Abstract
C1q nephropathy is an immune complex glomerulonephritis defined by the presence of mesangial immunoglobulins and complement deposits, most notably C1q, and the absence of clinical and laboratory evidence of systemic lupus erythematosus. Histology in C1q nephropathy is characterized by a slight to severe increase in mesangial cellularity and matrix, with or without segmental sclerosis. C1q nephropathy usually presents with nephrotic-range proteinuria in older children and young adults, and has a poor response to steroids.
We reported on 1-year-old-girl with C1q nephropathy. She had heavy proteinuria and edema with nephrotic syndrome. She was treated with oral prednisolone for 6 weeks, but predonisolone could not lead her to remission. It was diagnosed as steroid resistance nephrotic syndrome. Histology of the patient renal biopsy revealed a minimal change and immunofluorescene study revealed dominant positive staining (3+) of C1q in the glomerular mesangium with lesser C3, IgA, IgM. Staining for IgG was negative. Electron-dense deposits were present in the paramesangial area. There was no serological or clinical findings of lupus nephritis. The histopathological studies were compatible with C1q nephropathy. So we diagnosed C1q nephropathy with steroid-resistant nephrotic syndrome. We selected cyclosporine as therapy and were effective. The patient was led to complete remission. It is assumed that C1q nephropathy tends to occur in older children. But our patient was 1-year-old. C1q nephropathy should be added to the cause of steroid-resistant or steroid-dependent nephrotic syndrome in young children. In addition, it is reported that 10% of C1q nephropathy develops renal insufficiency. We have to be careful to progress of this patient and need more research about C1q nephropathy.
