Autoimmune hepatitis (AIH)
Autoimmune hepatitis (AIH) is a chronic disease of the liver of unknown cause. It can occur in all age groups but most patients are young and predominantly female (70%). Many patients have clinical (arthralgias 50%) and laboratory manifestations that resemble SLE. Patients commonly have positive ANAs, antibodies against smooth muscle antigen characteristically with specificity against F1 actin, hypergammaglobulinemia, and occasionally LE cells. They usually do not have antibodies against double-stranded DNA (dsDNA). Type I AIH has been described in patients with Sjögren’s syndrome, SLE, mixed connective tissue disease, and limited systemic sclerosis (CREST syndrome). Patients with type I AIH can have other autoantibodies such as atypical pANCAs (65%) and antibodies against soluble liver antigen (10% to 50%).