Proteomic Analysis for Cryofibrinogen: Associated Glomerulonephritis and Cryoglobulinemic Glomerulonephritis

Cryofibrinogen-associated glomerulonephritis (CF-GN) and cryoglobulinemic glomerulonephritis (CG-GN) are rare diseases that are both characterized by membranoproliferative glomerulonephritis (MPGN) with organized deposition of tubular or cylinder structures; however, they are distinguished by the absence or presence of immunoglobulins in CF-GN and CG-GN respectively. The diagnoses of the two disorders are based upon reversible cryoprecipitation of plasma or serum, clinical manifestations in the skin and the pathological characteristics seen during renal biopsy. Recently, a novel powerful laser microdissection (LMD) and liquid chromatography-tandem mass spectrometry (LCMS/MS) tool has been introduced to identify the components of electron dense deposits. In this review, we described the clinical characteristics and pathological features of CF-GN and CG-GN, and critically assessed the application of LCMS/MS to the diagnosis of kidney diseases among patients previously described. Notably, the practical information provided by proteomic analysis using LCMS/MS has an immense impact on establishing the specific diagnosis of these rare glomerulonephritis (GN) that have identical morphologies but different etiological molecules.