Susceptibility loci related to intestinal macrophage functions have been unraveled in Crohn’s disease patients, including NOD2, ATG16L1, CX3CR1, IL12p40, IL23R, JAK2, STAT3, and protein tyrosine phosphatase non-receptor type 2 (PTPN2) [14, 16, 17, 158–160]. Here, NOD2 is linked to Crohn disease.