C1q nephropathy is a proliferative glomerulopathy with extensive mesangial deposition of C1q. A three-year old boy presented with a nephrotic-range proteinuria during an acute phase of Epstein-Barr virus (EBV) infection, and he had a family history of Dent's disease. The renal biopsy findings were compatible with C1q nephropathy. However, EBV in situ hybridization was negative. The CLCN5 gene analysis revealed an R637X hemizygous mutation, which was the same as that detected in his maternal cousin, the proband of the family. The causal relationship between EBV infection and C1q nephropathy remains to be determined. Moreover, the effects of underlying Dent's disease in the process of C1q nephropathy has to be considered.
Biopsy ; Child, Preschool ; Epstein-Barr Virus Infections/metabolism ; Glomerulonephritis/pathology ; Humans ; In Situ Hybridization ; Infectious Mononucleosis/*complications/*diagnosis ; Kidney Diseases/*complications/*diagnosis ; Kidney Tubules/*pathology ; Male ; Membrane Glycoproteins/*chemistry ; Mutation ; Nephrosis ; Proteinuria/*complications/*diagnosis ; Receptors, Complement/*chemistry ; Treatment Outcome