Patterns of autoimmunity in primary biliary cirrhosis patients and their families: a population-based cohort study

Background: Primary biliary cirrhosis (PBC) is a chronic liver disease with autoimmune features but uncertain aetiology. Increased risk of PBC among relatives of patients may reflect common environmental factors, or inherited immunogenetic susceptibility. Associations between PBC and other autoimmune diseases have been reported, but their true extent and pattern is unknown. Aim: To examine the prevalence and association patterns of autoimmune disease in a representative group of PBC patients. Design: Clinical cohort study. Methods: We clinically assessed members of a geographically-based PBC patient cohort (n = 160) for the presence of additional autoimmune disease, using established specific diagnostic criteria. Results: Some 53% of patients had at least one additional autoimmune condition, and 63% had serum autoantibodies other than AMA or ANA. AMA+ patients had a significantly lower prevalence of additional autoimmunity than AMA- patients (49% vs. 79%; p < 0.01). The greatest relative increase in disease prevalence was for scleroderma (8% of patients). Autoimmune disease was present in 14% of first-degree relatives. Discussion: PBC patients and their families have a wide susceptibility to autoimmunity. This observation supports an autoimmune aetiology and suggests that the genetic basis of PBC is likely to be expressed, at least in part, through factors controlling immune tolerance in general.