A recurrent fibronectin glomerulopathy in a renal transplant patient: a case report

Pathologic-genomic correlation identified a novel variant in FN1 and established the diagnosis of recurrent fibronectin glomerulopathy in the kidney allograft

Fibronectin glomerulopathy is a rare inherited kidney disease, characterized by abnormal accumulation of fibronectin in the glomeruli. We report an exceptional case of recurrent fibronectin glomerulopathy first diagnosed in the kidney allograft. The presence of IgA staining in the native kidney biopsy and the reported family history of IgA nephropathy had led to initial pretransplant diagnosis of IgA nephropathy. At 4.5 years posttransplant, the patient presented with kidney insufficiency and minimal proteinuria. The allograft biopsy revealed glomerular deposits with very weak staining for immunoglobulins and vague filamentous material. Immunostaining for fibronectin was positive, and genetic studies showed a variant of unknown significance in the fibronectin 1 gene. Proteomic analyses of the glomeruli in the native kidney biopsy demonstrated large amount of fibronectin with abundant accumulation of the peptide synthesized by the detected variant. These findings established the diagnosis of recurrent fibronectin glomerulopathy secondary to a novel variant in the fibronectin 1 gene. This report sheds light on recurrent fibronectin glomerulopathy in the allograft, highlights the diagnostic pitfalls of the disease, and underscores the importance of pathologic-genomic correlation to establish the correct diagnosis.

Fibronectin glomerulopathy in a kidney allograft biopsy

BACKGROUND

Fibronectin glomerulopathy is a rare genetic nephropathy with only a few cases of post-transplant recurrence being reported previously. We highlight a case that was initially misdiagnosed and emphasize the importance of full immunofluorescence and electron microscopy evaluation in allograft biopsies.

CASE PRESENTATION

A 36-year-old male with a history of end-stage kidney disease secondary to biopsy-proven type 1 membranoproliferative glomerulonephritis (MPGN) status-post living unrelated donor kidney transplant 12 years prior, presented with increasing creatinine and proteinuria. Biopsy was performed and was consistent with fibronectin glomerulopathy. Subsequent genetic testing revealed an FN1 mutation, the primary gene associated with this condition.

CONCLUSIONS

Full histologic evaluation of the allograft biopsy corrected the diagnosis and additionally suggested that the patient's mother, who had expired in her 30s and had received a diagnosis of type 1 MPGN on autopsy, likely also had fibronectin glomerulopathy, enabling appropriate genetic counseling for the family.

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.

A child with genetic FN1 mutation in the absence of classic glomerulopathy with fibronectin deposits(GFND) findings on biopsy

Background

Glomerulopathy with fibronectin deposits (GFND) is a rare autosomal dominant genetic disorder, and proteinuria and hematuria are the most common clinical manifestations. The pathogenesis of this disease is primarily related to mutation of the fibronectin 1 gene. Unfortunately, without specific treatment, the prognosis remains poor. Here we present a case report that investigates the clinical characteristics, renal pathology, and gene testing of childhood GFND.

Case presentation

A two-year-old child was brought to our hospital for “persistent hematuria for 1 year and 10 months.” The disease onset was at the age of 4 months, with persistent microscopic hematuria accompanied by intermittent gross hematuria, occasionally with proteinuria, and without hypertension or renal failure. The chief complaint was intermittent gross hematuria, without massive proteinuria, hypertension, or renal failure. Family history: The child’s mother had microscopic hematuria, his maternal aunt had nephrotic syndrome due to focal segmental glomerulosclerosis, and his maternal grandmother had end-stage renal disease. No significant pathological changes were found in the renal pathological biopsy of the child under a light microscope. Under the electron microscope, the basement membrane was found to be of uneven thickness, ranging from 150 to 400 nm. The stratum compactum of the basement membrane was thickened, with a small part showing tear-like and cobweb-like morphology. No electron-dense deposits were found. The renal tubular epithelial cells were vacuolated, and there were no unique pathological changes in the renal interstitium. Immunofluorescence showed that IgG, IgM, IgA, C3, and C1q were all negative. Alport syndrome was preliminarily considered. However, exome sequencing revealed a mutated site in the fibronectin 1 gene. The child’s mother was the carrier of the pathogenic gene and the final diagnosis was GFND.

Conclusions

Fibronectin deposition is a typical pathological change in GFND, and the disease progresses slowly to end-stage renal disease. There is no specific treatment so far, and the prognosis is poor. The early onset of childhood patients may not show typical renal pathological changes, but only changes in the thickness of basement membrane, etc. Genome sequencing technology may helpful for the early diagnosis of GFND.

Case Report: Recurrent Deposition in Renal Allografts: A Rare Case of Fibronectin Glomerulopathy Overlooked in Native Kidneys

Fibronectin glomerulopathy (FNG) is a rare inherited kidney disease characterized by extensive deposition of fibronectin in the glomeruli, especially in the mesangial and subendothelial regions. The disease progresses slowly and eventually leads to kidney failure in 15–20 years. Here, we report an interesting case. The patient presented with proteinuria and was diagnosed with immune complex–mediated glomerulonephritis, and lupus nephritis was suspected. This patient progressed to end-stage renal disease after 18 years and received an allogeneic kidney transplant. However, proteinuria recurred 27 months after kidney transplantation. The renal biopsy found extensive deposition in glomeruli, and the patient was diagnosed with FNG using mass spectrometry analysis and confirmed by immunohistochemistry in both the native and transplanted kidneys. Gene sequencing revealed that a missense mutation in the fibronectin 1 (FN1) gene caused reduced binding to heparin, endothelial cells, and podocytes and impaired stress fiber formation. The patient had stable renal function but persistent nephrotic proteinuria after 6 months of follow-up. Given the persistence of abnormal circulating fibronectin levels, FNG can relapse following renal transplantation. The circulating fibronectin deposits on grafts, and renal function progressively deteriorates after recurrence. Therefore, whether renal transplantation is an acceptable treatment for FNG is still debatable.

Urinary Transferrin and Proinflammatory Markers Predict the Earliest Diabetic Nephropathy Onset

This study aimed to determine the earliest markers of diabetic nephropathy (DN) onset with discriminative potentials from controlled diabetes (CD). Methods: Sixty male Wistar rats were allocated in three groups (20/group), the two diabetic groups CD and DN received 45 and 65 mg/kg STZ in 0.1 mole/L citrate buffer; respectively, while control group received only the vehicle. Serum/urinary levels of glomerular, tubular, oxidative and proinflammatory markers were weekly monitored. Results: Each diabetic group showed a different pattern of inflammatory; oxidative and signs of nephropathy along the study period, but none had a discriminative power until the 4^th week. At this time point, levels of urinary transferrin; serum/urinary IL-6 and TNF-α as well as urinary IL-18 were significantly higher in DN group comparing to CD (P = 0.0217, <0.0001, 0.0005, 0.0004, 0.0006, 0.0019; respectively). Predictive thresholds of these markers were calculated by receiver operating characteristic (ROC) curve that showed area under curve (AUC) of 0.9375 for transferrin with cut-off value 35.2 mg/dL, and 1.000 for serum/urinary IL-6 and TNF-α and urinary IL-18 with cut-of values 224.1, 82.11, 6.596, 125.9 and 21.86 pg/mL; respectively. Conclusion: Urinary transferrin and the inflammatory endpoints proposed in this study might represent promising biomarkers for the early DN onset.

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.

Prednisone-induced sustained remission in a patient with familial fibronectin glomerulopathy (GFND)

Glomerulopathy with Fibronectin Deposits (GFND) is a rare, autosomal dominant disease characterized by proteinuria, hematuria and progressive renal failure associated with glomerular deposition of fibronectin, frequently resulting in end-stage renal disease (ESRD). There is no established treatment for this condition beyond conservative measures such as blood pressure control and the use of angiotensin-converting enzyme (ACE) inhibitors. We present a case of GFND associated with progressive chronic kidney disease (CKD) and nephrotic range proteinuria showing a sustained response to prednisone treatment. A 27-year-old G₂P₂ Caucasian female presented with 3 g/day of proteinuria, serum creatinine (Cr) 0.7 mg/dL, inactive urinary sediment and normotension without medication. She was part of a large family with glomerular disease, including three members who died of cerebral hemorrhage or stroke in their thirties. The patient's kidney biopsy showed mesangial deposition of fibronectin consistent with GFND. No interstitial fibrosis was seen. Genotyping revealed the Y973C FN1 gene mutation. Despite maximal tolerable ACE inhibition, proteinuria increased to 4-6 g/g Cr and serum Cr increased to 1.0 mg/dL. She was treated with prednisone 60 mg (~ 1 mg/Kg) daily for 2 mos and then tapered by ~ 0.2 mg/Kg every month for 6 mos of total therapy. Proteinuria decreased to ~ 1 g/g Cr for > 5 years and serum Cr stabilized in the 1.2 mg/dL range with treatment. No significant side effects were encountered. In conclusion, this protocol should be considered in GFND patients with nephrotic range proteinuria despite maximal angiotensin system inhibition who have relatively preserved renal function.

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.

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.