Diagnosis of renal amyloidosis by liquid chromatography-tandem mass spectrometry:experience from a single-center cohort study in China

To the Editor:Amyloidosis is caused by the extracellular deposition of insoluble beta-pleated protein fibrils in tissues and is classified according to the constituent proteins.The cause of amyloidosis can be traced to more than 30 kinds of malfolded proteins,and accurate amyloid typing is crucial for appropriate therapy.[1]The pathological diagnosis is confirmed with positive Congo red(CR)staining under a light microscope and 7 to 12 nm branching fibrils under an electron microscope.Further identification of some amyloid precursor proteins can resort to immunofluorescence(IF)and immunochemistry(IHC);however,the accuracy depends on the selected antibodies to a large extent.Laser microdissection coupled with liquid chromatography-tandem mass spectrometry(LMD/MS)can identify these proteins without the restriction of IF and IHC,although exquisite equipment and skilled specialists are required.[2]This study aimed to establish LMD/MS analysis of renal biopsy tissue and compare it with IHC on diagnostic sensitivity.