Table 1.

Features of ileal/ileocolonic Crohn’s disease, isolated colonic Crohn’s disease, and ulcerative colitis

Characteristics	Ileal and ileocolonic CD	Isolated colonic CD	Ulcerative colitis
Sex	Slight female predominance (55%)	Female predominance (65%)	Equal or slight male predominance
Genetics	Crohn’s-associated genotype including NOD2/CARD15	Genotype midway between CD and UC	UC-associated genotype including HLA-DRB1*01:03
Serology	ASCA commonly positive; pANCA usually negative	ASCA less commonly positive than ileal CD; pANCA positive	ASCA usually negative; pANCA commonly positive
Mucosa-associated microbiota	Marked changes commonly including increased proteobacteria (e.g., E. coli) and fusobacteria	Intermediate changes similar to ileal/ileocolonic CD but less consistent	Modest changes, including slight increase in E. coli
Response to mesalazine	No efficacy	No efficacy	Good efficacy
Response to anti-TNF	Good efficacy	Good efficacy, probably better than for ileal/ileocolonic CD	Good efficacy
Response to exclusive enteral nutrition	Good efficacy	Probably good efficacy	No efficacy
Surgery rate and type	Required in majority	Required in minority. High failure for pouch-anal reconstruction	Required in minority. Low failure for pouch-anal reconstruction

CD: Crohn’s disease; ASCA: Anti-Saccharomyces cerevisiae; HLA: Human leucocyte antigen; pANCA: Perinuclear antineutrophil cytoplasmic antibodies; TNF: Tumor necrosis factor; UC: Ulcerative colitis.