Fibronectin Glomerulopathy
Neeraja Kambham, MD
Key Facts
Terminology
Nonimmune lobular glomerulopathy with massive mesangial and subendothelial fibronectin deposits
Etiology/Pathogenesis
Autosomal dominant inheritance
Mutations in fibronectin FN1 gene documented recently in some patients
Microscopic Pathology
Glomeruli are diffusely enlarged with lobular accentuation and minimal hypercellularity
Deposits stain with PAS and trichrome but not with methenamine silver or Congo red
Ancillary Tests
Deposits stain for fibronectin but not for immunoglobulins, C3, or C1q
Fibrillar and granular deposits by EM
 Renal biopsy in a patient with fibronectin glomerulopathy shows PAS-positive material  expanding the mesangium and subendothelium of an enlarged glomerulus. |
 Intense immunofluorescence staining  is seen in glomerular deposits with antisera to fibronectin, consistent with FN glomerulopathy. Staining for immunoglobulins and complement is negative. |
TERMINOLOGY
Abbreviations
Fibronectin (FN) glomerulopathy
Definitions
Nonimmune lobular glomerulopathy with massive mesangial and subendothelial deposits composed of fibronectin
ETIOLOGY/PATHOGENESIS
Autosomal Dominant Inheritance
Mutations in fibronectin FN1 gene documented recently in some patients
FN1 gene mapped to region in chromosome 2q34
Abnormal FN may affect function of glomerular endothelial cells and podocytes
No role of villin, desmin, or uteroglobin genes
Glomerular Fibronectin Deposition
FN is an extracellular matrix glycoprotein involved in cellular adhesion, migration, and cytoskeleton maintenance
Deposition of plasma FN rather than local synthesis by mesangial cells
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