Familial clusters of ANCA small-vessel vasculitis.

Small-vessel vasculitides associated with the presence of antineutrophil cytoplasmic antibodies in the serum are characterized by inflammation and necrosis of small vessels. A pauci-immune necrotizing crescentic glomerulonephritis typically occurs when there is renal damage. Pathogenesis of these diseases remains unclear although infectious, genetic and environmental factors have been involved. Few familial clusters of antineutrophil cytoplasmic antibodies' small-vessel vasculitis are described in the literature. We report two families with first-degree relatives affected with antineutrophil cytoplasmic antibodies' small-vessel vasculitis.