CTNNB1 and Gardner syndrome: Two principal types of DTs have been identified: (1) the sporadic type, which is most common, and its pathogenesis is associated with mutations in the β-catenin gene (CTNNB1) [52]; (2) the genetic type, which is more frequently observed in Gardner syndrome [20], and linked to the adenomatous polyposis coli (APC) gene mutation [22].