Alternative pathway dysfunction in kidney disease: a case report and review of dense deposit disease and C3 glomerulopathy.

Dysfunction of the alternative pathway of complement activation provides a pathophysiologic link between the C3 glomerulopathies dense deposit disease and glomerulonephritis with C3 deposition and the clinically and histologically distinct atypical hemolytic uremic syndrome. Previously, dense deposit disease was known as membranoproliferative glomerulonephritis type II, but paucity or complete lack of immunoglobulin deposition on immunofluorescence staining and advances in our understanding of alternative pathway dysregulation have separated it from immune complex-mediated membranoproliferative glomerulonephritis types I and III. We discuss a case of dense deposit disease and review the current pathologic classification, clinical course, treatment options, and related conditions.