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Discussions and Knowledge Gaps

2

Is kidney transplantation appropriate in light chain deposition disease, and does recurrence in the graft depend on transplantation itself or on the state of the plasma cell clone at the time of transplant?

CONTROVERSY OPEN lcdd_transplant_recurrence

Attached to

pathophysiology#Clonal Plasma Cell Secretion of Free Light Chain treatments#Kidney Transplantation

The literature contains two apparently opposed findings. One series reports recurrence in three of four grafts, and a recent review concludes that renal allograft is not recommended because of the high incidence of relapse. Another series reports no recurrence up to nearly ten years, but only among patients whose clonal disorder was in sustained remission when they were transplanted. Read together these are not contradictory: the graft fails when the clone is still producing pathogenic light chain, because nothing about transplantation addresses the source of the protein. The apparent controversy about the procedure is better understood as a question about patient selection, and the proposed resolution is that haematologic remission status is the discriminator. It is recorded as open rather than resolved because no study has tested that reconciliation prospectively.

Proposed experiments

Graft outcome stratified by pre-transplant haematologic response depth

lcdd_transplant_by_remission_status

Assemble a multicentre cohort of transplant recipients with this disease, stratified by depth and duration of haematologic response at the time of transplantation and by serial free light chain measurement afterwards, with graft recurrence as the endpoint. If the reconciliation is right, recurrence should track residual clonal activity rather than time since transplant.

Show evidence (1 reference)

PMID:26915878 SUPPORT Human Clinical

"they have experienced a prolonged period of stable renal function with no clinically detectable disease"

Case-level support for the proposed reconciliation: grafts can be held long term when the clone is controlled. PARTIAL because it is a small number of cases and cannot by itself establish that remission status is the discriminator rather than one correlate of it.

What structural features determine whether a monoclonal light chain becomes glomerulopathic and causes this disease, rather than tubulopathic and causing cast nephropathy or Fanconi syndrome?

KNOWLEDGE GAP OPEN lcdd_glomerulopathic_vs_tubulopathic

Attached to

pathophysiology#Pathogenic Light Chain Variable Domain

The distinction is real and experimentally demonstrated rather than hypothetical: light chains previously characterised as tubulopathic do not produce the mesangial matrix response that glomerulopathic light chains do, in the same assay. Something in the variable domain sorts one destination from the other. Candidate determinants include isoelectric point, complementarity determining region hydrophobicity, glycosylation, and germline gene subgroup usage, but no rule predicts destination from sequence. This matters clinically because two patients with similar small clones can develop entirely different kidney diseases requiring different management, and there is currently no way to tell in advance which.

Proposed experiments

Sequence-to-destination mapping of pathogenic light chains

lcdd_lc_sequence_destination_map

Sequence the pathogenic light chain variable domain from a large series of patients with clinically and histologically classified renal lesions, and test whether isoelectric point, CDR hydrophobicity, glycosylation site presence, and germline subgroup predict glomerular versus tubular destination. Validate candidate determinants by expressing selected variants in the mesangial-cell assay in which the original distinction was drawn.

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Pathophysiology

8

Clonal Plasma Cell Secretion of Free Light Chain

A plasma cell clone, typically small and often below the burden that would define myeloma, secretes free immunoglobulin light chain in excess. The clone size is characteristically modest relative to the damage it does, which is the defining feature of monoclonal gammopathy of renal significance: the lesion is not the tumour burden but the physical properties of the protein.

plasma cell CL:0000786

immunoglobulin production GO:0002377 ↑ INCREASED

Downstream

Pathogenic Light Chain Variable Domain The secreted product carries the structural abnormality that makes it pathogenic.

Plasma Cell Endoplasmic Reticulum Stress Producing an awkwardly folding protein at high rate imposes a burden on the clone's own quality-control machinery.

Show evidence (1 reference)

PMID:32559766 SUPPORT Model Organism

"Our mouse model recapitulates the characteristic features of LCDD, including progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure."

The transgenic model demonstrates that plasma-cell secretion of the pathogenic light chain is sufficient to reproduce the disease, which is the claim this node carries.

Pathogenic Light Chain Variable Domain

The variable domain carries hydrophobic substitutions in its complementarity determining regions, sometimes an N-glycan, and a high isoelectric point. The positive charge is thought to drive deposition by complementarity with polyanionic basement membrane. This node, and not the clone, is the actual etiologic agent of the disease: the variable domain alone is sufficient to confer pathogenicity.

Downstream

Non-Fibrillar Basement Membrane Deposition The physical deposition step, driven by the domain's charge and hydrophobic character.

Mesangial Cell Surface Engagement and Phenotype Transformation Separately from depositing, the light chain acts as a ligand at the mesangial cell surface. Deposition and signalling are distinct consequences of the same molecule, which is why they are separate downstream edges rather than a chain.

Show evidence (1 reference)

PMID:32559766 SUPPORT Model Organism

"The variable domain of the LC bears alone the structural properties involved in its pathogenicity."

States that pathogenicity resides in the variable domain by itself, which is why this node sits between the clone and every downstream consequence.

Plasma Cell Endoplasmic Reticulum Stress

Producing a structurally awkward light chain at high output places the plasma cell clone under endoplasmic reticulum stress. This node exists because it is the therapeutic vulnerability of the disease rather than a step toward kidney injury: the clone has backed itself into a corner by making a protein its own folding machinery struggles with, and blocking the proteasome tips it over.

response to endoplasmic reticulum stress GO:0034976 ↑ INCREASED

Show evidence (1 reference)

PMID:32559766 SUPPORT Model Organism

"RNA sequencing conducted on PCs demonstrated that LCDD LC induces endoplasmic reticulum stress, likely accounting for the high efficiency of proteasome inhibitor-based therapy."

Establishes the endoplasmic reticulum stress and, in the authors' own words, connects it to why proteasome inhibition works so well in this disease.

Non-Fibrillar Basement Membrane Deposition

Linear and granular deposits of monoclonal light chain along glomerular and tubular basement membranes. They are Congo red negative and non-fibrillar, described as powdery on electron microscopy. This is the histological definition of the disease and the single most important thing distinguishing it from AL amyloidosis at the bench.

Downstream

Nodular Glomerulosclerosis Deposition contributes to the sclerotic lesion, but the bulk of the matrix is made by mesangial cells responding to the light chain rather than being the deposited light chain itself.

Show evidence (1 reference)

PMID:39196376 SUPPORT Human Clinical

"Light chain deposition disease (LCDD) is a rare hematologic disorder characterized by the deposition of non-amyloid monoclonal light chains in several organs."

States the non-amyloid character of the deposits, which is the property that defines this node and the reason the amyloidogenesis module is not declared.

Mesangial Cell Surface Engagement and Phenotype Transformation

The decisive mechanistic node, and the point at which this disease and AL amyloidosis part company. Light chains from patients with light chain deposition disease are NOT endocytosed by mesangial cells; they act at the cell surface, and the interaction drives apoptosis, transformation of the mesangial cell toward a myofibroblast phenotype, and secretion of matrix components and metalloproteinases. Amyloidogenic light chains from the same cell type do the opposite: they are avidly taken up and delivered to the lysosome, where fibrils form. Same cell, same class of ligand, opposite itinerary.

mesangial cell CL:0000650 myofibroblast phenotype acquired by the mesangial cell CL:0000186

Downstream

TGF-beta Driven Matrix Overproduction The transformed mesangial cell increases matrix output under TGF-beta control.

Failure of Matrix Degradation The same interaction reduces matrix-degrading activity, which is the second half of the imbalance.

Show evidence (3 references)

PMID:33163710 SUPPORT In Vitro

"Light chains from patients with LCDD exert their pathogenic signaling effect at the cell surface of mesangial cells."

States the surface-signalling mechanism, which is what makes the light chain a ligand rather than merely a precipitate.

PMID:33163710 SUPPORT In Vitro

"Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed."

The explicit contrast with amyloidogenic light chains in the same cell type. Curated here because it is the direct evidence that this disease does not proceed by the amyloid mechanism, and therefore the basis for declining conformance to the amyloidogenesis module.

PMID:33163710 SUPPORT In Vitro

"which include apoptosis, phenotype transformation, and secretion of extracellular matrix components and metalloproteinases"

Enumerates the cellular consequences of the surface interaction, including the phenotype transformation this node is named for.

TGF-beta Driven Matrix Overproduction

Mesangial cells exposed to glomerulopathic light chains increase production of type IV collagen, laminin, and fibronectin, with TGF-beta production and activity rising in parallel. The causal role of TGF-beta is established rather than inferred, because blocking it with antibody abolishes the effect.

transforming growth factor beta receptor signaling pathway GO:0007179 ↑ INCREASED extracellular matrix organization GO:0030198 ↑ INCREASED

Downstream

Nodular Glomerulosclerosis Sustained matrix overproduction expands the mesangium into nodules.

Show evidence (3 references)

PMID:7639331 SUPPORT In Vitro

"transforming growth factor-beta (TGF-beta) production and activity increased when mesangial cells were exposed to these proteins"

Establishes that the light chains raise TGF-beta production and activity in mesangial cells.

PMID:7639331 SUPPORT In Vitro

"anti-TGF-beta antibody abolished the inhibition of cell proliferation and the increase of extracellular matrix protein production caused by these light chains"

The blocking experiment, which converts the TGF-beta association into a causal claim: remove the cytokine and the phenotype disappears.

PMID:7639331 SUPPORT In Vitro

"These findings were not observed in mesangial cells exposed to human albumin and two other light chains previously characterized to be tubulopathic."

The specificity control, and mechanistically important beyond methodology: glomerulopathic and tubulopathic light chains are distinct populations, which is why a similar clone in another patient produces cast nephropathy or Fanconi syndrome instead of this disease.

Failure of Matrix Degradation

The other half of the imbalance, and the reason the glomerulus fills so quickly. Alongside increased matrix production, collagenase activity falls, so matrix that would normally be turned over accumulates. The mirror image in AL amyloidosis is exact: there, matrix production falls and collagenase activity rises, degrading matrix and facilitating amyloid deposition instead.

extracellular matrix disassembly GO:0022617 ↓ DECREASED

Downstream

Nodular Glomerulosclerosis Reduced turnover compounds increased production.

Show evidence (2 references)

PMID:10369104 SUPPORT In Vitro

"A concomitant decrease in collagenase IV activity further accentuates the accumulation of mesangial matrix."

States the fall in matrix-degrading activity that accompanies increased production.

PMID:10369104 SUPPORT In Vitro

"a decrease in ECM protein production and a stimulatory effect on collagenase IV is observed, which results in matrix degradation and facilitates amyloid deposition"

The mirror-image result for amyloidogenic light chains in the same experimental system. Curated as further evidence that the two diseases are mechanistically opposite at the mesangial cell rather than variants of one process.

Nodular Glomerulosclerosis

Nodular expansion of the mesangium, the characteristic light-microscopic lesion. It is a mesangial product rather than a pile of deposited light chain: the bulk of the nodule is matrix the mesangial cell was induced to make.

Downstream

Proteinuria Glomerular architectural destruction produces protein loss.

Chronic kidney disease Progressive nephron loss follows the sclerotic process.

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Nodular mesangial sclerosis was seen in 39 patients (61%)"

The sentence that actually supports this node: nodular mesangial sclerosis in 61 per cent of the series. The transplant-recurrence sentence previously quoted here supported the transplant discussion, not the histological lesion, and has been moved to where it belongs.

✶

Histopathology

2

Congo red negative granular basement membrane deposits

The histological finding on which the whole entry turns. Monotypic light chain is demonstrated along glomerular and tubular basement membranes by immunofluorescence, and the deposits are granular and powdery on electron microscopy rather than fibrillar, and negative on Congo red staining. That negativity is not a technicality: it is what separates this disease from AL amyloidosis, which deposits the same class of protein in the same organ by an opposite cellular route.

Show evidence (1 reference)

PMID:39196376 SUPPORT Human Clinical

"Light chain deposition disease (LCDD) is a rare hematologic disorder characterized by the deposition of non-amyloid monoclonal light chains in several organs."

States the non-amyloid character of the deposits, which is what Congo red negativity demonstrates at the bench and the reason amyloidogenesis conformance is declined in this entry.

Nodular mesangial sclerosis

Nodular expansion of the mesangium on light microscopy, present in the majority of biopsies. The nodules are largely matrix that the mesangial cell was induced to make rather than deposited light chain, which is why the lesion is disproportionate to the amount of protein visible by immunofluorescence.

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Nodular mesangial sclerosis was seen in 39 patients (61%)"

Quantifies the nodular lesion in the largest single-institution series.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

6

Cardiovascular 1

Hypertension HP:0000822

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"

Names hypertension among the presenting features of the series.

Genitourinary 4

Proteinuria HP:0000093

Show evidence (2 references)

PMID:32559766 SUPPORT Model Organism

"Our mouse model recapitulates the characteristic features of LCDD, including progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure."

Names nephrotic-range proteinuria among the characteristic features of the disease being modelled. Tagged MODEL_ORGANISM because the sentence describes the mouse.

PMID:22156754 SUPPORT Human Clinical

"Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"

Human clinical evidence for proteinuria at presentation, so this phenotype no longer rests on model-organism evidence alone.

Chronic kidney disease HP:0012622

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"22 (39%) progressed to ESRD"

Direct quantification of progression to end-stage renal disease, replacing the inferential support this phenotype previously relied on.

Renal insufficiency HP:0000083

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"

Names renal insufficiency first among the presenting features of the series.

Hematuria HP:0000790

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"

Names hematuria among the presenting features of the series.

Other 1

Extrarenal organ involvement FREQUENT Abnormality of the liver HP:0001392

Show evidence (1 reference)

PMID:30578255 SUPPORT Human Clinical

"35% of whom had symptomatic extrarenal (mostly hepatic and cardiac) involvement"

Quantifies symptomatic extrarenal involvement at 35 per cent and names the organs most often affected. The FREQUENT band covers 30 to 79 per cent.

🧬

Genetic Associations

1

Somatically rearranged immunoglobulin light chain variable gene

relationship_type: SOMATIC_DRIVER

Show evidence (2 references)

PMID:32559766 SUPPORT Model Organism

"The variable domain of the LC bears alone the structural properties involved in its pathogenicity."

Locates pathogenicity in the expressed variable domain, which is why this record describes a somatic rearrangement rather than binding a germline gene descriptor.

PMID:11423577 SUPPORT Human Clinical

"the composition of deposits included 11kappa/1lambda (LCDD)"

Supports the kappa predominance recorded in the notes above, which is the reverse of the lambda predominance seen in AL amyloidosis and is one of the simplest discriminators between them.

💊

Medical Actions

4

Bortezomib-Based Proteasome Inhibitor Therapy

Action: Pharmacotherapy NCIT:C15986

Agent: bortezomib CHEBI:52717 dexamethasone CHEBI:41879 cyclophosphamide CHEBI:4027

The treatment backbone, usually bortezomib with dexamethasone and often cyclophosphamide. It works by eliminating the clone rather than by touching the kidney, and it has an unusually direct mechanistic rationale for a cytotoxic regimen: the pathogenic light chain already places its own plasma cell under endoplasmic reticulum stress, so a clone straining its quality-control machinery is disproportionately vulnerable to blocking the proteasome. Renal response follows haematologic response, and benefit is greatest when treatment starts early, before sclerosis is fixed.

Mechanism Target:

INHIBITS Plasma Cell Endoplasmic Reticulum Stress — Blocks proteasomal disposal of misfolded protein in a clone already under endoplasmic reticulum stress from its own product, which is why the effect is selective for the pathogenic clone rather than generally cytotoxic.

Show evidence (1 reference)

PMID:32559766 SUPPORT Model Organism

"RNA sequencing conducted on PCs demonstrated that LCDD LC induces endoplasmic reticulum stress, likely accounting for the high efficiency of proteasome inhibitor-based therapy."

The authors connect the endoplasmic reticulum stress directly to the efficacy of proteasome inhibition, which is the rationale this link asserts.

Show evidence (1 reference)

PMID:26176826 SUPPORT Human Clinical

"bortezomib-based therapy is a promising treatment strategy in MIDD, mainly when used early in the disease course"

The authors' own summary, including the timing qualifier. Note they write "promising" rather than established, and the series is retrospective.

Autologous Stem Cell Transplantation

Action: Hematopoietic Cell Transplantation NCIT:C15431

High-dose therapy with autologous stem cell rescue for eligible patients. Deeper haematologic responses are achieved than with non-transplant, non proteasome-inhibitor approaches, though transplantation and proteasome inhibition are reported together in that comparison rather than against each other.

Mechanism Target:

INHIBITS Clonal Plasma Cell Secretion of Free Light Chain — Eliminates the clone and therefore the supply of pathogenic light chain, which is the only route by which any current therapy helps the kidney.

Show evidence (1 reference)

PMID:27501122 SUPPORT Human Clinical

"Patients receiving ASCT or PI-based therapies were more likely to achieve at least a hematologic CR/VGPR compared to those receiving other therapies"

Establishes superior haematologic response for these approaches, which is the intermediate outcome that determines renal outcome.

Show evidence (1 reference)

PMID:27501122 SUPPORT Human Clinical

"Patients receiving ASCT or PI-based therapies were more likely to achieve at least a hematologic CR/VGPR compared to those receiving other therapies"

PARTIAL because the comparison groups transplantation together with proteasome-inhibitor therapy against everything else, so it cannot separate the contribution of transplantation itself, and because the endpoint is haematologic rather than renal.

Kidney Transplantation

Action: Kidney Transplantation NCIT:C15265

Offered for end-stage renal disease, and genuinely contested. Series report recurrence in the graft in a majority of recipients, while another series reports no recurrence up to nearly ten years in patients whose clone was in sustained remission at the time of transplant. The two are reconcilable, and the discriminator appears to be haematologic remission status rather than transplantation itself; that reconciliation is curated as a discussion rather than resolved by picking a side.

Show evidence (2 references)

PMID:22156754 REFUTE Human Clinical

"The disease recurred in three of four patients who received a kidney transplant."

Refutes transplantation as safe in the unselected case: three of four grafts were affected by recurrent disease.

PMID:26392598 SUPPORT Human Clinical

"among those whose underlying clonal disorder was in sustained remission, there was no recurrence of LCDD up to 9.7 years later"

Supports transplantation in the specific circumstance of sustained clonal remission. PARTIAL rather than SUPPORT because the favourable outcome is conditional on remission status and the numbers are small.

Daratumumab

Action: Pharmacotherapy NCIT:C15986

Agent: daratumumab NCIT:C74007

Anti-CD38 monoclonal antibody, used as consolidation after conventional therapy in patients who have not reached a complete haematologic response. The evidence that touches this disease is thin and indirect.

Mechanism Target:

INHIBITS Clonal Plasma Cell Secretion of Free Light Chain — Targets CD38 on the plasma cell clone, reducing production of the pathogenic light chain. Like every other effective therapy here it acts on the clone rather than on the deposits.

Show evidence (1 reference)

PMID:34468250 SUPPORT Human Clinical

"We used as a consolidation a short course of daratumumab in 25 patients with AL amyloidosis or light chain deposition disease (LCDD), who had not achieved a haematologic complete response (hemCR) after standard therapy with bortezomib, cyclophosphamide and dexamethasone (VCD)"

PARTIAL because the cohort pools two diseases, so the effect on this one cannot be isolated, and because the endpoint is haematologic response rather than a renal outcome.

Show evidence (1 reference)

PMID:34468250 SUPPORT Human Clinical

"We used as a consolidation a short course of daratumumab in 25 patients with AL amyloidosis or light chain deposition disease (LCDD), who had not achieved a haematologic complete response (hemCR) after standard therapy with bortezomib, cyclophosphamide and dexamethasone (VCD)"

Establishes the setting in which the agent was used. PARTIAL, and deliberately quoted at the sentence that names the POOLED cohort rather than at the response figures, because those figures cover AL amyloidosis and this disease together and cannot be attributed to either alone.

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Biochemical Markers

1

Serum free light chain ratio (INCREASED)

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Serum free light chain ratio was abnormal in all 51 patients tested"

Abnormal in every patient in whom it was measured, which is the basis for treating it as the defining laboratory abnormality of the disease.

🔬

Diagnosis

2

Serum free light chain measurement with renal biopsy

The diagnostic spine. An abnormal free light chain ratio identifies the clone, and renal biopsy with immunofluorescence and electron microscopy identifies the lesion and distinguishes it from the alternatives. Neither alone is sufficient: a monoclonal gammopathy is common in older people and does not by itself explain renal impairment, while the biopsy appearance without demonstration of monotypic light chain does not distinguish this from diabetic nodular glomerulosclerosis.

Show evidence (1 reference)

PMID:22156754 SUPPORT Human Clinical

"Serum free light chain ratio was abnormal in all 51 patients tested"

The sensitivity of the free light chain ratio in this series is what makes it the appropriate screening arm of the diagnostic pair.

Congo red staining to exclude amyloidosis

Not an optional refinement but the step that assigns the diagnosis. Congo red negativity in the presence of monotypic light chain deposits establishes this disease rather than AL amyloidosis, and the two have different natural histories, different organ risks, and different mesangial mechanisms despite arising from the same class of protein.

Show evidence (1 reference)

PMID:33163710 SUPPORT In Vitro

"Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed."

The mechanistic reason the distinction matters: the two diseases differ in whether the light chain enters the cell at all, so a stain that separates them is separating two different pathologies rather than two appearances.

📊

Prevalence

1

Worldwide

Cases In Literature Ultra Rare

No population-based prevalence estimate exists. The disease is defined by renal biopsy in patients with a monoclonal gammopathy, so ascertainment depends heavily on biopsy practice and on whether small clones are investigated at all. The largest assembled series is a nationwide cohort of 255 patients with monoclonal immunoglobulin deposition disease, of whom 212 had this disease. Kappa light chains predominate over lambda, the reverse of AL amyloidosis.

Show evidence (1 reference)

PMID:30578255 SUPPORT Human Clinical

"We retrospectively studied a nationwide cohort of 255 patients, with biopsy-proven LCDD (n = 212)"

Gives the size of the largest assembled series and the number with this specific disease, which is what this record cites it for. It is not a population rate and is not presented as one.

🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Light Chain Deposition Disease:

AL amyloidosis

Overlapping Features The critical differential, and mechanistically the exact inverse. Both are caused by a monoclonal light chain deposited in tissue, but amyloidogenic light chains are endocytosed by mesangial cells and converted to fibrils in the lysosome while stimulating matrix degradation, whereas the light chains of this disease act at the cell surface without entering and drive matrix accumulation. Distinguished definitively at the bench: amyloid is Congo red positive and fibrillar, these deposits are Congo red negative and granular. Lambda light chains predominate in AL amyloidosis, kappa in this disease.

Show evidence (1 reference)

PMID:33163710 SUPPORT In Vitro

"Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed."

The experimental basis for treating these as mechanistically distinct diseases rather than variants of a single deposition process.

Cast nephropathy and light chain Fanconi syndrome

Overlapping Features Other renal consequences of a monoclonal light chain, produced by tubulopathic rather than glomerulopathic light chains. The same clone size and the same class of protein produce a different disease depending on properties of the variable domain, which is why the distinction is curated as an open question rather than an incidental classification.

Diabetic nodular glomerulosclerosis

Overlapping Features The main light-microscopic mimic, since nodular mesangial expansion looks similar. Distinguished by immunofluorescence showing monotypic light chain along basement membranes, which is absent in diabetic nephropathy, and by the clinical context.

{ }

Source YAML

click to show

name: Light Chain Deposition Disease
creation_date: "2026-08-16T00:00:00Z"
description: >-
  Light chain deposition disease is a monoclonal gammopathy of renal
  significance in which a small plasma cell clone, usually well below the
  threshold that would prompt myeloma treatment, secretes a free immunoglobulin
  light chain that deposits along basement membranes and destroys the kidney. The
  deposits are granular, powdery, and Congo red negative: they are not amyloid,
  and that distinction is the organising fact of the entry rather than a
  histological footnote.

  What makes the disease mechanistically interesting is that the light chain is
  not merely insoluble. It is a signalling molecule. Light chains from patients
  with light chain deposition disease are not taken up by mesangial cells at all;
  they act at the cell surface, driving the mesangial cell to transform toward a
  myofibroblast phenotype and to pour out extracellular matrix under TGF-beta
  control. At the same time matrix degradation falls, so the mesangium is caught
  in a vice with the tap opened and the drain plugged, and the glomerulus silts up
  into the nodular sclerosis that defines the biopsy.

  The contrast with AL amyloidosis is exact and inverted, which is why this entry
  does not conform to the amyloidogenesis module. Amyloidogenic light chains ARE
  endocytosed by the same cell, delivered to the lysosome, and converted to
  fibrils there, while stimulating matrix degradation. Same cell type, same class
  of ligand, opposite intracellular itinerary and opposite effect on matrix: AL
  hollows the mesangium out, this disease makes it build.

  Therapy follows the clone rather than the kidney. Nothing removes deposits
  directly; treatment works by shutting off production of the pathogenic light
  chain and letting tissue partially remodel. Proteasome inhibition is the
  backbone and has an unusually direct mechanistic rationale, since the pathogenic
  light chain places its own plasma cell under endoplasmic reticulum stress, and a
  clone already straining its quality-control machinery is disproportionately
  vulnerable to having that machinery blocked.
category: Acquired
disease_term:
  preferred_term: Light Chain Deposition Disease
  term:
    id: MONDO:0019730
    label: light chain deposition disease
synonyms:
- LCDD
- Randall-type monoclonal immunoglobulin deposition disease
notes: >-
  Module conformance was considered and deliberately declined for
  `amyloidogenesis`, which is the module this disease superficially resembles
  most. Both involve a monoclonal light chain falling out of solution in tissue,
  but the mechanisms are opposites at the decisive step. The amyloidogenesis
  module is built around protein misfolding into beta-sheet oligomers and
  formation of extracellular fibrils; the deposits here are non-fibrillar,
  granular, and Congo red negative, and MONDO itself classifies the disease under
  non-amyloid monoclonal immunoglobulin deposition disease. Declaring conformance
  would assert fibril formation that does not occur. The mirror-image evidence is
  curated on the mesangial node rather than left as prose.

  The fibrotic arm is closer to `fibrotic_response` and shares its logic of
  mesenchymal activation driving excessive matrix, but conformance is not declared
  here either, because the module's chain runs through inflammatory recruitment
  and the mechanism in this disease runs from direct receptor-level signalling by
  the light chain to mesangial phenotype transformation without an inflammatory
  intermediate. The resemblance is recorded here rather than asserted as a link.

  Highest-risk mis-annotation, flagged and avoided: HP:0001917 Renal amyloidosis.
  Binding any amyloid term to this disease would encode precisely the error the
  diagnostic literature exists to prevent. Similarly, MONDO carries "Bence Jones
  myeloma" and "Light chain disease" as synonyms of this concept; both are loose,
  both pull in myeloma and AL amyloidosis literature, and neither is adopted as a
  synonym here.

  Two evidence cautions carried from the source report. The daratumumab study
  pooled AL amyloidosis and this disease in one cohort, so its response figures
  are not disease-specific and are curated as PARTIAL with that stated. And
  several claims about direct renal effects of bortezomib and about transplant
  recurrence rates come from review full text rather than any abstract; where used
  they are quoted from a cached full-text record, and where not available they are
  described without being cited.
pathophysiology:
- name: Clonal Plasma Cell Secretion of Free Light Chain
  biological_scale: CELLULAR
  description: >-
    A plasma cell clone, typically small and often below the burden that would
    define myeloma, secretes free immunoglobulin light chain in excess. The clone
    size is characteristically modest relative to the damage it does, which is the
    defining feature of monoclonal gammopathy of renal significance: the lesion is
    not the tumour burden but the physical properties of the protein.
  cell_types:
  - preferred_term: plasma cell
    term:
      id: CL:0000786
      label: plasma cell
  biological_processes:
  - preferred_term: immunoglobulin production
    modifier: INCREASED
    term:
      id: GO:0002377
      label: immunoglobulin production
  evidence:
  - reference: PMID:32559766
    reference_title: "Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Our mouse model recapitulates the characteristic features of LCDD, including progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure."
    explanation: >-
      The transgenic model demonstrates that plasma-cell secretion of the
      pathogenic light chain is sufficient to reproduce the disease, which is the
      claim this node carries.
  downstream:
  - target: Pathogenic Light Chain Variable Domain
    causal_link_type: DIRECT
    description: >-
      The secreted product carries the structural abnormality that makes it
      pathogenic.
  - target: Plasma Cell Endoplasmic Reticulum Stress
    causal_link_type: DIRECT
    description: >-
      Producing an awkwardly folding protein at high rate imposes a burden on the
      clone's own quality-control machinery.
- name: Pathogenic Light Chain Variable Domain
  biological_scale: MOLECULAR
  description: >-
    The variable domain carries hydrophobic substitutions in its complementarity
    determining regions, sometimes an N-glycan, and a high isoelectric point. The
    positive charge is thought to drive deposition by complementarity with
    polyanionic basement membrane. This node, and not the clone, is the actual
    etiologic agent of the disease: the variable domain alone is sufficient to
    confer pathogenicity.
  evidence:
  - reference: PMID:32559766
    reference_title: "Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The variable domain of the LC bears alone the structural properties involved in its pathogenicity."
    explanation: >-
      States that pathogenicity resides in the variable domain by itself, which is
      why this node sits between the clone and every downstream consequence.
  downstream:
  - target: Non-Fibrillar Basement Membrane Deposition
    causal_link_type: DIRECT
    description: >-
      The physical deposition step, driven by the domain's charge and hydrophobic
      character.
  - target: Mesangial Cell Surface Engagement and Phenotype Transformation
    causal_link_type: DIRECT
    description: >-
      Separately from depositing, the light chain acts as a ligand at the mesangial
      cell surface. Deposition and signalling are distinct consequences of the same
      molecule, which is why they are separate downstream edges rather than a
      chain.
- name: Plasma Cell Endoplasmic Reticulum Stress
  biological_scale: CELLULAR
  description: >-
    Producing a structurally awkward light chain at high output places the plasma
    cell clone under endoplasmic reticulum stress. This node exists because it is
    the therapeutic vulnerability of the disease rather than a step toward kidney
    injury: the clone has backed itself into a corner by making a protein its own
    folding machinery struggles with, and blocking the proteasome tips it over.
  biological_processes:
  - preferred_term: response to endoplasmic reticulum stress
    modifier: INCREASED
    term:
      id: GO:0034976
      label: response to endoplasmic reticulum stress
  evidence:
  - reference: PMID:32559766
    reference_title: "Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "RNA sequencing conducted on PCs demonstrated that LCDD LC induces endoplasmic reticulum stress, likely accounting for the high efficiency of proteasome inhibitor-based therapy."
    explanation: >-
      Establishes the endoplasmic reticulum stress and, in the authors' own
      words, connects it to why proteasome inhibition works so well in this
      disease.
- name: Non-Fibrillar Basement Membrane Deposition
  biological_scale: TISSUE
  description: >-
    Linear and granular deposits of monoclonal light chain along glomerular and
    tubular basement membranes. They are Congo red negative and non-fibrillar,
    described as powdery on electron microscopy. This is the histological
    definition of the disease and the single most important thing distinguishing
    it from AL amyloidosis at the bench.
  evidence:
  - reference: PMID:39196376
    reference_title: "Light chain deposition disease: pathogenesis, clinical characteristics and treatment strategies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Light chain deposition disease (LCDD) is a rare hematologic disorder characterized by the deposition of non-amyloid monoclonal light chains in several organs."
    explanation: >-
      States the non-amyloid character of the deposits, which is the property that
      defines this node and the reason the amyloidogenesis module is not declared.
  downstream:
  - target: Nodular Glomerulosclerosis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Deposition contributes to the sclerotic lesion, but the bulk of the matrix is
      made by mesangial cells responding to the light chain rather than being the
      deposited light chain itself.
- name: Mesangial Cell Surface Engagement and Phenotype Transformation
  biological_scale: CELLULAR
  description: >-
    The decisive mechanistic node, and the point at which this disease and AL
    amyloidosis part company. Light chains from patients with light chain
    deposition disease are NOT endocytosed by mesangial cells; they act at the cell
    surface, and the interaction drives apoptosis, transformation of the mesangial
    cell toward a myofibroblast phenotype, and secretion of matrix components and
    metalloproteinases. Amyloidogenic light chains from the same cell type do the
    opposite: they are avidly taken up and delivered to the lysosome, where fibrils
    form. Same cell, same class of ligand, opposite itinerary.
  cell_types:
  - preferred_term: mesangial cell
    term:
      id: CL:0000650
      label: mesangial cell
  - preferred_term: myofibroblast phenotype acquired by the mesangial cell
    term:
      id: CL:0000186
      label: myofibroblast cell
  evidence:
  - reference: PMID:33163710
    reference_title: "Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Light chains from patients with LCDD exert their pathogenic signaling effect at the cell surface of mesangial cells."
    explanation: >-
      States the surface-signalling mechanism, which is what makes the light chain
      a ligand rather than merely a precipitate.
  - reference: PMID:33163710
    reference_title: "Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed."
    explanation: >-
      The explicit contrast with amyloidogenic light chains in the same cell type.
      Curated here because it is the direct evidence that this disease does not
      proceed by the amyloid mechanism, and therefore the basis for declining
      conformance to the amyloidogenesis module.
  - reference: PMID:33163710
    reference_title: "Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "which include apoptosis, phenotype transformation, and secretion of extracellular matrix components and metalloproteinases"
    explanation: >-
      Enumerates the cellular consequences of the surface interaction, including the
      phenotype transformation this node is named for.
  downstream:
  - target: TGF-beta Driven Matrix Overproduction
    causal_link_type: DIRECT
    description: >-
      The transformed mesangial cell increases matrix output under TGF-beta
      control.
  - target: Failure of Matrix Degradation
    causal_link_type: DIRECT
    description: >-
      The same interaction reduces matrix-degrading activity, which is the second
      half of the imbalance.
- name: TGF-beta Driven Matrix Overproduction
  biological_scale: TISSUE
  description: >-
    Mesangial cells exposed to glomerulopathic light chains increase production of
    type IV collagen, laminin, and fibronectin, with TGF-beta production and
    activity rising in parallel. The causal role of TGF-beta is established rather
    than inferred, because blocking it with antibody abolishes the effect.
  biological_processes:
  - preferred_term: transforming growth factor beta receptor signaling pathway
    modifier: INCREASED
    term:
      id: GO:0007179
      label: transforming growth factor beta receptor signaling pathway
  - preferred_term: extracellular matrix organization
    modifier: INCREASED
    term:
      id: GO:0030198
      label: extracellular matrix organization
  evidence:
  - reference: PMID:7639331
    reference_title: "Pathogenesis of glomerulosclerosis in light chain deposition disease. Role for transforming growth factor-beta."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "transforming growth factor-beta (TGF-beta) production and activity increased when mesangial cells were exposed to these proteins"
    explanation: >-
      Establishes that the light chains raise TGF-beta production and activity in
      mesangial cells.
  - reference: PMID:7639331
    reference_title: "Pathogenesis of glomerulosclerosis in light chain deposition disease. Role for transforming growth factor-beta."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "anti-TGF-beta antibody abolished the inhibition of cell proliferation and the increase of extracellular matrix protein production caused by these light chains"
    explanation: >-
      The blocking experiment, which converts the TGF-beta association into a
      causal claim: remove the cytokine and the phenotype disappears.
  - reference: PMID:7639331
    reference_title: "Pathogenesis of glomerulosclerosis in light chain deposition disease. Role for transforming growth factor-beta."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These findings were not observed in mesangial cells exposed to human albumin and two other light chains previously characterized to be tubulopathic."
    explanation: >-
      The specificity control, and mechanistically important beyond
      methodology: glomerulopathic and tubulopathic light chains are distinct
      populations, which is why a similar clone in another patient produces cast
      nephropathy or Fanconi syndrome instead of this disease.
  downstream:
  - target: Nodular Glomerulosclerosis
    causal_link_type: DIRECT
    description: >-
      Sustained matrix overproduction expands the mesangium into nodules.
- name: Failure of Matrix Degradation
  biological_scale: CELLULAR
  description: >-
    The other half of the imbalance, and the reason the glomerulus fills so
    quickly. Alongside increased matrix production, collagenase activity falls, so
    matrix that would normally be turned over accumulates. The mirror image in AL
    amyloidosis is exact: there, matrix production falls and collagenase activity
    rises, degrading matrix and facilitating amyloid deposition instead.
  biological_processes:
  - preferred_term: extracellular matrix disassembly
    modifier: DECREASED
    term:
      id: GO:0022617
      label: extracellular matrix disassembly
  evidence:
  - reference: PMID:10369104
    reference_title: "Glomerulopathic light chain-mesangial cell interactions modulate in vitro extracellular matrix remodeling and reproduce mesangiopathic findings documented in vivo."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "A concomitant decrease in collagenase IV activity further accentuates the accumulation of mesangial matrix."
    explanation: >-
      States the fall in matrix-degrading activity that accompanies increased
      production.
  - reference: PMID:10369104
    reference_title: "Glomerulopathic light chain-mesangial cell interactions modulate in vitro extracellular matrix remodeling and reproduce mesangiopathic findings documented in vivo."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "a decrease in ECM protein production and a stimulatory effect on collagenase IV is observed, which results in matrix degradation and facilitates amyloid deposition"
    explanation: >-
      The mirror-image result for amyloidogenic light chains in the same
      experimental system. Curated as further evidence that the two diseases are
      mechanistically opposite at the mesangial cell rather than variants of one
      process.
  downstream:
  - target: Nodular Glomerulosclerosis
    causal_link_type: DIRECT
    description: >-
      Reduced turnover compounds increased production.
- name: Nodular Glomerulosclerosis
  biological_scale: TISSUE
  description: >-
    Nodular expansion of the mesangium, the characteristic light-microscopic
    lesion. It is a mesangial product rather than a pile of deposited light chain:
    the bulk of the nodule is matrix the mesangial cell was induced to make.
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nodular mesangial sclerosis was seen in 39 patients (61%)"
    explanation: >-
      The sentence that actually supports this node: nodular mesangial sclerosis in
      61 per cent of the series. The transplant-recurrence sentence previously
      quoted here supported the transplant discussion, not the histological lesion,
      and has been moved to where it belongs.
  downstream:
  - target: Proteinuria
    causal_link_type: DIRECT
    description: >-
      Glomerular architectural destruction produces protein loss.
  - target: Chronic kidney disease
    causal_link_type: DIRECT
    description: >-
      Progressive nephron loss follows the sclerotic process.
phenotypes:
- name: Proteinuria
  category: Renal
  description: >-
    Protein loss, frequently in the nephrotic range, and usually the presenting
    abnormality alongside a rising creatinine.
  phenotype_term:
    preferred_term: Proteinuria
    term:
      id: HP:0000093
      label: Proteinuria
  evidence:
  - reference: PMID:32559766
    reference_title: "Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Our mouse model recapitulates the characteristic features of LCDD, including progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure."
    explanation: >-
      Names nephrotic-range proteinuria among the characteristic features of the
      disease being modelled. Tagged MODEL_ORGANISM because the sentence describes
      the mouse.
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"
    explanation: >-
      Human clinical evidence for proteinuria at presentation, so this phenotype no
      longer rests on model-organism evidence alone.
- name: Chronic kidney disease
  category: Renal
  description: >-
    Progressive loss of renal function, frequently to end-stage disease. The
    kidney is always involved in this disease, which is what separates it from
    other monoclonal gammopathies of renal significance in presentation.
  phenotype_term:
    preferred_term: Chronic kidney disease
    term:
      id: HP:0012622
      label: Chronic kidney disease
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "22 (39%) progressed to ESRD"
    explanation: >-
      Direct quantification of progression to end-stage renal disease, replacing the
      inferential support this phenotype previously relied on.
- name: Extrarenal organ involvement
  category: Systemic
  description: >-
    Although the kidney is always involved and dominates the presentation, roughly a
    third of patients have symptomatic disease elsewhere, most often hepatic and
    cardiac. This matters clinically because a patient whose renal disease is
    controlled may still be losing an organ that nobody is monitoring, and it
    matters mechanistically because deposition is a property of the circulating
    light chain rather than of the kidney.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormal liver or cardiac involvement by light chain deposition
    term:
      id: HP:0001392
      label: Abnormality of the liver
  evidence:
  - reference: PMID:30578255
    reference_title: "Randall-type monoclonal immunoglobulin deposition disease: novel insights from a nationwide cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "35% of whom had symptomatic extrarenal (mostly hepatic and cardiac) involvement"
    explanation: >-
      Quantifies symptomatic extrarenal involvement at 35 per cent and names the
      organs most often affected. The FREQUENT band covers 30 to 79 per cent.
- name: Renal insufficiency
  category: Renal
  description: >-
    Impaired renal function at presentation, the most common presenting
    abnormality. The kidney is involved in essentially every case, which is what
    brings these patients to attention at all given how small the underlying clone
    usually is.
  phenotype_term:
    preferred_term: Renal insufficiency
    term:
      id: HP:0000083
      label: Renal insufficiency
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"
    explanation: >-
      Names renal insufficiency first among the presenting features of the series.
- name: Hypertension
  category: Cardiovascular
  description: >-
    Raised blood pressure at presentation, part of the presenting renal syndrome
    rather than an independent comorbidity.
  phenotype_term:
    preferred_term: Hypertension
    term:
      id: HP:0000822
      label: Hypertension
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"
    explanation: >-
      Names hypertension among the presenting features of the series.
- name: Hematuria
  category: Renal
  description: >-
    Blood in the urine at presentation. Worth recording because it is not what a
    purely deposition-driven glomerulopathy would obviously predict, and it forms
    part of the nephritic-flavoured presentation that can misdirect toward a
    glomerulonephritis.
  phenotype_term:
    preferred_term: Hematuria
    term:
      id: HP:0000790
      label: Hematuria
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Presentation included renal insufficiency, proteinuria, hematuria, and hypertension"
    explanation: >-
      Names hematuria among the presenting features of the series.
genetic:
- name: Somatically rearranged immunoglobulin light chain variable gene
  relationship_type: SOMATIC_DRIVER
  notes: >-
    This is an acquired clonal disease, not an inherited one, and no germline
    predisposition gene is established. The driver is somatic: the rearranged and
    hypermutated immunoglobulin light-chain variable gene of the plasma cell clone
    encodes the protein that is itself the pathogenic agent. The literature records
    biased usage of particular V-kappa germline subgroups by these clones, and
    kappa light chains predominate over lambda, the reverse of AL amyloidosis. No
    gene descriptor is bound here because the association is with subgroup usage in
    a somatic rearrangement rather than with any variant in the patient's germline,
    and because the pathogenic property lies in the expressed variable domain
    rather than in the germline segment it derives from. Recorded as SOMATIC_DRIVER
    rather than CAUSATIVE for that reason.
  evidence:
  - reference: PMID:32559766
    reference_title: "Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The variable domain of the LC bears alone the structural properties involved in its pathogenicity."
    explanation: >-
      Locates pathogenicity in the expressed variable domain, which is why this
      record describes a somatic rearrangement rather than binding a germline gene
      descriptor.
  - reference: PMID:11423577
    reference_title: "Renal monoclonal immunoglobulin deposition disease: the disease spectrum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the composition of deposits included 11kappa/1lambda (LCDD)"
    explanation: >-
      Supports the kappa predominance recorded in the notes above, which is the
      reverse of the lambda predominance seen in AL amyloidosis and is one of the
      simplest discriminators between them.
biochemical:
- name: Serum free light chain ratio
  notes: >-
    The defining laboratory abnormality and the practical entry point to the
    diagnosis. An abnormal ratio between involved and uninvolved free light chains
    reflects the monoclonal clone, was abnormal in every patient tested in the
    largest single-institution series, and is also the measure by which
    haematologic response to treatment is judged. Its sensitivity is what makes it
    reasonable to look for this disease in a patient with unexplained renal
    impairment.
  presence: INCREASED
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Serum free light chain ratio was abnormal in all 51 patients tested"
    explanation: >-
      Abnormal in every patient in whom it was measured, which is the basis for
      treating it as the defining laboratory abnormality of the disease.
histopathology:
- name: Congo red negative granular basement membrane deposits
  description: >-
    The histological finding on which the whole entry turns. Monotypic light chain
    is demonstrated along glomerular and tubular basement membranes by
    immunofluorescence, and the deposits are granular and powdery on electron
    microscopy rather than fibrillar, and negative on Congo red staining. That
    negativity is not a technicality: it is what separates this disease from AL
    amyloidosis, which deposits the same class of protein in the same organ by an
    opposite cellular route.
  diagnostic: true
  evidence:
  - reference: PMID:39196376
    reference_title: "Light chain deposition disease: pathogenesis, clinical characteristics and treatment strategies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Light chain deposition disease (LCDD) is a rare hematologic disorder characterized by the deposition of non-amyloid monoclonal light chains in several organs."
    explanation: >-
      States the non-amyloid character of the deposits, which is what Congo red
      negativity demonstrates at the bench and the reason amyloidogenesis
      conformance is declined in this entry.
- name: Nodular mesangial sclerosis
  description: >-
    Nodular expansion of the mesangium on light microscopy, present in the majority
    of biopsies. The nodules are largely matrix that the mesangial cell was induced
    to make rather than deposited light chain, which is why the lesion is
    disproportionate to the amount of protein visible by immunofluorescence.
  diagnostic: true
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nodular mesangial sclerosis was seen in 39 patients (61%)"
    explanation: >-
      Quantifies the nodular lesion in the largest single-institution series.
diagnosis:
- name: Serum free light chain measurement with renal biopsy
  description: >-
    The diagnostic spine. An abnormal free light chain ratio identifies the clone,
    and renal biopsy with immunofluorescence and electron microscopy identifies the
    lesion and distinguishes it from the alternatives. Neither alone is sufficient:
    a monoclonal gammopathy is common in older people and does not by itself
    explain renal impairment, while the biopsy appearance without demonstration of
    monotypic light chain does not distinguish this from diabetic nodular
    glomerulosclerosis.
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Serum free light chain ratio was abnormal in all 51 patients tested"
    explanation: >-
      The sensitivity of the free light chain ratio in this series is what makes it
      the appropriate screening arm of the diagnostic pair.
- name: Congo red staining to exclude amyloidosis
  description: >-
    Not an optional refinement but the step that assigns the diagnosis. Congo red
    negativity in the presence of monotypic light chain deposits establishes this
    disease rather than AL amyloidosis, and the two have different natural
    histories, different organ risks, and different mesangial mechanisms despite
    arising from the same class of protein.
  evidence:
  - reference: PMID:33163710
    reference_title: "Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed."
    explanation: >-
      The mechanistic reason the distinction matters: the two diseases differ in
      whether the light chain enters the cell at all, so a stain that separates them
      is separating two different pathologies rather than two appearances.
treatments:
- name: Bortezomib-Based Proteasome Inhibitor Therapy
  description: >-
    The treatment backbone, usually bortezomib with dexamethasone and often
    cyclophosphamide. It works by eliminating the clone rather than by touching
    the kidney, and it has an unusually direct mechanistic rationale for a
    cytotoxic regimen: the pathogenic light chain already places its own plasma
    cell under endoplasmic reticulum stress, so a clone straining its
    quality-control machinery is disproportionately vulnerable to blocking the
    proteasome. Renal response follows haematologic response, and benefit is
    greatest when treatment starts early, before sclerosis is fixed.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: bortezomib
      term:
        id: CHEBI:52717
        label: bortezomib
    - preferred_term: dexamethasone
      term:
        id: CHEBI:41879
        label: dexamethasone
    - preferred_term: cyclophosphamide
      term:
        id: CHEBI:4027
        label: cyclophosphamide
  target_mechanisms:
  - target: Plasma Cell Endoplasmic Reticulum Stress
    treatment_effect: INHIBITS
    description: >-
      Blocks proteasomal disposal of misfolded protein in a clone already under
      endoplasmic reticulum stress from its own product, which is why the effect is
      selective for the pathogenic clone rather than generally cytotoxic.
    evidence:
    - reference: PMID:32559766
      reference_title: "Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "RNA sequencing conducted on PCs demonstrated that LCDD LC induces endoplasmic reticulum stress, likely accounting for the high efficiency of proteasome inhibitor-based therapy."
      explanation: >-
        The authors connect the endoplasmic reticulum stress directly to the
        efficacy of proteasome inhibition, which is the rationale this link
        asserts.
  evidence:
  - reference: PMID:26176826
    reference_title: "Bortezomib produces high hematological response rates with prolonged renal survival in monoclonal immunoglobulin deposition disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "bortezomib-based therapy is a promising treatment strategy in MIDD, mainly when used early in the disease course"
    explanation: >-
      The authors' own summary, including the timing qualifier. Note they write
      "promising" rather than established, and the series is retrospective.
- name: Autologous Stem Cell Transplantation
  description: >-
    High-dose therapy with autologous stem cell rescue for eligible patients.
    Deeper haematologic responses are achieved than with non-transplant, non
    proteasome-inhibitor approaches, though transplantation and proteasome
    inhibition are reported together in that comparison rather than against each
    other.
  therapeutic_modality: CELL_THERAPY
  treatment_term:
    preferred_term: Hematopoietic Cell Transplantation
    term:
      id: NCIT:C15431
      label: Hematopoietic Cell Transplantation
  target_mechanisms:
  - target: Clonal Plasma Cell Secretion of Free Light Chain
    treatment_effect: INHIBITS
    description: >-
      Eliminates the clone and therefore the supply of pathogenic light chain,
      which is the only route by which any current therapy helps the kidney.
    evidence:
    - reference: PMID:27501122
      reference_title: "Outcomes of patients with renal monoclonal immunoglobulin deposition disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients receiving ASCT or PI-based therapies were more likely to achieve at least a hematologic CR/VGPR compared to those receiving other therapies"
      explanation: >-
        Establishes superior haematologic response for these approaches, which is
        the intermediate outcome that determines renal outcome.
  evidence:
  - reference: PMID:27501122
    reference_title: "Outcomes of patients with renal monoclonal immunoglobulin deposition disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients receiving ASCT or PI-based therapies were more likely to achieve at least a hematologic CR/VGPR compared to those receiving other therapies"
    explanation: >-
      PARTIAL because the comparison groups transplantation together with
      proteasome-inhibitor therapy against everything else, so it cannot separate
      the contribution of transplantation itself, and because the endpoint is
      haematologic rather than renal.
- name: Kidney Transplantation
  description: >-
    Offered for end-stage renal disease, and genuinely contested. Series report
    recurrence in the graft in a majority of recipients, while another series
    reports no recurrence up to nearly ten years in patients whose clone was in
    sustained remission at the time of transplant. The two are reconcilable, and
    the discriminator appears to be haematologic remission status rather than
    transplantation itself; that reconciliation is curated as a discussion rather
    than resolved by picking a side.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Kidney Transplantation
    term:
      id: NCIT:C15265
      label: Kidney Transplantation
  evidence:
  - reference: PMID:22156754
    reference_title: "Renal monoclonal immunoglobulin deposition disease: a report of 64 patients from a single institution."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The disease recurred in three of four patients who received a kidney transplant."
    explanation: >-
      Refutes transplantation as safe in the unselected case: three of four grafts
      were affected by recurrent disease.
  - reference: PMID:26392598
    reference_title: "Natural history and outcome of light chain deposition disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "among those whose underlying clonal disorder was in sustained remission, there was no recurrence of LCDD up to 9.7 years later"
    explanation: >-
      Supports transplantation in the specific circumstance of sustained clonal
      remission. PARTIAL rather than SUPPORT because the favourable outcome is
      conditional on remission status and the numbers are small.
- name: Daratumumab
  description: >-
    Anti-CD38 monoclonal antibody, used as consolidation after conventional therapy
    in patients who have not reached a complete haematologic response. The evidence
    that touches this disease is thin and indirect.
  therapeutic_modality: MONOCLONAL_ANTIBODY
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: daratumumab
      term:
        id: NCIT:C74007
        label: Daratumumab
  target_mechanisms:
  - target: Clonal Plasma Cell Secretion of Free Light Chain
    treatment_effect: INHIBITS
    description: >-
      Targets CD38 on the plasma cell clone, reducing production of the pathogenic
      light chain. Like every other effective therapy here it acts on the clone
      rather than on the deposits.
    evidence:
    - reference: PMID:34468250
      reference_title: "Consolidation with a short course of daratumumab in patients with AL amyloidosis or light chain deposition disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We used as a consolidation a short course of daratumumab in 25 patients with AL amyloidosis or light chain deposition disease (LCDD), who had not achieved a haematologic complete response (hemCR) after standard therapy with bortezomib, cyclophosphamide and dexamethasone (VCD)"
      explanation: >-
        PARTIAL because the cohort pools two diseases, so the effect on this one
        cannot be isolated, and because the endpoint is haematologic response rather
        than a renal outcome.
  evidence:
  - reference: PMID:34468250
    reference_title: "Consolidation with a short course of daratumumab in patients with AL amyloidosis or light chain deposition disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We used as a consolidation a short course of daratumumab in 25 patients with AL amyloidosis or light chain deposition disease (LCDD), who had not achieved a haematologic complete response (hemCR) after standard therapy with bortezomib, cyclophosphamide and dexamethasone (VCD)"
    explanation: >-
      Establishes the setting in which the agent was used. PARTIAL, and deliberately
      quoted at the sentence that names the POOLED cohort rather than at the
      response figures, because those figures cover AL amyloidosis and this disease
      together and cannot be attributed to either alone.
  notes: >-
    The supporting study pooled patients with AL amyloidosis and with this disease
    into one cohort and reported response rates for the combined group. Those
    figures are therefore not disease-specific and are not curated as such, and no
    dedicated trial of daratumumab in light chain deposition disease exists. The
    treatment is recorded because it is used, not because its benefit here is
    established.
discussions:
- discussion_id: lcdd_transplant_recurrence
  prompt: >-
    Is kidney transplantation appropriate in light chain deposition disease, and
    does recurrence in the graft depend on transplantation itself or on the state
    of the plasma cell clone at the time of transplant?
  kind: CONTROVERSY
  status: OPEN
  attaches_to:
  - pathophysiology#Clonal Plasma Cell Secretion of Free Light Chain
  - treatments#Kidney Transplantation
  rationale: >-
    The literature contains two apparently opposed findings. One series reports
    recurrence in three of four grafts, and a recent review concludes that renal
    allograft is not recommended because of the high incidence of relapse. Another
    series reports no recurrence up to nearly ten years, but only among patients
    whose clonal disorder was in sustained remission when they were transplanted.
    Read together these are not contradictory: the graft fails when the clone is
    still producing pathogenic light chain, because nothing about transplantation
    addresses the source of the protein. The apparent controversy about the
    procedure is better understood as a question about patient selection, and the
    proposed resolution is that haematologic remission status is the discriminator.
    It is recorded as open rather than resolved because no study has tested that
    reconciliation prospectively.
  evidence:
  - reference: PMID:26915878
    reference_title: "Light Chain Deposition Disease After Kidney Transplantation With Long Graft Survival: Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "they have experienced a prolonged period of stable renal function with no clinically detectable disease"
    explanation: >-
      Case-level support for the proposed reconciliation: grafts can be held long
      term when the clone is controlled. PARTIAL because it is a small number of
      cases and cannot by itself establish that remission status is the
      discriminator rather than one correlate of it.
  proposed_experiments:
  - experiment_id: lcdd_transplant_by_remission_status
    name: Graft outcome stratified by pre-transplant haematologic response depth
    description: >-
      Assemble a multicentre cohort of transplant recipients with this disease,
      stratified by depth and duration of haematologic response at the time of
      transplantation and by serial free light chain measurement afterwards, with
      graft recurrence as the endpoint. If the reconciliation is right, recurrence
      should track residual clonal activity rather than time since transplant.
- discussion_id: lcdd_glomerulopathic_vs_tubulopathic
  prompt: >-
    What structural features determine whether a monoclonal light chain becomes
    glomerulopathic and causes this disease, rather than tubulopathic and causing
    cast nephropathy or Fanconi syndrome?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Pathogenic Light Chain Variable Domain
  rationale: >-
    The distinction is real and experimentally demonstrated rather than
    hypothetical: light chains previously characterised as tubulopathic do not
    produce the mesangial matrix response that glomerulopathic light chains do, in
    the same assay. Something in the variable domain sorts one destination from the
    other. Candidate determinants include isoelectric point, complementarity
    determining region hydrophobicity, glycosylation, and germline gene subgroup
    usage, but no rule predicts destination from sequence. This matters clinically
    because two patients with similar small clones can develop entirely different
    kidney diseases requiring different management, and there is currently no way
    to tell in advance which.
  proposed_experiments:
  - experiment_id: lcdd_lc_sequence_destination_map
    name: Sequence-to-destination mapping of pathogenic light chains
    description: >-
      Sequence the pathogenic light chain variable domain from a large series of
      patients with clinically and histologically classified renal lesions, and
      test whether isoelectric point, CDR hydrophobicity, glycosylation site
      presence, and germline subgroup predict glomerular versus tubular
      destination. Validate candidate determinants by expressing selected variants
      in the mesangial-cell assay in which the original distinction was drawn.
differential_diagnoses:
- name: AL amyloidosis
  description: >-
    The critical differential, and mechanistically the exact inverse. Both are
    caused by a monoclonal light chain deposited in tissue, but amyloidogenic light
    chains are endocytosed by mesangial cells and converted to fibrils in the
    lysosome while stimulating matrix degradation, whereas the light chains of this
    disease act at the cell surface without entering and drive matrix
    accumulation. Distinguished definitively at the bench: amyloid is Congo red
    positive and fibrillar, these deposits are Congo red negative and granular.
    Lambda light chains predominate in AL amyloidosis, kappa in this disease.
  evidence:
  - reference: PMID:33163710
    reference_title: "Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed."
    explanation: >-
      The experimental basis for treating these as mechanistically distinct
      diseases rather than variants of a single deposition process.
- name: Cast nephropathy and light chain Fanconi syndrome
  description: >-
    Other renal consequences of a monoclonal light chain, produced by tubulopathic
    rather than glomerulopathic light chains. The same clone size and the same
    class of protein produce a different disease depending on properties of the
    variable domain, which is why the distinction is curated as an open question
    rather than an incidental classification.
- name: Diabetic nodular glomerulosclerosis
  description: >-
    The main light-microscopic mimic, since nodular mesangial expansion looks
    similar. Distinguished by immunofluorescence showing monotypic light chain
    along basement membranes, which is absent in diabetic nephropathy, and by the
    clinical context.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    No population-based prevalence estimate exists. The disease is defined by renal
    biopsy in patients with a monoclonal gammopathy, so ascertainment depends
    heavily on biopsy practice and on whether small clones are investigated at all.
    The largest assembled series is a nationwide cohort of 255 patients with
    monoclonal immunoglobulin deposition disease, of whom 212 had this disease.
    Kappa light chains predominate over lambda, the reverse of AL amyloidosis.
  evidence:
  - reference: PMID:30578255
    reference_title: "Randall-type monoclonal immunoglobulin deposition disease: novel insights from a nationwide cohort study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We retrospectively studied a nationwide cohort of 255 patients, with biopsy-proven LCDD (n = 212)"
    explanation: >-
      Gives the size of the largest assembled series and the number with this
      specific disease, which is what this record cites it for. It is not a
      population rate and is not presented as one.

📚

References & Deep Research

Deep Research

1

Claude Code ▸

Light Chain Deposition Disease (LCDD) — Comprehensive Research Report

claude-haiku-4-5-20251001, claude-opus-5[1m] 28 citations 2026-08-16T10:15:45.723137

Light Chain Deposition Disease (LCDD) — Comprehensive Research Report

Prepared: 2026-08-16 · Target KB entry: kb/disorders/Light_Chain_Deposition_Disease.yaml · MONDO:0019730 · Category: Acquired

How to read this. Every numbered claim below is anchored to a PMID I actually pulled from PubMed during this session, and where I quote, the quote is verbatim from the abstract text I retrieved (exception flagged explicitly in §16). Ontology CURIEs marked ✅ were checked against this repo's validated term caches (cache/*/terms.csv) or a live OLS lookup; anything unverified is called out as such. Where the literature genuinely doesn't know something, I say so instead of filling the gap with vibes.

0. The one-paragraph version

Plasma cells are little protein factories, and normally the antibody light chains they churn out are disposable offcuts that the kidney filters and chews up without comment. In LCDD, one clone starts producing a light chain with a structurally weird variable domain — extra hydrophobic patches, sometimes a sugar stuck on, an unusually basic surface charge — and that molecule stops behaving like waste and starts behaving like mortar. It plasters itself in a fine, powdery, non-fibrillar layer along basement membranes, and where it touches mesangial cells in the glomerulus it doesn't just sit there: it signals, flipping those cells into a scar-making phenotype that pours out collagen IV, laminin, fibronectin and tenascin while simultaneously turning down the enzymes that would clear them. The result is nodular glomerulosclerosis and a kidney that silts up. It is emphatically not amyloid — Congo red stays stubbornly negative — and that distinction is the whole diagnostic hinge.

1. Disease Information

1.1 Definition

Light chain deposition disease is a systemic disorder in which a clonal plasma-cell or B-cell population secretes a monoclonal immunoglobulin light chain that deposits as Congo red–negative, non-fibrillar, granular ("powdery") material along basement membranes, most consequentially in the kidney. It sits inside the broader family of monoclonal immunoglobulin deposition disease (MIDD), also called Randall-type MIDD, which comprises three variants by deposit composition:

Variant	Deposit	Approximate share of MIDD
LCDD	light chain only	212/255 (83%) — Joly (PMID:30578255); 51/64 (80%) — Nasr (PMID:22156754)
HCDD	heavy chain only	23/255 (9%); 7/64 (11%)
LHCDD	both	20/255 (8%); 6/64 (9%)

"Monoclonal immunoglobulin deposition disease (MIDD) is a rare complication of B-cell clonal disorders, defined by Congo red negative-deposits of monoclonal light chain (LCDD), heavy chain (HCDD), or both (LHCDD). MIDD is a systemic disorder with prominent renal involvement, but little attention has been paid to the description of extrarenal manifestations." — Joly et al., Blood 2019 (PMID:30578255)

The condition was first delineated by Randall et al. in 1976 (PMID:814812), which is why "Randall-type" persists in the European literature:

"Clinical and pathologic correlations suggest that the retention and tissue deposition of light chains produced the organ dysfunction, inasmuch as free kappa light chain determinants were demonstrated histologically in the clinically affected organs. The deposition in these patients may be an extreme example of a common but previously unrecognized form of plasma cell dyscrasia." — Randall et al., Am J Med 1976 (PMID:814812)

1.2 Identifiers (verified via OLS, MONDO:0019730 cross-references)

Resource	ID	Notes
MONDO	`MONDO:0019730` ✅	label: light chain deposition disease
Orphanet	`ORPHA:93558`	MONDO `equivalentTo`
NCIT	`NCIT:C7727`	MONDO `equivalentTo`
UMLS	`C0238239`	MONDO `equivalentTo`
SNOMED CT	`373604002`	MONDO `equivalentTo`
MedGen	`65953`	MONDO `equivalentTo`
GARD	`0006906`
ICD-11 (foundation)	`1612001446`	inherited from Orphanet:93558
OMIM	none	Correct — LCDD is an acquired somatic clonal disorder with no Mendelian entry
ICD-10	no dedicated code	Coded by context (underlying myeloma C90.0, MGUS D47.2, or a renal N-code). Do not invent one.

⚠️ MeSH indexing trap worth recording in the KB. There is no dedicated MeSH descriptor for LCDD. PubMed's automatic term mapping expands "monoclonal immunoglobulin deposition disease" to "immunoglobulin light-chain amyloidosis"[MeSH Terms] — which is the wrong disease. Any literature-mining pipeline for this entry that leans on MeSH will silently pull AL amyloidosis papers. Search by free text and by the specific phrases instead.

1.3 Synonyms

Accurate: LCDD; light-chain deposition disease; Randall-type monoclonal immunoglobulin deposition disease (as the parent class); monoclonal light chain deposition disease; non-amyloid light chain deposition disease.

⚠️ MONDO synonyms to NOT propagate as exact matches. MONDO:0019730 carries Bence Jones myeloma, Light chain disease and Light chain gammopathy in its synonym list. These are historical, overbroad, and actively misleading — "light chain disease" in hematology usually means light-chain-only myeloma, a different entity. Flag these rather than curating them.

1.4 Data provenance character

Evidence for LCDD is almost entirely aggregated, retrospective, biopsy-anchored cohort data from a handful of referral centers (Mayo, Columbia, the French national amyloidosis/MIDD network in Poitiers–Limoges, UK National Amyloidosis Centre), supplemented by case reports and a small mechanistic literature (rat mesangial cell culture + one transgenic mouse). There is no randomized trial in LCDD and no population registry. Frequency figures throughout this report are therefore biopsy-series proportions, not population rates, and carry heavy referral bias.

2. Etiology

2.1 Primary cause

A clonal plasma-cell (or, less often, lymphoplasmacytic/B-cell) proliferation secreting a nephrotoxic monoclonal free light chain. The causal agent is the protein, not the tumor burden — which is why most LCDD patients have a clone far too small to qualify as symptomatic myeloma.

Hematologic substrate across the three largest series:

Series	MGRS / small clone	Symptomatic multiple myeloma	Other
Joly 2019, n=255 (PMID:30578255)	64%	34%	—
Nasr 2012, n=64 (PMID:22156754)	—	59% (38/64)	dysproteinemia evident in 97%
Pozzi 2003, n=63 (PMID:14655186)	32% "idiopathic"	65%	lymphoproliferative 3%
Cohen 2015, n=49 (PMID:26176826)	38/49 MGRS	10/49 MM	1 Waldenström

"Hematological diagnosis was monoclonal gammopathy of renal significance in 64% and symptomatic myeloma in 34%." — Joly et al. (PMID:30578255)

This is the definitional core of MGRS (monoclonal gammopathy of renal significance):

"the IKMG redefines MGRS as a clonal proliferative disorder that produces a nephrotoxic monoclonal immunoglobulin and does not meet previously defined haematological criteria for treatment of a specific malignancy." — Leung et al., Nat Rev Nephrol 2019 (PMID:30510265)

Rare LCDD cases occur with no demonstrable plasma cell disorder at all:

"LCDD typically arises secondary to an underlying plasma cell dyscrasia, such as monoclonal gammopathy of undetermined significance or multiple myeloma. However, rare cases can occur in the absence of a demonstrable plasma cell disorder." — Rai et al., AJNR 2025 (PMID:38914431)

2.2 The proximate molecular cause — a light chain with a bad variable domain

The pathogenicity is encoded in the V domain, and this is the single most mechanistically important fact in the entry. Three converging lines:

(a) Biased V-gene usage — the VκIV / IGKV4-1 subgroup.

"These data together with our previously published results, indicate the pathogenic potential of the rare V kappa IV subgroup and confirm the absence of detectable serum and urine free monoclonal light chains when they are N-glycosylated." — Denoroy, Déret & Aucouturier, Immunol Lett 1994 (PMID:7829131)

Note the second half of that sentence — N-glycosylated pathogenic light chains can be invisible on standard serum/urine assays. That is a diagnostic landmine.

(b) Somatic hypermutation planting hydrophobic and glycosylation-site residues.

"Four unique amino acid substitutions were found at positions -8, -3, -2 and -1 in the leader sequence and probably resulted in an unusual cleavage by signal peptidase, thus making the LC truncated by one residue and accounting for its unique hydrophobic N-terminus: Ile-Ile-Leu. Additional peculiarities were observed in the V region, including a Thr74-->Asn substitution creating a N-glycosylation site, and Thr53-->Ile, which was only reported once among human kappa III chains, in another LCDD case, and may be of special significance at a position usually harbouring a polar amino acid." — Decourt, Cogné & Rocca, Clin Exp Immunol 1996 (PMID:8918585)

(c) Surface charge — the CDRs run basic.

"Sequencing of 18 pathogenic LC showed high isoelectric point values of variable domain complementarity determining regions, possibly accounting for tissue deposition." — Joly et al. (PMID:30578255)

A basic (positively charged) CDR surface plus a polyanionic basement membrane is chemistry doing exactly what you'd expect — the light chain sticks where the charge complements it. That's the tidiest structure-to-lesion story in the whole disease.

(d) The V domain is sufficient. In the transgenic mouse (below), only the human V domain was transplanted:

"The variable domain of the LC bears alone the structural properties involved in its pathogenicity." — Bender et al., Blood 2020 (PMID:32559766)

2.3 Risk factors

Genetic (germline): No germline susceptibility locus is established for LCDD specifically. Familial clustering has not been demonstrated. Inherited risk, if any, is presumed to be that of the upstream plasma cell dyscrasia (MGUS/MM heritability), not of the deposition phenotype. Do not curate germline causal genes for this entry.

Somatic: The relevant "genetics" is entirely somatic and clone-restricted — the rearranged, hypermutated IGKV gene of the pathogenic clone (see §4).

Demographic / clinical: - Age — median 56 y (Nasr PMID:22156754; Sayed PMID:26392598); mean 58 ± 14.2 y (Pozzi PMID:14655186). Notably younger than AL amyloidosis or cast nephropathy: "Patients with MIDD generally present at a younger age than those with light chain amyloidosis or light chain cast nephropathy." (PMID:22156754). 36% of Nasr's cohort were ≤50 years. - Male sex — 63.5% male (Pozzi PMID:14655186). - Pre-existing MGUS or multiple myeloma — the dominant clinical risk state. - Age itself as a renal/patient risk multiplier — Pozzi: age RR 1.05 (95% CI 1.009–1.086) for renal outcome; RR 1.06 (1.03–1.1) for survival.

Environmental / occupational / infectious: None established for LCDD. The general MM/MGUS risk-factor literature (age, male sex, African ancestry, obesity, ionizing radiation, some pesticide exposures) applies only upstream and has never been shown to select for the depositing phenotype. Record as a knowledge gap rather than importing myeloma risk factors wholesale.

2.4 Protective factors

None identified. There are no protective germline variants, dietary factors, or exposures reported for LCDD. The only genuinely "protective" intervention is achieving a deep hematologic response (§12) — which is treatment, not prevention.

2.5 Gene–environment interactions

No data. Nothing in CTD, PheGenI, or the primary literature addresses GxE in LCDD. This is an honest blank.

3. Phenotypes

3.1 Renal (essentially universal — the kidney is always involved)

Phenotype	Suggested HP term	Frequency / evidence
Renal insufficiency	`HP:0000083` Renal insufficiency ✅	96% at presentation (acute 52%, chronic 44%) — Pozzi (PMID:14655186)
Proteinuria	`HP:0000093` Proteinuria ✅	84% with >1 g/day — Pozzi (PMID:14655186)
Nephrotic-range proteinuria	`HP:0012593` Nephrotic range proteinuria ✅	frequent; "nephrotic proteinuria" in pure MIDD — Lin (PMID:11423577)
Nephrotic syndrome	`HP:0000100` Nephrotic syndrome ✅	characteristic of the glomerular (nodular) form — Bender (PMID:32559766)
Elevated serum creatinine	`HP:0003259` Elevated circulating creatinine concentration ✅	mean serum Cr 4.2 mg/dL in pure MIDD; 7.8 mg/dL in LCDD+cast nephropathy (P=0.01) — Lin (PMID:11423577)
Hypertension	`HP:0000822` Hypertension ✅	listed as a presenting feature — Nasr (PMID:22156754)
Hematuria	`HP:0000790` Hematuria ✅ / `HP:0002907` Microscopic hematuria ✅	listed as a presenting feature — Nasr (PMID:22156754)
Acute kidney injury	`HP:0001919` Acute kidney injury ✅	the presentation when cast nephropathy coexists — Joly (PMID:30578255)
Chronic kidney disease	`HP:0012622` Chronic kidney disease ✅	dominant course
End-stage kidney disease	`HP:0003774` Stage 5 chronic kidney disease ✅	39% progressed to ESRD (Nasr PMID:22156754); 62% required dialysis (Sayed PMID:26392598)
Bence Jones proteinuria	`HP:0030156` Bence Jones Proteinuria ✅	context-dependent; absent when the LC is N-glycosylated (PMID:7829131)
Hypoalbuminemia / edema	`HP:0003073` ✅ / `HP:0000969` Edema ✅	secondary to nephrotic syndrome

"Renal presentation was acute kidney injury in patients with LCCD and CN, and chronic glomerular disease in the other types" — Joly et al. (PMID:30578255)

⚠️ Two ontology cautions for the curator: 1. There is no HPO term for "nodular glomerulosclerosis." I checked HPO via OLS; the nearest hits are HP:0033271 (Glomerular capillary microaneurysm) and HP:0000097 (Focal segmental glomerulosclerosis) — neither means the right thing. Curate nodular mesangial sclerosis as a histopathology finding, not a forced HP annotation. No term beats a bad one. 2. Never use HP:0001917 Renal amyloidosis on this entry. It exists in the cache and it is exactly the wrong claim — LCDD deposits are Congo-red-negative and non-fibrillar. This is the single highest-risk mis-annotation for LCDD.

3.2 Extrarenal — more common than the older literature suggested

The Joly nationwide cohort is the corrective here:

"35% of whom had symptomatic extrarenal (mostly hepatic and cardiac) involvement." … "This study highlights an unexpected frequency of extrarenal manifestations in MIDD." — Joly et al. (PMID:30578255)

Organ	Manifestations	Suggested HP term	Evidence
Liver	hepatomegaly, transaminase elevation, portal hypertension, fulminant hepatic failure; deposits in hepatic sinusoids	`HP:0002240` Hepatomegaly ✅, `HP:0001409` Portal hypertension ✅, `HP:0001399` Hepatic failure ✅	Joly PMID:30578255; Cassano 2024 PMID:39196376
Heart	diastolic dysfunction, conduction disturbance, arrhythmia, rarely an atrial mass; restrictive physiology	`HP:0011675` Arrhythmia ✅, `HP:0001635` Congestive heart failure ✅, `HP:0001723` Restrictive cardiomyopathy ✅	Joly PMID:30578255; Cassano PMID:39196376
CNS	intracerebral LCDD — mass-like or infiltrative lesions; choroid plexus deposits; a documented radiographic mimic of neoplasm	(no good HP term; curate as anatomic/imaging finding)	Rai et al. PMID:38914431
Lung	usually an incidental finding; symptomatic pulmonary LCDD (cystic/nodular disease) rare		Rai PMID:38914431; Cassano PMID:39196376
Peripheral nerve	reported but uncommon	`HP:0009830` Peripheral neuropathy ✅	Randall PMID:814812 (neurologic abnormalities in both index cases)
GI / endocrine	described in the original 1976 report		Randall PMID:814812

Prognostic weight of extrarenal disease: independently worsens patient (not renal) survival — RR 2.24 (95% CI 1.15–4.35) (Pozzi PMID:14655186).

3.3 Onset, severity, progression

Onset: adult, insidious. Median 56–58 y; 36% ≤50 y (PMID:22156754).
Diagnostic delay is the rule. "The interval between albuminuria or elevation in creatinine and MIDD diagnosis was 12 months suggesting a delay in diagnosis." — Kourelis et al. (PMID:27501122). And in Lin's series, "Renal biopsy diagnosis preceded clinical evidence of dysproteinemia in 68% of all cases" (PMID:11423577) — i.e., the kidney biopsy usually finds the clone, not the other way round.
Severity: moderate to severe; 69% of Kourelis' cohort had GFR <30 mL/min/1.73 m², 18% already on renal replacement therapy at diagnosis (PMID:27501122).
Progression: progressive, and the rate is modifiable by treatment — see the strikingly symmetric GFR slopes in §11.
Course pattern: chronic progressive; not relapsing-remitting, though clonal relapse can drive renal relapse.

3.4 Quality of life

No LCDD-specific QoL instrument data exists (no EQ-5D/SF-36/PROMIS study identified). Impact must be inferred from the dominant clinical burden: dialysis dependence in a majority (62%, PMID:26392598), nephrotic edema, and — for the myeloma-associated subset — the QoL profile of plasma cell dyscrasia and its therapy. Record this as a knowledge gap.

4. Genetic / Molecular Information

This is a somatic, clone-restricted molecular disease. There is no germline causal gene, no inheritance pattern, no carrier frequency, no penetrance. Curating it as a genetic disease would be a category error.

4.1 The relevant "gene" is the clone's rearranged immunoglobulin light chain locus

IGK locus (chromosome 2p11.2) — kappa light chains dominate. κ:λ = 68:32 (Pozzi PMID:14655186); 11 κ : 1 λ among pure LCDD in Lin's series (PMID:11423577).
IGKV4-1 (VκIV subgroup) — over-represented relative to its rarity in the normal repertoire (PMID:7829131). Suggested gene descriptor: HGNC symbol IGKV4-1 (lowercase hgnc: prefix per repo convention; CURIE not verified in this session — look it up before curating).
IGKV3 (VκIII) — also documented in LCDD with structural peculiarities (PMID:8918585).
IGL locus — the minority λ cases; no subgroup bias established.
IGH CH1 deletion — the defining lesion of HCDD, the sibling entity: "Cases of HCDD were associated with a CH1 deletion" (Lin, PMID:11423577). Mechanistically elegant: without CH1, the heavy chain escapes BiP-mediated ER retention and gets secreted without a partner light chain. Relevant as a differential/sibling, not for the LCDD entry itself.

4.2 Variant classification

ACMG/AMP classification does not apply — these are somatic hypermutations in a rearranged immunoglobulin V gene, evaluated by structural/biophysical consequence, not by pathogenicity tier. Population allele frequencies (gnomAD etc.) are meaningless here; the IG loci are somatically rearranged and hypermutated by design.

Variant types documented in pathogenic LCDD light chains: | Type | Consequence | Evidence | |---|---|---| | Missense in CDR/FR (polar → hydrophobic) | exposes hydrophobic surface, promotes aggregation/tissue binding | PMID:8918585; PMID:39196376 | | Missense creating N-glycosylation sequon (e.g. Thr74→Asn) | adds N-glycan; renders FLC undetectable in serum/urine assays | PMID:8918585; PMID:7829131 | | Leader-sequence substitutions | aberrant signal peptidase cleavage → truncated LC with hydrophobic N-terminus (Ile-Ile-Leu) | PMID:8918585 | | Cumulative basic-residue substitutions in CDRs | high CDR isoelectric point → charge-driven basement membrane binding | PMID:30578255 | | Small truncations | altered folding/deposition | PMID:39196376 |

Functional consequence class: this is a gain of pathological function at the protein level (the chain acquires a tissue-binding, cell-signaling activity it should not have). In dismech's schema this belongs on the light-chain descriptor as a modifier: GAIN_OF_FUNCTION-style activity claim on the process node rather than on a GeneticContext.functional_impact_category — there is no germline variant to hang a GeneticContext on. Be careful here; the two slots are not interchangeable (see CLAUDE.md "Gain/Loss of Function: which slot?").

4.3 Modifier genes, epigenetics, chromosomal abnormalities

Modifier genes: none identified.
Epigenetics: no DNA methylation or chromatin study specific to LCDD identified. Blank.
Clonal cytogenetics: the underlying plasma cell clone can carry standard myeloma cytogenetics; FISH is recommended by the IKMG for clonal characterization ("Additional genetic tests and fluorescent in situ hybridization studies are helpful for clonal identification and for generating treatment recommendations." — PMID:30510265). No LCDD-specific cytogenetic signature (e.g. a t(11;14) enrichment analogous to AL amyloidosis) was confirmed in the sources I retrieved — treat as an open question, not as absence.

5. Environmental Information

Environmental factors: none established.
Lifestyle factors: none established.
Infectious agents: none causal. One interesting confound from Lin's HCDD subgroup: "frequently had hypocomplementemia and a positive hepatitis C virus antibody but negative hepatitis C virus PCR" (PMID:11423577) — that is an HCDD observation, serology-positive/PCR-negative, and should not be imported into LCDD as an infectious trigger.

This section is genuinely empty for LCDD, and saying so is more useful than manufacturing plausible-sounding exposures.

6. Mechanism / Pathophysiology

Here is the causal chain, upstream → downstream, in the form the dismech pathograph wants.

Node 1 — Clonal plasma cell expansion and excess free light chain secretion

Scale: CELLULAR · Cell type: CL:0000786 plasma cell ✅ · Site: UBERON:0002371 bone marrow ✅ · Process: GO:0002377 immunoglobulin production ✅ (modifier: INCREASED)

A small clone — usually below the myeloma treatment threshold — secretes free light chains at high concentration. In the mouse model this had to be engineered deliberately: "High free LC levels were achieved after backcrossing with mice presenting increased PC differentiation and no immunoglobulin heavy chain production." (PMID:32559766)

Node 2 — Structurally abnormal light chain variable domain

Scale: MOLECULAR

The V domain carries hydrophobic CDR substitutions, sometimes an N-glycan, and a high isoelectric point (PMID:30578255; PMID:8918585; PMID:7829131). This node is the disease's actual etiologic agent, and it is sufficient on its own: "The variable domain of the LC bears alone the structural properties involved in its pathogenicity." (PMID:32559766)

Node 2b (parallel branch) — Plasma-cell endoplasmic reticulum stress

Scale: CELLULAR · Process: GO:0034976 response to endoplasmic reticulum stress ✅, GO:0030968 endoplasmic reticulum unfolded protein response ✅

"RNA sequencing conducted on PCs demonstrated that LCDD LC induces endoplasmic reticulum stress, likely accounting for the high efficiency of proteasome inhibitor-based therapy." — Bender et al. (PMID:32559766)

This is the mechanistic why behind bortezomib working so well, and it deserves its own node with an INHIBITS treatment edge from the proteasome inhibitor (GO:0043161 proteasome-mediated ubiquitin-dependent protein catabolic process ✅). The clone has effectively backed itself into a corner: it makes a protein so awkward to fold that its own quality-control machinery is running flat out, and a proteasome inhibitor tips it over.

Node 3 — Non-fibrillar deposition along basement membranes

Scale: TISSUE · Sites: UBERON:0005777 glomerular basement membrane ✅, UBERON:0009773 renal tubule ✅ (tubular BM), UBERON:0000074 renal glomerulus ✅

Linear/granular, Congo-red-negative, "powdery" on electron microscopy. The charge-complementarity story from Joly (high-pI CDRs vs. polyanionic BM) is the best current explanation.

Node 4 — Mesangial cell surface engagement and phenotype transformation

Scale: CELLULAR · Cell types: CL:0000650 mesangial cell ✅ → CL:0000186 myofibroblast cell ✅ · Processes: GO:0043123 positive regulation of canonical NF-kappaB signal transduction ✅, GO:0048008 platelet-derived growth factor receptor signaling pathway ✅

The critical mechanistic discriminator between LCDD and AL amyloidosis lives here, and it is beautiful:

"Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed. Light chains from patients with LCDD exert their pathogenic signaling effect at the cell surface of mesangial cells." — Herrera et al., Kidney Int Rep 2020 (PMID:33163710)

Same cell, same class of ligand, two completely different intracellular itineraries — one goes inside to the lysosome and comes out as fibrils, the other never crosses the membrane and instead shouts at a receptor. AL hollows the mesangium out; LCDD makes it build.

"The interaction with the pathogenic light chain elicits specific cellular processes, which include apoptosis, phenotype transformation, and secretion of extracellular matrix components and metalloproteinases." — Herrera et al. (PMID:33163710)

Node 5 — TGF-β–driven extracellular matrix overproduction

Scale: CELLULAR/TISSUE · Processes: GO:0007179 transforming growth factor beta receptor signaling pathway ✅ (modifier: INCREASED), GO:0030198 extracellular matrix organization ✅, GO:0085029 extracellular matrix assembly ✅

The landmark in-vitro demonstration:

"These proteins inhibited mesangial cell proliferation and increased production of matrix proteins, including type IV collagen, laminin, and fibronectin. By immunocytochemistry and bioassay, transforming growth factor-beta (TGF-beta) production and activity increased when mesangial cells were exposed to these proteins. Furthermore, anti-TGF-beta antibody abolished the inhibition of cell proliferation and the increase of extracellular matrix protein production caused by these light chains." — Zhu, Herrera, Murphy-Ullrich, Huang & Sanders, Am J Pathol 1995 (PMID:7639331)

That anti-TGF-β rescue is the causal proof, not just a correlation — block the cytokine and the phenotype goes away.

And the specificity control matters: "These findings were not observed in mesangial cells exposed to human albumin and two other light chains previously characterized to be tubulopathic." (PMID:7639331) — i.e., glomerulopathic and tubulopathic light chains are different populations, which is exactly why one patient gets LCDD and another with a similar clone gets Fanconi syndrome or cast nephropathy.

Node 6 — Failure of matrix degradation (the other half of the imbalance)

Scale: CELLULAR · Process: GO:0022617 extracellular matrix disassembly ✅ (modifier: DECREASED)

"When mesangial cells are incubated with LCDD-LCs, production of ECM proteins (collagen IV, laminin, fibronectin, and tenascin) is increased, with maximum effect at 72 hours post LC treatment. A concomitant decrease in collagenase IV activity further accentuates the accumulation of mesangial matrix. These effects are mediated through transforming growth factor-beta (TGF-beta) activation." — Herrera et al., Ultrastruct Pathol 1999 (PMID:10369104)

Same paper gives the mirror-image AL contrast: "In contrast, when mesangial cells are incubated with Am-LCs, a decrease in ECM protein production and a stimulatory effect on collagenase IV is observed, which results in matrix degradation and facilitates amyloid deposition."

The MMP-7 / tenascin-C axis is the more recently emphasized version of this: light chains suppress mesangial MMP-7 release, tenascin-C goes undegraded, matrix piles up (Cassano et al. 2024, PMID:39196376 — see §16 provenance caveat).

So the mesangium is caught in a two-sided vice: the faucet is opened and the drain is plugged. Neither alone would silt the glomerulus this fast.

Node 7 — Nodular glomerulosclerosis

Scale: TISSUE · Site: UBERON:0000074 renal glomerulus ✅

Nodular mesangial sclerosis in 61% (39/64) of Nasr's MIDD cohort (PMID:22156754); 100% of pure MIDD vs 18% of LCDD-with-cast-nephropathy in Lin's series (P<0.0001) (PMID:11423577). κ deposition was more often associated with nodular sclerosing glomerulopathy than λ (PMID:14655186).

Node 8 — Proteinuria, GFR decline, kidney failure

Scale: ORGANISM

"Our mouse model recapitulates the characteristic features of LCDD, including progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure." — Bender et al. (PMID:32559766)

Node 9 (parallel) — Extrarenal deposition and organ dysfunction

Liver sinusoids, myocardium, choroid plexus, lung (§3.2).

6.1 What the mouse transcriptome says about sequence of events

"Finally, transcriptome analysis of presclerotic glomeruli revealed that proliferation and extracellular matrix remodeling represented the first steps of glomerulosclerosis, paving the way for future therapeutic strategies in LCDD and other kidney diseases featuring diffuse glomerulosclerosis, particularly diabetic nephropathy." — Bender et al. (PMID:32559766)

Worth flagging: the mouse's presclerotic glomeruli show proliferation first, whereas the classic in-vitro data show light chains inhibiting mesangial proliferation (PMID:7639331). That is a genuine tension between the in-vitro and in-vivo models — an excellent candidate for a KNOWLEDGE_GAP or HUMAN_MODEL_MISMATCH discussion in the entry rather than a paper-over.

6.2 Reversibility — the deposits are not permanent

"Accordingly, reduction of circulating pathogenic LC was efficiently achieved and not only preserved renal function but also partially reversed kidney lesions." — Bender et al. (PMID:32559766)

This is mechanistically load-bearing: turn off the tap and the sink partially drains. It reframes LCDD as a dynamic equilibrium, not a one-way accretion, and justifies aggressive clone-directed therapy even in advanced renal disease.

6.3 Not covered by the literature

Metabolomics, lipidomics, single-cell/spatial transcriptomics, proteomics beyond mass-spec typing of deposits, and CRISPR/RNAi functional screens: no LCDD-specific studies identified. The Bender bulk RNA-seq (PMID:32559766) is the only omics dataset of consequence. Record the rest as gaps.

7. Anatomical Structures Affected

Organ level

Structure	UBERON	Role
Kidney	`UBERON:0002113` ✅	Primary — always involved
Liver	`UBERON:0002107` ✅	Secondary; most common extrarenal site (with heart)
Heart / myocardium	`UBERON:0000948` ✅ / `UBERON:0002349` ✅	Secondary
Choroid plexus	`UBERON:0001886` ✅	CNS deposition site
Lung	`UBERON:0002048` ✅	Usually incidental
Peripheral nervous system	`UBERON:0000010` ✅	Uncommon
Bone marrow	`UBERON:0002371` ✅	Source compartment (the clone)

Body systems: urinary/renal (primary); hepatobiliary, cardiovascular, nervous, respiratory (secondary); hematologic/immune (source).

Tissue and cell level

Structure	Term	Note
Glomerular basement membrane	`UBERON:0005777` ✅	primary deposition surface
Renal tubule (tubular BM)	`UBERON:0009773` ✅	linear LC staining along TBM is a classic IF finding
Renal glomerulus / mesangium	`UBERON:0000074` ✅	site of nodular sclerosis
Mesangial cell	`CL:0000650` ✅	the effector cell
Myofibroblast	`CL:0000186` ✅	the transformed mesangial phenotype
Plasma cell	`CL:0000786` ✅	source cell
Podocyte	`CL:0000653` ✅	secondarily injured (proteinuria) — mechanistically less studied
Proximal tubule epithelial cell	`CL:1000838` ✅	relevant to the differential (tubulopathic LC → Fanconi), not core LCDD

Subcellular level (GO Cellular Component — not verified against cache; look up before curating)

Basement membrane (extracellular matrix compartment) — the deposition site
Endoplasmic reticulum — plasma-cell stress compartment (PMID:32559766)
Lysosome — notable by its absence in LCDD; it is the AL-amyloidosis route (PMID:33163710)

Localization

Bilateral and diffuse in the kidney. Systemic/multi-organ. Not lateralized.

8. Temporal Development

Onset: adult; median 56 y (PMID:22156754; PMID:26392598), mean 58 y (PMID:14655186). Insidious in the glomerular form; abrupt (AKI) when light chain cast nephropathy coexists (PMID:30578255).

Stages (no formal staging system exists — this is a descriptive synthesis): 1. Occult — nephrotoxic monoclonal LC circulating; MGUS-level clone; no renal signal. 2. Early renal — albuminuria/proteinuria and a creatinine drift. Median ~12 months elapse here before diagnosis (PMID:27501122). 3. Established — nodular glomerulosclerosis, nephrotic-range proteinuria, GFR <30 in ~69% at diagnosis (PMID:27501122). 4. End-stage — dialysis dependence in 39–62% (PMID:22156754; PMID:26392598). 5. Extrarenal/systemic — hepatic and cardiac deposition; drives mortality independent of renal course (PMID:14655186).

Progression rate — and its treatment dependence. The Sayed dichotomy is the most useful single number pair in the disease:

"with a mean improvement in glomerular filtration rate (GFR) of 6.1 mL/min/year among those achieving a complete or very good partial hematologic response (VGPR) with chemotherapy, most of whom remained dialysis independent, compared with a mean GFR loss of 6.5 mL/min/year among those achieving only a partial or no hematologic response (P < .009), most of whom developed end-stage renal disease (ESRD; P = .005)." — Sayed et al., Blood 2015 (PMID:26392598)

+6.1 vs −6.5 mL/min/year. The same disease, running in two directions, and the switch is the depth of the hematologic response.

Course: chronic progressive; lifelong. No spontaneous remission is described. Remission is treatment-induced and is a hematologic remission that the kidney then follows (or fails to follow, if fibrosis has already set).

Critical intervention window: before severe interstitial fibrosis and before GFR falls below ~30. Two independent series converge on this: - "Predictive factors were pre-treatment eGFR over 30 ml/min per 1.73 m(2) and post-treatment dFLC under 40 mg/l" (Cohen, PMID:26176826) - "FLC response ≥ VGPR and absence of severe interstitial fibrosis were independent predictors of renal response." (Joly, PMID:30578255)

9. Inheritance and Population

Epidemiology

No reliable incidence or prevalence figure exists. Cassano et al. state it plainly: LCDD is "a relatively rare condition with unknown incidence in literature because often its not diagnosed, in asymptomatic phases" (PMID:39196376). For scale: the largest series ever assembled is 255 MIDD patients from an entire French national referral network (PMID:30578255); Mayo accumulated 88 MIDD patients over 22 years (1992–2014) (PMID:27501122). Orphanet classifies it as a rare disease (ORPHA:93558).

For the dismech prevalence block: use measure_type: UNKNOWN or prevalence_class: RARE with the source phrasing in notes. Do not manufacture a rate_per_100000 — none is defensible from this literature.

Inheritance

Not heritable. Acquired somatic clonal disorder. No inheritance pattern, penetrance, expressivity, anticipation, mosaicism, founder effect, consanguinity role, or carrier frequency applies. Leave the inheritance: block absent rather than curating "not applicable" as a value.

Demographics

Sex ratio: male-predominant, 63.5% male (M:F ≈ 1.7:1) (PMID:14655186); male predominance also noted by PMID:39196376.
Light chain isotype: κ ≫ λ; 68:32 (PMID:14655186), 11:1 in pure LCDD (PMID:11423577). This is a far stronger κ bias than AL amyloidosis, where λ dominates — a useful discriminating feature.
Age distribution: peak 5th–6th decade; younger than AL amyloidosis and cast nephropathy (PMID:22156754); 36% ≤50 y.
Ethnicity / geography: no established variation. All large series are from Western referral centers (US, France, UK, Italy) — ascertainment, not biology, likely explains that. Record as a gap.

10. Diagnostics

10.1 The diagnostic spine: kidney biopsy + monoclonal protein studies

"The diagnosis of MGRS-related disease is established by kidney biopsy and immunofluorescence studies to identify the monotypic immunoglobulin deposits... Accordingly, the IKMG recommends a kidney biopsy in patients suspected of having MGRS to maximize the chance of correct diagnosis. Serum and urine protein electrophoresis and immunofixation, as well as analyses of serum free light chains, should also be performed to identify the monoclonal immunoglobulin... Finally, bone marrow aspiration and biopsy should be conducted to identify the lymphoproliferative clone. Flow cytometry can be helpful in identifying small clones." — Leung et al. (PMID:30510265)

10.2 Laboratory

Test	Finding	Sensitivity
Serum free light chain (sFLC) ratio	abnormal	100% (51/51 tested) — Nasr (PMID:22156754). "Serum free light chain ratio is abnormal in all MIDD patients, whereas only three-quarters have abnormal serum protein electrophoresis."
SPEP	M-spike	73% (47/64) — Nasr (PMID:22156754)
Serum/urine immunofixation	monoclonal band	complements SPEP
Serum creatinine / eGFR	elevated / reduced	~96% abnormal (PMID:14655186)
24h urine protein	>1 g/d in 84% (PMID:14655186)
Urinalysis / sediment	proteinuria ± hematuria
dFLC (involved − uninvolved)	used for hematologic response; <40 mg/L post-treatment predicts renal response (PMID:26176826)
Bone marrow aspirate/biopsy + flow + FISH	clone identification	per IKMG (PMID:30510265)

⚠️ The N-glycosylation blind spot. Glycosylated pathogenic light chains may be undetectable in serum and urine (PMID:7829131). A negative FLC screen does not exclude LCDD when the biopsy shows monotypic deposits.

LOINC anchors (for reference_ranges if curated): serum kappa FLC, lambda FLC, and κ/λ ratio have LOINC codes; I did not verify specific LOINC IDs in this session — look them up rather than guessing.

10.3 Kidney biopsy — the definitive test

Modality	Finding
Light microscopy	Nodular mesangial (glomerulo)sclerosis — 61% of MIDD (PMID:22156754), 100% of pure MIDD (PMID:11423577). Also membranoproliferative-like patterns, GBM duplication, increased lobulation (PMID:39196376). Tubulointerstitial fibrosis (a key prognostic feature, PMID:30578255).
Congo red	NEGATIVE — no apple-green birefringence. This is the defining negative.
Immunofluorescence	Monotypic (single-isotype) light chain staining, linear along glomerular AND tubular basement membranes and in mesangial nodules. κ in ~2/3 to 11/12 of cases.
Electron microscopy	Non-fibrillar, non-organized, finely granular/"powdery" electron-dense deposits along the inner aspect of the GBM and the outer aspect of the TBM (PMID:39196376).
Mass spectrometry	Laser-capture microdissection + LC-MS/MS for deposit typing when IF is equivocal — standard at referral centers.

Pathologic terminology now has a formal consensus — worth citing in the entry for definitional grounding: Nasr SH, Royal V, et al. "Renal Pathology Society/International Kidney and Monoclonal Gammopathy Research Group consensus on pathologic definitions and terminology of monoclonal gammopathy-associated kidney lesions." Kidney Int. 2025 Aug;108(2):184-193 (PMID:40280412).

10.4 Imaging and functional testing

Kidney ultrasound — pre-biopsy; nonspecific.
Echocardiography / cardiac MRI — for cardiac involvement; diastolic dysfunction, wall thickening. Cardiac LCDD can mimic cardiac amyloidosis on imaging but is Congo-red-negative on biopsy.
Liver imaging / LFTs — hepatic involvement.
Brain MRI — for the rare intracerebral form; "the diverse imaging presentations of this disease... can closely resemble other neurologic pathologies. Recognizing these potential mimics is crucial for avoiding misdiagnosis" (PMID:38914431).
ECG / Holter — conduction disease and arrhythmia (PMID:39196376).

10.5 Genetic testing

Germline genetic testing has no role. No WGS/WES/panel/CMA/karyotype/FISH/mtDNA/repeat-expansion indication for the patient's constitutional genome. FISH is used on the clone for hematologic risk stratification (PMID:30510265). Curate this as an explicit negative — it's the kind of thing that otherwise gets hallucinated into a rare-disease entry by pattern-matching.

10.6 Differential diagnosis (distinguishing features)

Differential	How to tell it apart
Diabetic nodular glomerulosclerosis (Kimmelstiel-Wilson)	The #1 morphologic mimic. IF is negative for monotypic LC; no BM linear staining; diabetes history.
AL amyloidosis	Congo red positive, apple-green birefringence, fibrils 8–12 nm on EM; λ-predominant; mesangial LC is endocytosed to lysosomes rather than acting at the cell surface (PMID:33163710)
Light chain cast nephropathy (myeloma kidney)	Tubular casts, AKI presentation, higher creatinine (mean 7.8 vs 4.2 mg/dL), less nodular glomerulopathy (18% vs 100%), far more often overt MM (91% vs 31%) — all from Lin (PMID:11423577). Can coexist with LCDD (58/212 LCDD cases in Joly).
HCDD / LHCDD	IF shows heavy chain (± LC); HCDD associated with CH1 deletion and hypocomplementemia (PMID:11423577)
Fibrillary GN / immunotactoid GN	Organized fibrils/microtubules on EM
MPGN / C3 glomerulopathy	C3-dominant IF; MGRS-associated C3G has minimal Ig deposits (PMID:30510265)
Fanconi syndrome from tubulopathic LC	Different light chain population entirely — the tubulopathic LCs did not produce the mesangial phenotype in vitro (PMID:7639331)
Amyloid-negative organized deposits, cryocrystalglobulinemia	Crystalline deposits; distinct V-domain determinants (PMID:10828030)

10.7 Screening

There is no population screening for LCDD and none is warranted. The rational secondary-prevention approach is: in patients with a known monoclonal gammopathy, monitor albuminuria/proteinuria and eGFR, and biopsy the kidney on unexplained renal deterioration — precisely because the 12-month diagnostic lag (PMID:27501122) is where kidneys are lost.

11. Outcome / Prognosis

Survival

Metric	Value	Source
Median estimated patient survival	14.0 years	Sayed, n=53 (PMID:26392598)
Alive at censor	64%	Sayed (PMID:26392598)
Mean patient survival	90 months	Nasr, n=64 (PMID:22156754)
5-year overall survival	67%	Kourelis, n=88 (PMID:27501122)
Mean patient survival, pure MIDD	54 months	Lin (PMID:11423577)
Mean patient survival, LCDD + cast nephropathy	22 months	Lin (PMID:11423577)
Deaths in bortezomib-treated cohort	5/49 at median 54 mo follow-up	Cohen (PMID:26176826)

Renal survival

Metric	Value	Source
Median renal survival from diagnosis	5.4 years	Sayed (PMID:26392598)
Mean renal survival	64 months	Nasr (PMID:22156754)
5-year renal survival	57%	Kourelis (PMID:27501122)
Progression to ESRD	39% (22/56)	Nasr (PMID:22156754)
Required dialysis	62%	Sayed (PMID:26392598)
Reached uremia (incidence rate)	23.7 per 100 patient-years	Pozzi (PMID:14655186)
Median survival from starting dialysis	5.2 years	Sayed (PMID:26392598)
Mean renal survival, LCDD + cast nephropathy	4 months	Lin (PMID:11423577)

Prognostic factors

Renal outcome: - Baseline eGFR / serum creatinine (the single most consistent factor): "On multivariate analysis, initial creatinine was the only predictor of renal and patient survival in pure MIDD" (PMID:11423577); "a baseline GFR < 20 mL/min/1.73 m2... independently predictive of progression to dialysis" (PMID:27501122); pre-treatment eGFR >30 (PMID:26176826) - Depth of hematologic response — ≥VGPR (PMID:30578255; PMID:26392598); post-treatment dFLC <40 mg/L, "the sole predictive factor of renal response by multivariable analysis" (PMID:26176826) - Absence of severe interstitial fibrosis (PMID:30578255) - Age (RR 1.05 per year) (PMID:14655186) - Hard constraint: "Renal response occurred in 62 patients (36%), all of whom had achieved hematological response." (PMID:30578255) — no renal response occurred without a hematologic response. Zero exceptions in 255 patients.

Patient outcome: age (RR 1.06), symptomatic MM (RR 2.75, 95% CI 1.22–6.2), extrarenal LC deposition (RR 2.24, 95% CI 1.15–4.35) (PMID:14655186).

Notably NOT prognostic: histologic parameters. "While kappa-LC deposition was more frequently associated with nodular sclerosing glomerulopathy, histological parameters were not predictors of renal/patient prognosis." (PMID:14655186)

Dialysis is worth doing

"The survival of the uremic patients undergoing dialysis was similar to that of patients not reaching uremia." … "Dialysis is worth performing in uremic LCDD patients." — Pozzi et al. (PMID:14655186)

Trend over time

"The prognosis for MIDD is improving compared with historical controls, likely reflecting earlier detection and improved therapies." — Nasr et al. (PMID:22156754)

12. Treatment

Governing principle: treat the clone, not the kidney. There is no therapy that removes deposits directly; everything works by shutting off the supply of pathogenic light chain and letting the tissue partially remodel (PMID:32559766).

12.1 Proteasome inhibitor–based therapy — current backbone

Bortezomib + dexamethasone ± cyclophosphamide (the "VCd"-type regimen).

"Here we retrospectively studied 49 patients with MIDD who received a median of 4.5 cycles of intravenous bortezomib plus dexamethasone... The overall hematologic response rate, based on the difference between involved and uninvolved serum-free light chains (dFLCs), was 91%... Renal response was achieved in 26 patients, with a 35% increase in median eGFR and an 86% decrease in median 24-h proteinuria... Thus, bortezomib-based therapy is a promising treatment strategy in MIDD, mainly when used early in the disease course." — Cohen et al., Kidney Int 2015 (PMID:26176826)

Mechanistic justification (a rare case where the drug rationale is directly evidenced): the pathogenic light chain puts the plasma cell under ER stress, so proteasome blockade is disproportionately lethal to that clone (PMID:32559766). Bortezomib may also act on the kidney directly via NF-κB inhibition and TGF-β1 reduction (PMID:39196376 — full-text claim, see §16).

Suggested annotation:

treatment_term: {preferred_term: Pharmacotherapy, term: {id: NCIT:C15986, label: Pharmacotherapy}}   # ✅
therapeutic_agent:
  - {preferred_term: bortezomib, term: {id: CHEBI:52717, label: bortezomib}}                          # ✅
  - {preferred_term: dexamethasone, term: {id: CHEBI:41879, label: dexamethasone}}                    # ✅
  - {preferred_term: cyclophosphamide, term: {id: CHEBI:4027, label: cyclophosphamide}}               # ✅
therapeutic_modality: SMALL_MOLECULE
target_mechanisms:
  - target: <the plasma-cell ER-stress / LC-secretion node>
    treatment_effect: INHIBITS

(NCIT also has NCIT:C1851 Bortezomib ✅ if a drug-class NCIT term is preferred; note the repo memory that NCIT drug terms often fail therapeutic_agent enum validation — prefer CHEBI here.)

12.2 Autologous stem cell transplantation

"Fifty-three (60%) received an autologous stem cell transplant (ASCT) or proteasome inhibitor (PI)-based treatments. Patients receiving ASCT or PI-based therapies were more likely to achieve at least a hematologic CR/VGPR compared to those receiving other therapies: 66% vs 2%, p < 0.0001." — Kourelis et al. (PMID:27501122)

That 66% vs 2% gap is not subtle. But note the honest caveat from the 2024 review: ASCT patients "seem to achieve deeper and durable hematologic remissions and organ responses," though "no statistically significant superiority can be demonstrated over non-transplant approaches" (PMID:39196376).

Terms: NCIT:C16039 Autologous Hematopoietic Stem Cell Transplantation ✅ (or NCIT:C15431 Hematopoietic Cell Transplantation ✅); therapeutic_modality: CELL_THERAPY; conditioning agent CHEBI:28876 melphalan ✅.

12.3 Anti-CD38 monoclonal antibody (daratumumab)

Evidence in LCDD specifically is thin but real — a consolidation study that pooled AL amyloidosis and LCDD:

"We used as a consolidation a short course of daratumumab in 25 patients with AL amyloidosis or light chain deposition disease (LCDD), who had not achieved a haematologic complete response (hemCR) after standard therapy with bortezomib, cyclophosphamide and dexamethasone (VCD)... One month after consolidation completion, 8 patients (32%) achieved a hemCR, of whom 5 (20%) became also MRD negative." — Kastritis et al., Amyloid 2021 (PMID:34468250)

⚠️ Curation caution: this cohort is mixed AL + LCDD. Do not quote the 32% hemCR as an LCDD-specific figure. There is no dedicated daratumumab-in-LCDD trial — my PubMed title search for daratumumab + deposition disease returned nothing.

Terms: NCIT:C74007 Daratumumab ✅; therapeutic_modality: MONOCLONAL_ANTIBODY; NCIT:C20401 Monoclonal Antibody ✅.

12.4 Immunomodulatory drugs

Thalidomide (CHEBI:9513 ✅) and lenalidomide (CHEBI:63791 ✅) were used as add-ons in 6/49 of the Cohen cohort (PMID:26176826). Lenalidomide requires renal dose adjustment and is generally second-line here. Weak evidence base.

12.5 Kidney transplantation — the genuinely contested question

The literature has moved, and the entry should capture both positions with their evidence:

Position A — high recurrence, be cautious. "The disease recurred in three of four patients who received a kidney transplant." — Nasr (PMID:22156754). The 2024 review: "Renal allograft is not recommended, due to high incidence of relapse," with recurrence "after a median of 33.3 months in 5 of the 7 patients" (PMID:39196376).

Position B — safe if the clone is in sustained remission first. "Seven patients received a renal transplant, and among those whose underlying clonal disorder was in sustained remission, there was no recurrence of LCDD up to 9.7 years later." — Sayed (PMID:26392598). And case-level support that bortezomib can rescue a recurring graft: "they have experienced a prolonged period of stable renal function with no clinically detectable disease. These unique cases highlight the possibility to achieve long-term stable graft function and disease remission after renal transplantation for LCDD." (Kuppachi, PMID:26915878).

These are reconcilable — the discriminator is hematologic remission status at the time of transplant, not transplantation per se. That reconciliation is a good candidate for a discussions block rather than picking a winner.

Terms: NCIT:C15265 Kidney Transplantation ✅; NCIT:C15248 Hemodialysis ✅; NCIT:C15289 Organ Transplantation ✅; NCIT:C15747 Supportive Care ✅.

12.6 Supportive care

RAAS blockade for proteinuria, blood-pressure control, management of nephrotic syndrome, renal replacement therapy. No LCDD-specific supportive-care trial exists.

12.7 Treatment algorithm (synthesized)

Confirm by kidney biopsy (IF + EM + Congo red) and identify the clone (sFLC, SPEP/IFE, marrow, flow, FISH).
Treat early — before eGFR <30 and before severe interstitial fibrosis (PMID:26176826; PMID:30578255).
Bortezomib-based induction; target ≥VGPR / dFLC <40 mg/L, not merely "a response."
Consider ASCT in eligible patients for depth/durability (PMID:27501122).
Daratumumab consolidation if the hemCR target is missed (PMID:34468250, mixed cohort).
Kidney transplant only after sustained clonal remission (PMID:26392598).
Monitor sFLC/dFLC longitudinally as the surrogate for renal protection.

12.8 Response criteria — an active methodological problem

Renal response in MIDD has been assessed using criteria borrowed from AL amyloidosis or from IMWG (PMID:27501122), and a 2025 Leukemia paper explicitly addresses "Refining renal response assessment in monoclonal immunoglobulin deposition disease: Challenges, limitations and need for consensus." Worth recording as a live gap — cross-study response rates are not strictly comparable.

12.9 Pharmacogenomics, gene therapy, RNA therapy, gene editing

None applicable / none reported for LCDD. No PharmGKB/CPIC guidance specific to this disease. Don't invent an ASO or gene-therapy angle here.

12.10 Clinical trials

I identified no LCDD-specific interventional trial with an NCT identifier. LCDD patients are typically enrolled in AL amyloidosis or MGRS trials, or treated off-protocol on myeloma regimens. If the entry gets a clinical_trials: block, it should probably stay empty rather than importing AL amyloidosis trials — and remember phase:/status: are enums (PHASE_III, COMPLETED), not prose.

13. Prevention

Primary prevention: none exists. You cannot prevent the emergence of a clone with a structurally unlucky V domain.
Secondary prevention (early detection): this is where the leverage is. In anyone with a known monoclonal gammopathy, track proteinuria/albuminuria and eGFR, and biopsy on unexplained decline. The 12-month lag between the first renal signal and diagnosis (PMID:27501122) is an unforced loss, and the treatment window closes with fibrosis (PMID:30578255).
Tertiary prevention: aggressive clone-directed therapy targeting ≥VGPR to prevent ESKD (PMID:26392598), and confirmed sustained remission before kidney transplant to prevent allograft recurrence (PMID:26392598).
Immunization / vaccines: not applicable to the disease; standard immunosuppression-related vaccination applies to treated patients.
Genetic screening / counseling / prenatal testing / PGD: not applicable. Somatic, non-heritable.
Public health and environmental interventions: not applicable — no environmental cause is known.

14. Other Species / Natural Disease

Taxonomy: Human — NCBITaxon:9606. Experimental mouse — NCBITaxon:10090. Rat (in-vitro mesangial cell source) — NCBITaxon:10116. (CURIEs standard; not verified against repo cache this session.)
Breed (VBO): not applicable.
Natural disease in other species: I found no report of naturally occurring LCDD in any non-human species. Dogs, cats, and horses do develop plasma cell myeloma and AL amyloidosis, but a natural Randall-type non-amyloid light chain deposition disease is not documented in the sources I retrieved (no OMIA entry surfaced). Record as "not reported," not as "does not occur" — absence of evidence, and veterinary renal biopsy with immunofluorescence is uncommon.
Comparative pathology: The disease is fundamentally a product of somatic hypermutation in an immunoglobulin V gene — a process conserved across jawed vertebrates — so there is no a priori barrier to it occurring in other mammals. It may simply be under-ascertained.
Evolutionary conservation of mechanism: The downstream half (mesangial TGF-β–driven matrix accumulation) is deeply conserved and shared with diabetic nephropathy and other sclerosing glomerulopathies — the Bender authors say so explicitly (PMID:32559766). The upstream half (a specific human V-gene-derived pathogenic protein) is idiosyncratic to the individual patient's clone.
Zoonotic potential / cross-species transmission: none. Not transmissible.

15. Model Organisms

15.1 The flagship model — transgenic LCDD mouse (Bender/Sirac 2020)

Citation: Bender S, Ayala MV, Bonaud A, Javaugue V, et al. Blood. 2020;136(14):1645-1656. PMID:32559766

Attribute	Detail
Type	Genetically engineered mouse (mammalian, in vivo)
Construction	Site-directed insertion of the variable domain of a pathogenic human LC gene into the mouse immunoglobulin κ locus, so all plasma cells produce it; backcrossed onto a background with increased PC differentiation and no IgH production to achieve high free LC levels
Recapitulates	"progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure"
Key mechanistic finding	LC induces ER stress in plasma cells (RNA-seq) → explains proteasome-inhibitor efficacy
Rescue arm	Reduction of circulating pathogenic LC "not only preserved renal function but also partially reversed kidney lesions" — a `RESTORED` readout
Novel biology	Presclerotic glomeruli show proliferation and ECM remodeling as the first steps

Suggested modeled_mechanisms links: | Target node | relationship | fidelity | limitations | |---|---|---|---| | Nodular glomerulosclerosis / progressive glomerulosclerosis | RECAPITULATES | HIGH | requires an engineered high-FLC background (IgH-null, enhanced PC differentiation) that does not correspond to any human hematologic state | | Plasma cell ER stress | RECAPITULATES | MODERATE | transcriptomic inference; bulk RNA-seq | | Nephrotic-range proteinuria / kidney failure | RECAPITULATES | HIGH | — | | Extrarenal (hepatic/cardiac/CNS) deposition | (not demonstrated) | — | the model is renal-centric; the 35% extrarenal burden seen in humans (PMID:30578255) is not addressed | | Reversibility on LC reduction | RESCUES | MODERATE | partial reversal only |

Model limitations to record honestly: single human V domain (one patient's clone, not a panel); mouse Igκ-locus context; no myeloma tumor burden; extrarenal involvement not modeled; the proliferation-first finding is in tension with in-vitro anti-proliferative LC data (PMID:7639331).

15.2 In vitro — cultured mesangial cells + patient-derived light chains

The workhorse system, and it's genuinely elegant: purify light chains from the urine of biopsy-proven patients, put them on cultured mesangial cells grown on an artificial matrix, and watch the human lesion reassemble in a dish.

Study	System	Finding
Zhu et al. 1995 (PMID:7639331)	Cultured rat mesangial cells + 2 urinary LCs from biopsy-proven LCDD patients; human albumin and 2 tubulopathic LCs as controls	↓ proliferation, ↑ collagen IV/laminin/fibronectin, ↑ TGF-β; anti-TGF-β abolishes both effects
Herrera et al. 1999 (PMID:10369104)	Mesangial cells on artificial matrix + LCDD-LC vs amyloidogenic-LC	↑ ECM (incl. tenascin) peaking at 72 h, ↓ collagenase IV; "The immunomorphologic mesangial alterations observed in biopsy material are closely reproduced in vitro"
Herrera et al. 2020 review (PMID:33163710)	Synthesis	LCDD-LC signals at the cell surface; AL-LC is endocytosed to lysosomes

Evidence-source tagging: all three are IN_VITRO (rat-derived cells, not a whole animal — per the repo's classification rules, cultured cells are IN_VITRO even when the cells are animal-derived).

15.3 Related engineered models (adjacent, cite with care)

Cryocrystalglobulinemia hybridoma-graft mouse (Rengers et al., Blood 2000, PMID:10828030) — not LCDD, but directly relevant to the "V domain determines the lesion" principle: "A limited variation in the V(kappa) domain thus proved able to increase secretion, to abrogate crystallization, and to modify patterns of glomerular lesions and deposits." A three-amino-acid deletion in Vκ CDR1 switched the entire renal phenotype. Use this as supporting evidence for the V-domain-determines-pathology node, clearly labeled as a different deposition disease.
HCDD mouse models exist in the Limoges group's output but I did not verify a specific PMID in this session — do not cite one from memory.

15.4 Not available

No zebrafish, Drosophila, C. elegans, yeast, iPSC, organoid, or organ-chip model of LCDD identified. No CRISPR/RNAi functional screen. No immortalized LCDD cell line in Cellosaurus that I could confirm. These are real gaps and worth stating as such — a NAM (organ-chip glomerulus + patient LC) is an obvious unbuilt experiment.

15.5 Resources

MGI (for the transgenic line), Alliance of Genome Resources. No dedicated LCDD model repository.

16. Provenance, verification status, and curation cautions

Sources whose quotes are verbatim from PubMed abstracts I retrieved this session (safe for snippet: after a just fetch-reference + just count-verified-snippets check): PMIDs 814812, 7639331, 7829131, 8918585, 10369104, 10828030, 11423577, 14655186, 22156754, 26176826, 26392598, 26915878, 27501122, 30510265, 30578255, 31767034, 32559766, 33163710, 33801393, 34468250, 38914431.

⚠️ PMID:39196376 (Cassano et al., Ann Hematol 2024) — quotes in this report come from the article FULL TEXT via PMC, not the abstract. Under this repo's rules, just validate-disorders runs with --no-full-text, so a snippet drawn from the body will fail CI even though the text is genuine. Either find the equivalent claim in another paper's abstract, or commit the full-text cache file, or drop the snippet and keep the description.

PMID:40280412 (RPS/IKMG pathologic definitions consensus, Kidney Int 2025) — I have the citation and title but did not retrieve its abstract body. Cite it structurally; do not quote it.

Other verification notes: - The 2025 Leukemia paper on refining renal response assessment in MIDD was seen in search results only — I did not retrieve a PMID for it. Look it up before citing. - HGNC CURIEs for IGKV4-1 etc. are not verified; GO Cellular Component and LOINC IDs are not verified; NCBITaxon CURIEs are standard but not cache-checked. - All HP / GO / CL / UBERON / CHEBI / NCIT CURIEs marked ✅ were read directly from this repository's validated caches, or (for the "no nodular glomerulosclerosis term" finding) from a live OLS query. - Highest-risk mis-annotation for this entry: HP:0001917 Renal amyloidosis. LCDD is Congo-red-negative and non-fibrillar. Using an amyloid term here would encode the exact error the whole diagnostic literature exists to prevent. - Second-highest risk: importing MONDO's loose synonyms (Bence Jones myeloma, Light chain disease) as exact synonyms. - Third: treating MeSH-mapped search results as LCDD literature — PubMed silently rewrites the query to AL amyloidosis.

Sources

Primary literature (PubMed): - PMID:814812 — Randall et al., Manifestations of systemic light chain deposition, Am J Med 1976 - PMID:7639331 — Zhu et al., Pathogenesis of glomerulosclerosis in LCDD: role for TGF-β, Am J Pathol 1995 - PMID:7829131 — Denoroy et al., Overrepresentation of the VκIV subgroup in LCDD, Immunol Lett 1994 - PMID:8918585 — Decourt et al., Structural peculiarities of a truncated VκIII light chain, Clin Exp Immunol 1996 - PMID:10369104 — Herrera et al., Glomerulopathic light chain–mesangial cell interactions, Ultrastruct Pathol 1999 - PMID:10828030 — Rengers et al., Heavy and light chain primary structures control IgG3 nephritogenicity, Blood 2000 - PMID:11423577 — Lin et al., Renal MIDD: the disease spectrum, JASN 2001 - PMID:14655186 — Pozzi et al., LCDD with renal involvement, Am J Kidney Dis 2003 - PMID:22156754 — Nasr et al., Renal MIDD: 64 patients, CJASN 2012 - PMID:26176826 — Cohen et al., Bortezomib in MIDD, Kidney Int 2015 - PMID:26392598 — Sayed et al., Natural history and outcome of LCDD, Blood 2015 - PMID:26915878 — Kuppachi et al., LCDD after kidney transplantation, Transplant Proc 2016 - PMID:27501122 — Kourelis et al., Outcomes of patients with renal MIDD, Am J Hematol 2016 - PMID:30510265 — Leung et al., IKMG consensus on MGRS, Nat Rev Nephrol 2019 - PMID:30578255 — Joly et al., Randall-type MIDD nationwide cohort, Blood 2019 - PMID:31767034 — Wang et al., Pathogenesis of renal injury and treatment in LCDD, J Transl Med 2019 - PMID:32559766 — Bender et al., Immunoglobulin light-chain toxicity in a mouse model of LCDD, Blood 2020 - PMID:33163710 — Herrera et al., Understanding mesangial pathobiology in AL-amyloidosis and LCDD, Kidney Int Rep 2020 - PMID:33801393 — Cohen et al., Randall-type MIDD: new insights, Diagnostics 2021 - PMID:34468250 — Kastritis et al., Daratumumab consolidation in AL amyloidosis or LCDD, Amyloid 2021 - PMID:38914431 — Rai et al., Light-chain deposition diseases of the CNS, AJNR 2025 - PMID:39196376 — Cassano et al., LCDD: pathogenesis, clinical characteristics and treatment strategies, Ann Hematol 2024 - PMID:40280412 — Nasr, Royal et al., RPS/IKMG consensus on pathologic definitions, Kidney Int 2025

Ontology / terminology resources: - MONDO:0019730 via EBI OLS4 - Orphanet ORPHA:93558 - Pathology Outlines — Light chain deposition disease - Kidney International — Diagnosis of monoclonal gammopathy of renal significance - Nature/Leukemia — Refining renal response assessment in MIDD (2025)

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome	Count
References checked	24
Resolved	24
Unresolved (possible confabulation)	0
Unverifiable	0

All extracted references resolved successfully.

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Light Chain Deposition Disease (LCDD) — Comprehensive Research Report

0. The one-paragraph version

1. Disease Information

1.1 Definition

1.2 Identifiers (verified via OLS, MONDO:0019730 cross-references)

1.3 Synonyms

1.4 Data provenance character

2. Etiology

2.1 Primary cause

2.2 The proximate molecular cause — a light chain with a bad variable domain

2.3 Risk factors

2.4 Protective factors

2.5 Gene–environment interactions

3. Phenotypes

3.1 Renal (essentially universal — the kidney is always involved)

3.2 Extrarenal — more common than the older literature suggested

3.3 Onset, severity, progression

3.4 Quality of life

4. Genetic / Molecular Information

4.1 The relevant "gene" is the clone's rearranged immunoglobulin light chain locus

4.2 Variant classification

4.3 Modifier genes, epigenetics, chromosomal abnormalities

5. Environmental Information

6. Mechanism / Pathophysiology

Node 1 — Clonal plasma cell expansion and excess free light chain secretion

Node 2 — Structurally abnormal light chain variable domain

Node 2b (parallel branch) — Plasma-cell endoplasmic reticulum stress

Node 3 — Non-fibrillar deposition along basement membranes

Node 4 — Mesangial cell surface engagement and phenotype transformation

Node 5 — TGF-β–driven extracellular matrix overproduction

Node 6 — Failure of matrix degradation (the other half of the imbalance)

Node 7 — Nodular glomerulosclerosis

Node 8 — Proteinuria, GFR decline, kidney failure

Node 9 (parallel) — Extrarenal deposition and organ dysfunction

6.1 What the mouse transcriptome says about sequence of events

6.2 Reversibility — the deposits are not permanent

6.3 Not covered by the literature

7. Anatomical Structures Affected

Organ level

Tissue and cell level

Subcellular level (GO Cellular Component — not verified against cache; look up before curating)

Localization

8. Temporal Development

9. Inheritance and Population

Epidemiology

Inheritance

Demographics

10. Diagnostics

10.1 The diagnostic spine: kidney biopsy + monoclonal protein studies

10.2 Laboratory

10.3 Kidney biopsy — the definitive test

10.4 Imaging and functional testing

10.5 Genetic testing

10.6 Differential diagnosis (distinguishing features)

10.7 Screening

11. Outcome / Prognosis

Survival

Renal survival

Prognostic factors

Dialysis is worth doing

Trend over time

12. Treatment

12.1 Proteasome inhibitor–based therapy — current backbone

12.2 Autologous stem cell transplantation