The first renal biopsy showed solitary IgM lambda deposition without IgG deposition, whereas a repeat biopsy, performed approximately 2 years later because of exacerbation of nephrotic syndrome, showed diminished IgM staining and positive staining for IgG (predominantly IgG2, accompanied by a lesser degree of IgG4) without light chain restriction in routine IF staining using fresh frozen tissue sections. Here, CD40LG is linked to nephrotic syndrome.