Autoimmune Hepatitis in the East and the West

meaningful comparison of AIH studies conducted in different parts of the world [7, 8] . It is interesting to note that the incidence and prevalence of AIH are consistently reported as lower in the East than in the West as summarized by Enomoto et al. [6] . In the West, the prevalence of AIH was reported as 15–25 cases per 100,000 inhabitants, whereas much lower rates of 4–5 cases per 100,000 inhabitants were reported in the East [9] . Comparing the prevalence and incidence from different regions is not always easy, as the methodology and quality of the studies may have a profound effect on the results. For example, an ineffective case identification methodology would inevitably lead to an underestimation of prevalence and incidence rates. Therefore, one could question whether the lower AIH prevalence in the East could solely be explained by the paucity of high-quality population-based AIH studies. Interestingly, a population-based study performed in New Zealand has convincingly shown that the AIH prevalence is indeed different between various ethnic groups that reside in Canterbury [10] . This study shows that Caucasians have a significantly higher AIH prevalence (28 per 100,000) than Asians or Maoris (5–7 per 100,000) in Canterbury despite being exposed to similar environmental factors. This result suggests that the Autoimmune hepatitis (AIH) is a chronic progressive liver disease characterized by unresolving inflammation of the liver, hypergammaglobulinemia, production of autoantibodies, characteristic histological features of lymphoplasmacytic interface hepatitis, and responsiveness to immunosuppression [1, 2] . It is a serious condition that is associated with at least a 2-fold higher mortality than that of the general population [3, 4] . Although it is understood that there is an autoimmune basis to the pathogenesis of AIH, its precise etiology remains unknown. Epidemiology is an important part of etiologic research, as information gained from epidemiological studies can be a powerful tool by which to gain important insights into the disease. The current working model postulates that environmental triggers, a failure of immune tolerance mechanisms, and a genetic predisposition collaborate to induce an uninhibited T cell-mediated immune attack upon hepatocytes [5] . In this issue, Enomoto et al. [6] have provided an excellent summary of the similarities and differences in the epidemiology of AIH between the East and the West. The establishment of the standardized AIH diagnostic criteria by the International AIH Group has ensured consistent case definitions in AIH research, providing a Published online: February 1, 2017