Introduction: Familial auto-immune hepatitis is unusual. We report a case in which hepatitis was associated with a deficiency in the C4 component of the complement.
Exegesis: Type 1 auto-immune hepatitis A was diagnosed in a 38-year-old woman presenting with systemic lupus erythematosus. Her daughter had to undergo a splenectomy for immunologic thrombocytopenic purpura when she was 9 years old. When she turned 13, she further developed type 1 autoimmune hepatitis. During follow-up (4 and 8 years, respectively), both patients had a mild deficiency in C4.
Conclusion: C4 deficiency is not only frequently observed in relatives of patients with auto-immune hepatitis, but also in familial systemic lupus. This abnormality may have had a crucial pathogenic role in these two patients.