Features and outcome of AIH patients without elevation of IgG

Background & Aims High IgG levels are considered a hallmark of autoimmune hepatitis (AIH). A subgroup of patients with AIH has IgG within the normal range despite evidence of clinical disease activity. The clinical significance of this biomarker has not been explored. Methods In a European multicentre study we compared biochemical, clinical and histological features from patients with AIH and normal IgG-values at diagnosis to an age- and sex-matched control group of patients with typical AIH presenting with elevated IgG. Data were assessed at diagnosis, after 12 months of therapy and at last follow-up. Results Out of 1,318 patients with AIH, 130 (10%) had normal IgG at presentation. Histological and biochemical parameters at diagnosis, as well as treatment response, showed no difference between groups. Stable remission off treatment was achieved more commonly in the normal IgG group than in the typical AIH group (24 vs. 8%; p = 0.0012). Patients of the control group not only had higher IgG levels (29.5 ± 5.8 vs. 12.5 ± 3.2 g/L; p
Graphical abstract
Highlights • Patients with AIH and normal IgG comprise around 10% of all patients with AIH. • These patients are indistinguishable from patients with typical AIH by biochemical markers or liver histology. • They have no selective IgG elevation, with lower IgG and IgA levels than patients with typical AIH. • These patients might represent a subgroup in whom there is a high chance of successful drug withdrawal.