Clinical manifestations of inflammatory bowel disease: East and West differences.

Inflammatory bowel disease (IBD) is very common in developed countries, while it is relatively uncommon in Asian countries. However, the incidence of IBD has been increasing in some Asian countries in recent years. Most cases of ulcerative colitis (UC) in Asia are of the chronic relapsing type, run a milder course, and the fulminant type is rarely seen. There is no difference in clinical manifestations between Asian and developed countries. The incidence of Crohn's Disease (CD) is mainly in males in Asia, while it is mainly in females in developed countries. The clinical manifestations of CD are similar between both sets of countries. In China there are less fistulae and perianal diseases, and extraintestinal manifestations of CD are uncommon. In China, 5.6% of patients with UC have a family history, which is lower than 10-20% in developed countries. NOD2/CARD15 variants in the locus of 16q112 (IBD1) are significantly associated with the susceptibility of CD in developed countries, but NOD2/CARD15 variants have not been found in Asian CD patients.