This is a mechanism module, not a specific disease. Disorder entries reference individual nodes via conforms_to (e.g., "nephrotic_podocyte_injury#Glomerular Filtration Barrier Breakdown"). The module defines the expected pathophysiology structure; conforming nodes in disorder files should include the corresponding podocyte cell type, biological processes, and causal edges, specialized to their etiologic context. Key disorder-specific substitutions: genetic forms substitute the mutated slit-diaphragm/cytoskeleton gene product (nephrin in NPHS1, podocin in NPHS2); minimal change disease and primary FSGS substitute a circulating permeability factor or immune mechanism as the trigger; secondary forms (diabetic nephropathy, lupus, membranous) substitute their specific glomerular insult while preserving podocyte injury as the central lesion.
Podocyte Injury
trigger
A circulating permeability factor, immune or toxic mechanism, or an inherited mutation in a slit-diaphragm or cytoskeletal protein (nephrin, podocin, or actin-regulating proteins) injures the glomerular podocyte. Across primary, genetic, and secondary nephrotic syndromes the initiating lesion converges on the podocyte and its actin cytoskeleton, the central target whose perturbation begins the pathway to filtration barrier failure.
Downstream
-
Foot Process Effacement and Slit Diaphragm Disruption
Glomerular Filtration Barrier Breakdown
central effector
Loss of foot process and slit diaphragm integrity, together with podocyte, glomerular basement membrane, and endothelial dysfunction, breaks down the size- and charge-selective glomerular filtration barrier. The barrier can no longer restrain plasma proteins, so albumin and larger proteins pass into the urinary space. This is the central effector step that converts a podocyte structural lesion into pathological filtration.
Downstream
-
Massive Proteinuria with Podocyte Loss
Massive Proteinuria with Podocyte Loss
effector
Sustained barrier failure produces massive proteinuria. Because podocytes are terminally differentiated and do not normally divide, ongoing injury leads to their detachment from the glomerular basement membrane and progressive podocyte loss. Once podocyte loss exceeds a critical threshold in a glomerulus, glomerulosclerosis develops and the glomerulus is progressively obliterated, establishing chronic, often progressive disease.
Nephrotic Syndrome
consequence
The convergent clinical consequence of glomerular filtration barrier failure is nephrotic syndrome: nephrotic-range proteinuria with hypoalbuminemia, peripheral edema, and hyperlipidemia. Whatever the initiating podocyte insult — minimal change disease, focal segmental glomerulosclerosis, genetic podocyte-gene disorders, or secondary causes — the disease-defining phenotype is shared, with complications including thrombosis and infection.