Based on a pathway analysis of gene relationships across implicated loci (GRAIL) of a recent GWAS meta-analysis in CD demonstrating a potential interaction between the PTPN2-related gene PTPN22 and NOD2[19], we also performed analysis for gene-gene interaction between PTPN2 and NOD2 regarding CD susceptibility. Here, PTPN2 is linked to Cowden disease.