CTNNA1 and Crohn disease: In addition, a pathogenic mutation, likely somatic, in CTNNA1 (another WNT pathway–related gene that encodes for α1 catenin, a protein involved in cell adhesion and whose mutations are found in a minority of hereditary diffuse gastric cancers50) was identified in a Crohn disease–associated, APC-WT PCC-NOS, whereas no mutation involving the CTNNB1 gene encoding β-catenin was found in our series.