A case of congenital nephrotic syndrome associated with positive C1q immunofluorescence

We present a 1-month-old girl with a congenital nephrotic syndrome and unusual histological findings. Immunofluorescence microscopy demonstrated granular mesangial deposition of C1q and electron microscopy revealed electron-dense mesangial deposits. Her heavy proteinuria gradually decreased and the steroid therapy did not have a significant effect. Her renal function was normal throughout the entire period of observation. The clinical evidence and histopathological features of this patient were compatible with C1q nephropathy.