Mutations in genes encoding members of the WNT signaling pathway—i.e., Catenin Beta 1 (CTNNB1), AXIN1 and Adenomatous Polyposis Coli (APC)—are hallmarks of less differentiated thyroid carcinomas, in particular, ATCs [69]. This evidence concerns the gene APC and Ehlers-Danlos syndrome, musculocontractural type.