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Classifications

Harrison's Part

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Inheritance

1

Autosomal dominant inheritance HP:0000006

The gene-disease relationship, where curated at all, is curated as autosomal dominant: reported probands carry heterozygous LAMA4 variants, and in the one published multi-generation family the variant segregated with disease in the proband and two affected brothers while unaffected relatives did not carry it. This is the mode of inheritance ClinGen records for the relationship, and it is recorded here with the same Limited evidence caveat that applies to the relationship itself.

Autosomal dominant inheritance

Show evidence (2 references)

CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z SUPPORT Other

ClinGen records autosomal dominant inheritance for the LAMA4-DCM relationship. Marked PARTIAL because the same row classifies the clinical validity of that relationship as Limited, so the inheritance mode is recorded as the mode of a relationship that is not established.

PMID:39686469 SUPPORT Human Clinical

"A missense heterozygous mutation c.652G > A (p.G218R) in Laminin Subunit Alpha-4 (LAMA4) gene was identified in proband and his 2 brothers with relevant clinical symptoms."

Documents a heterozygous variant present in three affected members of one family, the segregation pattern on which the dominant model rests.

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Discussions and Knowledge Gaps

2

Is LAMA4 a cause of human dilated cardiomyopathy at all, and if so by what genetic mechanism?

KNOWLEDGE GAP OPEN lama4_dcm_gene_disease_validity

Attached to

pathophysiology#LAMA4 Integrin-Interacting-Domain Variant

ClinGen's Dilated Cardiomyopathy GCEP classifies the LAMA4-DCM relationship as Limited. Every strand of the human evidence has a specific weakness: the founding alleles came from a candidate screen prompted by a zebrafish result rather than from independent segregation analysis; the later p.Gly218Arg allele is a ClinVar variant of uncertain significance supported by in silico prediction; and the infantile case carried a known MYH7 DCM mutation alongside the LAMA4 variant. The mechanistic work is correspondingly lopsided — the mouse and zebrafish data are strong for the pathway and the binding data are quantitative, but neither addresses whether heterozygous human LAMA4 missense alleles are sufficient to cause disease. Until this is resolved no clinical inference should be drawn from a LAMA4 variant, and this entry curates the mechanism as proposed rather than established.

Proposed experiments

Case-control rare-variant burden test for LAMA4 in dilated cardiomyopathy

exp_cmd1jj_case_control_burden

Test whether rare LAMA4 variants, and specifically integrin-domain missense variants, are enriched in large sequenced dilated-cardiomyopathy cohorts relative to ancestry-matched population controls — the analysis that would move the ClinGen classification in either direction, and the one that has not been reported.

Knock-in mouse carrying a human LAMA4 integrin-domain allele

exp_cmd1jj_integrin_domain_knockin_mouse

Generate a heterozygous knock-in of p.Pro943Leu or the murine equivalent and test whether it produces cardiac disease, which would distinguish a dominant effect of the disease alleles from the complete-absence phenotype of the existing null.

Show evidence (2 references)

CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z SUPPORT Other

The expert-panel classification that defines this gap.

PMID:30650640 SUPPORT Human Clinical

"Inheritance of two genetic variants may have a synergistic or dose effect to cause severe DCM."

The authors' own framing of the infantile case as digenic, which is why it cannot be counted as independent evidence for LAMA4.

Does a constitutive Lama4-null mouse that develops cardiac HYPERTROPHY model a human disease defined by ventricular DILATION, and does absence of the chain model a missense loss of integrin binding?

HUMAN MODEL MISMATCH OPEN lama4_mouse_geometry_mismatch

Attached to

pathophysiology#Adverse Ventricular Remodeling

The mouse evidence carries almost all the mechanistic weight in this entry, and it differs from the human disease in two ways that are easy to elide. First, geometry: the null mouse was described as gradually developing cardiac hypertrophy with impaired function, whereas the human entity is a dilated cardiomyopathy. Second, allele class: a constitutive null models complete absence of laminin alpha-4, while the human integrin-domain alleles are heterozygous missense and nonsense changes whose proposed effect is loss of a specific protein-protein interaction. A model of absence cannot by itself establish that the human alleles act the way the entry proposes, and the Lama4-null mouse additionally develops chronic kidney disease, so it is not a cardiac-restricted model.

Proposed experiments

Serial cardiac imaging of an integrin-domain knock-in versus the null

exp_cmd1jj_serial_imaging_knockin

Compare chamber geometry, ejection fraction and myocardial perfusion over time between a heterozygous integrin-domain knock-in, the Lama4 null, and wild type, to establish whether the human allele class produces a dilated rather than hypertrophic phenotype and whether the microvascular lesion precedes the myocardial one.

Show evidence (2 references)

PMID:16204254 SUPPORT Model Organism

"we demonstrate that laminin alpha4 deficient mice gradually develop cardiac hypertrophy with impaired function"

States the mouse geometry that differs from the human dilated phenotype.

PMID:20035058 SUPPORT Model Organism

"Lama4-/- mice have progressive glomerular and tubulointerstitial fibrosis"

Documents a progressive renal phenotype in the same null, supporting the point that it is not a cardiac-restricted model.

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Pathophysiology

9

LAMA4 Integrin-Interacting-Domain Variant

The two founding LAMA4 alleles, p.Pro943Leu and p.Arg1073X, were identified by candidate screening of severe dilated cardiomyopathy patients after a zebrafish forward-genetic screen placed laminin-alpha-4 upstream of integrin and integrin-linked kinase. Both fall in the integrin-interacting domain of the protein. A third reported allele, p.Gly218Arg, lies in a laminin EGF-like domain instead and is annotated as of uncertain significance in ClinVar, so this node does not claim a single shared structural class for all reported variants.

LAMA4 hgnc:6484

basement membrane GO:0005604

Downstream

Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane The integrin-domain substitutions were measured to reduce affinity for integrin, which is the immediate molecular consequence asserted for them.

Show evidence (4 references)

PMID:17646580 SUPPORT Human Clinical

"We identified 2 novel amino acid residue-altering mutations"

Establishes that two novel LAMA4 alleles were identified in the severe dilated cardiomyopathy screen. Quoted without the bracketed protein-change annotations because bracketed spans are stripped before snippet matching.

PMID:17646580 SUPPORT Human Clinical

"in the integrin-interacting domain of the LAMA4 gene"

Localises those alleles to the integrin-interacting domain, which is the structural basis for the next node.

PMID:39686469 SUPPORT Human Clinical

"The p.G218R mutation is located in a conservative area within the laminin epidermal growth factor (EGF)-like domain of LAMA4 with uncertain significance in ClinVar archive."

Documents a later-reported allele in a different domain and its uncertain ClinVar classification. Marked PARTIAL because it qualifies rather than extends the integrin-domain model.

+ 1 more reference

Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane

Laminin alpha-4 is a component of the laminin-8 and -9 heterotrimers of the cardiac extracellular matrix, where it serves both as a structural protein and as a signalling ligand. Losing its integrin-binding capacity degrades the cell-matrix link that normally couples a cardiomyocyte and a microvascular endothelial cell to the basement membrane, and it is upstream of integrin-linked kinase, the shared node the zebrafish screen identified. This is the disorder-specific substitution for the module's primary insult: a cell-matrix adhesion and outside-in signalling lesion rather than a sarcomere defect. The mouse data below place a boundary on how far the lesion extends — it does not destabilise the dystrophin-glycoprotein complex or the sarcolemmal integrin complex, and it does not by itself stop an isolated cardiomyocyte contracting.

cardiac muscle cell CL:0000746 cardiac endothelial cell CL:0010008

cell-matrix adhesion GO:0007160 ↓ DECREASED

basement membrane GO:0005604

Animal models

Lama4-null mouse Mus musculus partially recapitulates The model recapitulates this node's positive content - absence of the chain degrades the cardiac basement membrane - and what it adds is a pair of informative NEGATIVE readouts that BOUND the mechanism: the lesion does not destabilise the sarcolemmal adhesion complexes, and it does not by itself stop an isolated cardiomyocyte contracting. Those negatives are why this entry routes the disease through the microvasculature rather than through a contractile or dystrophin-glycoprotein defect. The mechanism they exclude, sarcolemmal destabilisation, is deliberately not curated as a node here, so the negatives are carried as readouts on this link rather than as a separate failure claim.

Zebrafish lost-contact (loc) ilk mutant Danio rerio partially recapitulates Establishes genetically that the laminin-alpha-4 / integrin / ILK axis is required for myocardial function and that its disruption damages cardiomyocytes and endothelial cells together.

Downstream

Cardiac Microvascular Structural Defect The most abundant site of laminin alpha-4 in the heart is the microvascular basement membrane, and it is the vasculature that is structurally abnormal when the chain is absent.

Endothelial Cell Loss in the Myocardium In the human study the loss of endothelial cells in affected patients was attributed directly to the mutant genes, which is the observation that makes this a two-cell-type disease rather than a myocyte disease.

Show evidence (4 references)

PMID:17646580 SUPPORT Model Organism

"Additional experiments revealed the epistatic regulation between laminin-alpha4 (Lama4), integrin, and Ilk, which led us to screen for mutations in the human ILK and LAMA4 genes in patients with severe dilated cardiomyopathy."

Establishes the laminin-alpha-4 / integrin / ILK axis that this node represents, and that it was defined genetically in zebrafish before the human screen.

PMID:16204254 SUPPORT Model Organism

"Laminin alpha4 chain is a component of extracellular matrix (ECM) laminin-8 and -9 and serves dual roles as a structure protein and as a signaling molecule."

States the dual structural and signalling role of the chain, which is what makes loss of its integrin engagement more than a mechanical defect.

PMID:39337275 SUPPORT Other

"The laminin subunit alpha 4 gene (LAMA4, MIM 600133) is implicated in the structural integrity of the heart through the formation of laminins 8 and 9, which are major components of the basement membranes in cardiac tissues."

Places laminin alpha-4 in the cardiac basement membrane as part of the laminin-8/-9 heterotrimers, which is the structure this node concerns.

+ 1 more reference

Cardiac Microvascular Structural Defect

Absence of the alpha-4 chain leaves malformed cardiac vessels with widened pericapillary extracellular-matrix spaces. This is the arm of the mechanism that has no counterpart in the sarcomeric dilated cardiomyopathies, and it is the reason a matrix protein that is not part of the contractile apparatus can produce a cardiomyopathy.

capillary endothelial cell CL:0002144

basement membrane GO:0005604

capillary UBERON:0001982

Animal models

Lama4-null mouse Mus musculus recapitulates Ultrastructural demonstration that loss of the chain produces malformed cardiac vessels with widened pericapillary matrix.

Downstream

Myocardial Ischemia from Microcirculatory Insufficiency Abnormal cardiovascular matrix structure was interpreted by the authors as causing insufficient oxygen supply to the heart.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"Electron microscopy confirmed malformed blood vessels and wide pericapillary ECM spaces, suggesting the presence of microcirculation abnormalities in Lama4-/- mutant hearts."

The structural finding this node records.

Endothelial Cell Loss in the Myocardium

Loss of myocardial endothelial cells was reported in affected patients and attributed to the mutant genes. It is curated as a separate node from the structural vascular defect because the human and mouse observations are different in kind — cell loss in patient material versus vessel malformation on mouse electron microscopy — and neither has been shown to precede the other.

cardiac endothelial cell CL:0010008

Downstream

Myocardial Ischemia from Microcirculatory Insufficiency Loss of the capillary endothelium reduces the exchange surface available to the myocardium, converging with the structural vascular defect on inadequate oxygen delivery.

Show evidence (2 references)

PMID:17646580 SUPPORT Human Clinical

"the loss of endothelial cells in affected patients as a direct consequence of the mutant genes"

Documents endothelial cell loss in affected patients.

PMID:17646580 SUPPORT Human Clinical

"This is the first report on mutations in the laminin, integrin, and ILK system in human cardiomyopathy, which has consequences for endothelial cells as well as for cardiomyocytes"

States the two-cell-type character of the mechanism that this node and the cardiomyocyte arm together represent.

Myocardial Ischemia from Microcirculatory Insufficiency

Inadequate microcirculatory oxygen delivery to the myocardium. In the Lama4-null mouse this was inferred from a hypoxic transcriptional signature — elevated Hif1a and Vegfa transcripts — read together with foci of cardiomyocyte degeneration and fibrosis. This is the point at which a vascular lesion becomes a myocardial one.

heart UBERON:0000948

Animal models

Lama4-null mouse Mus musculus recapitulates A hypoxic transcriptional signature with degeneration and fibrosis supports sustained cardiac ischemia as the consequence of the vascular defect.

Downstream

Adverse Ventricular Remodeling Repeated ischemic injury with myocyte degeneration and interstitial fibrosis is remodeling, and it is where the disorder-specific arm rejoins the conserved cardiomyopathy chain.

Neurohormonal Activation Falling contractile performance from ischemic myocardial injury engages the compensatory neurohormonal axes, as in cardiomyopathy generally.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"elevated levels of hypoxia-inducible factor 1alpha (Hif1alpha) and vascular endothelial growth factor A (Vegfa) transcripts, along with multiple foci of cardiomyocyte degeneration and fibrosis suggested sustained cardiac ischemia"

The transcriptional and histological basis for inferring sustained cardiac ischemia, quoted with the authors' own hedge ("suggested").

Neurohormonal Activation

As in any cardiomyopathy, falling contractile performance activates the renin-angiotensin-aldosterone and sympathetic axes, which are compensatory acutely and maladaptive chronically, driving hypertrophy, myocyte loss and fibrosis. This node carries no LAMA4-specific evidence and does not pretend to: it is the shared module step, and it is here because it is the axis that the only available therapy acts on.

response to angiotensin GO:1990776 ↑ INCREASED

Downstream

Adverse Ventricular Remodeling Chronic neurohormonal activation drives the hypertrophy, myocyte loss and interstitial fibrosis that constitute adverse remodeling.

Show evidence (1 reference)

PMID:25445411 SUPPORT Other

"The systemic as well as the tissue RAAS are also dedicated to promote tissue remodeling, particularly relevant after damage, when chronic activation may configure as a maladaptive response, leading to fibrosis, hypertrophy and apoptosis, and organ dysfunction."

Shared module evidence that chronic renin-angiotensin-aldosterone activation is the maladaptive amplifier between a myocardial insult and structural remodeling. Evidence source is OTHER because this is a review.

Adverse Ventricular Remodeling

Cardiomyocyte loss, cardiac fibroblast activation and interstitial matrix deposition remodel the ventricle. The Lama4-null mouse showed foci of cardiomyocyte degeneration and fibrosis, and — a point worth preserving rather than smoothing into the DCM narrative — the mouse phenotype was described as gradually developing cardiac hypertrophy with impaired function rather than as frank dilation. The human reports are of dilated cardiomyopathy. The two are not the same geometry, and this entry does not assume the mouse dilates.

fibroblast of cardiac tissue CL:0002548 cardiac muscle cell CL:0000746

extracellular matrix organization GO:0030198 ↑ INCREASED cardiac muscle cell apoptotic process GO:0010659 ↑ INCREASED

heart left ventricle UBERON:0002084

Downstream

Left Ventricular Dilation and Systolic Dysfunction Progressive remodeling produces the dilated, poorly contracting ventricle that defines the human phenotype.

Show evidence (2 references)

PMID:16204254 SUPPORT Model Organism

"we demonstrate that laminin alpha4 deficient mice gradually develop cardiac hypertrophy with impaired function"

Documents progressive remodeling with impaired function in the null mouse. Marked PARTIAL because the described geometry is hypertrophy rather than the dilation seen in the human reports.

PMID:22752727 SUPPORT Other

"The pathophysiological basis of heart failure is cardiac remodeling, a process that comprises structural and functional changes including cardiomyocyte proliferation, hypertrophy, necrosis, apoptosis, autophagy, interstitial fibrosis, contractile dysfunction and ventricular dilatation."

Shared module evidence enumerating the components of adverse remodeling that this node represents.

Left Ventricular Dilation and Systolic Dysfunction

Left ventricular enlargement with reduced contractility and impaired systolic function — the phenotype by which every reported LAMA4 proband came to attention. In the one reported multi-generation family it was accompanied by conduction system disease.

cardiac muscle cell CL:0000746

heart contraction GO:0060047 ↓ DECREASED

heart left ventricle UBERON:0002084

Downstream

Dilated cardiomyopathy The dilated, hypocontractile ventricle is the diagnostic phenotype.

Structural Cardiac Impairment and Heart Failure Progressive loss of systolic function produces symptomatic heart failure.

Cardiac conduction abnormality Conduction system disease segregated with the LAMA4 variant alongside dilated cardiomyopathy in the one reported family. No mechanism linking the laminin lesion to the conduction system has been proposed, so this edge records co-segregation, not an explained route.

Show evidence (1 reference)

PMID:30650640 SUPPORT Human Clinical

"Dilated cardiomyopathy (DCM) is a rare cardiac disease characterised by left ventricular enlargement, reduced left ventricular contractility, and impaired systolic function."

Defines the physiological endpoint this node represents.

Structural Cardiac Impairment and Heart Failure

The clinical endpoint: symptomatic heart failure from structural and functional cardiac impairment, managed as heart failure of any cause because no LAMA4-directed therapy exists. Severe disease at presentation was a feature of the founding cohort, who were ascertained as severe dilated cardiomyopathy patients.

heart contraction GO:0060047 ⚠ ABNORMAL

Downstream

Congestive heart failure Structural and functional cardiac impairment presents clinically as congestive heart failure.

Show evidence (2 references)

PMID:17646580 SUPPORT Human Clinical

"which ultimately leads to heart failure"

States heart failure as the endpoint of the proposed disease mechanism.

PMID:31073128 SUPPORT Other

"As DCM eventually leads to impaired contractility, standard approaches to prevent or treat heart failure are the first-line treatment for patients with DCM."

Shared module evidence that the dilated cardiomyopathy process culminates in impaired contractility managed as heart failure.

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Pathograph

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

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Phenotypes

4

Dilated cardiomyopathy Cardiovascular HP:0001644

Show evidence (2 references)

PMID:17646580 SUPPORT Human Clinical

"which led us to screen for mutations in the human ILK and LAMA4 genes in patients with severe dilated cardiomyopathy"

Establishes severe dilated cardiomyopathy as the phenotype of the cohort in which the founding LAMA4 variants were found.

PMID:39686469 SUPPORT Human Clinical

"Clinical data, family histories, and blood samples were collected from the proband and family members in a Chinese family presenting with DCM and conduction system disease."

Documents dilated cardiomyopathy in the one reported multi-generation LAMA4 family.

Cardiac conduction abnormality Cardiovascular HP:0031546

Show evidence (1 reference)

PMID:39686469 SUPPORT Human Clinical

"Individuals without carrying this mutation in this family had no symptoms or cardiac structural abnormality related to DCM or conduction system disease."

Documents conduction system disease segregating with the variant in this family. Marked PARTIAL because it rests on a single family.

Reduced left ventricular ejection fraction Cardiovascular HP:0012664

Show evidence (1 reference)

PMID:30650640 SUPPORT Human Clinical

"left ventricular enlargement, reduced left ventricular contractility, and impaired systolic function"

Names reduced left ventricular contractility and impaired systolic function as defining features of the dilated cardiomyopathy phenotype for which the reported LAMA4 patients were ascertained.

Congestive heart failure Cardiovascular HP:0001635

Show evidence (1 reference)

PMID:17646580 SUPPORT Human Clinical

"as a direct consequence of the mutant genes, which ultimately leads to heart failure"

Names heart failure as the clinical endpoint in affected patients.

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Genetic Associations

1

LAMA4 variants of limited and disputed clinical validity (Limited)

Gene: LAMA4 hgnc:6484 relationship_type: DISPUTED

Show evidence (4 references)

CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z REFUTE Other

ClinGen's Dilated Cardiomyopathy GCEP classifies the LAMA4-DCM gene-disease relationship as Limited. Recorded as REFUTE against the implicit claim that LAMA4 is an established cause of dilated cardiomyopathy.

PMID:33947203 SUPPORT Other

"We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes."

The recommendation of the same expert panel, which is why this entry does not treat LAMA4 variants as diagnostic.

PMID:30650640 SUPPORT Human Clinical

"In Family A, there was digenic inheritance of two heterozygous variants: a novel variant in LAMA4 (c.3925G > A, p.Asp1309Asn) and a known DCM mutation in MYH7 (c.2770G > A; p.Glu924Lys)."

Shows a reported LAMA4 variant co-occurring with an established MYH7 DCM mutation, so it cannot be scored as independent evidence for LAMA4.

+ 1 more reference

Variants (4)

p.Pro943Leu

Missense variant in the integrin-interacting domain; measured integrin affinity Kd 5 +/- 3 micromol/L versus 440 +/- 20 nmol/L for wild type.

p.Arg1073X

Nonsense variant in the integrin-interacting domain; measured integrin affinity Kd 1 +/- 0.2 micromol/L versus 440 +/- 20 nmol/L for wild type.

p.Gly218Arg

Missense variant in a laminin EGF-like domain, reported in a Chinese family with dilated cardiomyopathy and conduction system disease; classified as of uncertain significance in ClinVar, with the pathogenicity claim resting on bioinformatic prediction.

p.Asp1309Asn

Missense variant reported in an infantile dilated cardiomyopathy case that also carried the known MYH7 DCM mutation p.Glu924Lys; the authors proposed a synergistic or dose effect of the two variants rather than a LAMA4-only cause.

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Medical Actions

5

Guideline-Directed Heart Failure Pharmacotherapy

Action: Pharmacotherapy NCIT:C15986

Agent: ACE inhibitor NCIT:C247 beta-blocker NCIT:C29576 mineralocorticoid receptor antagonist (spironolactone as the class exemplar) NCIT:C840 angiotensin receptor-neprilysin inhibitor (sacubitril/valsartan) NCIT:C190796 SGLT2 inhibitor NCIT:C98083

Standard therapy for left ventricular systolic dysfunction, targeting the neurohormonal amplifier of adverse remodeling. There is no LAMA4-specific disease-modifying therapy and no trial has enrolled on the basis of LAMA4 genotype, so management is the generic dilated-cardiomyopathy regimen.

Mechanism Target:

INHIBITS Neurohormonal Activation — Neurohormonal blockade interrupts the maladaptive amplifier between myocardial injury and adverse ventricular remodeling. This is a class-level mechanism, unmodified by LAMA4 genotype.

Show evidence (1 reference)

PMID:31073128 SUPPORT Other

"As DCM eventually leads to impaired contractility, standard approaches to prevent or treat heart failure are the first-line treatment for patients with DCM."

Establishes standard heart-failure therapy as first-line management for dilated cardiomyopathy.

Show evidence (3 references)

PMID:31073128 SUPPORT Other

"As DCM eventually leads to impaired contractility, standard approaches to prevent or treat heart failure are the first-line treatment for patients with DCM."

Establishes the treatment framework applied to this entity.

PMID:42475150 SUPPORT Other

"beta-blockers, and mineralocorticoid receptor antagonists, which improve survival and reduce hospitalizations"

Names the neurohormonal-blockade components of contemporary HFrEF therapy and their outcome benefit. Evidence source is OTHER because this is a narrative review of trials rather than a trial report, and none of the trials enrolled on LAMA4 genotype.

PMID:42475150 SUPPORT Other

"The use of sodium-glucose cotransporter-2 (SGLT2) inhibitors and intravenous iron therapy has also become integral to treatment, showing benefits in reducing mortality and improving symptoms."

Supports inclusion of an SGLT2 inhibitor among the contemporary HFrEF agents listed on this treatment.

Cardiac Resynchronization Therapy

Category: Therapeutic Action: cardiac resynchronization therapy Ontology label: Cardiac Resynchronization Therapy NCIT:C80436

Biventricular pacing for patients with systolic dysfunction and conduction delay. It is included here specifically because conduction system disease was reported alongside dilated cardiomyopathy in the one published LAMA4 family, which is the setting in which resynchronization becomes relevant — but the indication follows general heart-failure criteria, not genotype, and no LAMA4 patient has been reported to have received it.

Mechanism Target:

MODULATES Left Ventricular Dilation and Systolic Dysfunction — Resynchronizing ventricular contraction improves mechanical efficiency in a dilated, dyssynchronous ventricle. It does not act on the laminin lesion.

Show evidence (1 reference)

PMID:31073128 SUPPORT Other

"Cardiac resynchronization therapy and implantable cardioverter-defibrillators may be required to prevent life-threatening arrhythmias."

Establishes resynchronization therapy as part of standard DCM management. Marked PARTIAL because the quoted sentence frames both devices in terms of arrhythmia prevention, whereas resynchronization's action on this node is mechanical.

Show evidence (1 reference)

PMID:42475150 SUPPORT Other

"Device therapies, such as implantable cardioverter-defibrillators (ICDs), cardiac resynchronization therapy (CRT), and left ventricular assist devices (LVADs), are critical for advanced cases."

Names resynchronization therapy among the device therapies used in advanced heart failure with reduced ejection fraction.

Advanced Heart Failure Therapy (mechanical circulatory support and transplantation)

Category: Therapeutic Action: heart transplantation Ontology label: Heart Transplantation NCIT:C15246

For disease refractory to medical and device therapy the remaining options are a left ventricular assist device and heart transplantation. This is curated as the endpoint of the generic dilated-cardiomyopathy pathway: no LAMA4 patient has been reported to have received either, and nothing about the proposed laminin mechanism predicts a different response, so no genotype-specific claim is made.

Show evidence (1 reference)

PMID:42475150 SUPPORT Other

"left ventricular assist devices (LVADs), are critical for advanced cases"

Establishes mechanical circulatory support as part of the management of advanced heart failure with reduced ejection fraction, which is the setting this treatment records.

Implantable Cardioverter Defibrillator

Action: implantable cardioverter-defibrillator placement Ontology label: Implantable Cardioverter-Defibrillator Placement NCIT:C80435

Device therapy for prevention of sudden cardiac death, indicated by general cardiomyopathy and arrhythmia guidelines. It is noted here because conduction system disease was reported alongside dilated cardiomyopathy in one LAMA4 family; no LAMA4-specific risk-stratification rule exists.

Show evidence (1 reference)

PMID:31073128 SUPPORT Other

"Cardiac resynchronization therapy and implantable cardioverter-defibrillators may be required to prevent life-threatening arrhythmias."

Establishes device therapy as part of standard dilated-cardiomyopathy management.

Genetic Counseling with Explicit Discussion of Limited Gene-Disease Validity

Action: Genetic counseling Ontology label: Genetic Counseling NCIT:C15240

Counseling for families in whom a LAMA4 variant is reported must convey that the gene-disease relationship is classified as Limited and that variants in such genes should not be used to make or exclude a clinical diagnosis or to direct predictive testing of relatives. Cardiac surveillance of first-degree relatives is driven by the clinical phenotype in the family, not by LAMA4 carrier status.

Show evidence (2 references)

PMID:33947203 SUPPORT Other

"We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes."

The expert-panel recommendation that this counseling point implements.

PMID:33947203 SUPPORT Other

"Clinical genetic testing panels include most high-evidence genes; however, genes lacking robust evidence are also commonly included."

Explains why a LAMA4 result reaches families at all despite the Limited classification, which is the situation this counseling addresses.

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Diagnosis

3

Echocardiography

First-line and usually diagnostic. Left ventricular internal dimensions and ejection fraction establish the dilated, hypocontractile phenotype, and the diagnosis of dilated cardiomyopathy is itself a clinical one that requires excluding loading conditions and coronary disease sufficient to explain the findings. Nothing about the imaging is LAMA4-specific.

echocardiography NCIT:C16525

Show evidence (2 references)

PMID:31073128 SUPPORT Other

"Echocardiography and other imaging techniques are required to assess ventricular dysfunction and adverse myocardial remodelling"

Establishes echocardiography as the required modality for assessing the ventricular dysfunction that defines DCM, of which CMD1JJ is a proposed genetic form.

PMID:31073128 SUPPORT Other

"Dilated cardiomyopathy (DCM) is a clinical diagnosis characterized by left ventricular or biventricular dilation and impaired contraction that is not explained by abnormal loading conditions (for example, hypertension and valvular heart disease) or coronary artery disease."

States the exclusion criteria that define the diagnosis, which is what makes echocardiography necessary but not sufficient.

Cardiac Magnetic Resonance Imaging

Cardiac MRI adds what echocardiography cannot: tissue characterisation, and with it the risk stratification that actually drives management in nonischemic dilated cardiomyopathy. In a meta-analysis of 103 studies and 29,687 patients, late gadolinium enhancement - both its presence and its extent - was associated with higher all-cause and cardiovascular mortality, arrhythmic events and heart failure events, while left ventricular ejection fraction was NOT associated with all-cause mortality or arrhythmic outcomes. That inversion is the point: the number echocardiography gives you is the weaker prognostic marker. None of this is LAMA4-specific, and no reported LAMA4 patient has published CMR.

cardiac magnetic resonance imaging NCIT:C16809

Show evidence (3 references)

PMID:39298146 SUPPORT Human Clinical

"Late gadolinium enhancement (LGE) presence and extent (per 1%) were associated with higher all-cause mortality"

Establishes late gadolinium enhancement as a prognostic marker in nonischemic dilated cardiomyopathy, which is what CMR adds beyond echocardiography.

PMID:39298146 SUPPORT Human Clinical

"A total of 103 studies including 29 687 patients with NIDCM were analyzed."

Gives the size of the evidence base behind the prognostic claim.

PMID:39298146 SUPPORT Human Clinical

"Left ventricular ejection fraction (LVEF) (per 1%) was not associated with all-cause mortality"

The negative result that makes the CMR entry worth curating separately from echocardiography: ejection fraction, the echo-derived measure, does not carry the mortality signal that LGE does.

Molecular Genetic Testing (Multigene Cardiomyopathy Panel)

Every reported LAMA4 proband was ascertained by sequencing, and in the published cases that was either a candidate screen or a broad cardiomyopathy panel or exome. THE RESULT MUST NOT BE OVER-READ. LAMA4 sits outside the core diagnostic gene set, its ClinGen classification is Limited, and reported LAMA4 variants have included ClinVar variants of uncertain significance and variants co-occurring with an established DCM mutation in another gene. A LAMA4 finding should not be used on its own to make or exclude a diagnosis, nor to direct predictive testing of relatives; the same expert panel that classified the gene recommends caution in interpreting variants in variable-evidence DCM genes.

genetic testing NCIT:C15709

Show evidence (5 references)

PMID:39686469 SUPPORT Human Clinical

"A genetic analysis was performed using next generation sequencing (NGS)."

Documents the sequencing route by which a LAMA4 variant reached a family with dilated cardiomyopathy.

PMID:33947203 SUPPORT Other

"Clinical genetic testing panels include most high-evidence genes; however, genes lacking robust evidence are also commonly included."

Explains how a variant in a Limited-evidence gene such as LAMA4 reaches a family at all, which is the interpretive hazard this entry records.

PMID:33947203 SUPPORT Other

"We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes."

The expert-panel recommendation that governs how a LAMA4 result should be used.

+ 2 more references

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Prevalence

1

Worldwide

Unknown Not yet documented

No population-based prevalence estimate exists for a LAMA4-specific form of dilated cardiomyopathy, and none can be derived while the gene-disease relationship itself is classified as Limited. Reported human LAMA4 cardiomyopathy amounts to a handful of index cases and small families. For context, dilated cardiomyopathy overall has been reported at around 1 in 2700 in the USA and 1 in 7000 in Japan; LAMA4 accounts for no established share of that.

Show evidence (1 reference)

PMID:30650640 SUPPORT Human Clinical

"prevalences of 1 in 2700 have been reported in the USA"

Provides a population figure for dilated cardiomyopathy as a whole. Marked PARTIAL because it is not a LAMA4-specific estimate, which is exactly the point this record makes.

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Animal Models

2

Lama4-null mouse

Constitutive laminin alpha-4 chain knockout mouse, the principal in vivo evidence for the microvascular mechanism. It is a null, not a knock-in of a human integrin-domain allele, so it models absence of the chain rather than the specific loss of integrin binding proposed for the human variants.

Species

Mus musculus

Genotype

Lama4-/-

Publication

PMID:16204254

Pathograph links

Cardiac Microvascular Structural Defect recapitulates fidelity: moderate Ultrastructural demonstration that loss of the chain produces malformed cardiac vessels with widened pericapillary matrix.

Limitations: A constitutive null models complete absence of the chain rather than the missense loss of integrin binding proposed for the human disease alleles, and the mouse cardiac phenotype was described as gradually developing hypertrophy with impaired function rather than as ventricular dilation. Lama4-null mice also develop chronic kidney disease, so the null is not cardiac-restricted.

Readouts

Cardiac vessel ultrastructure and pericapillary matrix width

Direction: ALTERED

Interpretation: Malformed vessels and widened pericapillary matrix are the structural readout of the microvascular defect.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"Electron microscopy confirmed malformed blood vessels and wide pericapillary ECM spaces, suggesting the presence of microcirculation abnormalities in Lama4-/- mutant hearts."

Reports the electron-microscopic measurement behind this readout.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"Our study links the genetic deficiency of an ECM protein to cardiomyopathy and implies a novel pathway of idiopathic cardiomyopathy in human."

The authors' own statement of what the model establishes, which is what makes it informative for this node.

Myocardial Ischemia from Microcirculatory Insufficiency recapitulates fidelity: moderate A hypoxic transcriptional signature with degeneration and fibrosis supports sustained cardiac ischemia as the consequence of the vascular defect.

Limitations: Ischemia was inferred from Hif1a/Vegfa transcript elevation and histology rather than measured directly as myocardial perfusion or oxygen tension, and the authors' own wording is "suggested". No comparable measurement exists in a human LAMA4 carrier.

Readouts

Hif1a and Vegfa transcript levels

Direction: INCREASED

Interpretation: Elevated hypoxia-response transcripts are the surrogate readout for sustained myocardial ischemia in this model.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"elevated levels of hypoxia-inducible factor 1alpha (Hif1alpha) and vascular endothelial growth factor A (Vegfa) transcripts"

Reports the direction of the hypoxia-marker measurement.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"insufficient oxygen supply to the heart and the subsequent ischemic cardiac phenotype observed"

The authors' causal conclusion, which is the claim this link asserts the model supports.

Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane partially recapitulates fidelity: low The model recapitulates this node's positive content - absence of the chain degrades the cardiac basement membrane - and what it adds is a pair of informative NEGATIVE readouts that BOUND the mechanism: the lesion does not destabilise the sarcolemmal adhesion complexes, and it does not by itself stop an isolated cardiomyocyte contracting. Those negatives are why this entry routes the disease through the microvasculature rather than through a contractile or dystrophin-glycoprotein defect. The mechanism they exclude, sarcolemmal destabilisation, is deliberately not curated as a node here, so the negatives are carried as readouts on this link rather than as a separate failure claim.

Limitations: This is a null allele rather than an integrin-binding-deficient missense knock-in, so the negative result bounds what absence of the chain does; it cannot exclude a dominant-negative or altered-signalling effect specific to the human integrin-domain alleles, which has never been tested in vivo.

Readouts

Dystrophin-glycoprotein and integrin beta-1D complex levels

Direction: UNCHANGED

Interpretation: Sarcolemmal adhesion complexes are unaltered, excluding the muscular-dystrophy route to cardiomyopathy in this model.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"No alteration in integrin beta 1D protein was observed in terms of expression level or distribution pattern"

Reports the negative measurement on the sarcolemmal integrin complex.

Isolated cardiomyocyte contractility

Direction: UNCHANGED

Interpretation: Mutant cardiomyocytes contract normally in isolation, which is why this entry does not model a primary contractile-protein defect.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"cardiomyocytes isolated from Lama4-/- mutant hearts maintained their contractility in vitro"

Reports the preserved-contractility measurement.

Show evidence (1 reference)

PMID:16204254 SUPPORT Model Organism

"indicating that the postnatal development of cardiac hypertrophy and cardiomyopathy in these mice is unlikely associated with the stability of sarcolemmal DGC and integrin complexes"

The authors explicitly rule out the sarcolemmal-complex route, which is the negative claim this link records.

Zebrafish lost-contact (loc) ilk mutant

The forward-genetic screen mutant that started the whole line of work. It is an ilk mutant, not a lama4 mutant, and is included because the epistatic relationship it defined between Lama4, integrin and Ilk is the sole reason LAMA4 was screened in human patients at all.

Species

Danio rerio

Genotype

ilk nonsense mutation (lost-contact, loc)

Publication

PMID:17646580

Pathograph links

Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane partially recapitulates fidelity: low Establishes genetically that the laminin-alpha-4 / integrin / ILK axis is required for myocardial function and that its disruption damages cardiomyocytes and endothelial cells together.

Limitations: The mutated gene is ilk, not lama4, so the model demonstrates the pathway's requirement rather than the consequence of a laminin lesion; and it is a zebrafish embryonic heart, which differs in chamber anatomy, conduction and haemodynamic load from the adult human ventricle in which the disease presents.

Readouts

Myocardial function and cardiomyocyte/endothelial integrity

Direction: DECREASED

Interpretation: Severe myocardial dysfunction with combined cardiomyocyte and endothelial defects is the phenotypic readout of disrupting the axis.

Show evidence (1 reference)

PMID:17646580 SUPPORT Model Organism

"This loc/ilk mutant is associated with a severe defect in cardiomyocytes and endothelial cells that leads to severe myocardial dysfunction."

Reports the cardiac phenotype of the mutant.

Show evidence (1 reference)

PMID:17646580 SUPPORT Model Organism

"We used a forward genetic screen in zebrafish to identify novel genes required for myocardial function and were able to identify the lost-contact (loc) mutant, which encodes a nonsense mutation in the integrin-linked kinase (ilk) gene."

Establishes the model's origin and what it was selected for, which is what makes it informative for the pathway node.

{ }

Source YAML

click to show

name: Dilated Cardiomyopathy 1JJ
creation_date: "2026-08-25T00:00:00Z"
category: Mendelian
synonyms:
- CMD1JJ
- dilated cardiomyopathy type 1JJ
- LAMA4 familial isolated dilated cardiomyopathy
- familial isolated dilated cardiomyopathy caused by mutation in LAMA4
description: >-
  Dilated cardiomyopathy 1JJ (CMD1JJ) is the LAMA4-attributed node of the
  familial isolated dilated cardiomyopathy series. LAMA4 encodes laminin
  alpha-4, a chain of the laminin-8/-9 heterotrimers that form the basement
  membrane surrounding cardiomyocytes and, most abundantly, the cardiac
  microvasculature. The two founding disease alleles fall in the
  integrin-interacting domain and were shown by surface-plasmon-resonance
  binding measurements to lose integrin-binding affinity by roughly an order of
  magnitude, which is what makes this entity mechanistically unlike the
  sarcomeric dilated cardiomyopathies: the proposed lesion is in the
  laminin-integrin-ILK linkage between a cardiomyocyte and its matrix, and it
  acts on the endothelium as well as on the myocyte. The Lama4-null mouse is
  explicit on this point — sarcolemmal dystrophin-glycoprotein and integrin
  complexes are intact and isolated mutant cardiomyocytes still contract, while
  the hearts show malformed vessels, widened pericapillary matrix, a hypoxic
  transcriptional signature, and foci of myocyte degeneration and fibrosis. The
  disease is therefore modelled here as a microvascular and cell-matrix-adhesion
  route into the conserved maladaptive-remodeling pathway rather than as a
  primary contractile-protein defect.


  THE GENE-DISEASE RELATIONSHIP IS NOT ESTABLISHED. The ClinGen Dilated
  Cardiomyopathy Gene Curation Expert Panel classified LAMA4-dilated
  cardiomyopathy as LIMITED evidence on 2024-11-15 under SOP10, and the same
  panel's published curation recommends that only high-evidence DCM genes be
  used in clinical practice. Reported human LAMA4 variants have included ones of
  uncertain significance in ClinVar and ones found together with a second
  cardiomyopathy-gene variant. This entry therefore curates the proposed
  mechanism as a proposed mechanism: the gene-disease dispute is carried in the
  genetic block, in a dedicated discussion, and on the causal edges, and no node
  asserts that LAMA4 variation is a proven monogenic cause of human dilated
  cardiomyopathy.
disease_term:
  preferred_term: dilated cardiomyopathy 1JJ
  term:
    id: MONDO:0014095
    label: dilated cardiomyopathy 1JJ
parents:
- Dilated Cardiomyopathy
classifications:
  harrisons_chapter:
  - classification_value: CARDIOVASCULAR
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: NOT_YET_DOCUMENTED
  notes: >-
    No population-based prevalence estimate exists for a LAMA4-specific form of
    dilated cardiomyopathy, and none can be derived while the gene-disease
    relationship itself is classified as Limited. Reported human LAMA4
    cardiomyopathy amounts to a handful of index cases and small families. For
    context, dilated cardiomyopathy overall has been reported at around 1 in
    2700 in the USA and 1 in 7000 in Japan; LAMA4 accounts for no established
    share of that.
  evidence:
  - reference: PMID:30650640
    reference_title: "Digenic Inheritance of LAMA4 and MYH7 Mutations in Patient with Infantile Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "prevalences of 1 in 2700 have been reported in the USA"
    explanation: >-
      Provides a population figure for dilated cardiomyopathy as a whole. Marked
      PARTIAL because it is not a LAMA4-specific estimate, which is exactly the
      point this record makes.
inheritance:
- name: Autosomal dominant inheritance
  description: >-
    The gene-disease relationship, where curated at all, is curated as autosomal
    dominant: reported probands carry heterozygous LAMA4 variants, and in the one
    published multi-generation family the variant segregated with disease in the
    proband and two affected brothers while unaffected relatives did not carry
    it. This is the mode of inheritance ClinGen records for the relationship, and
    it is recorded here with the same Limited evidence caveat that applies to the
    relationship itself.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  evidence:
  - reference: CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z
    reference_title: "LAMA4 / dilated cardiomyopathy (Limited)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "LAMA4 | HGNC:6484 | dilated cardiomyopathy | MONDO:0005021 | AD | Limited"
    explanation: >-
      ClinGen records autosomal dominant inheritance for the LAMA4-DCM
      relationship. Marked PARTIAL because the same row classifies the clinical
      validity of that relationship as Limited, so the inheritance mode is
      recorded as the mode of a relationship that is not established.
  - reference: PMID:39686469
    reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A missense heterozygous mutation c.652G > A (p.G218R) in Laminin Subunit Alpha-4 (LAMA4) gene was identified in proband and his 2 brothers with relevant clinical symptoms."
    explanation: >-
      Documents a heterozygous variant present in three affected members of one
      family, the segregation pattern on which the dominant model rests.
pathophysiology:
- name: LAMA4 Integrin-Interacting-Domain Variant
  biological_scale: MOLECULAR
  role: trigger
  description: >-
    The two founding LAMA4 alleles, p.Pro943Leu and p.Arg1073X, were identified
    by candidate screening of severe dilated cardiomyopathy patients after a
    zebrafish forward-genetic screen placed laminin-alpha-4 upstream of integrin
    and integrin-linked kinase. Both fall in the integrin-interacting domain of
    the protein. A third reported allele, p.Gly218Arg, lies in a laminin
    EGF-like domain instead and is annotated as of uncertain significance in
    ClinVar, so this node does not claim a single shared structural class for all
    reported variants.
  genes:
  - preferred_term: LAMA4
    term:
      id: hgnc:6484
      label: LAMA4
  cellular_components:
  - preferred_term: basement membrane
    term:
      id: GO:0005604
      label: basement membrane
  evidence:
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified 2 novel amino acid residue-altering mutations"
    explanation: >-
      Establishes that two novel LAMA4 alleles were identified in the severe
      dilated cardiomyopathy screen. Quoted without the bracketed protein-change
      annotations because bracketed spans are stripped before snippet matching.
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "in the integrin-interacting domain of the LAMA4 gene"
    explanation: >-
      Localises those alleles to the integrin-interacting domain, which is the
      structural basis for the next node.
  - reference: PMID:39686469
    reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The p.G218R mutation is located in a conservative area within the laminin epidermal growth factor (EGF)-like domain of LAMA4 with uncertain significance in ClinVar archive."
    explanation: >-
      Documents a later-reported allele in a different domain and its uncertain
      ClinVar classification. Marked PARTIAL because it qualifies rather than
      extends the integrin-domain model.
  - reference: PMID:39337275
    reference_title: "Unveiling the Spectrum of Minor Genes in Cardiomyopathies: A Narrative Review."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "These mutations, located within the integrin-interacting domain, disrupt the interaction between laminins and integrin receptors, thereby affecting the cellular adhesion and signal transduction pathways that are critical for cardiac function"
    explanation: >-
      Independent review restating the domain localisation of the two founding
      alleles and the adhesion/signalling consequence proposed for them.
  downstream:
  - target: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
    causal_link_type: DIRECT
    description: >-
      The integrin-domain substitutions were measured to reduce affinity for
      integrin, which is the immediate molecular consequence asserted for them.
    evidence:
    - reference: PMID:17646580
      reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "point to the loss of integrin-binding capacity in case of the Pro943Leu (Kd=5+/-3 micromol/L) and Arg1073X LAMA4 (Kd=1+/-0.2 micromol/L) mutants compared with the wild-type LAMA4 protein (Kd=440+/-20 nmol/L)"
      explanation: >-
        Quantitative binding data giving the measured loss of integrin affinity
        for both alleles against wild type.
- name: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
  biological_scale: MOLECULAR
  role: central_effector
  conforms_to: "cardiomyopathy_maladaptive_remodeling#Primary Cardiomyocyte Insult"
  description: >-
    Laminin alpha-4 is a component of the laminin-8 and -9 heterotrimers of the
    cardiac extracellular matrix, where it serves both as a structural protein
    and as a signalling ligand. Losing its integrin-binding capacity degrades the
    cell-matrix link that normally couples a cardiomyocyte and a microvascular
    endothelial cell to the basement membrane, and it is upstream of
    integrin-linked kinase, the shared node the zebrafish screen identified. This
    is the disorder-specific substitution for the module's primary insult: a
    cell-matrix adhesion and outside-in signalling lesion rather than a sarcomere
    defect. The mouse data below place a boundary on how far the lesion extends —
    it does not destabilise the dystrophin-glycoprotein complex or the sarcolemmal
    integrin complex, and it does not by itself stop an isolated cardiomyocyte
    contracting.
  cell_types:
  - preferred_term: cardiac muscle cell
    term:
      id: CL:0000746
      label: cardiac muscle cell
  - preferred_term: cardiac endothelial cell
    term:
      id: CL:0010008
      label: cardiac endothelial cell
  biological_processes:
  - preferred_term: cell-matrix adhesion
    term:
      id: GO:0007160
      label: cell-matrix adhesion
    modifier: DECREASED
  cellular_components:
  - preferred_term: basement membrane
    term:
      id: GO:0005604
      label: basement membrane
  evidence:
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Additional experiments revealed the epistatic regulation between laminin-alpha4 (Lama4), integrin, and Ilk, which led us to screen for mutations in the human ILK and LAMA4 genes in patients with severe dilated cardiomyopathy."
    explanation: >-
      Establishes the laminin-alpha-4 / integrin / ILK axis that this node
      represents, and that it was defined genetically in zebrafish before the
      human screen.
  - reference: PMID:16204254
    reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Laminin alpha4 chain is a component of extracellular matrix (ECM) laminin-8 and -9 and serves dual roles as a structure protein and as a signaling molecule."
    explanation: >-
      States the dual structural and signalling role of the chain, which is what
      makes loss of its integrin engagement more than a mechanical defect.
  - reference: PMID:39337275
    reference_title: "Unveiling the Spectrum of Minor Genes in Cardiomyopathies: A Narrative Review."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The laminin subunit alpha 4 gene (LAMA4, MIM 600133) is implicated in the structural integrity of the heart through the formation of laminins 8 and 9, which are major components of the basement membranes in cardiac tissues."
    explanation: >-
      Places laminin alpha-4 in the cardiac basement membrane as part of the
      laminin-8/-9 heterotrimers, which is the structure this node concerns.
  - reference: PMID:16204254
    reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We show that depletion of laminin alpha4 chain did not alter the levels of dystrophin-glycoprotein complex (DGC) components or affect cell membrane integrity."
    explanation: >-
      Bounds the lesion: it does not act through the dystrophin-glycoprotein
      complex, which is the mechanism of the muscular-dystrophy cardiomyopathies.
  downstream:
  - target: Cardiac Microvascular Structural Defect
    causal_link_type: DIRECT
    description: >-
      The most abundant site of laminin alpha-4 in the heart is the
      microvascular basement membrane, and it is the vasculature that is
      structurally abnormal when the chain is absent.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Electron microscopy confirmed malformed blood vessels and wide pericapillary ECM spaces, suggesting the presence of microcirculation abnormalities in Lama4-/- mutant hearts."
      explanation: >-
        Ultrastructural demonstration that loss of the chain produces malformed
        vessels and abnormal pericapillary matrix.
  - target: Endothelial Cell Loss in the Myocardium
    causal_link_type: DIRECT
    description: >-
      In the human study the loss of endothelial cells in affected patients was
      attributed directly to the mutant genes, which is the observation that
      makes this a two-cell-type disease rather than a myocyte disease.
    evidence:
    - reference: PMID:17646580
      reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Additional functional data point to the loss of endothelial cells in affected patients as a direct consequence of the mutant genes, which ultimately leads to heart failure."
      explanation: >-
        Attributes endothelial cell loss in affected patients directly to the
        mutant genes.
- name: Cardiac Microvascular Structural Defect
  biological_scale: TISSUE
  role: amplifier
  description: >-
    Absence of the alpha-4 chain leaves malformed cardiac vessels with widened
    pericapillary extracellular-matrix spaces. This is the arm of the mechanism
    that has no counterpart in the sarcomeric dilated cardiomyopathies, and it is
    the reason a matrix protein that is not part of the contractile apparatus can
    produce a cardiomyopathy.
  cell_types:
  - preferred_term: capillary endothelial cell
    term:
      id: CL:0002144
      label: capillary endothelial cell
  locations:
  - preferred_term: capillary
    term:
      id: UBERON:0001982
      label: capillary
  cellular_components:
  - preferred_term: basement membrane
    term:
      id: GO:0005604
      label: basement membrane
  evidence:
  - reference: PMID:16204254
    reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Electron microscopy confirmed malformed blood vessels and wide pericapillary ECM spaces, suggesting the presence of microcirculation abnormalities in Lama4-/- mutant hearts."
    explanation: >-
      The structural finding this node records.
  downstream:
  - target: Myocardial Ischemia from Microcirculatory Insufficiency
    causal_link_type: DIRECT
    description: >-
      Abnormal cardiovascular matrix structure was interpreted by the authors as
      causing insufficient oxygen supply to the heart.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "mutation in the laminin alpha4 chain leads to abnormal cardiovascular ECM structure that cause insufficient oxygen supply to the heart and the subsequent ischemic cardiac phenotype observed"
      explanation: >-
        The authors' own causal statement from matrix structure to insufficient
        oxygen supply.
- name: Endothelial Cell Loss in the Myocardium
  biological_scale: CELLULAR
  role: amplifier
  description: >-
    Loss of myocardial endothelial cells was reported in affected patients and
    attributed to the mutant genes. It is curated as a separate node from the
    structural vascular defect because the human and mouse observations are
    different in kind — cell loss in patient material versus vessel malformation
    on mouse electron microscopy — and neither has been shown to precede the
    other.
  cell_types:
  - preferred_term: cardiac endothelial cell
    term:
      id: CL:0010008
      label: cardiac endothelial cell
  evidence:
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the loss of endothelial cells in affected patients as a direct consequence of the mutant genes"
    explanation: >-
      Documents endothelial cell loss in affected patients.
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This is the first report on mutations in the laminin, integrin, and ILK system in human cardiomyopathy, which has consequences for endothelial cells as well as for cardiomyocytes"
    explanation: >-
      States the two-cell-type character of the mechanism that this node and the
      cardiomyocyte arm together represent.
  downstream:
  - target: Myocardial Ischemia from Microcirculatory Insufficiency
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Loss of the capillary endothelium reduces the exchange surface available to
      the myocardium, converging with the structural vascular defect on
      inadequate oxygen delivery.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "insufficient oxygen supply to the heart and the subsequent ischemic cardiac phenotype observed"
      explanation: >-
        Supports the ischemic endpoint of the microvascular arm. Marked PARTIAL
        because the mouse study documents vessel malformation rather than
        endothelial cell loss, so the specific step from cell loss to ischemia is
        inferred.
- name: Myocardial Ischemia from Microcirculatory Insufficiency
  biological_scale: TISSUE
  role: effector
  description: >-
    Inadequate microcirculatory oxygen delivery to the myocardium. In the
    Lama4-null mouse this was inferred from a hypoxic transcriptional signature —
    elevated Hif1a and Vegfa transcripts — read together with foci of
    cardiomyocyte degeneration and fibrosis. This is the point at which a
    vascular lesion becomes a myocardial one.
  locations:
  - preferred_term: heart
    term:
      id: UBERON:0000948
      label: heart
  evidence:
  - reference: PMID:16204254
    reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "elevated levels of hypoxia-inducible factor 1alpha (Hif1alpha) and vascular endothelial growth factor A (Vegfa) transcripts, along with multiple foci of cardiomyocyte degeneration and fibrosis suggested sustained cardiac ischemia"
    explanation: >-
      The transcriptional and histological basis for inferring sustained cardiac
      ischemia, quoted with the authors' own hedge ("suggested").
  downstream:
  - target: Adverse Ventricular Remodeling
    causal_link_type: DIRECT
    description: >-
      Repeated ischemic injury with myocyte degeneration and interstitial
      fibrosis is remodeling, and it is where the disorder-specific arm rejoins
      the conserved cardiomyopathy chain.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "multiple foci of cardiomyocyte degeneration and fibrosis"
      explanation: >-
        Documents the myocyte loss and fibrosis that constitute the remodeling
        response in this model.
  - target: Neurohormonal Activation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Falling contractile performance from ischemic myocardial injury engages the
      compensatory neurohormonal axes, as in cardiomyopathy generally.
    evidence:
    - reference: PMID:25445411
      reference_title: "Biomarkers of activation of renin-angiotensin-aldosterone system in heart failure: how useful, how feasible?"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        The systemic as well as the tissue RAAS are also dedicated to promote
        tissue remodeling, particularly relevant after damage, when chronic
        activation may configure as a maladaptive response, leading to fibrosis,
        hypertrophy and apoptosis, and organ dysfunction.
      explanation: >-
        Shared module-level evidence that tissue damage engages the RAAS as a
        maladaptive amplifier. This is class-level, not LAMA4-specific, and is
        cited as such.
- name: Neurohormonal Activation
  biological_scale: ORGANISM
  role: amplifier
  conforms_to: "cardiomyopathy_maladaptive_remodeling#Neurohormonal Activation"
  description: >-
    As in any cardiomyopathy, falling contractile performance activates the
    renin-angiotensin-aldosterone and sympathetic axes, which are compensatory
    acutely and maladaptive chronically, driving hypertrophy, myocyte loss and
    fibrosis. This node carries no LAMA4-specific evidence and does not pretend
    to: it is the shared module step, and it is here because it is the axis that
    the only available therapy acts on.
  biological_processes:
  - preferred_term: response to angiotensin
    term:
      id: GO:1990776
      label: response to angiotensin
    modifier: INCREASED
  evidence:
  - reference: PMID:25445411
    reference_title: "Biomarkers of activation of renin-angiotensin-aldosterone system in heart failure: how useful, how feasible?"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The systemic as well as the tissue RAAS are also dedicated to promote
      tissue remodeling, particularly relevant after damage, when chronic
      activation may configure as a maladaptive response, leading to fibrosis,
      hypertrophy and apoptosis, and organ dysfunction.
    explanation: >-
      Shared module evidence that chronic renin-angiotensin-aldosterone
      activation is the maladaptive amplifier between a myocardial insult and
      structural remodeling. Evidence source is OTHER because this is a review.
  downstream:
  - target: Adverse Ventricular Remodeling
    causal_link_type: DIRECT
    description: >-
      Chronic neurohormonal activation drives the hypertrophy, myocyte loss and
      interstitial fibrosis that constitute adverse remodeling.
    evidence:
    - reference: PMID:22752727
      reference_title: "The role of TWEAK/Fn14 in cardiac remodeling."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        The pathophysiological basis of heart failure is cardiac remodeling, a
        process that comprises structural and functional changes including
        cardiomyocyte proliferation, hypertrophy, necrosis, apoptosis, autophagy,
        interstitial fibrosis, contractile dysfunction and ventricular dilatation.
      explanation: >-
        Shared module evidence enumerating the remodeling components that follow
        neurohormonal activation. Evidence source is OTHER because this is a
        mechanistic review.
- name: Adverse Ventricular Remodeling
  biological_scale: TISSUE
  role: central_effector
  conforms_to: "cardiomyopathy_maladaptive_remodeling#Ventricular Remodeling"
  description: >-
    Cardiomyocyte loss, cardiac fibroblast activation and interstitial matrix
    deposition remodel the ventricle. The Lama4-null mouse showed foci of
    cardiomyocyte degeneration and fibrosis, and — a point worth preserving
    rather than smoothing into the DCM narrative — the mouse phenotype was
    described as gradually developing cardiac hypertrophy with impaired function
    rather than as frank dilation. The human reports are of dilated
    cardiomyopathy. The two are not the same geometry, and this entry does not
    assume the mouse dilates.
  cell_types:
  - preferred_term: fibroblast of cardiac tissue
    term:
      id: CL:0002548
      label: fibroblast of cardiac tissue
  - preferred_term: cardiac muscle cell
    term:
      id: CL:0000746
      label: cardiac muscle cell
  locations:
  - preferred_term: heart left ventricle
    term:
      id: UBERON:0002084
      label: heart left ventricle
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: INCREASED
  - preferred_term: cardiac muscle cell apoptotic process
    term:
      id: GO:0010659
      label: cardiac muscle cell apoptotic process
    modifier: INCREASED
  evidence:
  - reference: PMID:16204254
    reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "we demonstrate that laminin alpha4 deficient mice gradually develop cardiac hypertrophy with impaired function"
    explanation: >-
      Documents progressive remodeling with impaired function in the null mouse.
      Marked PARTIAL because the described geometry is hypertrophy rather than
      the dilation seen in the human reports.
  - reference: PMID:22752727
    reference_title: "The role of TWEAK/Fn14 in cardiac remodeling."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The pathophysiological basis of heart failure is cardiac remodeling, a
      process that comprises structural and functional changes including
      cardiomyocyte proliferation, hypertrophy, necrosis, apoptosis, autophagy,
      interstitial fibrosis, contractile dysfunction and ventricular dilatation.
    explanation: >-
      Shared module evidence enumerating the components of adverse remodeling
      that this node represents.
  downstream:
  - target: Left Ventricular Dilation and Systolic Dysfunction
    causal_link_type: DIRECT
    description: >-
      Progressive remodeling produces the dilated, poorly contracting ventricle
      that defines the human phenotype.
    evidence:
    - reference: PMID:39686469
      reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Dilated cardiomyopathy (DCM) is characterized by ventricular dilation and poor systolic function."
      explanation: >-
        Defines the dilated, hypocontractile endpoint of the remodeling process.
- name: Left Ventricular Dilation and Systolic Dysfunction
  biological_scale: ORGANISM
  role: effector
  conforms_to: "cardiomyopathy_maladaptive_remodeling#Progressive Contractile Dysfunction"
  description: >-
    Left ventricular enlargement with reduced contractility and impaired systolic
    function — the phenotype by which every reported LAMA4 proband came to
    attention. In the one reported multi-generation family it was accompanied by
    conduction system disease.
  cell_types:
  - preferred_term: cardiac muscle cell
    term:
      id: CL:0000746
      label: cardiac muscle cell
  locations:
  - preferred_term: heart left ventricle
    term:
      id: UBERON:0002084
      label: heart left ventricle
  biological_processes:
  - preferred_term: heart contraction
    term:
      id: GO:0060047
      label: heart contraction
    modifier: DECREASED
  evidence:
  - reference: PMID:30650640
    reference_title: "Digenic Inheritance of LAMA4 and MYH7 Mutations in Patient with Infantile Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dilated cardiomyopathy (DCM) is a rare cardiac disease characterised by left ventricular enlargement, reduced left ventricular contractility, and impaired systolic function."
    explanation: >-
      Defines the physiological endpoint this node represents.
  downstream:
  - target: Dilated cardiomyopathy
    causal_link_type: DIRECT
    description: >-
      The dilated, hypocontractile ventricle is the diagnostic phenotype.
    evidence:
    - reference: PMID:17646580
      reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "thus providing a new genetic basis for dilated cardiomyopathy in humans"
      explanation: >-
        The authors' framing of the phenotype the identified variants were
        proposed to explain.
  - target: Structural Cardiac Impairment and Heart Failure
    causal_link_type: DIRECT
    description: >-
      Progressive loss of systolic function produces symptomatic heart failure.
    evidence:
    - reference: PMID:17646580
      reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "as a direct consequence of the mutant genes, which ultimately leads to heart failure"
      explanation: >-
        States heart failure as the clinical endpoint of the proposed mechanism.
  - target: Cardiac conduction abnormality
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Conduction system disease segregated with the LAMA4 variant alongside
      dilated cardiomyopathy in the one reported family. No mechanism linking the
      laminin lesion to the conduction system has been proposed, so this edge
      records co-segregation, not an explained route.
    evidence:
    - reference: PMID:39686469
      reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Individuals without carrying this mutation in this family had no symptoms or cardiac structural abnormality related to DCM or conduction system disease."
      explanation: >-
        Documents that both the structural and the conduction phenotype tracked
        with carrier status in this family. Marked PARTIAL because no mechanism
        is offered and the family is a single observation.
- name: Structural Cardiac Impairment and Heart Failure
  biological_scale: ORGANISM
  role: consequence
  conforms_to: "cardiomyopathy_maladaptive_remodeling#Structural Cardiac Impairment and Heart Failure"
  description: >-
    The clinical endpoint: symptomatic heart failure from structural and
    functional cardiac impairment, managed as heart failure of any cause because
    no LAMA4-directed therapy exists. Severe disease at presentation was a
    feature of the founding cohort, who were ascertained as severe dilated
    cardiomyopathy patients.
  biological_processes:
  - preferred_term: heart contraction
    term:
      id: GO:0060047
      label: heart contraction
    modifier: ABNORMAL
  evidence:
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which ultimately leads to heart failure"
    explanation: >-
      States heart failure as the endpoint of the proposed disease mechanism.
  - reference: PMID:31073128
    reference_title: "Dilated cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      As DCM eventually leads to impaired contractility, standard approaches to
      prevent or treat heart failure are the first-line treatment for patients
      with DCM.
    explanation: >-
      Shared module evidence that the dilated cardiomyopathy process culminates
      in impaired contractility managed as heart failure.
  downstream:
  - target: Congestive heart failure
    causal_link_type: DIRECT
    description: >-
      Structural and functional cardiac impairment presents clinically as
      congestive heart failure.
    evidence:
    - reference: PMID:17646580
      reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "as a direct consequence of the mutant genes, which ultimately leads to heart failure"
      explanation: >-
        Names heart failure as the clinical endpoint reached by the proposed
        mechanism.
phenotypes:
- category: Cardiovascular
  name: Dilated cardiomyopathy
  description: >-
    Left ventricular dilation with systolic dysfunction — the phenotype for which
    every reported LAMA4 proband was ascertained, ranging from severe adult
    disease in the founding cohort to infantile presentation at 7 to 10 months of
    age in the digenic Saudi case.
  phenotype_term:
    preferred_term: Dilated cardiomyopathy
    term:
      id: HP:0001644
      label: Dilated cardiomyopathy
  evidence:
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which led us to screen for mutations in the human ILK and LAMA4 genes in patients with severe dilated cardiomyopathy"
    explanation: >-
      Establishes severe dilated cardiomyopathy as the phenotype of the cohort in
      which the founding LAMA4 variants were found.
  - reference: PMID:39686469
    reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical data, family histories, and blood samples were collected from the proband and family members in a Chinese family presenting with DCM and conduction system disease."
    explanation: >-
      Documents dilated cardiomyopathy in the one reported multi-generation LAMA4
      family.
- category: Cardiovascular
  name: Cardiac conduction abnormality
  description: >-
    Conduction system disease reported alongside dilated cardiomyopathy, and
    tracking with carrier status, in one Chinese family. It is not part of the
    founding description and has not been reported in the other LAMA4 cases, so
    it is curated as a feature of one family rather than of the entity.
  phenotype_term:
    preferred_term: Cardiac conduction abnormality
    term:
      id: HP:0031546
      label: Cardiac conduction abnormality
  evidence:
  - reference: PMID:39686469
    reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals without carrying this mutation in this family had no symptoms or cardiac structural abnormality related to DCM or conduction system disease."
    explanation: >-
      Documents conduction system disease segregating with the variant in this
      family. Marked PARTIAL because it rests on a single family.
- category: Cardiovascular
  name: Reduced left ventricular ejection fraction
  description: >-
    Impaired systolic function with reduced contractility, the functional half of
    the dilated phenotype and the measurement on which management decisions in
    dilated cardiomyopathy are actually made.
  phenotype_term:
    preferred_term: Reduced left ventricular ejection fraction
    term:
      id: HP:0012664
      label: Reduced left ventricular ejection fraction
  evidence:
  - reference: PMID:30650640
    reference_title: "Digenic Inheritance of LAMA4 and MYH7 Mutations in Patient with Infantile Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "left ventricular enlargement, reduced left ventricular contractility, and impaired systolic function"
    explanation: >-
      Names reduced left ventricular contractility and impaired systolic function
      as defining features of the dilated cardiomyopathy phenotype for which the
      reported LAMA4 patients were ascertained.
- category: Cardiovascular
  name: Congestive heart failure
  description: >-
    Symptomatic heart failure is the clinical endpoint attributed to the proposed
    mechanism, and severe disease characterised the ascertainment cohort.
  phenotype_term:
    preferred_term: Congestive heart failure
    term:
      id: HP:0001635
      label: Congestive heart failure
  evidence:
  - reference: PMID:17646580
    reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "as a direct consequence of the mutant genes, which ultimately leads to heart failure"
    explanation: >-
      Names heart failure as the clinical endpoint in affected patients.
diagnosis:
- name: Echocardiography
  description: >-
    First-line and usually diagnostic. Left ventricular internal dimensions and
    ejection fraction establish the dilated, hypocontractile phenotype, and the
    diagnosis of dilated cardiomyopathy is itself a clinical one that requires
    excluding loading conditions and coronary disease sufficient to explain the
    findings. Nothing about the imaging is LAMA4-specific.
  diagnosis_term:
    preferred_term: echocardiography
    term:
      id: NCIT:C16525
      label: Echocardiography Test
  evidence:
  - reference: PMID:31073128
    reference_title: "Dilated cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Echocardiography and other imaging techniques are required to assess
      ventricular dysfunction and adverse myocardial remodelling
    explanation: >-
      Establishes echocardiography as the required modality for assessing the
      ventricular dysfunction that defines DCM, of which CMD1JJ is a proposed
      genetic form.
  - reference: PMID:31073128
    reference_title: "Dilated cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Dilated cardiomyopathy (DCM) is a clinical diagnosis characterized by left
      ventricular or biventricular dilation and impaired contraction that is not
      explained by abnormal loading conditions (for example, hypertension and
      valvular heart disease) or coronary artery disease.
    explanation: >-
      States the exclusion criteria that define the diagnosis, which is what
      makes echocardiography necessary but not sufficient.
- name: Cardiac Magnetic Resonance Imaging
  description: >-
    Cardiac MRI adds what echocardiography cannot: tissue characterisation, and
    with it the risk stratification that actually drives management in
    nonischemic dilated cardiomyopathy. In a meta-analysis of 103 studies and
    29,687 patients, late gadolinium enhancement - both its presence and its
    extent - was associated with higher all-cause and cardiovascular mortality,
    arrhythmic events and heart failure events, while left ventricular ejection
    fraction was NOT associated with all-cause mortality or arrhythmic outcomes.
    That inversion is the point: the number echocardiography gives you is the
    weaker prognostic marker. None of this is LAMA4-specific, and no reported
    LAMA4 patient has published CMR.
  diagnosis_term:
    preferred_term: cardiac magnetic resonance imaging
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  evidence:
  - reference: PMID:39298146
    reference_title: "Risk Stratification in Nonischemic Dilated Cardiomyopathy Using CMR Imaging: A Systematic Review and Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Late gadolinium enhancement (LGE) presence and extent (per 1%) were associated with higher all-cause mortality"
    explanation: >-
      Establishes late gadolinium enhancement as a prognostic marker in
      nonischemic dilated cardiomyopathy, which is what CMR adds beyond
      echocardiography.
  - reference: PMID:39298146
    reference_title: "Risk Stratification in Nonischemic Dilated Cardiomyopathy Using CMR Imaging: A Systematic Review and Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 103 studies including 29 687 patients with NIDCM were analyzed."
    explanation: >-
      Gives the size of the evidence base behind the prognostic claim.
  - reference: PMID:39298146
    reference_title: "Risk Stratification in Nonischemic Dilated Cardiomyopathy Using CMR Imaging: A Systematic Review and Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Left ventricular ejection fraction (LVEF) (per 1%) was not associated with all-cause mortality"
    explanation: >-
      The negative result that makes the CMR entry worth curating separately from
      echocardiography: ejection fraction, the echo-derived measure, does not
      carry the mortality signal that LGE does.
- name: Molecular Genetic Testing (Multigene Cardiomyopathy Panel)
  description: >-
    Every reported LAMA4 proband was ascertained by sequencing, and in the
    published cases that was either a candidate screen or a broad cardiomyopathy
    panel or exome. THE RESULT MUST NOT BE OVER-READ. LAMA4 sits outside the core
    diagnostic gene set, its ClinGen classification is Limited, and reported
    LAMA4 variants have included ClinVar variants of uncertain significance and
    variants co-occurring with an established DCM mutation in another gene. A
    LAMA4 finding should not be used on its own to make or exclude a diagnosis,
    nor to direct predictive testing of relatives; the same expert panel that
    classified the gene recommends caution in interpreting variants in
    variable-evidence DCM genes.
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: PMID:39686469
    reference_title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A genetic analysis was performed using next generation sequencing (NGS)."
    explanation: >-
      Documents the sequencing route by which a LAMA4 variant reached a family
      with dilated cardiomyopathy.
  - reference: PMID:33947203
    reference_title: "Evidence-Based Assessment of Genes in Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Clinical genetic testing panels include most high-evidence genes; however, genes lacking robust evidence are also commonly included."
    explanation: >-
      Explains how a variant in a Limited-evidence gene such as LAMA4 reaches a
      family at all, which is the interpretive hazard this entry records.
  - reference: PMID:33947203
    reference_title: "Evidence-Based Assessment of Genes in Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes."
    explanation: >-
      The expert-panel recommendation that governs how a LAMA4 result should be
      used.
  - reference: PMID:20301486
    reference_title: Dilated Cardiomyopathy Overview.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Provide a basic view of genetic risk assessment of at-risk asymptomatic
      relatives of a proband with DCM to inform cardiac surveillance and allow
      early detection and treatment of DCM to improve long-term outcome
    explanation: >-
      The GeneReviews chapter's stated purpose for relatives of a DCM proband:
      cardiac surveillance driven by genetic risk assessment. This is why this
      entry's counseling entry directs surveillance of relatives by the clinical
      phenotype in the family rather than by LAMA4 carrier status - the
      surveillance recommendation is real, but a Limited-evidence gene cannot
      carry the risk assessment it depends on.
  - reference: PMID:20301486
    reference_title: Dilated Cardiomyopathy Overview.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Provide the evaluation strategy of a proband with nonsyndromic DCM
    explanation: >-
      The GeneReviews DCM overview supplies the proband evaluation strategy that
      a gene-specific entry such as this one sits inside. Evidence source is
      OTHER because GeneReviews is an expert-authored review resource; note that
      the cached PubMed record for this chapter contains only its stated purpose,
      so no clinical-characteristics text could be mined from it.
genetic:
- name: LAMA4 variants of limited and disputed clinical validity
  gene_term:
    preferred_term: LAMA4
    term:
      id: hgnc:6484
      label: LAMA4
  association: Limited
  relationship_type: DISPUTED
  notes: >-
    Curated as DISPUTED rather than CAUSATIVE. The ClinGen Dilated Cardiomyopathy
    Gene Curation Expert Panel classified the LAMA4-dilated cardiomyopathy
    relationship as LIMITED on 2024-11-15 under SOP10, and the panel's published
    curation of 51 DCM genes recommends that high-evidence genes be used in
    clinical practice with caution exercised for variable-evidence genes.
    Individually, the reported human evidence is thin in the specific ways that
    produce a Limited classification: the two founding alleles (p.Pro943Leu,
    p.Arg1073X) came from a candidate screen driven by a zebrafish result rather
    than from independent segregation; the later p.Gly218Arg allele is of
    uncertain significance in ClinVar and its pathogenicity claim rests on in
    silico prediction; and the infantile case carried a LAMA4 variant together
    with a known MYH7 DCM mutation, so the LAMA4 contribution cannot be isolated
    from it. Note that MONDO nonetheless models CMD1JJ as a gene-anchored
    disease concept, which is why this entry exists — the DISPUTED marker records
    the evidence state, it does not retire the concept.
  variants:
  - name: p.Pro943Leu
    description: >-
      Missense variant in the integrin-interacting domain; measured integrin
      affinity Kd 5 +/- 3 micromol/L versus 440 +/- 20 nmol/L for wild type.
  - name: p.Arg1073X
    description: >-
      Nonsense variant in the integrin-interacting domain; measured integrin
      affinity Kd 1 +/- 0.2 micromol/L versus 440 +/- 20 nmol/L for wild type.
  - name: p.Gly218Arg
    description: >-
      Missense variant in a laminin EGF-like domain, reported in a Chinese family
      with dilated cardiomyopathy and conduction system disease; classified as of
      uncertain significance in ClinVar, with the pathogenicity claim resting on
      bioinformatic prediction.
  - name: p.Asp1309Asn
    description: >-
      Missense variant reported in an infantile dilated cardiomyopathy case that
      also carried the known MYH7 DCM mutation p.Glu924Lys; the authors proposed a
      synergistic or dose effect of the two variants rather than a LAMA4-only
      cause.
  evidence:
  - reference: CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z
    reference_title: "LAMA4 / dilated cardiomyopathy (Limited)"
    supports: REFUTE
    evidence_source: OTHER
    snippet: "LAMA4 | HGNC:6484 | dilated cardiomyopathy | MONDO:0005021 | AD | Limited"
    explanation: >-
      ClinGen's Dilated Cardiomyopathy GCEP classifies the LAMA4-DCM
      gene-disease relationship as Limited. Recorded as REFUTE against the
      implicit claim that LAMA4 is an established cause of dilated cardiomyopathy.
  - reference: PMID:33947203
    reference_title: "Evidence-Based Assessment of Genes in Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes."
    explanation: >-
      The recommendation of the same expert panel, which is why this entry does
      not treat LAMA4 variants as diagnostic.
  - reference: PMID:30650640
    reference_title: "Digenic Inheritance of LAMA4 and MYH7 Mutations in Patient with Infantile Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In Family A, there was digenic inheritance of two heterozygous variants: a novel variant in LAMA4 (c.3925G > A, p.Asp1309Asn) and a known DCM mutation in MYH7 (c.2770G > A; p.Glu924Lys)."
    explanation: >-
      Shows a reported LAMA4 variant co-occurring with an established MYH7 DCM
      mutation, so it cannot be scored as independent evidence for LAMA4.
  - reference: PMID:39337275
    reference_title: "Unveiling the Spectrum of Minor Genes in Cardiomyopathies: A Narrative Review."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Nowadays, a set of core genes is included in diagnostic panels for ACM, DCM, and HCM. On the other hand, despite their lesser-known status, variants in the minor genes may contribute to disease mechanisms and influence prognosis."
    explanation: >-
      LAMA4 is surveyed in this review as one of the cardiomyopathy MINOR genes,
      i.e. outside the diagnostic core set. That placement is the independent
      literature counterpart of the ClinGen Limited classification, and it is
      why this entry curates the relationship rather than asserting it.
animal_models:
- name: Lama4-null mouse
  species: Mus musculus
  genotype: Lama4-/-
  publication: PMID:16204254
  description: >-
    Constitutive laminin alpha-4 chain knockout mouse, the principal in vivo
    evidence for the microvascular mechanism. It is a null, not a knock-in of a
    human integrin-domain allele, so it models absence of the chain rather than
    the specific loss of integrin binding proposed for the human variants.
  modeled_mechanisms:
  - target: Cardiac Microvascular Structural Defect
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Ultrastructural demonstration that loss of the chain produces malformed
      cardiac vessels with widened pericapillary matrix.
    limitations: >-
      A constitutive null models complete absence of the chain rather than the
      missense loss of integrin binding proposed for the human disease alleles,
      and the mouse cardiac phenotype was described as gradually developing
      hypertrophy with impaired function rather than as ventricular dilation.
      Lama4-null mice also develop chronic kidney disease, so the null is not
      cardiac-restricted.
    readouts:
    - name: Cardiac vessel ultrastructure and pericapillary matrix width
      target: Cardiac Microvascular Structural Defect
      direction: ALTERED
      interpretation: >-
        Malformed vessels and widened pericapillary matrix are the structural
        readout of the microvascular defect.
      evidence:
      - reference: PMID:16204254
        reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Electron microscopy confirmed malformed blood vessels and wide pericapillary ECM spaces, suggesting the presence of microcirculation abnormalities in Lama4-/- mutant hearts."
        explanation: >-
          Reports the electron-microscopic measurement behind this readout.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Our study links the genetic deficiency of an ECM protein to cardiomyopathy and implies a novel pathway of idiopathic cardiomyopathy in human."
      explanation: >-
        The authors' own statement of what the model establishes, which is what
        makes it informative for this node.
  - target: Myocardial Ischemia from Microcirculatory Insufficiency
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      A hypoxic transcriptional signature with degeneration and fibrosis supports
      sustained cardiac ischemia as the consequence of the vascular defect.
    limitations: >-
      Ischemia was inferred from Hif1a/Vegfa transcript elevation and histology
      rather than measured directly as myocardial perfusion or oxygen tension,
      and the authors' own wording is "suggested". No comparable measurement
      exists in a human LAMA4 carrier.
    readouts:
    - name: Hif1a and Vegfa transcript levels
      target: Myocardial Ischemia from Microcirculatory Insufficiency
      direction: INCREASED
      interpretation: >-
        Elevated hypoxia-response transcripts are the surrogate readout for
        sustained myocardial ischemia in this model.
      evidence:
      - reference: PMID:16204254
        reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "elevated levels of hypoxia-inducible factor 1alpha (Hif1alpha) and vascular endothelial growth factor A (Vegfa) transcripts"
        explanation: >-
          Reports the direction of the hypoxia-marker measurement.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "insufficient oxygen supply to the heart and the subsequent ischemic cardiac phenotype observed"
      explanation: >-
        The authors' causal conclusion, which is the claim this link asserts the
        model supports.
  - target: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      The model recapitulates this node's positive content - absence of the chain
      degrades the cardiac basement membrane - and what it adds is a pair of
      informative NEGATIVE readouts that BOUND the mechanism: the lesion does not
      destabilise the sarcolemmal adhesion complexes, and it does not by itself
      stop an isolated cardiomyocyte contracting. Those negatives are why this
      entry routes the disease through the microvasculature rather than through a
      contractile or dystrophin-glycoprotein defect. The mechanism they exclude,
      sarcolemmal destabilisation, is deliberately not curated as a node here, so
      the negatives are carried as readouts on this link rather than as a
      separate failure claim.
    limitations: >-
      This is a null allele rather than an integrin-binding-deficient missense
      knock-in, so the negative result bounds what absence of the chain does; it
      cannot exclude a dominant-negative or altered-signalling effect specific to
      the human integrin-domain alleles, which has never been tested in vivo.
    readouts:
    - name: Dystrophin-glycoprotein and integrin beta-1D complex levels
      target: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
      direction: UNCHANGED
      interpretation: >-
        Sarcolemmal adhesion complexes are unaltered, excluding the
        muscular-dystrophy route to cardiomyopathy in this model.
      evidence:
      - reference: PMID:16204254
        reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "No alteration in integrin beta 1D protein was observed in terms of expression level or distribution pattern"
        explanation: >-
          Reports the negative measurement on the sarcolemmal integrin complex.
    - name: Isolated cardiomyocyte contractility
      target: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
      direction: UNCHANGED
      interpretation: >-
        Mutant cardiomyocytes contract normally in isolation, which is why this
        entry does not model a primary contractile-protein defect.
      evidence:
      - reference: PMID:16204254
        reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "cardiomyocytes isolated from Lama4-/- mutant hearts maintained their contractility in vitro"
        explanation: >-
          Reports the preserved-contractility measurement.
    evidence:
    - reference: PMID:16204254
      reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "indicating that the postnatal development of cardiac hypertrophy and cardiomyopathy in these mice is unlikely associated with the stability of sarcolemmal DGC and integrin complexes"
      explanation: >-
        The authors explicitly rule out the sarcolemmal-complex route, which is
        the negative claim this link records.
- name: Zebrafish lost-contact (loc) ilk mutant
  species: Danio rerio
  genotype: ilk nonsense mutation (lost-contact, loc)
  publication: PMID:17646580
  description: >-
    The forward-genetic screen mutant that started the whole line of work. It is
    an ilk mutant, not a lama4 mutant, and is included because the epistatic
    relationship it defined between Lama4, integrin and Ilk is the sole reason
    LAMA4 was screened in human patients at all.
  modeled_mechanisms:
  - target: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Establishes genetically that the laminin-alpha-4 / integrin / ILK axis is
      required for myocardial function and that its disruption damages
      cardiomyocytes and endothelial cells together.
    limitations: >-
      The mutated gene is ilk, not lama4, so the model demonstrates the pathway's
      requirement rather than the consequence of a laminin lesion; and it is a
      zebrafish embryonic heart, which differs in chamber anatomy, conduction and
      haemodynamic load from the adult human ventricle in which the disease
      presents.
    readouts:
    - name: Myocardial function and cardiomyocyte/endothelial integrity
      target: Loss of Laminin-Integrin Binding at the Cardiac Basement Membrane
      direction: DECREASED
      interpretation: >-
        Severe myocardial dysfunction with combined cardiomyocyte and endothelial
        defects is the phenotypic readout of disrupting the axis.
      evidence:
      - reference: PMID:17646580
        reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "This loc/ilk mutant is associated with a severe defect in cardiomyocytes and endothelial cells that leads to severe myocardial dysfunction."
        explanation: >-
          Reports the cardiac phenotype of the mutant.
    evidence:
    - reference: PMID:17646580
      reference_title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "We used a forward genetic screen in zebrafish to identify novel genes required for myocardial function and were able to identify the lost-contact (loc) mutant, which encodes a nonsense mutation in the integrin-linked kinase (ilk) gene."
      explanation: >-
        Establishes the model's origin and what it was selected for, which is
        what makes it informative for the pathway node.
treatments:
- name: Guideline-Directed Heart Failure Pharmacotherapy
  description: >-
    Standard therapy for left ventricular systolic dysfunction, targeting the
    neurohormonal amplifier of adverse remodeling. There is no LAMA4-specific
    disease-modifying therapy and no trial has enrolled on the basis of LAMA4
    genotype, so management is the generic dilated-cardiomyopathy regimen.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: ACE inhibitor
      term:
        id: NCIT:C247
        label: ACE Inhibitor
    - preferred_term: beta-blocker
      term:
        id: NCIT:C29576
        label: Beta-Adrenergic Antagonist
    - preferred_term: mineralocorticoid receptor antagonist (spironolactone as the class exemplar)
      term:
        id: NCIT:C840
        label: Spironolactone
    - preferred_term: angiotensin receptor-neprilysin inhibitor (sacubitril/valsartan)
      term:
        id: NCIT:C190796
        label: Angiotensin Receptor-Neprilysin Inhibitor
    - preferred_term: SGLT2 inhibitor
      term:
        id: NCIT:C98083
        label: SGLT2 Inhibitor
  target_mechanisms:
  - target: Neurohormonal Activation
    treatment_effect: INHIBITS
    description: >-
      Neurohormonal blockade interrupts the maladaptive amplifier between
      myocardial injury and adverse ventricular remodeling. This is a class-level
      mechanism, unmodified by LAMA4 genotype.
    evidence:
    - reference: PMID:31073128
      reference_title: "Dilated cardiomyopathy."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        As DCM eventually leads to impaired contractility, standard approaches to
        prevent or treat heart failure are the first-line treatment for patients
        with DCM.
      explanation: >-
        Establishes standard heart-failure therapy as first-line management for
        dilated cardiomyopathy.
  evidence:
  - reference: PMID:31073128
    reference_title: "Dilated cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      As DCM eventually leads to impaired contractility, standard approaches to
      prevent or treat heart failure are the first-line treatment for patients
      with DCM.
    explanation: >-
      Establishes the treatment framework applied to this entity.
  - reference: PMID:42475150
    reference_title: "Heart Failure With Reduced Ejection Fraction Update: A Review Of Clinical Trials and New Therapeutic Considerations."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "beta-blockers, and mineralocorticoid receptor antagonists, which improve survival and reduce hospitalizations"
    explanation: >-
      Names the neurohormonal-blockade components of contemporary HFrEF therapy
      and their outcome benefit. Evidence source is OTHER because this is a
      narrative review of trials rather than a trial report, and none of the
      trials enrolled on LAMA4 genotype.
  - reference: PMID:42475150
    reference_title: "Heart Failure With Reduced Ejection Fraction Update: A Review Of Clinical Trials and New Therapeutic Considerations."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The use of sodium-glucose cotransporter-2 (SGLT2) inhibitors and intravenous iron therapy has also become integral to treatment, showing benefits in reducing mortality and improving symptoms."
    explanation: >-
      Supports inclusion of an SGLT2 inhibitor among the contemporary HFrEF
      agents listed on this treatment.
- name: Cardiac Resynchronization Therapy
  description: >-
    Biventricular pacing for patients with systolic dysfunction and conduction
    delay. It is included here specifically because conduction system disease was
    reported alongside dilated cardiomyopathy in the one published LAMA4 family,
    which is the setting in which resynchronization becomes relevant — but the
    indication follows general heart-failure criteria, not genotype, and no
    LAMA4 patient has been reported to have received it.
  action_category: THERAPEUTIC
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: cardiac resynchronization therapy
    term:
      id: NCIT:C80436
      label: Cardiac Resynchronization Therapy
  target_mechanisms:
  - target: Left Ventricular Dilation and Systolic Dysfunction
    treatment_effect: MODULATES
    description: >-
      Resynchronizing ventricular contraction improves mechanical efficiency in a
      dilated, dyssynchronous ventricle. It does not act on the laminin lesion.
    evidence:
    - reference: PMID:31073128
      reference_title: "Dilated cardiomyopathy."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Cardiac resynchronization therapy and implantable cardioverter-defibrillators
        may be required to prevent life-threatening arrhythmias.
      explanation: >-
        Establishes resynchronization therapy as part of standard DCM management.
        Marked PARTIAL because the quoted sentence frames both devices in terms
        of arrhythmia prevention, whereas resynchronization's action on this node
        is mechanical.
  evidence:
  - reference: PMID:42475150
    reference_title: "Heart Failure With Reduced Ejection Fraction Update: A Review Of Clinical Trials and New Therapeutic Considerations."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Device therapies, such as implantable cardioverter-defibrillators (ICDs), cardiac resynchronization therapy (CRT), and left ventricular assist devices (LVADs), are critical for advanced cases."
    explanation: >-
      Names resynchronization therapy among the device therapies used in advanced
      heart failure with reduced ejection fraction.
- name: Advanced Heart Failure Therapy (mechanical circulatory support and transplantation)
  description: >-
    For disease refractory to medical and device therapy the remaining options
    are a left ventricular assist device and heart transplantation. This is
    curated as the endpoint of the generic dilated-cardiomyopathy pathway: no
    LAMA4 patient has been reported to have received either, and nothing about
    the proposed laminin mechanism predicts a different response, so no
    genotype-specific claim is made.
  action_category: THERAPEUTIC
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: heart transplantation
    term:
      id: NCIT:C15246
      label: Heart Transplantation
  notes: >-
    Mechanical circulatory support is named in the cited evidence alongside
    transplantation and is covered by this entry's description; `treatment_term`
    binds to transplantation because NCIT's device terms and the surgical
    modality cannot both be carried on one record.
  evidence:
  - reference: PMID:42475150
    reference_title: "Heart Failure With Reduced Ejection Fraction Update: A Review Of Clinical Trials and New Therapeutic Considerations."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "left ventricular assist devices (LVADs), are critical for advanced cases"
    explanation: >-
      Establishes mechanical circulatory support as part of the management of
      advanced heart failure with reduced ejection fraction, which is the setting
      this treatment records.
- name: Implantable Cardioverter Defibrillator
  description: >-
    Device therapy for prevention of sudden cardiac death, indicated by general
    cardiomyopathy and arrhythmia guidelines. It is noted here because conduction
    system disease was reported alongside dilated cardiomyopathy in one LAMA4
    family; no LAMA4-specific risk-stratification rule exists.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: implantable cardioverter-defibrillator placement
    term:
      id: NCIT:C80435
      label: Implantable Cardioverter-Defibrillator Placement
  evidence:
  - reference: PMID:31073128
    reference_title: "Dilated cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Cardiac resynchronization therapy and implantable cardioverter-defibrillators
      may be required to prevent life-threatening arrhythmias.
    explanation: >-
      Establishes device therapy as part of standard dilated-cardiomyopathy
      management.
- name: Genetic Counseling with Explicit Discussion of Limited Gene-Disease Validity
  description: >-
    Counseling for families in whom a LAMA4 variant is reported must convey that
    the gene-disease relationship is classified as Limited and that variants in
    such genes should not be used to make or exclude a clinical diagnosis or to
    direct predictive testing of relatives. Cardiac surveillance of first-degree
    relatives is driven by the clinical phenotype in the family, not by LAMA4
    carrier status.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:33947203
    reference_title: "Evidence-Based Assessment of Genes in Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes."
    explanation: >-
      The expert-panel recommendation that this counseling point implements.
  - reference: PMID:33947203
    reference_title: "Evidence-Based Assessment of Genes in Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Clinical genetic testing panels include most high-evidence genes; however, genes lacking robust evidence are also commonly included."
    explanation: >-
      Explains why a LAMA4 result reaches families at all despite the Limited
      classification, which is the situation this counseling addresses.
discussions:
- discussion_id: lama4_dcm_gene_disease_validity
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is LAMA4 a cause of human dilated cardiomyopathy at all, and if so by what
    genetic mechanism?
  attaches_to:
  - "pathophysiology#LAMA4 Integrin-Interacting-Domain Variant"
  rationale: >-
    ClinGen's Dilated Cardiomyopathy GCEP classifies the LAMA4-DCM relationship
    as Limited. Every strand of the human evidence has a specific weakness: the
    founding alleles came from a candidate screen prompted by a zebrafish result
    rather than from independent segregation analysis; the later p.Gly218Arg
    allele is a ClinVar variant of uncertain significance supported by in silico
    prediction; and the infantile case carried a known MYH7 DCM mutation
    alongside the LAMA4 variant. The mechanistic work is correspondingly
    lopsided — the mouse and zebrafish data are strong for the pathway and the
    binding data are quantitative, but neither addresses whether heterozygous
    human LAMA4 missense alleles are sufficient to cause disease. Until this is
    resolved no clinical inference should be drawn from a LAMA4 variant, and
    this entry curates the mechanism as proposed rather than established.
  proposed_experiments:
  - experiment_id: exp_cmd1jj_case_control_burden
    name: Case-control rare-variant burden test for LAMA4 in dilated cardiomyopathy
    description: >-
      Test whether rare LAMA4 variants, and specifically integrin-domain missense
      variants, are enriched in large sequenced dilated-cardiomyopathy cohorts
      relative to ancestry-matched population controls — the analysis that would
      move the ClinGen classification in either direction, and the one that has
      not been reported.
  - experiment_id: exp_cmd1jj_integrin_domain_knockin_mouse
    name: Knock-in mouse carrying a human LAMA4 integrin-domain allele
    description: >-
      Generate a heterozygous knock-in of p.Pro943Leu or the murine equivalent
      and test whether it produces cardiac disease, which would distinguish a
      dominant effect of the disease alleles from the complete-absence phenotype
      of the existing null.
  evidence:
  - reference: CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z
    reference_title: "LAMA4 / dilated cardiomyopathy (Limited)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "LAMA4 | HGNC:6484 | dilated cardiomyopathy | MONDO:0005021 | AD | Limited"
    explanation: >-
      The expert-panel classification that defines this gap.
  - reference: PMID:30650640
    reference_title: "Digenic Inheritance of LAMA4 and MYH7 Mutations in Patient with Infantile Dilated Cardiomyopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Inheritance of two genetic variants may have a synergistic or dose effect to cause severe DCM."
    explanation: >-
      The authors' own framing of the infantile case as digenic, which is why it
      cannot be counted as independent evidence for LAMA4.
- discussion_id: lama4_mouse_geometry_mismatch
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Does a constitutive Lama4-null mouse that develops cardiac HYPERTROPHY model
    a human disease defined by ventricular DILATION, and does absence of the
    chain model a missense loss of integrin binding?
  attaches_to:
  - "pathophysiology#Adverse Ventricular Remodeling"
  rationale: >-
    The mouse evidence carries almost all the mechanistic weight in this entry,
    and it differs from the human disease in two ways that are easy to elide.
    First, geometry: the null mouse was described as gradually developing cardiac
    hypertrophy with impaired function, whereas the human entity is a dilated
    cardiomyopathy. Second, allele class: a constitutive null models complete
    absence of laminin alpha-4, while the human integrin-domain alleles are
    heterozygous missense and nonsense changes whose proposed effect is loss of a
    specific protein-protein interaction. A model of absence cannot by itself
    establish that the human alleles act the way the entry proposes, and the
    Lama4-null mouse additionally develops chronic kidney disease, so it is not a
    cardiac-restricted model.
  proposed_experiments:
  - experiment_id: exp_cmd1jj_serial_imaging_knockin
    name: Serial cardiac imaging of an integrin-domain knock-in versus the null
    description: >-
      Compare chamber geometry, ejection fraction and myocardial perfusion over
      time between a heterozygous integrin-domain knock-in, the Lama4 null, and
      wild type, to establish whether the human allele class produces a dilated
      rather than hypertrophic phenotype and whether the microvascular lesion
      precedes the myocardial one.
  evidence:
  - reference: PMID:16204254
    reference_title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "we demonstrate that laminin alpha4 deficient mice gradually develop cardiac hypertrophy with impaired function"
    explanation: >-
      States the mouse geometry that differs from the human dilated phenotype.
  - reference: PMID:20035058
    reference_title: "Laminin alpha4-null mutant mice develop chronic kidney disease with persistent overexpression of platelet-derived growth factor."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Lama4-/- mice have progressive glomerular and tubulointerstitial fibrosis"
    explanation: >-
      Documents a progressive renal phenotype in the same null, supporting the
      point that it is not a cardiac-restricted model.
notes: >-
  Scope and epistemic stance: MONDO models CMD1JJ as a gene-anchored member of the
  familial isolated dilated cardiomyopathy series, and this entry follows that
  concept. It does NOT follow it into asserting that LAMA4 is an established cause
  of human dilated cardiomyopathy — ClinGen's Dilated Cardiomyopathy GCEP
  classifies that relationship as Limited, and the entry carries the dispute in
  the description, the genetic block (`relationship_type: DISPUTED`, with a
  REFUTE-typed ClinGen evidence item), a dedicated KNOWLEDGE_GAP discussion, and
  the treatment block.


  The pathograph is deliberately routed through a microvascular and
  cell-matrix-adhesion arm rather than through a primary contractile-protein
  lesion, because that is what the evidence says: the Lama4-null mouse's
  cardiomyocytes contract normally in isolation and its sarcolemmal
  dystrophin-glycoprotein and integrin complexes are intact, while its vessels
  are malformed and its myocardium hypoxic. That negative result is curated
  structurally, as a pair of `UNCHANGED` readouts on the Lama4-null model link,
  rather than left as prose.


  No `datasets:` block is curated: no LAMA4-cardiomyopathy-specific omics
  accession was identified, and searching the gene alone would surface datasets
  about whatever else LAMA4 is studied for, which is the Named Entity Confusion
  hazard the dataset SOP warns about.


  No ORPHA evidence asserted. `just refresh-orphadata` is currently failing on a
  manifest checksum mismatch and no cached ORPHA record for this concept was
  available.
references:
- reference: PMID:17646580
  title: "Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells."
  findings: []
- reference: PMID:16204254
  title: "Cardiomyopathy associated with microcirculation dysfunction in laminin alpha4 chain-deficient mice."
  findings: []
- reference: PMID:39686469
  title: "A potential pathogenic mutation of LAMA4 in a Chinese family with dilated cardiomyopathy and conduction system disease."
  findings: []
- reference: PMID:30650640
  title: "Digenic Inheritance of LAMA4 and MYH7 Mutations in Patient with Infantile Dilated Cardiomyopathy."
  findings: []
- reference: PMID:33947203
  title: "Evidence-Based Assessment of Genes in Dilated Cardiomyopathy."
  findings: []
- reference: PMID:20035058
  title: "Laminin alpha4-null mutant mice develop chronic kidney disease with persistent overexpression of platelet-derived growth factor."
  findings: []
- reference: PMID:31073128
  title: "Dilated cardiomyopathy."
  findings: []
- reference: PMID:22752727
  title: "The role of TWEAK/Fn14 in cardiac remodeling."
  findings: []
- reference: PMID:25445411
  title: "Biomarkers of activation of renin-angiotensin-aldosterone system in heart failure: how useful, how feasible?"
  findings: []
- reference: PMID:42475150
  title: "Heart Failure With Reduced Ejection Fraction Update: A Review Of Clinical Trials and New Therapeutic Considerations."
  findings: []
- reference: PMID:39298146
  title: "Risk Stratification in Nonischemic Dilated Cardiomyopathy Using CMR Imaging: A Systematic Review and Meta-Analysis."
  findings: []
- reference: PMID:20301486
  title: Dilated Cardiomyopathy Overview.
  tags:
  - GeneReviews
  findings: []
- reference: PMID:39337275
  title: "Unveiling the Spectrum of Minor Genes in Cardiomyopathies: A Narrative Review."
  findings: []
- reference: CGGV:assertion_e937f98e-7577-48bd-a24a-361634ba0a8d-2024-11-15T170000.000Z
  title: "LAMA4 / dilated cardiomyopathy (Limited)"
  findings: []

📚

References & Deep Research

References

14

PMID:17646580

Laminin-alpha4 and integrin-linked kinase mutations cause human cardiomyopathy via simultaneous defects in cardiomyocytes and endothelial cells.