Making sense of the spectrum of glomerular disease associated with complement dysregulation

Over recent years, complement has emerged as a major player in the development of a number of glomerular diseases, including atypical haemolytic uraemic syndrome, membranoproliferative glomerulonephritis and the recently described C3 glomerulonephritis. Some patients and pedigrees show overlapping features of these conditions. Intriguingly, a few complement gene mutations are common to different disease phenotypes. In this review, we explore the evidence for complement dysregulation in these diseases and the clinical interface between them, and present a hypothesis to explain the variable phenotype associated with dysregulation of the alternative complement pathway.