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In DNA from the BCC and the odontogenic keratocyst, heterozygosity for the likely pathogenic variant in <jats:italic>PTCH1<\/jats:italic>: c.2917C&gt;T p.(Gln973*) was identified, alongside additional <jats:italic>PTCH1<\/jats:italic> variants specific to each tissue. A hereditary predisposition should be suspected in cancer patients diagnosed at an unusually young age for their tumour type and\/or in individuals presenting with dysmorphic features. In cases where the two-hit mechanism is involved, and with no pathogenic variant detected in blood, sequencing should be repeated in two or more samples from affected tissue.<\/jats:p>","DOI":"10.1136\/bcr-2025-265876","type":"journal-article","created":{"date-parts":[[2025,7,29]],"date-time":"2025-07-29T03:40:20Z","timestamp":1753760420000},"page":"e265876","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":1,"title":["Mosaicism for a variant in <i>PTCH1<\/i> causing nevoid basal cell carcinoma syndrome"],"prefix":"10.1136","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5408-8701","authenticated-orcid":false,"given":"Inger Norlyk","family":"Sheyanth","sequence":"first","affiliation":[{"name":"Department of Clinical Genetics, Aalborg University Hospital, Aalborg, 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