PTPN2 and inflammatory bowel disease: First, Genome Wide Association Scans (GWAS) [9]–[19] and candidate gene approach [20]–[25] led to the identification of more than 30 susceptibility loci for CD and UC and identified “IBD-specific” gene variants within these loci (eg. CARD15, TNFSF15, IL23R, ATG16L1, IRGM, PTPN2).