Fibronectin Glomerulopathy: An Unusual Cause of Adult-Onset Nephrotic Syndrome

Generation of an induced pluripotent stem cell line XJHi001-A from a fibronectin glomerulopathy patient carrying a heterozygous NM_212482.2(C.5888-1G > C) mutation in the FN1 gene

Fibronectin glomerulopathy (FNG) is an autosomal dominant disease, and nearly half of patients are involved in a mutation of the fibronectin gene (FN1). By using electrotransformation, we generated an induced pluripotent stem cell (iPSC) line from peripheral blood mononuclear cells (PBMCs) of a 32-years-old female patient who carried a heterozygous NM_212482.2(C.5888-1G > C) mutation in the FN1 gene. This cellular model is a useful tool to investigate pathogenic mechanisms in FNG and to develop potential treatments for FNG.

Fibronectin glomerulopathy with monoclonal gammopathy responding to bortezomib plus dexamethasone: a case report

BACKGROUND

Fibronectin glomerulopathy is a rare, familial glomerular disease characterized by mesangial fibronectin deposition in the glomeruli. It is caused by the genetic defect in fibronectin and does not involve the activation of the immune system. Therefore, glomerular immunoglobulin and complement staining is generally absent or weak. Monoclonal gammopathy (MG) is an increasing cause of renal lesion, featured by light chain (κ or λ) and/or heavy chain restriction in glomeruli. Herein, we report a case of fibronectin glomerulopathy presenting as strong IgA and C3 immunostaining in renal biopsy, concomitant with monoclonal gammopathy (monoclonal IgA κ).

CASE PRESENTATION

A 44-year-old female was admitted to our hospital for one-month pedal edema. The serum albumin of 19.6 g/l, and the 24-h urine protein was 15.092 g. Immunofixation electrophoresis displayed monoclonal IgA. The renal biopsy showed the mesangial deposits positive for IgA (3+) and C3 (3+) and also for IgG (2+), IgM (2+), and C1q (2+) IF microscopy. In addition, the staining intensity of light chain κ was slight greater than that of light chain λ. The glomerular deposits were strongly positive by FN by immuohistochemistry. The patient was treated with bortezomib, dexamethasone in combination with cyclophosphamide and gained partial remission.

CONCLUSION

We present the first FNG patient with strong IgA and C3 immunostaining in the context of monoclonal IgA κ in the circulation. Perhaps FNG, monoclonal IgA κ and immune activation are potentially interplayed and eventually induce renal injuries.

Bortezomib-containing regiment in treating glomerulopathy with fibronectin deposits combined with monoclonal gammopathy of undetermined significance: a case report and literature review

Background

Glomerulopathy with fibronectin deposits (GFND) is a newly recognized rare glomerular disease. As its onset can be stably inherited in affected families without sex differences and fibronectin 1 (FN1) mutations can be detected in 40% of patients’ families, GFND is considered to be an autosomal dominant genetic disease. The main clinical manifestations are proteinuria, progressive renal failure, edema, hypertension, hematuria, and type 4 renal tubular acidosis. The diagnosis was confirmed by renal biopsy, and there was no specific treatment. Monoclonal gammopathy refers to the existence of monoclonal immunoglobulin (MIg) produced by monoclonal plasma cells in serum. When MIg damages the kidney by direct deposition or indirect mechanisms, it is defined as monoclonal gammopathy of renal significance (MGRS). The principle of treatment is to inhibit plasma cells from producing MIg.

Case Description

We report the efficacy of a case of GFND combined with monoclonal gammopathy of undetermined significance (MGUS) treated with a bortezomib-containing regimen. A 44-year-old female patient was admitted to the hospital for “edema of both lower extremities for 1 month and aggravation for 5 days”. In May 2018, after exertion, the patient developed edema of both lower extremities, accompanied by foamy urine with no obvious deepening of urine color or decreased output, no gross hematuria, and gradual aggravation with fatigue.

Conclusions

After treatment, the edema of patient subsided, urinary protein decreased significantly, and serum albumin increased near to normal. It is achieving a very good therapeutic effect and long-term event-free survival. The treatment is safety and there are no obvious toxic side effects. It provides a new idea for the treatment of GFND.

Extraglomerular Vascular Involvement of Glomerulopathy with Fibronectin Deposits

Glomerulopathy with fibronectin deposits (GFND) is a rare hereditary kidney disease with autosomal dominant inheritance. A 21-year-old woman who had been diagnosed with GFND 10 years ago was admitted for investigation of a rapid decline in her renal function, hemolytic anemia, and cardiac dysfunction. A renal biopsy showed GFND accompanied by extraglomerular vascular lesions. Comprehensive treatments against hypertension and anemia improved the renal function. Although there have been few reports of vascular lesions in GFND, we suspect that endothelial hyperpermeability resulting from hypertension caused the fibronectin deposition and narrowing of the extraglomerular vascular lumens, thereby accelerating hypertension and inducing hemolytic anemia.

Clinicopathologic Features and Outcomes in Fibronectin Glomerulopathy: A Case Series of 19 Patients

Aims: To describe the characteristics and prognosis of 19 patients with fibronectin glomerulopathy (FNG) and evaluate prognostic factors associated with poor renal outcomes.

Methods: Included in this retrospective study was 19 FNG patients in Nanjing Glomerulonephritis Registry system. Associations between the clinical parameters, pathological features, and renal outcomes were evaluated by Kaplan-Meier survival analysis.

Results: Of the 19 FNG patients included in this study, 8 (42.1%) were women. The median age of the 19 FNG patients was 31 (17–71) years, and the median disease duration 48 (1–175) months at diagnosis. At the time of renal biopsy, the mean serum creatinine (Scr) was 1.22 ± 0.16 mg/dl and urinary protein was 6.24 ± 0.97 mg/24 h. Renal biopsy showed a lobular appearance with cellular mesangial nodules expanded by matrix in 14 cases. After a median follow-up period of 87 months (interquartile range 34–114.5 months), 8 FNG patients developed renal function decline, including 7 progressing into end-stage renal disease (ESRD) and 1 presenting with by a 2-fold-increase in Scr. Scr and proteinuria remained stable in the remaining 11 patients. Kaplan-Meier survival analysis showed that nephrotic range proteinuria (P = 0.022) and focal glomerular sclerosis (P = 0.028) were associated with renal function decline.

Conclusions: Nephrotic range proteinuria and focal glomerular sclerosis were associated with renal function decline during the follow-up period of the FNG patients in our series. FNG Patients at risk of renal function decline should be identified preferentially and given more progressive and effective therapies to prevent further disease progression.

A novel single amino acid deletion impairs fibronectin function and causes familial glomerulopathy with fibronectin deposits: case report of a family

Background

Glomerulopathy with fibronectin deposits is an autosomal dominant disease associated with proteinuria, hematuria, hypertension and renal function decline. Forty percent of the cases are caused by mutations in FN1, the gene that encodes fibronectin.

Case presentation

This report describes two cases of Glomerulopathy with fibronectin deposits, involving a 47-year-old father and a 14-year-old son. The renal biopsies showed glomeruli with endocapillary hypercellularity and large amounts of mesangial and subendothelial eosinophilic deposits. Immunohistochemistry for fibronectin was markedly positive. Whole exome sequencing identified a novel FN1 mutation that leads to an amino-acid deletion in both patients (Ile1988del), a variant that required primary amino-acid sequence analysis for assessment of pathogenicity. Our primary sequence analyses revealed that Ile1988 is very highly conserved among relative sequences and is positioned in a C-terminal FN3 domain containing heparin- and fibulin-1-binding sites. This mutation was predicted as deleterious and molecular mechanics simulations support that it can change the tertiary structure and affect the complex folding and its molecular functionality.

Conclusion

The current report not only documents the occurrence of two GFND cases in an affected family and deeply characterizes its anatomopathological features but also identifies a novel pathogenic mutation in FN1, analyzes its structural and functional implications, and supports its pathogenicity.

A novel variant in FN1 in a family with fibronectin glomerulopathy

Glomerulopathy with fibronectin deposits (GFND) is a rare glomerular disorder. We report a 28-year-old male diagnosed with GFND by mass spectrometry on kidney biopsy tissue. Whole-exome sequencing (WES) identified that a previously undescribed FN1 gene mutation (c.3051G > T, p.W1017C) was likely responsible for this patient’s fibronectin glomerulopathy. We discuss the implications of this novel variant of FN1 and the importance of WES to identify a mutation in a gene of interest.

MicroRNA-139 targets fibronectin 1 to inhibit papillary thyroid carcinoma progression

Thyroid cancer is the most common tumour of the endocrine system, and its incidence rate has markedly increased over the past several decades. Aberrantly expressed microRNAs (miRNAs) are reportedly involved in the formation and progression of papillary thyroid carcinoma (PTC) by regulating their target genes. Thus, miRNAs may be potential molecular biomarkers for the prediction and prognosis of PTC, and also as novel therapeutic targets for patients with PTC. miR-139 has recently been reported to be aberrantly expressed in several types of cancer. However, the expression levels, biological functions and the associated molecular mechanism of miR-139 in PTC have not been clearly elucidated. The results of the present study revealed that miR-139 expression was downregulated in PTC tissues and cell lines when compared with adjacent normal tissues and normal human thyroid cells, respectively. The restoration of miR-139 expression suppressed cellular proliferation and invasion in PTC in vitro. In addition, fibronectin 1 (FN1) was identified as a direct target of miR-139 in PTC. Furthermore, FN1 was highly expressed in PTC tissues and negatively associated with miR-139 expression. Moreover, the tumour-suppressive effects of miR-139 overexpression on PTC cells were ameliorated by ectopic FN1 expression. To the best of our knowledge, the present study is the first to demonstrate that miR-139 may serve as a tumour suppressor and serve important roles in inhibiting tumourigenesis by targeting FN1 in PTC cells.

Fibronectin glomerulopathy complicated with persistent cloaca and congenital esophageal atresia: a case report and literature review

BACKGROUND

Fibronectin glomerulopathy is a rare, inherited, autosomal dominant, glomerular disease characterized by proteinuria, microscopic hematuria, hypertension, massive glomerular deposits of fibronectin, and slow progression to end-stage renal failure. Because the incident of fibronectin glomerulopathy is extremely low, the pathophysiology, genetic abnormalities, epidemiology, and mechanisms remain to be elucidated.

CASE PRESENTATION

We report a 21-year-old woman with fibronectin glomerulopathy, who had been diagnosed with persistent cloaca and congenital esophageal atresia at birth. She developed proteinuria and hematuria 7 months before admission. Urinary protein and serum creatinine levels were 3.38 g/gCr and 0.73 mg/dL. Renal biopsy showed severe mesangial widening due to massive deposits, which was positive periodic acid-Schiff and negative methenamine silver. Immunostaining was negative for immunoglobulin but positive for fibronectin. Electron microscopy showed diffuse mesangial granular deposits. Thus she was diagnosed with fibronectin glomerulopathy, despite a negative family history of kidney disease and lack of any known missense mutations of fibronectin 1 gene.

CONCLUSION

We report a patient who developed fibronectin glomerulopathy during the clinical course of extremely rare congenital malformations, including persistent cloaca and congenital esophageal atresia. We describe a case of this condition in detail and summarize the 75 case reports of fibronectin glomerulopathy.

Monoclonal immunoglobulin-associated proliferative glomerulonephritis characterized by organized deposits of striated ultra-substructures: A case report

We herein report the case of a 64-year-old male who presented with progressive glomerulonephritis notable for organized and striated ultra-substructures. The patient was diagnosed with hypertension and proteinuria 3 years prior to admission and subsequently developed nephrotic syndrome and impairment of renal function. Laboratory tests did not reveal any evidence of infections or autoimmune diseases. Monoclonal gammopathy was not detected in serum or urine, although a small population of abnormal plasma cell clones was detected by flow cytometry. A renal biopsy showed mesangial and endocapillary proliferative glomerulonephritis with lobular accentuation, accompanied with focal and segmental double-contour formation. Additionally, moderate tubulointerstitial scarring and arteriosclerosis were noted. Immunofluorescence staining revealed positive staining for IgG, IgM, C3, C1q, and fibrinogen. IgG subclass and light chain staining showed restricted positivity for IgG1κ. Electron microscopy demonstrated massive amounts of subendothelial deposits with a fibrillary and branching profile. At higher magnification, a periodic striated pattern was observed within the microfilament-like structures. Immunohistochemical staining was negative for myoglobin, laminin, and collagens (type III and IV). Steroid and antihypertensive therapy did not show improvement in renal function. The second biopsy performed 2 years later revealed a similar lobular proliferative glomerulonephritis pattern with more extensive tubulointerstitial damage, indicating poor response to immunosuppressive therapy. The patient progressed to end-stage renal disease and required hemodialysis. We discuss the possible origins of the deposits with unusual substructures observed in this case.

A novel FN1 variant associated with familial hematuria: TBMN?

OBJECTIVE

Thin basement membrane nephropathy (TBMN), an autosomal dominant inherited condition in general, is characterized clinically by persistent hematuria and pathologically by thinning of glomerular basement membrane. TBMN is occasionally accompanied with proteinuria, hypertension and renal impairment in some cases. The aim of this study is to explore the genetic defect in a Chinese pedigree with familial hematuria.

DESIGN AND METHODS

A four-generation Chinese Han pedigree with familial hematuria was recruited. Exome sequencing was conducted in the proband diagnosed as TBMN, followed by verification in the proband and other family members with Sanger sequencing.

RESULTS

A novel missense variant, c.4616C>G (p.S1539C), in the fibronectin 1 gene (FN1), was identified, and it co-segregated with the disease condition in the family. It was not observed in 100 normal controls.

CONCLUSIONS

A missense variant in the FN1 gene is possibly responsible for familial hematuria or TBMN in this family, which may broaden the phenotype and mutation spectrums of the FN1 gene. A male patient in this family progressed to end-stage renal disease requiring kidney transplantation, supporting that familial hematuria or TBMN may not always be as benign as generally thought. The findings may have new implications for clinical monitoring and genetic counseling of the family, and may also help understand the pathogenesis.

Fibronectin glomerulopathy

Fibronectin glomerulopathy occurs between the second and fifth decades of life in most patients, and it is known to be slowly progressive with mild proteinuria leading to kidney failure. The case of a 78-year-old woman with a rapid course of nephrotic syndrome due to fibronectin glomerulopathy is reported. She had proteinuria that rapidly increased to 6.8 g/day in a month and microscopic haematuria. A renal biopsy specimen showed lobular glomerulopathy and membranoproliferative glomerulonephritis-like lesions on light microscopy. There was scanty staining for immunoglobulins and complement. Electron microscopy revealed granular deposits with fibril formation. Immunohistochemistry of the fibronectin showed intense staining in the mesangium and peripheral loop. Therefore, this case was diagnosed as fibronectin glomerulopathy. The kidney function was rapidly decreasing, necessitating haemodialysis 2 months after renal biopsy. It is important to consider fibronectin glomerulopathy in the differential diagnosis of nephrotic syndrome in older people.