Do C1q or IgM nephropathies predict disease severity in children with minimal change nephrotic syndrome?

Background: It has been suggested that C1q and immunoglobulin M (IgM) nephropathy are variants of minimal change nephrotic syndrome (MCNS). Many researchers believe that these two conditions signify a worse prognosis for children with MCNS in comparison with immunofluorescence (IF)-negative MCNS. The aim of our study was to determine the prognostic significance of C1q nephropathy and IgM nephropathy in children with MCNS.

Methods: Fifty-five children with MCNS who had been biopsied over the course of 24 years at our institution were retrospectively categorized into three groups on the basis of IF microscopy findings: IF-negative MCNS (29/55 patients), MCNS with IgM nephropathy (19/55 patients), and MCNS with C1q nephropathy (7/55 patients). Clinical characteristics at disease presentation, clinical course, and renal outcome were compared between groups during the median follow-up period of 16.9 years (minimum 1.0, maximum 31.1 years).

Results: No statistically significant differences in clinical characteristics at disease presentation, clinical course, and renal outcome were found. Children with IgM nephropathy, C1q nephropathy, and IF-negative MCNS were clinically indistinguishable.

Conclusions: We concluded that C1q or IgM nephropathy variants do not seem to signify a worse prognosis in children with MCNS in comparison with IF-negative MCNS.