Characteristic features of ileal CD include the reduced expression of α-defensins HD-5 and HD-6, which are expressed by Paneth cells [75], and low Wnt/β-catenin signaling, as exemplified by low expression or genetic variants of TCF-4 [76,77], TCF-1 [78], and LRP6 [79]. This evidence concerns the gene LRP6 and Cowden disease.