Membranoproliferative glomerulonephritis and C3 glomerulonephritis: Frequency, clinical features, and outcome in children

AimC3 glomerulonephritis (C3GN) is a recently described disease that is related to membranoproliferative glomerulonephritis (MPGN). We retrospectively compared the frequencies, clinical characteristics, treatment modalities, and outcomes of C3GN and MPGN in a cohort of Japanese children. MethodsChildren who were pathologically diagnosed with MPGN (type I or III) in our hospital were divided into two groups based on immunofluorescence imaging of renal biopsies: children with MPGN induced by classical complement pathway activation (classical MPGN) and children with C3GN. ResultsOf 14 children with MPGN (five boys), four had classical MPGN, eight had C3GN, and two had unclassifiable glomerulonephritis. Four children with classical MPGN and seven with C3GN received methylprednisolone pulse therapy followed by oral prednisolone for 2 years (MPT+PSL therapy). Subsequently, six of seven children with C3GN received combined therapy (prednisolone, azathioprine, and anticoagulants) for 2 years because they responded poorly to MPT+PSL therapy. At the last follow-up visit, two children with classical MPGN and seven with C3GN had not achieved remission. One child with classical MPGN and five with C3GN had hypocomplementaemia at the last follow-up. None of the children had renal impairment. ConclusionMore than half of the patients previously diagnosed with MPGN fulfilled the criteria for C3GN in children. C3GN may be more refractory than classical MPGN to immunosuppressant therapy. Summary at a Glance The emergence of the term C3 glomerulonephropathy (C3 glomerulonephritis) in recent years is a step on the pathway towards an aetiological classification of glomerular disease, reflecting our increased understanding of disease pathogenesis. Okuda etal. present a retrospective study from two paediatric centres in Japan on the clinical features of C3 glomerulopathy in children re-classified as having this condition.