Diagnosis is made with a simplified scoring system: ANA or SMA ≥1:40 (1 point), ANA or SMA ≥1:80 or LKM1 ≥1:40 or SLA positive (2 points), serum IgG upper limit of normal (1 point), serum IgG >1.1 x upper limit of normal (2 points), histology compatible (presence of interface hepatitis but not all three features are seen) with AIH (2 points), histology typical (presence of all three major features: interface hepatitis, rosettes, and emperipolesis) of AIH (2 points), negative hepatitis viral markers (2 points). The gene discussed is SMN1; the disease is hepatitis A virus infection.