{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T01:52:04Z","timestamp":1787017924500,"version":"build-2736575974"},"reference-count":0,"publisher":"S. Karger AG","issue":"5-6","license":[{"start":{"date-parts":[[2018,1,1]],"date-time":"2018-01-01T00:00:00Z","timestamp":1514764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.karger.com\/Services\/SiteLicenses"},{"start":{"date-parts":[[2018,1,1]],"date-time":"2018-01-01T00:00:00Z","timestamp":1514764800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/www.karger.com\/Services\/SiteLicenses"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Neurodegener Dis"],"published-print":{"date-parts":[[2018]]},"abstract":"<jats:p>&lt;b&gt;&lt;i&gt;Background:&lt;\/i&gt;&lt;\/b&gt; European studies identified the &lt;i&gt;C9orf72&lt;\/i&gt; repeat expansion as the most frequent genetic alteration in patients with Huntington disease (HD)-like phenotypes but negative HD genetic testing. &lt;b&gt;&lt;i&gt;Objective:&lt;\/i&gt;&lt;\/b&gt; To investigate &lt;i&gt;C9orf72&lt;\/i&gt; repeat expansion frequency in individuals tested for HD in a North American tertiary referral laboratory. &lt;b&gt;&lt;i&gt;Methods:&lt;\/i&gt;&lt;\/b&gt; Three hundred and seventy-three cases (115 positive and 258 negative for HD) were evaluated by genotyping PCR, with follow-up Southern blot and 5\u2032 repeat methylation status assessment by combined repeat-primed and methylation-specific PCR in a subset. &lt;b&gt;&lt;i&gt;Results:&lt;\/i&gt;&lt;\/b&gt; Three cases (all HD-negative) tested positive: 2 had &amp;#x3e; 2,000 repeats and were methylated, 1 had 80\u2013100 repeats and was unmethylated. Two cases (1 HD-positive and 1 HD-negative) had intermediate alleles (20\u201329 repeats) and were unmethylated. The remaining 368 cases were negative (&amp;#x3c; 20 repeats). &lt;i&gt;C9orf72&lt;\/i&gt; repeat expansion was absent in patients with HD and was identified in a small subset (1.2%) of patients with negative HD genetic testing. &lt;b&gt;&lt;i&gt;Conclusion:&lt;\/i&gt;&lt;\/b&gt; These findings suggest that &lt;i&gt;C9orf72&lt;\/i&gt; repeat expansion does not coexist with &lt;i&gt;HTT&lt;\/i&gt; repeat expansion and that &lt;i&gt;C9orf72&lt;\/i&gt; repeat expansion testing is unnecessary for patients with HD. In addition, &lt;i&gt;C9orf72&lt;\/i&gt; evaluation may be considered for individuals negative for HD genetic testing. Similar to in previous studies, methylation of &lt;i&gt;C9orf72&lt;\/i&gt; repeat expansion was limited to large expansions.<\/jats:p>","DOI":"10.1159\/000492499","type":"journal-article","created":{"date-parts":[[2018,10,18]],"date-time":"2018-10-18T17:04:19Z","timestamp":1539882259000},"page":"239-253","source":"Crossref","is-referenced-by-count":9,"title":["C9orf72 Repeat Expansion Frequency among Patients with Huntington Disease Genetic Testing"],"prefix":"10.1159","volume":"18","author":[{"given":"Cristiane\u00a0M.","family":"Ida","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Malinda\u00a0L.","family":"Butz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrick\u00a0A.","family":"Lundquist","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D.\u00a0Brian","family":"Dawson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"127","published-online":{"date-parts":[[2018,10,18]]},"container-title":["Neurodegenerative Diseases"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/492499","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/492499","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T12:55:26Z","timestamp":1745412926000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000492499"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018]]},"references-count":0,"journal-issue":{"issue":"5-6","published-online":{"date-parts":[[2019,4,11]]},"published-print":{"date-parts":[[2019,4,16]]}},"URL":"https:\/\/doi.org\/10.1159\/000492499","archive":["Portico"],"relation":{},"ISSN":["1660-2854","1660-2862"],"issn-type":[{"value":"1660-2854","type":"print"},{"value":"1660-2862","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018]]}}}