Clinicopathological analysis of DNAJ heat shock protein family member B9-positive fibrillary glomerulonephritis / 中华肾脏病杂志

ABSTRACT

Objective:To summarize and analyze the clinicopathological characteristics of patients with DNAJ heat shock protein family member B9 (DNAJB9)-positive fibrillary glomerulonephritis (FGN).Methods:The clinical and pathological data of 5 patients with DNAJB9-positive FGN diagnosed in Peking University First Hospital from January 2011 to January 2021 were retrospectively collected and analyzed.Results:Among the 5 patients, the female to male ratio was 4∶1, and the median age was 29 years old (24-71 years old). The clinical manifestations included 2 cases with nephrotic syndrome and 3 cases with proteinuria. One patient had gross hematuria, and 4 cases had mild microscopic hematuria. None of the 5 patients had evidence of monoclonal gammopathy. The renal pathological pattern of FGN showed mesangial-proliferative glomerulonephritis, mesangial nodular sclerosis, membranoproliferative glomerulonephritis, and atypical membranous nephropathy. Crescents formation could be accompanied. Immunofluorescence staining showed smudgy and granular IgG and C3 deposition in the mesangial region and capillary wall, and the subtypes of IgG were mainly IgG1 and IgG4. Under electron microscopy, fibrillary deposits with a diameter of 8-30 nm were observed in the mesangial and subendothelial area, accompanied by deposition in basement membrane and occasionally subepithelial area. The renal prognosis of FGN patients was poor. One patient entered end-stage renal disease within one week, and another patient entered end-stage renal disease within one year despite immunosuppressant therapy in 2 cases with nephrotic syndrome at onset. One patient had worsening proteinuria despite renin-angiotensin system (RAS) blocker treatment. Two patients achieved complete renal remission and stable renal function after RAS blocker treatment.Conclusions:Most FGN patients in China are young people. The main clinical manifestations are proteinuria or mild microscopic hematuria. The diagnosis depends on the discovery of fibrillary deposits in the mesangial area and subendothelial area with a diameter of about 10-30 nm under the electron microscope. DNAJB9 protein immunohistochemical staining can be used as an important marker for the diagnosis of FGN. The prognosis of FGN kidney is poor, and there is no effective targeted treatment option now.