Background: Immunoglobulin A nephropathy (IgAN) can exist as a primary glomerulonephritis (GN) or in association with various clinical conditions, suggesting that it could include several heterogeneous disorders. The familial form of IgAN has been increasingly recognized, supporting the suggestion that genetic factors could be involved in the disease pathogenesis, although it remains unclear whether the familial form is itself heterogeneous.
Methods: This study included 24 patients with a biopsy-proven IgAN from 11 unrelated families coming from five geographically distinct regions of Italy, and 90 of their relatives investigated for the presence of nephritis.