IgA nephropathy associated with seronegative spondylarthropathies.

Three patients with a seronegative spondylarthropathy were found to have IgA nephropathy. Two patients had ankylosing spondylitis (one with psoriasis), and one had incomplete Reiter's syndrome. All three had a focal proliferative glomerulonephritis with IgA-dominant mesangial immune deposits. One patient had a leukocytoclastic vasculitis. This association of IgA nephropathy with seronegative spondylarthropathies raises the possibility of a common or related pathogenesis. There is evidence to suggest that both diseases are mediated by genetically controlled immune responses to mucosal contact with etiologic antigens.