused by germline mutations in the tumor suppressor gene <em>APC<\/em>, is one of the most common types of hereditary colorectal cancer. However, in a considerable fraction of families the disease remains unexplained.<\/p>\n<p>This is the first study which comprehensively explored the impact of low-level <em>APC<\/em> mutational mosaicism. Multiple colorectal polyps in addition to leukocyte DNA were systematically analysed in a sufficient number (n=20) of patients with unexplained sporadic polyposis using high-throughput sequencing techniques. In 25% of patients, the same pathogenic <em>APC<\/em> mutation was identified in \u2265 two polyps, strongly suggesting <em>APC<\/em> mosaicism as underlying cause of the disease. In 60% of these cases, the mosaic level in leukocyte DNA was clearly below the sensitivity threshold of routine diagnostics.<\/p>\n<p>Our multiple polyp approach demonstrates that low-level <em>APC<\/em> mosaic mutations contribute significantly to the etiology of adenomatous polyposis. This has important implications for both routine work-up and strategies to identify new causative genes in patient with unexplained polyposis. (By Dr. med. Isabel Spier, <a href=\"http:\/\/jmg.bmj.com\/content\/early\/2015\/11\/26\/jmedgenet-2015-103468\">http:\/\/jmg.bmj.com\/content\/early\/2015\/11\/26\/jmedgenet-2015-103468<\/a> )<\/p>\n<p><a href=\"https:\/\/stg-blogs.bmj.com\/jmg\/files\/2015\/11\/Abbildung_JMG-Blog_02.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-831\" src=\"https:\/\/stg-blogs.bmj.com\/jmg\/files\/2015\/11\/Abbildung_JMG-Blog_02-300x225.jpg\" alt=\"Abbildung_JMG-Blog_02\" width=\"300\" height=\"225\" srcset=\"https:\/\/stg-blogs.bmj.com\/jmg\/files\/2015\/11\/Abbildung_JMG-Blog_02-300x225.jpg 300w, https:\/\/stg-blogs.bmj.com\/jmg\/files\/2015\/11\/Abbildung_JMG-Blog_02.jpg 960w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>Drs. Stefan Aretz and Isabel Spier<!--TrendMD v2.4.8--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Familial Adenomatous Polyposis (FAP), caused by germline mutations in the tumor suppressor gene APC, is one of the most common types of hereditary colorectal cancer. However, in a considerable fraction of families the disease remains unexplained. This is the first study which comprehensively explored the impact of low-level APC mutational mosaicism. Multiple colorectal polyps in [&#8230;]<\/p>\n<p><a class=\"btn btn-secondary understrap-read-more-link\" href=\"https:\/\/stg-blogs.bmj.com\/jmg\/2015\/11\/28\/low-level-apc-mutational-mosaicism-is-the-underlying-cause-in-a-substantial-fraction-of-unexplained-colorectal-adenomatous-polyposis-cases\/\">Read More&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-830","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/posts\/830","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/comments?post=830"}],"version-history":[{"count":0,"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/posts\/830\/revisions"}],"wp:attachment":[{"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/media?parent=830"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/categories?post=830"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/jmg\/wp-json\/wp\/v2\/tags?post=830"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}