Recently, genome-wide association studies (GWAS) and epidemiological studies have revealed that a considerable number of gene variations, such as in nucleotide oligomerization domain 2 (NOD2)5, 6, autophagy related 16-like 1(ATG16L1)7, signal transducer and activator of transcription 3 (STAT3)8, 9, immunity-related GTPase family M (IRGM)10 and interleukin 23 receptor (IL23R)11, 12, are closely related to IBD susceptibility. Here, IL23R is linked to inflammatory bowel disease.