Similarities and Differences in Autoimmune Hepatitis Epidemiology between East and West: Autoimmune Hepatitis in East Asia, Southeast Asia, and South Asia.

BACKGROUND: Autoimmune hepatitis (AIH) is a relatively rare disease that can develop regardless of age or ethnicity. However, its clinical features differ between eastern and western populations due to several heterogeneous genetic and environmental factors. We herein report the clinical characteristics of AIH patients in East Asia, Southeast Asia, and South Asia. SUMMARY AND KEY MESSAGES: The prevalence of AIH in eastern countries is considered to be lower than in western countries. Although a few young patients with type 2 AIH have been observed in South Asia, most patients in Asia are middle-aged women with type 1 AIH who respond well to steroid-based immunosuppressive therapy. Human leukocyte antigen DR4 is suggested to be an influential factor in the genetic background of AIH patients in Asia, particularly in East Asia. Notably, AIH may be induced by some societal- or culture-associated medicines, including herbal medicines. The IAIHG (International Autoimmune Hepatitis Group) scoring systems are generally accepted as the standard diagnostic methods for AIH in Asian countries. The results of repeated nationwide surveys in Japan suggest that the clinical features of AIH patients in East Asia are changing, with IgG levels and rates of anti-nuclear antibody positivity decreasing.