Clinical | Age at diagnosis < 40 years |
Perianal disease at diagnosis | |
Need for steroids during first flare | |
Early use of azathioprine or anti-TNF | |
Small bowel disease location | |
Prior appendectomy | |
Environmental | Smoking |
Endoscopic | Deep mucosal laceration |
Genetic | Janus-associated kinase 2 (JAK2) |
ATG16L1 | |
NOD2/CARD15 mutations on both chromosomes | |
TNF superfamily 15 (TNFSF15) in Asians | |
5T5T in the MMP3 gene | |
rs1363670 | |
Serological | Antimicrobial antibodies |
Anti-Saccharomyces cerevisiae (ASCA) IgA in Asians |