The immunity to IBD was reported to be strongly determined by polymorphisms in bacterial sensor genes in the host including nucleotide-binding oligomerization domain-containing protein 2 (NOD2), which is also named as caspase recruitment domain-containing protein 15 (CARD15) [16, 17], and toll-like receptor 4 (TLR4) [18]. Here, NOD2 is linked to inflammatory bowel disease.