Genetic distinctions between types 1 and 2 autoimmune hepatitis.

Objectives: Our aim was to determine whether alleles affecting susceptibility to type 1 autoimmune hepatitis in the United States occur as commonly in German patients with type 2 disease.
Methods: DNA specimens from 12 German patients with type 2 autoimmune hepatitis were tested for class II alleles of the major histocompatibility complex by polymerase chain reaction using sequence specific primers. Eighty-six American patients with type 1 disease and 102 Caucasoid normal subjects from the United States were tested in a similar manner.
Results: American patients with type 1 autoimmune hepatitis had DRB1*03 alleles more commonly than the German patients with type 2 disease (51% vs 17%, p = 0.03) and DRB1*0301 occurred more frequently in the type 1 patients (51% vs 17%, p = 0.03). The frequency of DRB1*04 alleles was also higher in the type 1 patients after exclusion of the DR1*03 alleles (64% vs 20%, p = 0.01). In contrast, patients with type 2 disease more commonly had DRB1*07 (p = 0.003), DRB1*15 (p = 0.004), and DQB1*06 (p = 0.0004). DRB1*07 (p = 0.005), DRB4*01 (p = 0.03), and DQB1*06 (p = 0.03) also occurred more frequently in the type 2 patients from Germany than in the normal subjects from the United States, although none of these frequencies were statistically significant by an adjusted p value.
Conclusions: German patients with type 2 autoimmune hepatitis do not have the same susceptibility alleles as American patients with type 1 disease. Regional differences in prevalence may reflect the genetic profiles of the populations at risk.