Jervell and Lange-Nielsen Syndrome 2

Mendelian MONDO:0012871 Pathograph 13 Show in embeddings browser Jervell and Lange-Nielsen Syndrome Cardiac Arrhythmia Channelopathy Sensorineural Hearing Loss

Jervell and Lange-Nielsen syndrome 2 (JLNS2) is an ultra-rare autosomal recessive cardioauditory channelopathy caused by biallelic loss-of-function variants in KCNE1, which encodes MinK, the single-transmembrane-domain beta subunit that assembles with the KCNQ1 alpha subunit to form the slow delayed-rectifier potassium (IKs) channel. JLNS2 is the allelic recessive counterpart of KCNE1-related autosomal dominant long QT syndrome (LQT5): a single heterozygous KCNE1 variant produces, at best, a low-penetrance dominant QT-prolongation phenotype, while biallelic loss essentially abolishes IKs current and produces the severe recessive JLNS phenotype. The IKs channel is expressed in both cardiac myocytes, where it contributes to repolarization of the ventricular action potential, and in the marginal cells of the stria vascularis of the inner ear, where it drives potassium secretion into the endolymph that generates and maintains the endocochlear potential required for hair-cell mechanotransduction. Biallelic KCNE1 loss therefore produces a two-organ phenotype: congenital profound bilateral sensorineural deafness from collapse of the endocochlear potential, together with marked QT-interval prolongation and a risk of torsade de pointes, ventricular fibrillation, syncope, and sudden cardiac death from loss of ventricular repolarization reserve. JLNS2 is distinguished from the more common JLNS1 (biallelic KCNQ1 variants) only by the causal gene, and the two are clinically similar at the bedside, but JLNS2 is markedly rarer - approximately 90% of JLNS cases are attributable to KCNQ1 and only about 10% to KCNE1 - and the limited comparative data available suggest a milder arrhythmic course than JLNS1. This entry is careful not to import JLNS1 (KCNQ1) case series, severity estimates, or vestibular-dysfunction findings, which are curated separately.

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Mappings
1
Inheritance
7
Pathophys.
8
Phenotypes
1
Hypotheses
1
Gaps
13
Pathograph
1
Genes
7
Medical Actions
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Trials
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Models
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References
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Deep Research
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Mappings

MONDO
MONDO:0012871 Jervell and Lange-Nielsen syndrome 2
skos:exactMatch MONDO
MONDO:0012871 is the primary disease term for this entry, cross-referenced to OMIM:612347, with KCNE1 (HGNC:6240) asserted as the causal gene via RO:0004003.
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Inheritance

1
Autosomal Recessive HP:0000007
JLNS2 is inherited in an autosomal recessive manner. Affected individuals are homozygous or compound heterozygous for KCNE1 loss-of-function variants; parents are typically heterozygous carriers who are usually clinically unaffected or show only mild, incompletely penetrant QT prolongation (the allelic dominant LQT5 phenotype). At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic or mildly affected carrier, and a 25% chance of being unaffected and non-carrier.
Autosomal recessive inheritance
Show evidence (3 references)
PMID:20301579 SUPPORT Other
"JLNS is inherited in an autosomal recessive manner. Parents of a child with JLNS are usually heterozygotes; rarely, only one parent is heterozygous"
GeneReviews establishes the autosomal recessive inheritance pattern and typical carrier status of parents.
PMID:30461122 SUPPORT Human Clinical
"heterozygotes for loss-of-function variants of KCNE1 may have normal QT intervals while biallelic null alleles are associated with JLNS2"
Documents that biallelic KCNE1 loss of function, not heterozygosity, is required for the fully penetrant JLNS2 phenotype.
PMID:20301579 SUPPORT Other
"At conception, each sib of an affected individual usually has a 25% chance of being affected with JLNS, a 50% chance of being a carrier of a JLNS-causing pathogenic variant and potentially at risk for LQTS, and a 25% chance of being unaffected and not a carrier."
GeneReviews states the exact per-pregnancy recurrence-risk figures (25% affected, 50% carrier, 25% unaffected non-carrier) summarized in this node's description.

Mechanistic Hypotheses

1
Variant-specific dominant-negative versus simple loss-of-function/haploinsufficiency KCNE1 mechanism
variant_specific_dominant_negative_vs_haploinsufficiency EMERGING
Evidence balance 2 support
KCNE1 loss-of-function variants appear to split mechanistically by variant. A large 2025 functional screen found no apparent dominant-negative effect on wild-type IKs current among the KCNE1 variants it tested when coexpressed with wild-type KCNE1, consistent with a simple recessive loss-of-function/haploinsufficiency mechanism requiring biallelic loss for JLNS2. However, an independent study of KCNE1 nonsense and missense alleles reports that coassembly of certain other mutant KCNE1 monomers with wild-type KCNQ1 subunits produces dominant Romano-Ward syndrome via a dominant-negative mechanism. Whether these are truly non-overlapping variant classes, or whether the discrepancy partly reflects differences in the specific variants and assay conditions tested, is not yet resolved.
Show evidence (2 references)
PMID:41200805 SUPPORT In Vitro
"We observed no apparent dominant-negative effects when variant and wild-type KCNE1 were coexpressed."
Direct functional data supporting a simple loss-of-function/ haploinsufficiency mechanism for the specific KCNE1 variant panel tested.
PMID:30461122 SUPPORT Human Clinical
"Coassembly of certain mutant KCNE1 monomers with wild-type KCNQ1 subunits results in RWS by a dominant negative mechanism."
Independent evidence that at least some KCNE1 missense variants act dominantly through a dominant-negative mechanism, the counterpoint this hypothesis has to reconcile with the functional screen's negative finding.
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Discussions and Knowledge Gaps

1
Do genotype-confirmed human JLNS2 (biallelic KCNE1) patients have clinically significant vestibular dysfunction, as Kcne1-/- mice do?
HUMAN MODEL MISMATCH OPEN jlns2_vestibular_human_model_mismatch
Kcne1-/- mice show clear structural and functional vestibular involvement: KCNQ1/KCNE1 channels are expressed in vestibular dark cells as well as strial marginal cells, and untreated Kcne1-/- mice show abnormal endolymphatic-space development, vestibular hair cell degeneration, and impaired vestibular behavior that gene therapy can rescue (PMID:33514733). However, the only quantitative human vestibular study of JLNS (PMID:25471708) genotyped its cohort and found all 14 tested cases carried double KCNQ1 (JLNS1) mutations, not KCNE1. Whether the mouse vestibular phenotype translates to genotype-confirmed human JLNS2 patients is therefore untested, and this entry deliberately does not curate vestibular dysfunction as an established JLNS2 phenotype.
Proposed experiments
Genotype-stratified human vestibular function study in JLNS2
exp_jlns2_genotype_stratified_vestibular_function
Vestibular function testing (post-rotatory nystagmus, video head impulse testing) in a cohort of genotype-confirmed KCNE1/JLNS2 patients, analogous to the KCNQ1-genotyped study already published for JLNS1 (PMID:25471708).
Show evidence (1 reference)
PMID:33514733 SUPPORT Model Organism
"Mutations in voltage-gated potassium channel KCNE1 cause Jervell and Lange-Nielsen syndrome type 2 (JLNS2), resulting in congenital deafness and vestibular dysfunction."
Source of the mouse-model vestibular-dysfunction claim that motivates this discussion.

Pathophysiology

7
Biallelic KCNE1 Loss of Function
Biallelic loss-of-function variants in KCNE1 abolish or severely reduce the regulatory (beta-subunit) contribution of MinK to the IKs channel complex. Because KCNE1 must coassemble with KCNQ1 to generate a normal IKs current, homozygous or compound heterozygous KCNE1 variants produce the same downstream functional deficit as biallelic KCNQ1 loss (JLNS1), even though the two genes encode structurally distinct subunits of the same channel. High-throughput voltage-clamp profiling shows that most disease-associated KCNE1 variants reduce IKs current density in the homozygous state without dominant-negative behavior on coexpressed wild-type subunits, consistent with a recessive disease mechanism.
KCNE1 hgnc:6240 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves KCNE1 (hgnc:6240). hgnc:6240 is a gene from the HUGO Gene Nomenclature Committee.
potassium ion transmembrane transport GO:0071805 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased potassium ion transmembrane transport (GO:0071805). GO:0071805 is a biological process from the Gene Ontology. ↓ DECREASED
ion channel regulator activity GO:0099106 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased ion channel regulator activity (GO:0099106). GO:0099106 is a molecular function from the Gene Ontology. ↓ DECREASED
Show evidence (2 references)
PMID:42389506 SUPPORT Other
"KCNE1 specifically encodes the beta subunit (mink) of IKs"
Establishes KCNE1/MinK as the regulatory beta subunit whose biallelic loss is the molecular trigger of JLNS2.
PMID:41200805 SUPPORT In Vitro
"Approximately half (47 of 95) of the KCNE1 variants tested in the homozygous state exhibited peak current densities significantly different from WT IKs."
Direct high-throughput functional data quantifying the frequency and magnitude of IKs current disruption caused by KCNE1 variants in the homozygous state.
Loss of IKs Current in Cardiac Myocytes
Reduced IKs current diminishes repolarization reserve and delays completion of the ventricular action potential, prolonging the QT interval measured on the surface ECG.
cardiomyocyte CL:0000746 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves cardiomyocyte, annotated with cardiac muscle cell (CL:0000746). CL:0000746 is a cell type from the Cell Ontology.
potassium ion transmembrane transport GO:0071805 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased potassium ion transmembrane transport (GO:0071805). GO:0071805 is a biological process from the Gene Ontology. ↓ DECREASED membrane repolarization during cardiac muscle cell action potential GO:0086013 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves dysregulated membrane repolarization during cardiac muscle cell action potential (GO:0086013). GO:0086013 is a biological process from the Gene Ontology. ↕ DYSREGULATED
monoatomic ion channel activity GO:0005216 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves abnormal monoatomic ion channel activity (GO:0005216). GO:0005216 is a molecular function from the Gene Ontology. ⚠ ABNORMAL
heart UBERON:0000948 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in heart (UBERON:0000948). UBERON:0000948 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
GeneReviews documents the marked QTc prolongation that results from reduced ventricular repolarization reserve in JLNS.
Arrhythmogenic Substrate and Ventricular Tachyarrhythmia
Prolonged, heterogeneous ventricular repolarization predisposes to early afterdepolarizations and re-entrant torsade de pointes, which can degenerate into sustained ventricular tachycardia or ventricular fibrillation. Available comparative data suggest that this arrhythmic risk is present but lower in genotype-confirmed JLNS2 (biallelic KCNE1) than in JLNS1 (biallelic KCNQ1).
heart UBERON:0000948 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in heart (UBERON:0000948). UBERON:0000948 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (2 references)
PMID:42389506 SUPPORT Human Clinical
"Children carrying KCNQ1 variants exhibit an approximately sixfold higher risk of ventricular arrhythmia than those with KCNE1 variants."
Directly quantifies the reduced (but nonzero) ventricular arrhythmia risk specific to KCNE1 (JLNS2) relative to KCNQ1 (JLNS1) genotypes, supporting the entry's emphasis on JLNS2-specific severity data rather than JLNS1 figures.
PMID:31941373 SUPPORT Human Clinical
"Event incidence did not differ significantly for Type 2 Jervell and Lange-Nielsen syndrome patients relative to the overall heterozygous cohort (10.5%"
Directly quantifies the definite arrhythmic event rate (10.5%, 2 of 19 genotype-confirmed patients) in the largest reported JLNS2 cohort, providing a JLNS2-specific severity estimate rather than an imported JLNS1 figure.
Syncope and Sudden Cardiac Death
The clinical endpoint of the cardiac branch of JLNS2: exertion-, emotion-, or auditory-stimulus-triggered syncope, and a risk of sudden cardiac death from malignant ventricular arrhythmia, most pronounced in early childhood.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright. Fifty percent of individuals with JLNS had cardiac events before age three years."
GeneReviews describes the classic clinical presentation and early childhood timing of cardiac events in JLNS overall.
Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells
KCNQ1/KCNE1 IKs channels on the apical membrane of stria vascularis marginal cells drive the transepithelial potassium flux that generates and maintains the endocochlear potential, the unusually positive extracellular potential in the endolymph that provides the electrochemical driving force for hair-cell mechanotransduction. Loss of KCNE1 function collapses this potassium-secretory current, disrupting cochlear ionic homeostasis.
strial marginal cell CL:0002492 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves strial marginal cell (CL:0002492). CL:0002492 is a cell type from the Cell Ontology.
potassium ion transmembrane transport GO:0071805 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased potassium ion transmembrane transport (GO:0071805). GO:0071805 is a biological process from the Gene Ontology. ↓ DECREASED
stria vascularis of cochlear duct UBERON:0002282 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in stria vascularis of cochlear duct (UBERON:0002282). UBERON:0002282 is an anatomical location from the Uberon multi-species anatomy ontology. cochlea UBERON:0001844 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in cochlea (UBERON:0001844). UBERON:0001844 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (2 references)
PMID:33514733 SUPPORT Model Organism
"In the inner ear, KCNQ1/KCNE1 potassium channels are expressed exclusively in the apical membrane of marginal cells (MCs) in the stria vascularis (SV) and in vestibular dark cells"
Confirms the strial marginal cell localization of the KCNQ1/KCNE1 channel complex central to this node.
PMID:42389506 SUPPORT Other
"The K+ concentration is markedly increased in the endolymph, and the influx of K+ into hair cells upon stimulation plays a pivotal role in transducing sound into neural signals."
Establishes the mechanistic link between strial potassium secretion, the endolymph's high K+ concentration, and hair-cell mechanotransduction.
Endocochlear Potential Collapse and Hair Cell Degeneration
Without the endocochlear potential, hair-cell mechanotransduction fails and cochlear hair cells undergo degeneration. Because mammalian cochlear hair cells do not regenerate, this loss is irreversible.
cochlea UBERON:0001844 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in cochlea (UBERON:0001844). UBERON:0001844 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (1 reference)
PMID:33514733 SUPPORT Model Organism
"Results showed early treatment prevented collapse of the Reissner's membrane and vestibular wall, retained the normal size of the semicircular canals, and prevented the degeneration of inner ear cells."
Demonstrates, by rescue, that untreated Kcne1 loss causes structural collapse of the cochlear duct and degeneration of inner ear cells.
Congenital Profound Bilateral Sensorineural Hearing Loss
The clinical endpoint of the cochlear branch of JLNS2: congenital, profound, bilateral sensorineural hearing loss present from birth. Unlike several other conformers of this module (e.g., noise- or age-related hearing loss), the JLNS deficit is typically already maximal at birth rather than accruing progressively over time; conformance here reflects the shared irreversible, non-regenerating hair-cell-loss endpoint rather than a claim of ongoing postnatal worsening.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
GeneReviews defines the congenital, profound, bilateral character of the hearing loss.

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Jervell and Lange-Nielsen Syndrome 2 Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.

Phenotypes

8
Blood 1
Iron-Deficiency Anemia HP:0001891 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Iron deficiency anemia (HP:0001891). HP:0001891 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Iron-deficient anemia and elevated levels of gastrin are also frequent features of JLNS."
GeneReviews lists iron-deficient anemia among the frequent additional features of JLNS.
Cardiovascular 3
Prolonged QT Interval VERY_FREQUENT HP:0001657 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Prolonged QT interval (HP:0001657). HP:0001657 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
GeneReviews establishes marked QTc prolongation as a defining feature of JLNS.
Ventricular Arrhythmia Ventricular tachycardia HP:0004756 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ventricular tachycardia (HP:0004756). HP:0004756 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:31941373 SUPPORT Human Clinical
"Event incidence did not differ significantly for Type 2 Jervell and Lange-Nielsen syndrome patients relative to the overall heterozygous cohort (10.5%"
Direct quantitative arrhythmic event rate in the largest reported genotype-confirmed JLNS2 cohort.
PMID:42389506 SUPPORT Human Clinical
"Children carrying KCNQ1 variants exhibit an approximately sixfold higher risk of ventricular arrhythmia than those with KCNE1 variants."
Quantifies the reduced, but nonzero, ventricular arrhythmia risk associated specifically with KCNE1 (JLNS2) genotypes relative to KCNQ1 (JLNS1).
Syncope HP:0001279 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Syncope (HP:0001279). HP:0001279 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright."
GeneReviews describes the classic exertion/emotion-triggered syncopal presentation of JLNS.
Constitutional 1
Sudden Cardiac Death Risk Sudden death HP:0001699 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Sudden death (HP:0001699). HP:0001699 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"More than half of untreated children with JLNS die before age 15 years."
GeneReviews establishes the high untreated mortality of JLNS overall.
Other 3
Congenital Profound Bilateral Sensorineural Hearing Loss Congenital sensorineural hearing impairment HP:0008527 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Congenital sensorineural hearing impairment (HP:0008527). HP:0008527 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
GeneReviews establishes congenital profound bilateral sensorineural hearing loss as a defining feature of JLNS.
Torsade de Pointes HP:0001664 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Torsade de pointes (HP:0001664). HP:0001664 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Prolongation of the QTc interval is associated with tachyarrhythmias, including ventricular tachycardia, episodes of torsade de pointes ventricular tachycardia, and ventricular fibrillation, which may culminate in syncope or sudden death."
GeneReviews documents torsade de pointes as a characteristic tachyarrhythmia in JLNS.
Elevated Serum Gastrin Hypergastrinemia HP:0500167 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypergastrinemia (HP:0500167). HP:0500167 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Iron-deficient anemia and elevated levels of gastrin are also frequent features of JLNS."
GeneReviews lists elevated gastrin as a frequent additional feature of JLNS.
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Genetic Associations

1
KCNE1
Gene: KCNE1 hgnc:6240 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is KCNE1 (hgnc:6240). hgnc:6240 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (4 references)
PMID:20301579 SUPPORT Other
"The diagnosis of JLNS is established in a child with congenital sensorineural deafness, long QT interval, and presence of biallelic pathogenic variants in either KCNQ1 or KCNE1."
GeneReviews establishes KCNE1 as one of the two genes in which biallelic pathogenic variants cause JLNS.
PMID:41200805 SUPPORT In Vitro
"KCNE1 is a recognized cause of the autosomal recessive Jervell and Lange-Nielson syndrome type 2 (JLN2)."
Confirms KCNE1 as the accepted causal gene for the recessive JLNS2 phenotype curated in this entry.
PMID:41200805 SUPPORT In Vitro
"Most dysfunctional variants exhibited loss-of-function properties. We observed no apparent dominant-negative effects when variant and wild-type KCNE1 were coexpressed."
Direct functional electrophysiology showing loss-of-function as the predominant mechanism of disease-associated KCNE1 variants, without dominant-negative behavior, consistent with a recessive disease mechanism.
+ 1 more reference
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Medical Actions

7
Beta-Blocker Therapy
Action: beta-blocker therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is beta-blocker therapy, annotated with Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Agent: beta-adrenergic antagonist NCIT:C29576 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses beta-adrenergic antagonist (NCIT:C29576). NCIT:C29576 is a therapeutic agent from the NCI Thesaurus.
First-line anti-adrenergic pharmacotherapy for JLNS, though reported to be only partially effective; arrhythmia persists in a substantial proportion of patients despite beta-blocker treatment.
Mechanism Target:
INHIBITS Arrhythmogenic Substrate and Ventricular Tachyarrhythmia — Anti-adrenergic therapy reduces the likelihood that exertion- or emotion-related sympathetic triggers will precipitate malignant ventricular arrhythmia.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"beta-adrenergic blockers for long QT interval (Note: Beta-blocker treatment is only partially effective.)"
GeneReviews recommends beta-blockers as first-line therapy while explicitly noting only partial effectiveness in JLNS.
Show evidence (2 references)
PMID:42389506 SUPPORT Human Clinical
"The efficacy of beta‐blockers and left cardiac sympathetic denervation is limited in patients with JLNS, as arrhythmia persists in 51%–85% of cases despite beta‐blocker treatment"
Quantifies the limited efficacy of beta-blocker therapy in JLNS, motivating escalation to device therapy in many patients.
PMID:20301579 SUPPORT Other
"Beta-blocker dose should be regularly assessed for efficacy and adverse effects, with evaluation every three to six months during rapid growth phases"
GeneReviews surveillance guidance: beta-blocker dosing requires periodic reassessment, especially during rapid childhood growth phases, because weight-based dosing can fall out of therapeutic range.
Implantable Cardioverter-Defibrillator Placement
Action: implantable cardioverter-defibrillator placementNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is implantable cardioverter-defibrillator placement (NCIT:C80435). NCIT:C80435 is a clinical intervention from the NCI Thesaurus. Ontology label: Implantable Cardioverter-Defibrillator Placement NCIT:C80435
Device therapy for patients with a history of cardiac arrest, malignant events despite beta-blocker therapy, or otherwise judged high risk.
Show evidence (2 references)
PMID:20301579 SUPPORT Other
"implantable cardioverter defibrillators (ICDs) for those with a history of cardiac arrest and/or failure to respond to other treatments"
GeneReviews recommends ICD placement for high-risk or treatment-refractory JLNS patients.
PMID:20301579 SUPPORT Other
"periodic evaluations of ICDs for inappropriate shocks and pocket or lead complications"
GeneReviews surveillance guidance: implanted devices require periodic evaluation for inappropriate shocks and pocket/lead complications.
Left Cardiac Sympathetic Denervation
Action: left cardiac sympathetic denervationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is left cardiac sympathetic denervation, annotated with Surgical Procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
Surgical anti-adrenergic escalation considered when arrhythmia persists despite beta-blocker therapy or when device therapy is unsuitable; a review of JLNS management describes beta-blocker and left cardiac sympathetic denervation efficacy as both limited, since arrhythmia persists in 51-85% of cases despite beta-blocker treatment.
Mechanism Target:
INHIBITS Arrhythmogenic Substrate and Ventricular Tachyarrhythmia — Left cardiac sympathetic denervation reduces arrhythmia-provoking sympathetic input when pharmacologic anti-adrenergic therapy (beta blockade) is insufficient.
Show evidence (1 reference)
PMID:42389506 SUPPORT Human Clinical
"The efficacy of beta‐blockers and left cardiac sympathetic denervation is limited in patients with JLNS, as arrhythmia persists in 51%–85% of cases despite beta‐blocker treatment"
States that left cardiac sympathetic denervation is used alongside beta-blockade in JLNS management, though the same review notes both interventions have limited efficacy against persistent arrhythmia.
Show evidence (1 reference)
PMID:42389506 SUPPORT Human Clinical
"left cervical sympathectomy is planned if malignant ventricular arrhythmias recur"
Documents left cardiac sympathetic denervation (cervical sympathectomy) as the planned escalation step in JLNS patients with recurrent malignant ventricular arrhythmia.
Catheter Ablation of Triggering Ectopy
Action: cardiac radiofrequency ablationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is cardiac radiofrequency ablation (NCIT:C170884). NCIT:C170884 is a clinical intervention from the NCI Thesaurus. Ontology label: Cardiac Radiofrequency Ablation NCIT:C170884
Radiofrequency catheter ablation of the premature ventricular contraction that triggers arrhythmia storm has been reported as an effective alternative or adjunct to device therapy in an individual genotype-confirmed KCNE1 (JLNS2) patient who could not undergo ICD implantation.
Show evidence (1 reference)
PMID:33040543 SUPPORT Human Clinical
"Ablation was successfully performed to eliminate the triggering PVC... During the 12-month follow-up, no syncope or fatal arrhythmia was found in this patient."
Direct clinical case report of successful radiofrequency ablation controlling fatal arrhythmia in a genotype-confirmed KCNE1 patient.
Cochlear Implantation
Category: Therapeutic Action: cochlear implantationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is cochlear implantation, annotated with Surgical Procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
Surgical cochlear implantation to treat the congenital profound sensorineural hearing loss of JLNS.
Target Phenotypes: Congenital sensorineural hearing impairment HP:0008527 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Congenital sensorineural hearing impairment (HP:0008527). HP:0008527 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"Cochlear implantation to treat hearing loss"
GeneReviews lists cochlear implantation as standard management of hearing loss in JLNS.
Avoidance of QT-Prolonging Drugs and Arrhythmia Triggers
Category: Counseling / Informational Action: risk factor avoidance counselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is risk factor avoidance counseling, annotated with Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Avoidance of drugs that further prolong the QT interval and of activities or circumstances known to precipitate syncopal events, plus special anesthetic precautions given the increased risk of arrhythmia during anesthesia.
Show evidence (2 references)
PMID:20301579 SUPPORT Other
"Agents/circumstances to avoid: Drugs that cause further prolongation of the QT interval; activities known to precipitate syncopal events in persons with long QT syndrome."
GeneReviews specifies the agents and circumstances to avoid in JLNS management.
PMID:20301579 SUPPORT Other
"Training for family members in cardiopulmonary resuscitation; use of an ID bracelet explaining the diagnosis; notifying local emergency medical services of high-risk persons with JLNS."
GeneReviews recommends family CPR training and emergency-preparedness measures as part of routine JLNS risk-factor avoidance and emergency planning.
Genetic Counseling
Category: Counseling / Informational Action: genetic counselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is genetic counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. Ontology label: Genetic Counseling NCIT:C15240
Autosomal recessive genetic counseling for families, including the 25% per-pregnancy recurrence risk for carrier couples, evaluation of at-risk relatives by newborn hearing screening and ECG, and consideration of whether a mother carrying an affected fetus herself has long QT syndrome.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"At conception, each sib of an affected individual usually has a 25% chance of being affected with JLNS, a 50% chance of being a carrier of a JLNS-causing pathogenic variant and potentially at risk for LQTS, and a 25% chance of being unaffected and not a carrier."
GeneReviews specifies the recurrence-risk figures used in genetic counseling for JLNS families.
🌍

Environmental Factors

1
Exertion, Emotional Stress, or Sudden Fright
exposure to strenuous exercise ECTO:6000031 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is exposure to strenuous exercise (ECTO:6000031). ECTO:6000031 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
Modeled here specifically for exertion/exercise, the concept with an available ECTO exposure term (ECTO:6000031, exposure to strenuous exercise); emotional stress and sudden fright are named in the same GeneReviews sentence but have no comparably specific ECTO exposure term and are recorded only in this node's free-text description.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright."
Establishes that exertion is a recognized exposure in JLNS rather than an inferred one. The mechanism link below carries its own evidence for the separate claim that this exposure acts on the arrhythmogenic substrate node.
Mechanism Target:
TRIGGERS Arrhythmogenic Substrate and Ventricular Tachyarrhythmia — Exertion, emotional stress, and sudden fright are the classic adrenergic triggers for syncopal arrhythmic events in JLNS; the same triggers motivate the anti-adrenergic rationale of beta-blocker therapy and the exercise/trigger-avoidance counseling in treatments.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright."
GeneReviews documents exertion, emotional stress, and sudden fright as the classic triggers of syncopal arrhythmic events in JLNS.
🔬

Diagnosis

3
Combined Clinical and Molecular Diagnostic Criteria
JLNS2 is diagnosed by the combination of the characteristic phenotype (congenital sensorineural deafness plus a prolonged QT interval) and confirmatory molecular testing showing biallelic pathogenic KCNE1 variants.
clinical assessment NCIT:C124351 NCI Thesaurus (NCIT)
Results: A child presenting with congenital sensorineural deafness and a prolonged QT interval, in whom molecular testing identifies biallelic pathogenic KCNE1 (or KCNQ1) variants, meets the diagnostic criteria for JLNS.
Show evidence (1 reference)
PMID:20301579 SUPPORT Other
"The diagnosis of JLNS is established in a child with congenital sensorineural deafness, long QT interval, and presence of biallelic pathogenic variants in either KCNQ1 or KCNE1."
GeneReviews states the combined clinical-plus-molecular diagnostic criteria for JLNS, of which the KCNE1 arm defines JLNS2.
Molecular Genetic Testing
Molecular confirmation of biallelic KCNE1 pathogenic variants is required to distinguish JLNS2 from JLNS1 (biallelic KCNQ1) and from heterozygous KCNE1-related dominant LQT5, which lacks congenital deafness.
molecular genetic testing NCIT:C19770 NCI Thesaurus (NCIT)
Results: Detection of two pathogenic KCNE1 alleles (homozygous or compound heterozygous) in trans confirms JLNS2 and distinguishes it from the allelic dominant LQT5 phenotype, in which only one KCNE1 allele is affected.
Show evidence (1 reference)
PMID:30461122 SUPPORT Human Clinical
"heterozygotes for loss-of-function variants of KCNE1 may have normal QT intervals while biallelic null alleles are associated with JLNS2"
Establishes that molecular zygosity (biallelic versus heterozygous) is the diagnostic feature that separates JLNS2 from the milder dominant KCNE1 phenotype.
Resting Electrocardiography with QTc Assessment
Baseline 12-lead ECG measurement of the corrected QT interval is the core diagnostic procedure for identifying the QT-prolongation component of JLNS2.
clinical assessment NCIT:C124351 NCI Thesaurus (NCIT)
Results: A markedly prolonged QTc, usually >500 msec in JLNS, supports the cardiac component of the diagnosis.
NCIT does not provide an ECG-specific diagnostic term here, so the preferred term is narrowed in the name and description.
Show evidence (1 reference)
"characterized by a prolongation of QTc interval on ECG"
A 2024 congenital LQTS review states that ECG-measured QTc prolongation is the defining diagnostic feature of the QT-prolongation component shared by all congenital LQTS subtypes, including JLNS.
📊

Prevalence

2
Worldwide
Unknown Ultra Rare
No direct birth-prevalence estimate for JLNS2 specifically has been published; JLNS overall (both genes) is estimated at roughly 1 in 200,000 to 1 in 1,000,000, and approximately 90% of genotyped JLNS cases are attributable to KCNQ1 rather than KCNE1, making JLNS2 a small minority of an already rare disease.
Show evidence (1 reference)
PMID:42389506 SUPPORT Other
"Approximately 90% of cases of JLNS are associated with KCNQ1 variants, and the remaining cases are attributable to KCNE1 variants"
Establishes that KCNE1 (JLNS2) accounts for only a minority of genotyped JLNS cases, the basis for treating JLNS2 as markedly rarer than JLNS1.
Worldwide (carrier frequency, functional-variant estimate)
Carrier Frequency 96.7 per 100,000 Not yet documented
Estimated by applying Hardy-Weinberg principles to gnomAD allele counts of KCNE1 variants shown experimentally to reduce IKs current density below 50% of wild type; 1 in 1034 converts to approximately 96.7 per 100,000. This is a carrier-frequency estimate, not a measured disease birth prevalence.
Show evidence (1 reference)
PMID:41200805 SUPPORT Computational
"The population carrier frequency of JLN2 was calculated as 1 in 1034."
Direct quantitative carrier-frequency estimate for JLNS2 derived from high-throughput functional profiling of KCNE1 variants combined with population allele-frequency data.
🔬

Clinical Trials

1
NCT06534671 PHASE_IV COMPLETED
A single-participant Vanderbilt University Medical Center trial testing the acute effect of a single intravenous dose of diltiazem, a calcium channel blocker, on the QT interval in a genetically confirmed JLNS patient. The trial's public summary does not specify whether the participant carried KCNQ1 or KCNE1 variants, so it is recorded here as JLNS-wide (not confirmed JLNS2-specific) evidence.
Target Phenotypes: Prolonged QT interval HP:0001657 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets Prolonged QT interval (HP:0001657). HP:0001657 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
"This study will test the effect of diltiazem, a calcium channel blocking drug, on the QT interval in patients with Jervell and Lange-Nielsen syndrome. This will be a single IV dose and acute effects (within minutes) will be observed."
ClinicalTrials.gov summary of the only identified JLNS-specific interventional trial testing a candidate acute QT-shortening agent.
🐁

Animal Models

1
Kcne1 knockout mouse
Species
Mouse
Genotype
Kcne1-/-
Publication
Show evidence (1 reference)
PMID:33514733 SUPPORT Model Organism
"Mutations in voltage-gated potassium channel KCNE1 cause Jervell and Lange-Nielsen syndrome type 2 (JLNS2), resulting in congenital deafness and vestibular dysfunction. We conducted gene therapy by injecting viral vectors using the canalostomy approach in Kcne1-/- mice to treat both the hearing..."
Establishes the Kcne1-/- mouse as a genetically precise model of the human KCNE1 loss-of-function lesion underlying JLNS2.
{ }

Source YAML

click to show
name: Jervell and Lange-Nielsen Syndrome 2
creation_date: "2026-08-17T00:00:00Z"
description: >-
  Jervell and Lange-Nielsen syndrome 2 (JLNS2) is an ultra-rare autosomal
  recessive cardioauditory channelopathy caused by biallelic loss-of-function
  variants in KCNE1, which encodes MinK, the single-transmembrane-domain beta
  subunit that assembles with the KCNQ1 alpha subunit to form the slow
  delayed-rectifier potassium (IKs) channel. JLNS2 is the allelic recessive
  counterpart of KCNE1-related autosomal dominant long QT syndrome (LQT5):
  a single heterozygous KCNE1 variant produces, at best, a low-penetrance
  dominant QT-prolongation phenotype, while biallelic loss essentially
  abolishes IKs current and produces the severe recessive JLNS phenotype. The
  IKs channel is expressed in both cardiac myocytes, where it contributes to
  repolarization of the ventricular action potential, and in the marginal
  cells of the stria vascularis of the inner ear, where it drives potassium
  secretion into the endolymph that generates and maintains the endocochlear
  potential required for hair-cell mechanotransduction. Biallelic KCNE1 loss
  therefore produces a two-organ phenotype: congenital profound bilateral
  sensorineural deafness from collapse of the endocochlear potential, together
  with marked QT-interval prolongation and a risk of torsade de pointes,
  ventricular fibrillation, syncope, and sudden cardiac death from loss of
  ventricular repolarization reserve. JLNS2 is distinguished from the more
  common JLNS1 (biallelic KCNQ1 variants) only by the causal gene, and the two
  are clinically similar at the bedside, but JLNS2 is markedly rarer -
  approximately 90% of JLNS cases are attributable to KCNQ1 and only about 10%
  to KCNE1 - and the limited comparative data available suggest a milder
  arrhythmic course than JLNS1. This entry is careful not to import JLNS1
  (KCNQ1) case series, severity estimates, or vestibular-dysfunction findings,
  which are curated separately.
category: Mendelian
disease_term:
  preferred_term: Jervell and Lange-Nielsen syndrome 2
  term:
    id: MONDO:0012871
    label: Jervell and Lange-Nielsen syndrome 2
synonyms:
- JLNS2
- Jervell and Lange-Nielsen syndrome type 2
- Jervell and Lange-Nielsen syndrome caused by mutation in KCNE1
- KCNE1 Jervell and Lange-Nielsen syndrome
parents:
- Jervell and Lange-Nielsen Syndrome
- Cardiac Arrhythmia
- Channelopathy
- Sensorineural Hearing Loss
notes: >-
  IDENTITY / NEC NOTE. MONDO:0012871 (OMIM:612347) is explicitly defined as
  "Any Jervell and Lange-Nielsen syndrome in which the cause of the disease is
  a mutation in the KCNE1 gene" and asserts RO:0004003 to HGNC:6240 (KCNE1);
  it is_a both MONDO:0002441 (Jervell and Lange-Nielsen syndrome) and
  MONDO:0013372 (long QT syndrome 5). This entry is curated strictly against
  the KCNE1 identity. The allelic, more common recessive form caused by
  biallelic KCNQ1 variants (JLNS1, MONDO:0024540) is curated separately and no
  JLNS1-specific case data, prevalence figures, or phenotype findings
  (including the KCNQ1-genotyped vestibular-dysfunction series of Winbo et al.,
  PMID:25471708, whose 14/14 genotyped subjects all carried double KCNQ1
  mutations) are imported here.

  RARITY. JLNS2 is markedly rarer than JLNS1: approximately 90% of JLNS cases
  are attributable to KCNQ1 variants and only about 10% to KCNE1 (PMID:42389506).
  A 2025 functional-profiling study of 95 KCNE1 variants estimated a JLNS2
  population carrier frequency of 1 in 1034 using Hardy-Weinberg principles
  applied to gnomAD allele counts of dysfunctional variants (PMID:41200805).
  The largest genotype-confirmed JLNS2 cohort assembled to date is 19 patients,
  drawn from an international multicenter LQT5 study (PMID:31941373). Case
  counts and severity figures in this entry are held to that scale rather than
  to JLNS1's more extensively reported literature.

  ALLELIC SPECTRUM. KCNE1 produces a genotype-phenotype spectrum rather than a
  strict dominant/recessive dichotomy: heterozygous carriers of KCNE1
  loss-of-function variants are usually clinically silent or show only a low
  ECG penetrance (dominant LQT5), while biallelic null alleles are required for
  the fully penetrant recessive JLNS2 phenotype (PMID:30461122, PMID:41200805).
  ClinGen's gene curation working group considers the evidence for autosomal
  dominant KCNE1-LQT5 causality disputed even though KCNE1 is an accepted
  cause of recessive JLNS2 (PMID:41200805). Long_QT_Syndrome.yaml curates the
  dominant LQT5 (Type 5) subtype of that spectrum; this entry curates the
  distinct, more severe biallelic phenotype.

  HUMAN/MOUSE VESTIBULAR MISMATCH. Kcne1-/- mice show clear structural and
  functional vestibular involvement (endolymphatic-space abnormality,
  vestibular dark cell and hair cell degeneration, impaired vestibular
  function rescued by gene therapy; PMID:33514733). No genotype-confirmed
  human vestibular data specific to KCNE1/JLNS2 patients have been identified;
  the only quantitative human vestibular study of JLNS (PMID:25471708) enrolled
  exclusively double-KCNQ1 (JLNS1) cases. This is recorded as a
  HUMAN_MODEL_MISMATCH discussion rather than as an established human
  phenotype.

  MODULE CONFORMANCE SCOPE. The cardiac branch declares conforms_to against
  cardiac_ion_channel_repolarization. The cochlear branch declares conforms_to
  against sensorineural_hair_cell_loss starting at "Cochlear Ionic Homeostasis
  Disruption and Oxidative Stress" (whose own description explicitly names
  potassium-recycling/endocochlear-potential failure as a covered mechanism),
  rather than at the module's "Cochlear Sensory Epithelium Insult" entry node,
  because the primary JLNS2 lesion is a stria vascularis marginal-cell ionic
  defect rather than a primary hair-cell stereociliary/mechanotransduction
  defect.
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0012871
      label: Jervell and Lange-Nielsen syndrome 2
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: >-
      MONDO:0012871 is the primary disease term for this entry, cross-referenced
      to OMIM:612347, with KCNE1 (HGNC:6240) asserted as the causal gene via
      RO:0004003.
inheritance:
- name: Autosomal Recessive
  description: >-
    JLNS2 is inherited in an autosomal recessive manner. Affected individuals
    are homozygous or compound heterozygous for KCNE1 loss-of-function
    variants; parents are typically heterozygous carriers who are usually
    clinically unaffected or show only mild, incompletely penetrant QT
    prolongation (the allelic dominant LQT5 phenotype). At conception, each
    sib of an affected individual has a 25% chance of being affected, a 50%
    chance of being an asymptomatic or mildly affected carrier, and a 25%
    chance of being unaffected and non-carrier.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "JLNS is inherited in an autosomal recessive manner. Parents of a child with JLNS are usually heterozygotes; rarely, only one parent is heterozygous"
    explanation: >-
      GeneReviews establishes the autosomal recessive inheritance pattern and
      typical carrier status of parents.
  - reference: PMID:30461122
    reference_title: "Mutational and phenotypic spectra of KCNE1 deficiency in Jervell and Lange-Nielsen Syndrome and Romano-Ward Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "heterozygotes for loss-of-function variants of KCNE1 may have normal QT intervals while biallelic null alleles are associated with JLNS2"
    explanation: >-
      Documents that biallelic KCNE1 loss of function, not heterozygosity, is
      required for the fully penetrant JLNS2 phenotype.
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "At conception, each sib of an affected individual usually has a 25% chance of being affected with JLNS, a 50% chance of being a carrier of a JLNS-causing pathogenic variant and potentially at risk for LQTS, and a 25% chance of being unaffected and not a carrier."
    explanation: >-
      GeneReviews states the exact per-pregnancy recurrence-risk figures
      (25% affected, 50% carrier, 25% unaffected non-carrier) summarized in
      this node's description.
prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: ULTRA_RARE
  notes: >-
    No direct birth-prevalence estimate for JLNS2 specifically has been
    published; JLNS overall (both genes) is estimated at roughly 1 in 200,000
    to 1 in 1,000,000, and approximately 90% of genotyped JLNS cases are
    attributable to KCNQ1 rather than KCNE1, making JLNS2 a small minority of
    an already rare disease.
  evidence:
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Approximately 90% of cases of JLNS are associated with KCNQ1 variants, and the remaining cases are attributable to KCNE1 variants"
    explanation: >-
      Establishes that KCNE1 (JLNS2) accounts for only a minority of genotyped
      JLNS cases, the basis for treating JLNS2 as markedly rarer than JLNS1.
- population: Worldwide (carrier frequency, functional-variant estimate)
  measure_type: CARRIER_FREQUENCY
  prevalence_class: NOT_YET_DOCUMENTED
  rate_per_100000: 96.7
  notes: >-
    Estimated by applying Hardy-Weinberg principles to gnomAD allele counts of
    KCNE1 variants shown experimentally to reduce IKs current density below 50%
    of wild type; 1 in 1034 converts to approximately 96.7 per 100,000. This is
    a carrier-frequency estimate, not a measured disease birth prevalence.
  evidence:
  - reference: PMID:41200805
    reference_title: "Functional Profiling of KCNE1 Variants Informs Population Carrier Frequency of Jervell and Lange-Nielsen Syndrome Type 2."
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: "The population carrier frequency of JLN2 was calculated as 1 in 1034."
    explanation: >-
      Direct quantitative carrier-frequency estimate for JLNS2 derived from
      high-throughput functional profiling of KCNE1 variants combined with
      population allele-frequency data.
genetic:
- name: KCNE1
  notes: >-
    KCNE1 (21q22.11) encodes MinK, a 129-amino-acid single-transmembrane-domain
    protein that is the regulatory beta subunit of the IKs channel; it must
    coassemble with the KCNQ1 (Kv7.1) alpha subunit to generate the slow
    delayed-rectifier potassium current. A 2025 high-throughput voltage-clamp
    screen of 95 KCNE1 variants found that about half exhibited peak current
    densities significantly different from wild type when studied in the
    homozygous state, with most dysfunctional variants showing loss-of-function
    properties and no apparent dominant-negative effect on the specific
    variant panel tested when variant and wild-type KCNE1 were coexpressed.
    This is not a categorical claim that KCNE1 variants are never
    dominant-negative: a separate study of KCNE1 nonsense alleles reports that
    coassembly of certain other mutant KCNE1 monomers with wild-type KCNQ1
    subunits does produce dominant Romano-Ward syndrome via a dominant-negative
    mechanism. The two observations are reconciled, not contradictory, by
    variant-specific mechanism: most loss-of-function KCNE1 alleles behave as
    simple recessive nulls requiring biallelic loss for JLNS2, while a smaller
    set of missense alleles instead act dominantly through interference with
    wild-type KCNQ1/KCNE1 complexes.
  gene_term:
    preferred_term: KCNE1
    term:
      id: hgnc:6240
      label: KCNE1
  relationship_type: CAUSATIVE
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of JLNS is established in a child with congenital sensorineural deafness, long QT interval, and presence of biallelic pathogenic variants in either KCNQ1 or KCNE1."
    explanation: >-
      GeneReviews establishes KCNE1 as one of the two genes in which biallelic
      pathogenic variants cause JLNS.
  - reference: PMID:41200805
    reference_title: "Functional Profiling of KCNE1 Variants Informs Population Carrier Frequency of Jervell and Lange-Nielsen Syndrome Type 2."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "KCNE1 is a recognized cause of the autosomal recessive Jervell and Lange-Nielson syndrome type 2 (JLN2)."
    explanation: >-
      Confirms KCNE1 as the accepted causal gene for the recessive JLNS2
      phenotype curated in this entry.
  - reference: PMID:41200805
    reference_title: "Functional Profiling of KCNE1 Variants Informs Population Carrier Frequency of Jervell and Lange-Nielsen Syndrome Type 2."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Most dysfunctional variants exhibited loss-of-function properties. We observed no apparent dominant-negative effects when variant and wild-type KCNE1 were coexpressed."
    explanation: >-
      Direct functional electrophysiology showing loss-of-function as the
      predominant mechanism of disease-associated KCNE1 variants, without
      dominant-negative behavior, consistent with a recessive disease
      mechanism.
  - reference: PMID:33040543
    reference_title: "Treatment on arrhythmia electric storm in a Jervell and Lange-Nielsen syndrome patient by ablation of the triggering premature ventricular contraction: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient has A to G missense mutation in KCNE1 gene, and a subunit with abnormal structure, which is the basis for congenital deafness."
    explanation: >-
      Independent clinical case confirming a KCNE1 missense variant as the
      basis of a patient's congenital deafness component of JLNS.
pathophysiology:
- name: Biallelic KCNE1 Loss of Function
  conforms_to: "cardiac_ion_channel_repolarization#Cardiac Ion-Channel or Calcium-Handling Variant"
  role: trigger
  biological_scale: MOLECULAR
  description: >-
    Biallelic loss-of-function variants in KCNE1 abolish or severely reduce
    the regulatory (beta-subunit) contribution of MinK to the IKs channel
    complex. Because KCNE1 must coassemble with KCNQ1 to generate a normal IKs
    current, homozygous or compound heterozygous KCNE1 variants produce the
    same downstream functional deficit as biallelic KCNQ1 loss (JLNS1), even
    though the two genes encode structurally distinct subunits of the same
    channel. High-throughput voltage-clamp profiling shows that most
    disease-associated KCNE1 variants reduce IKs current density in the
    homozygous state without dominant-negative behavior on coexpressed
    wild-type subunits, consistent with a recessive disease mechanism.
  genes:
  - preferred_term: KCNE1
    term:
      id: hgnc:6240
      label: KCNE1
  molecular_functions:
  - preferred_term: ion channel regulator activity
    term:
      id: GO:0099106
      label: ion channel regulator activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: potassium ion transmembrane transport
    term:
      id: GO:0071805
      label: potassium ion transmembrane transport
    modifier: DECREASED
  evidence:
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "KCNE1 specifically encodes the beta subunit (mink) of IKs"
    explanation: >-
      Establishes KCNE1/MinK as the regulatory beta subunit whose biallelic
      loss is the molecular trigger of JLNS2.
  - reference: PMID:41200805
    reference_title: "Functional Profiling of KCNE1 Variants Informs Population Carrier Frequency of Jervell and Lange-Nielsen Syndrome Type 2."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Approximately half (47 of 95) of the KCNE1 variants tested in the homozygous state exhibited peak current densities significantly different from WT IKs."
    explanation: >-
      Direct high-throughput functional data quantifying the frequency and
      magnitude of IKs current disruption caused by KCNE1 variants in the
      homozygous state.
  downstream:
  - target: Loss of IKs Current in Cardiac Myocytes
    description: >-
      IKs generated by the KCNQ1/KCNE1 complex is a major repolarizing current
      in cardiac myocytes; loss of KCNE1 function reduces this current in the
      heart.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:42389506
      reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "The ion channel subunits encoded by KCNQ1 and KCNE1 generate slow delayed rectifier potassium currents (IKs), which are essential for endolymph production in the inner ear and cardiomyocyte action potential (AP)"
      explanation: >-
        States both the cardiac and cochlear roles of the KCNQ1/KCNE1 IKs
        complex, the basis of this branch of the fork.
  - target: Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells
    description: >-
      The same KCNQ1/KCNE1 IKs channel complex is expressed on the apical
      membrane of marginal cells of the stria vascularis, where it drives
      potassium secretion into the endolymph; loss of KCNE1 function reduces
      this current in the inner ear.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33514733
      reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "In the inner ear, KCNQ1/KCNE1 potassium channels are expressed exclusively in the apical membrane of marginal cells (MCs) in the stria vascularis (SV) and in vestibular dark cells"
      explanation: >-
        Establishes the specific inner-ear cellular localization of the
        KCNQ1/KCNE1 channel complex whose loss initiates the cochlear branch
        of the phenotype.
- name: Loss of IKs Current in Cardiac Myocytes
  conforms_to: "cardiac_ion_channel_repolarization#Altered Action Potential and Calcium Handling"
  role: intermediate
  biological_scale: CELLULAR
  description: >-
    Reduced IKs current diminishes repolarization reserve and delays
    completion of the ventricular action potential, prolonging the QT
    interval measured on the surface ECG.
  cell_types:
  - preferred_term: cardiomyocyte
    term:
      id: CL:0000746
      label: cardiac muscle cell
  biological_processes:
  - preferred_term: potassium ion transmembrane transport
    term:
      id: GO:0071805
      label: potassium ion transmembrane transport
    modifier: DECREASED
  - preferred_term: membrane repolarization during cardiac muscle cell action potential
    term:
      id: GO:0086013
      label: membrane repolarization during cardiac muscle cell action potential
    modifier: DYSREGULATED
  molecular_functions:
  - preferred_term: monoatomic ion channel activity
    term:
      id: GO:0005216
      label: monoatomic ion channel activity
    modifier: ABNORMAL
  locations:
  - preferred_term: heart
    term:
      id: UBERON:0000948
      label: heart
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
    explanation: >-
      GeneReviews documents the marked QTc prolongation that results from
      reduced ventricular repolarization reserve in JLNS.
  downstream:
  - target: Arrhythmogenic Substrate and Ventricular Tachyarrhythmia
    description: >-
      Markedly prolonged repolarization creates a substrate for triggered
      activity and re-entrant ventricular tachyarrhythmia, including torsade
      de pointes and ventricular fibrillation.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:20301579
      reference_title: "Jervell and Lange-Nielsen Syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Prolongation of the QTc interval is associated with tachyarrhythmias, including ventricular tachycardia, episodes of torsade de pointes ventricular tachycardia, and ventricular fibrillation, which may culminate in syncope or sudden death."
      explanation: >-
        GeneReviews directly links QTc prolongation to the tachyarrhythmic and
        fatal outcomes of JLNS.
- name: Arrhythmogenic Substrate and Ventricular Tachyarrhythmia
  conforms_to: "cardiac_ion_channel_repolarization#Ventricular Tachyarrhythmia"
  role: intermediate
  biological_scale: TISSUE
  description: >-
    Prolonged, heterogeneous ventricular repolarization predisposes to
    early afterdepolarizations and re-entrant torsade de pointes, which can
    degenerate into sustained ventricular tachycardia or ventricular
    fibrillation. Available comparative data suggest that this arrhythmic risk
    is present but lower in genotype-confirmed JLNS2 (biallelic KCNE1) than in
    JLNS1 (biallelic KCNQ1).
  locations:
  - preferred_term: heart
    term:
      id: UBERON:0000948
      label: heart
  evidence:
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Children carrying KCNQ1 variants exhibit an approximately sixfold higher risk of ventricular arrhythmia than those with KCNE1 variants."
    explanation: >-
      Directly quantifies the reduced (but nonzero) ventricular arrhythmia
      risk specific to KCNE1 (JLNS2) relative to KCNQ1 (JLNS1) genotypes,
      supporting the entry's emphasis on JLNS2-specific severity data rather
      than JLNS1 figures.
  - reference: PMID:31941373
    reference_title: "An International Multicenter Evaluation of Type 5 Long QT Syndrome: A Low Penetrant Primary Arrhythmic Condition."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Event incidence did not differ significantly for Type 2 Jervell and Lange-Nielsen syndrome patients relative to the overall heterozygous cohort (10.5%"
    explanation: >-
      Directly quantifies the definite arrhythmic event rate (10.5%, 2 of 19
      genotype-confirmed patients) in the largest reported JLNS2 cohort,
      providing a JLNS2-specific severity estimate rather than an imported
      JLNS1 figure.
  downstream:
  - target: Syncope and Sudden Cardiac Death
    description: >-
      Sustained ventricular tachyarrhythmia can cause hemodynamic collapse,
      manifesting as syncope, and can be fatal if not promptly terminated.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:20301579
      reference_title: "Jervell and Lange-Nielsen Syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "More than half of untreated children with JLNS die before age 15 years."
      explanation: >-
        GeneReviews documents the high untreated mortality of JLNS overall,
        underscoring the clinical severity of the arrhythmic branch even
        though JLNS2 specifically carries a lower event rate than JLNS1.
- name: Syncope and Sudden Cardiac Death
  conforms_to: "cardiac_ion_channel_repolarization#Syncope and Sudden Cardiac Death"
  role: effector
  biological_scale: ORGANISM
  description: >-
    The clinical endpoint of the cardiac branch of JLNS2: exertion-, emotion-,
    or auditory-stimulus-triggered syncope, and a risk of sudden cardiac death
    from malignant ventricular arrhythmia, most pronounced in early childhood.
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright. Fifty percent of individuals with JLNS had cardiac events before age three years."
    explanation: >-
      GeneReviews describes the classic clinical presentation and early
      childhood timing of cardiac events in JLNS overall.
- name: Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells
  conforms_to: "sensorineural_hair_cell_loss#Cochlear Ionic Homeostasis Disruption and Oxidative Stress"
  role: intermediate
  biological_scale: CELLULAR
  description: >-
    KCNQ1/KCNE1 IKs channels on the apical membrane of stria vascularis
    marginal cells drive the transepithelial potassium flux that generates and
    maintains the endocochlear potential, the unusually positive extracellular
    potential in the endolymph that provides the electrochemical driving force
    for hair-cell mechanotransduction. Loss of KCNE1 function collapses this
    potassium-secretory current, disrupting cochlear ionic homeostasis.
  cell_types:
  - preferred_term: strial marginal cell
    term:
      id: CL:0002492
      label: strial marginal cell
  biological_processes:
  - preferred_term: potassium ion transmembrane transport
    term:
      id: GO:0071805
      label: potassium ion transmembrane transport
    modifier: DECREASED
  locations:
  - preferred_term: stria vascularis of cochlear duct
    term:
      id: UBERON:0002282
      label: stria vascularis of cochlear duct
  - preferred_term: cochlea
    term:
      id: UBERON:0001844
      label: cochlea
  evidence:
  - reference: PMID:33514733
    reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In the inner ear, KCNQ1/KCNE1 potassium channels are expressed exclusively in the apical membrane of marginal cells (MCs) in the stria vascularis (SV) and in vestibular dark cells"
    explanation: >-
      Confirms the strial marginal cell localization of the KCNQ1/KCNE1
      channel complex central to this node.
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The K+ concentration is markedly increased in the endolymph, and the influx of K+ into hair cells upon stimulation plays a pivotal role in transducing sound into neural signals."
    explanation: >-
      Establishes the mechanistic link between strial potassium secretion,
      the endolymph's high K+ concentration, and hair-cell mechanotransduction.
  downstream:
  - target: Endocochlear Potential Collapse and Hair Cell Degeneration
    description: >-
      Loss of strial potassium secretion collapses the endocochlear potential
      and the driving force for hair-cell mechanotransduction.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33514733
      reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Both Kcne1−/− and Kcnq1−/− mice exhibit an abnormal development of the endolymphatic space, severe degeneration of the hair cells (HCs), and spiral ganglion neurons (SGNs)"
      explanation: >-
        Direct mouse-model evidence that Kcne1 loss produces endolymphatic
        abnormality and hair cell/spiral ganglion degeneration, mirroring the
        Kcnq1 (JLNS1) model.
- name: Endocochlear Potential Collapse and Hair Cell Degeneration
  conforms_to: "sensorineural_hair_cell_loss#Hair Cell Mechanotransduction Failure and Death"
  role: intermediate
  biological_scale: CELLULAR
  description: >-
    Without the endocochlear potential, hair-cell mechanotransduction fails
    and cochlear hair cells undergo degeneration. Because mammalian cochlear
    hair cells do not regenerate, this loss is irreversible.
  locations:
  - preferred_term: cochlea
    term:
      id: UBERON:0001844
      label: cochlea
  evidence:
  - reference: PMID:33514733
    reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Results showed early treatment prevented collapse of the Reissner's membrane and vestibular wall, retained the normal size of the semicircular canals, and prevented the degeneration of inner ear cells."
    explanation: >-
      Demonstrates, by rescue, that untreated Kcne1 loss causes structural
      collapse of the cochlear duct and degeneration of inner ear cells.
  downstream:
  - target: Congenital Profound Bilateral Sensorineural Hearing Loss
    description: >-
      Irreversible hair-cell loss and collapse of the endocochlear potential
      produce permanent, congenital sensorineural hearing loss.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:20301579
      reference_title: "Jervell and Lange-Nielsen Syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
      explanation: >-
        GeneReviews establishes congenital profound bilateral sensorineural
        hearing loss as a defining, present-from-birth feature of JLNS.
- name: Congenital Profound Bilateral Sensorineural Hearing Loss
  conforms_to: "sensorineural_hair_cell_loss#Progressive Sensorineural Hearing Loss"
  role: effector
  biological_scale: ORGANISM
  description: >-
    The clinical endpoint of the cochlear branch of JLNS2: congenital,
    profound, bilateral sensorineural hearing loss present from birth. Unlike
    several other conformers of this module (e.g., noise- or age-related
    hearing loss), the JLNS deficit is typically already maximal at birth
    rather than accruing progressively over time; conformance here reflects
    the shared irreversible, non-regenerating hair-cell-loss endpoint rather
    than a claim of ongoing postnatal worsening.
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
    explanation: >-
      GeneReviews defines the congenital, profound, bilateral character of the
      hearing loss.
mechanistic_hypotheses:
- hypothesis_group_id: variant_specific_dominant_negative_vs_haploinsufficiency
  hypothesis_label: Variant-specific dominant-negative versus simple loss-of-function/haploinsufficiency KCNE1 mechanism
  status: EMERGING
  description: >-
    KCNE1 loss-of-function variants appear to split mechanistically by
    variant. A large 2025 functional screen found no apparent dominant-negative
    effect on wild-type IKs current among the KCNE1 variants it tested when
    coexpressed with wild-type KCNE1, consistent with a simple recessive
    loss-of-function/haploinsufficiency mechanism requiring biallelic loss for
    JLNS2. However, an independent study of KCNE1 nonsense and missense
    alleles reports that coassembly of certain other mutant KCNE1 monomers
    with wild-type KCNQ1 subunits produces dominant Romano-Ward syndrome via a
    dominant-negative mechanism. Whether these are truly non-overlapping
    variant classes, or whether the discrepancy partly reflects differences in
    the specific variants and assay conditions tested, is not yet resolved.
  evidence:
  - reference: PMID:41200805
    reference_title: "Functional Profiling of KCNE1 Variants Informs Population Carrier Frequency of Jervell and Lange-Nielsen Syndrome Type 2."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We observed no apparent dominant-negative effects when variant and wild-type KCNE1 were coexpressed."
    explanation: >-
      Direct functional data supporting a simple loss-of-function/
      haploinsufficiency mechanism for the specific KCNE1 variant panel tested.
  - reference: PMID:30461122
    reference_title: "Mutational and phenotypic spectra of KCNE1 deficiency in Jervell and Lange-Nielsen Syndrome and Romano-Ward Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Coassembly of certain mutant KCNE1 monomers with wild-type KCNQ1 subunits results in RWS by a dominant negative mechanism."
    explanation: >-
      Independent evidence that at least some KCNE1 missense variants act
      dominantly through a dominant-negative mechanism, the counterpoint this
      hypothesis has to reconcile with the functional screen's negative
      finding.
discussions:
- discussion_id: jlns2_vestibular_human_model_mismatch
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - "pathophysiology#Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells"
  prompt: >-
    Do genotype-confirmed human JLNS2 (biallelic KCNE1) patients have
    clinically significant vestibular dysfunction, as Kcne1-/- mice do?
  rationale: >-
    Kcne1-/- mice show clear structural and functional vestibular involvement:
    KCNQ1/KCNE1 channels are expressed in vestibular dark cells as well as
    strial marginal cells, and untreated Kcne1-/- mice show abnormal
    endolymphatic-space development, vestibular hair cell degeneration, and
    impaired vestibular behavior that gene therapy can rescue (PMID:33514733).
    However, the only quantitative human vestibular study of JLNS
    (PMID:25471708) genotyped its cohort and found all 14 tested cases carried
    double KCNQ1 (JLNS1) mutations, not KCNE1. Whether the mouse vestibular
    phenotype translates to genotype-confirmed human JLNS2 patients is
    therefore untested, and this entry deliberately does not curate vestibular
    dysfunction as an established JLNS2 phenotype.
  evidence:
  - reference: PMID:33514733
    reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Mutations in voltage-gated potassium channel KCNE1 cause Jervell and Lange-Nielsen syndrome type 2 (JLNS2), resulting in congenital deafness and vestibular dysfunction."
    explanation: >-
      Source of the mouse-model vestibular-dysfunction claim that motivates
      this discussion.
  proposed_experiments:
  - experiment_id: exp_jlns2_genotype_stratified_vestibular_function
    name: Genotype-stratified human vestibular function study in JLNS2
    description: >-
      Vestibular function testing (post-rotatory nystagmus, video head impulse
      testing) in a cohort of genotype-confirmed KCNE1/JLNS2 patients,
      analogous to the KCNQ1-genotyped study already published for JLNS1
      (PMID:25471708).
phenotypes:
- category: Ear
  name: Congenital Profound Bilateral Sensorineural Hearing Loss
  description: >-
    Congenital, profound, bilateral sensorineural hearing loss is a defining
    feature of JLNS, present from birth or identified on newborn hearing
    screening.
  phenotype_term:
    preferred_term: Congenital sensorineural hearing impairment
    term:
      id: HP:0008527
      label: Congenital sensorineural hearing impairment
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
    explanation: >-
      GeneReviews establishes congenital profound bilateral sensorineural
      hearing loss as a defining feature of JLNS.
- category: Cardiovascular
  name: Prolonged QT Interval
  description: >-
    Marked prolongation of the corrected QT interval (QTc), usually greater
    than 500 msec, is a defining feature of JLNS.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Prolonged QT interval
    term:
      id: HP:0001657
      label: Prolonged QT interval
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital profound bilateral sensorineural hearing loss and long QTc, usually >500 msec."
    explanation: >-
      GeneReviews establishes marked QTc prolongation as a defining feature of
      JLNS.
- category: Cardiovascular
  name: Ventricular Arrhythmia
  description: >-
    Genotype-confirmed KCNE1 (JLNS2) patients are at risk of definite
    arrhythmic events (appropriate ICD shock, aborted cardiac arrest, or
    sudden cardiac death), reported at a lower rate than in KCNQ1 (JLNS1)
    patients in the largest comparative cohort to date.
  phenotype_term:
    preferred_term: Ventricular tachycardia
    term:
      id: HP:0004756
      label: Ventricular tachycardia
  evidence:
  - reference: PMID:31941373
    reference_title: "An International Multicenter Evaluation of Type 5 Long QT Syndrome: A Low Penetrant Primary Arrhythmic Condition."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Event incidence did not differ significantly for Type 2 Jervell and Lange-Nielsen syndrome patients relative to the overall heterozygous cohort (10.5%"
    explanation: >-
      Direct quantitative arrhythmic event rate in the largest reported
      genotype-confirmed JLNS2 cohort.
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Children carrying KCNQ1 variants exhibit an approximately sixfold higher risk of ventricular arrhythmia than those with KCNE1 variants."
    explanation: >-
      Quantifies the reduced, but nonzero, ventricular arrhythmia risk
      associated specifically with KCNE1 (JLNS2) genotypes relative to KCNQ1
      (JLNS1).
- category: Cardiovascular
  name: Torsade de Pointes
  description: >-
    QTc prolongation in JLNS is associated with episodes of torsade de pointes
    ventricular tachycardia, which may culminate in syncope or sudden death.
  phenotype_term:
    preferred_term: Torsade de pointes
    term:
      id: HP:0001664
      label: Torsade de pointes
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Prolongation of the QTc interval is associated with tachyarrhythmias, including ventricular tachycardia, episodes of torsade de pointes ventricular tachycardia, and ventricular fibrillation, which may culminate in syncope or sudden death."
    explanation: >-
      GeneReviews documents torsade de pointes as a characteristic
      tachyarrhythmia in JLNS.
- category: Cardiovascular
  name: Syncope
  description: >-
    The classic presentation of JLNS is a deaf child who experiences
    syncopal episodes during periods of stress, exercise, or fright.
  phenotype_term:
    preferred_term: Syncope
    term:
      id: HP:0001279
      label: Syncope
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright."
    explanation: >-
      GeneReviews describes the classic exertion/emotion-triggered syncopal
      presentation of JLNS.
- category: Cardiovascular
  name: Sudden Cardiac Death Risk
  description: >-
    Untreated JLNS carries a high risk of premature death from malignant
    ventricular arrhythmia; more than half of untreated children die before
    age 15 years.
  phenotype_term:
    preferred_term: Sudden death
    term:
      id: HP:0001699
      label: Sudden death
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "More than half of untreated children with JLNS die before age 15 years."
    explanation: >-
      GeneReviews establishes the high untreated mortality of JLNS overall.
- category: Hematologic
  name: Iron-Deficiency Anemia
  description: >-
    Iron-deficient anemia is a frequent, non-cardioauditory feature of JLNS,
    of uncertain mechanistic relationship to the primary channelopathy.
  phenotype_term:
    preferred_term: Iron deficiency anemia
    term:
      id: HP:0001891
      label: Iron deficiency anemia
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Iron-deficient anemia and elevated levels of gastrin are also frequent features of JLNS."
    explanation: >-
      GeneReviews lists iron-deficient anemia among the frequent additional
      features of JLNS.
- category: Gastrointestinal
  name: Elevated Serum Gastrin
  description: >-
    Elevated serum gastrin levels are a frequent, non-cardioauditory feature
    of JLNS.
  phenotype_term:
    preferred_term: Hypergastrinemia
    term:
      id: HP:0500167
      label: Hypergastrinemia
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Iron-deficient anemia and elevated levels of gastrin are also frequent features of JLNS."
    explanation: >-
      GeneReviews lists elevated gastrin as a frequent additional feature of
      JLNS.
environmental:
- name: Exertion, Emotional Stress, or Sudden Fright
  exposure_term:
    preferred_term: exposure to strenuous exercise
    term:
      id: ECTO:6000031
      label: exposure to strenuous exercise
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright."
    explanation: >-
      Establishes that exertion is a recognized exposure in JLNS rather
      than an inferred one. The mechanism link below carries its own
      evidence for the separate claim that this exposure acts on the
      arrhythmogenic substrate node.
  influences_mechanisms:
  - target: Arrhythmogenic Substrate and Ventricular Tachyarrhythmia
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: >-
      Exertion, emotional stress, and sudden fright are the classic
      adrenergic triggers for syncopal arrhythmic events in JLNS; the same
      triggers motivate the anti-adrenergic rationale of beta-blocker
      therapy and the exercise/trigger-avoidance counseling in
      treatments.
    evidence:
    - reference: PMID:20301579
      reference_title: "Jervell and Lange-Nielsen Syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "The classic presentation of JLNS is a deaf child who experiences syncopal episodes during periods of stress, exercise, or fright."
      explanation: >-
        GeneReviews documents exertion, emotional stress, and sudden fright
        as the classic triggers of syncopal arrhythmic events in JLNS.
  notes: >-
    Modeled here specifically for exertion/exercise, the concept with an
    available ECTO exposure term (ECTO:6000031, exposure to strenuous
    exercise); emotional stress and sudden fright are named in the same
    GeneReviews sentence but have no comparably specific ECTO exposure term
    and are recorded only in this node's free-text description.
treatments:
- name: Beta-Blocker Therapy
  description: >-
    First-line anti-adrenergic pharmacotherapy for JLNS, though reported to be
    only partially effective; arrhythmia persists in a substantial proportion
    of patients despite beta-blocker treatment.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: beta-blocker therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: beta-adrenergic antagonist
      term:
        id: NCIT:C29576
        label: Beta-Adrenergic Antagonist
  target_mechanisms:
  - target: Arrhythmogenic Substrate and Ventricular Tachyarrhythmia
    treatment_effect: INHIBITS
    description: >-
      Anti-adrenergic therapy reduces the likelihood that exertion- or
      emotion-related sympathetic triggers will precipitate malignant
      ventricular arrhythmia.
    evidence:
    - reference: PMID:20301579
      reference_title: "Jervell and Lange-Nielsen Syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "beta-adrenergic blockers for long QT interval (Note: Beta-blocker treatment is only partially effective.)"
      explanation: >-
        GeneReviews recommends beta-blockers as first-line therapy while
        explicitly noting only partial effectiveness in JLNS.
  evidence:
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The efficacy of beta‐blockers and left cardiac sympathetic denervation is limited in patients with JLNS, as arrhythmia persists in 51%–85% of cases despite beta‐blocker treatment"
    explanation: >-
      Quantifies the limited efficacy of beta-blocker therapy in JLNS,
      motivating escalation to device therapy in many patients.
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Beta-blocker dose should be regularly assessed for efficacy and adverse effects, with evaluation every three to six months during rapid growth phases"
    explanation: >-
      GeneReviews surveillance guidance: beta-blocker dosing requires
      periodic reassessment, especially during rapid childhood growth
      phases, because weight-based dosing can fall out of therapeutic range.
  notes: >-
    GeneReviews recommends reassessing beta-blocker dose for efficacy and
    adverse effects every three to six months during rapid growth phases.
- name: Implantable Cardioverter-Defibrillator Placement
  description: >-
    Device therapy for patients with a history of cardiac arrest, malignant
    events despite beta-blocker therapy, or otherwise judged high risk.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: implantable cardioverter-defibrillator placement
    term:
      id: NCIT:C80435
      label: Implantable Cardioverter-Defibrillator Placement
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "implantable cardioverter defibrillators (ICDs) for those with a history of cardiac arrest and/or failure to respond to other treatments"
    explanation: >-
      GeneReviews recommends ICD placement for high-risk or treatment-refractory
      JLNS patients.
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "periodic evaluations of ICDs for inappropriate shocks and pocket or lead complications"
    explanation: >-
      GeneReviews surveillance guidance: implanted devices require periodic
      evaluation for inappropriate shocks and pocket/lead complications.
  notes: >-
    GeneReviews recommends periodic ICD evaluation for inappropriate shocks
    and pocket or lead complications.
- name: Left Cardiac Sympathetic Denervation
  description: >-
    Surgical anti-adrenergic escalation considered when arrhythmia persists
    despite beta-blocker therapy or when device therapy is unsuitable; a
    review of JLNS management describes beta-blocker and left cardiac
    sympathetic denervation efficacy as both limited, since arrhythmia
    persists in 51-85% of cases despite beta-blocker treatment.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: left cardiac sympathetic denervation
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Arrhythmogenic Substrate and Ventricular Tachyarrhythmia
    treatment_effect: INHIBITS
    description: >-
      Left cardiac sympathetic denervation reduces arrhythmia-provoking
      sympathetic input when pharmacologic anti-adrenergic therapy (beta
      blockade) is insufficient.
    evidence:
    - reference: PMID:42389506
      reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The efficacy of beta‐blockers and left cardiac sympathetic denervation is limited in patients with JLNS, as arrhythmia persists in 51%–85% of cases despite beta‐blocker treatment"
      explanation: >-
        States that left cardiac sympathetic denervation is used alongside
        beta-blockade in JLNS management, though the same review notes both
        interventions have limited efficacy against persistent arrhythmia.
  evidence:
  - reference: PMID:42389506
    reference_title: "Jervell and Lange-Nielsen Syndrome Related Clinical Genetics and Experimental Models."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "left cervical sympathectomy is planned if malignant ventricular arrhythmias recur"
    explanation: >-
      Documents left cardiac sympathetic denervation (cervical sympathectomy)
      as the planned escalation step in JLNS patients with recurrent
      malignant ventricular arrhythmia.
  notes: >-
    Efficacy data are JLNS-wide (both JLNS1 and JLNS2) rather than
    KCNE1-genotype-specific; no genotype-stratified LCSD outcome data for
    JLNS2 alone were identified.
- name: Catheter Ablation of Triggering Ectopy
  description: >-
    Radiofrequency catheter ablation of the premature ventricular contraction
    that triggers arrhythmia storm has been reported as an effective
    alternative or adjunct to device therapy in an individual genotype-confirmed
    KCNE1 (JLNS2) patient who could not undergo ICD implantation.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: cardiac radiofrequency ablation
    term:
      id: NCIT:C170884
      label: Cardiac Radiofrequency Ablation
  evidence:
  - reference: PMID:33040543
    reference_title: "Treatment on arrhythmia electric storm in a Jervell and Lange-Nielsen syndrome patient by ablation of the triggering premature ventricular contraction: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ablation was successfully performed to eliminate the triggering PVC... During the 12-month follow-up, no syncope or fatal arrhythmia was found in this patient."
    explanation: >-
      Direct clinical case report of successful radiofrequency ablation
      controlling fatal arrhythmia in a genotype-confirmed KCNE1 patient.
  notes: >-
    Reported in a single genotype-confirmed KCNE1 patient who could not
    undergo ICD implantation for economic reasons; not established as a
    JLNS2-specific standard of care.
- name: Cochlear Implantation
  description: >-
    Surgical cochlear implantation to treat the congenital profound
    sensorineural hearing loss of JLNS.
  therapeutic_modality: SURGERY
  action_category: THERAPEUTIC
  treatment_term:
    preferred_term: cochlear implantation
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_phenotypes:
  - preferred_term: Congenital sensorineural hearing impairment
    term:
      id: HP:0008527
      label: Congenital sensorineural hearing impairment
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Cochlear implantation to treat hearing loss"
    explanation: >-
      GeneReviews lists cochlear implantation as standard management of
      hearing loss in JLNS.
  notes: >-
    A JLNS review notes that among documented cases, some patients undergoing
    cochlear implantation experienced significant arrhythmic events
    perioperatively, underscoring the importance of anesthetic and
    perioperative arrhythmia precautions in this population (PMID:42389506).
- name: Avoidance of QT-Prolonging Drugs and Arrhythmia Triggers
  description: >-
    Avoidance of drugs that further prolong the QT interval and of activities
    or circumstances known to precipitate syncopal events, plus special
    anesthetic precautions given the increased risk of arrhythmia during
    anesthesia.
  therapeutic_modality: BEHAVIORAL
  action_category: COUNSELING_INFORMATIONAL
  treatment_term:
    preferred_term: risk factor avoidance counseling
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Agents/circumstances to avoid: Drugs that cause further prolongation of the QT interval; activities known to precipitate syncopal events in persons with long QT syndrome."
    explanation: >-
      GeneReviews specifies the agents and circumstances to avoid in JLNS
      management.
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Training for family members in cardiopulmonary resuscitation; use of an ID bracelet explaining the diagnosis; notifying local emergency medical services of high-risk persons with JLNS."
    explanation: >-
      GeneReviews recommends family CPR training and emergency-preparedness
      measures as part of routine JLNS risk-factor avoidance and emergency
      planning.
  notes: >-
    GeneReviews also recommends ensuring availability of automated external
    defibrillators where appropriate, family training in cardiopulmonary
    resuscitation, use of a medical-alert ID bracelet, and notifying local
    emergency medical services of high-risk individuals.
- name: Genetic Counseling
  description: >-
    Autosomal recessive genetic counseling for families, including the 25%
    per-pregnancy recurrence risk for carrier couples, evaluation of at-risk
    relatives by newborn hearing screening and ECG, and consideration of
    whether a mother carrying an affected fetus herself has long QT syndrome.
  therapeutic_modality: OTHER
  action_category: COUNSELING_INFORMATIONAL
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "At conception, each sib of an affected individual usually has a 25% chance of being affected with JLNS, a 50% chance of being a carrier of a JLNS-causing pathogenic variant and potentially at risk for LQTS, and a 25% chance of being unaffected and not a carrier."
    explanation: >-
      GeneReviews specifies the recurrence-risk figures used in genetic
      counseling for JLNS families.
animal_models:
- name: Kcne1 knockout mouse
  species: Mouse
  genotype: Kcne1-/-
  publication: PMID:33514733
  modeled_mechanisms:
  - target: Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Kcne1-/- mice lack Kcne1 expression in strial marginal cells and
      vestibular dark cells, the same cell types that express the KCNQ1/KCNE1
      complex in humans, and show abnormal endolymphatic-space development.
    limitations: >-
      Mouse cochlear structure, developmental timing, and the extent of
      vestibular involvement are not identical to human JLNS2; no
      genotype-confirmed human vestibular data exist for direct comparison
      (see the HUMAN_MODEL_MISMATCH discussion on this node).
    evidence:
    - reference: PMID:33514733
      reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Both Kcne1−/− and Kcnq1−/− mice exhibit an abnormal development of the endolymphatic space, severe degeneration of the hair cells (HCs), and spiral ganglion neurons (SGNs)"
      explanation: >-
        Supports treating the Kcne1-/- mouse as informative for the
        strial-marginal-cell potassium-secretion node: it reproduces the
        expected downstream endolymphatic and hair-cell consequences of losing
        the same channel complex.
    readouts:
    - name: Reissner's membrane and vestibular wall collapse
      target: Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells
      direction: RESTORED
      interpretation: >-
        Early AAV1-CB7-Kcne1 gene therapy via the posterior semicircular canal
        prevented collapse of Reissner's membrane and the vestibular wall and
        preserved normal semicircular canal size, demonstrating the causal role
        of Kcne1 loss in this structural degeneration.
      evidence:
      - reference: PMID:33514733
        reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Results showed early treatment prevented collapse of the Reissner's membrane and vestibular wall, retained the normal size of the semicircular canals, and prevented the degeneration of inner ear cells."
        explanation: >-
          Rescue experiment demonstrating that structural cochlear/vestibular
          degeneration in Kcne1-/- mice is caused by loss of Kcne1 function.
    - name: Auditory brainstem response threshold
      target: Loss of IKs-Mediated Potassium Secretion in Stria Vascularis Marginal Cells
      direction: RESTORED
      interpretation: >-
        High-dosage gene therapy preserved auditory function in 16 of 20
        treated Kcne1-/- mice for at least five months, supporting a causal
        link between restored strial Kcne1 expression and preserved hearing.
      evidence:
      - reference: PMID:33514733
        reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "In a dose-dependent manner, the treatment preserved auditory (16 out of 20 mice) and vestibular (20/20) functions in mice treated with the high-dosage for at least five months."
        explanation: >-
          Dose-dependent, quantitative auditory and vestibular functional
          rescue data from the Kcne1-/- mouse gene-therapy study.
  evidence:
  - reference: PMID:33514733
    reference_title: "Gene therapy via canalostomy approach preserves auditory and vestibular functions in a mouse model of Jervell and Lange-Nielsen syndrome type 2."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Mutations in voltage-gated potassium channel KCNE1 cause Jervell and Lange-Nielsen syndrome type 2 (JLNS2), resulting in congenital deafness and vestibular dysfunction. We conducted gene therapy by injecting viral vectors using the canalostomy approach in Kcne1-/- mice to treat both the hearing and vestibular symptoms."
    explanation: >-
      Establishes the Kcne1-/- mouse as a genetically precise model of the
      human KCNE1 loss-of-function lesion underlying JLNS2.
diagnosis:
- name: Combined Clinical and Molecular Diagnostic Criteria
  description: >-
    JLNS2 is diagnosed by the combination of the characteristic phenotype
    (congenital sensorineural deafness plus a prolonged QT interval) and
    confirmatory molecular testing showing biallelic pathogenic KCNE1
    variants.
  results: >-
    A child presenting with congenital sensorineural deafness and a
    prolonged QT interval, in whom molecular testing identifies biallelic
    pathogenic KCNE1 (or KCNQ1) variants, meets the diagnostic criteria for
    JLNS.
  diagnosis_term:
    preferred_term: clinical assessment
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  evidence:
  - reference: PMID:20301579
    reference_title: "Jervell and Lange-Nielsen Syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of JLNS is established in a child with congenital sensorineural deafness, long QT interval, and presence of biallelic pathogenic variants in either KCNQ1 or KCNE1."
    explanation: >-
      GeneReviews states the combined clinical-plus-molecular diagnostic
      criteria for JLNS, of which the KCNE1 arm defines JLNS2.
- name: Molecular Genetic Testing
  description: >-
    Molecular confirmation of biallelic KCNE1 pathogenic variants is
    required to distinguish JLNS2 from JLNS1 (biallelic KCNQ1) and from
    heterozygous KCNE1-related dominant LQT5, which lacks congenital
    deafness.
  results: >-
    Detection of two pathogenic KCNE1 alleles (homozygous or compound
    heterozygous) in trans confirms JLNS2 and distinguishes it from the
    allelic dominant LQT5 phenotype, in which only one KCNE1 allele is
    affected.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
  evidence:
  - reference: PMID:30461122
    reference_title: "Mutational and phenotypic spectra of KCNE1 deficiency in Jervell and Lange-Nielsen Syndrome and Romano-Ward Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "heterozygotes for loss-of-function variants of KCNE1 may have normal QT intervals while biallelic null alleles are associated with JLNS2"
    explanation: >-
      Establishes that molecular zygosity (biallelic versus heterozygous) is
      the diagnostic feature that separates JLNS2 from the milder dominant
      KCNE1 phenotype.
- name: Resting Electrocardiography with QTc Assessment
  description: >-
    Baseline 12-lead ECG measurement of the corrected QT interval is the core
    diagnostic procedure for identifying the QT-prolongation component of
    JLNS2.
  results: >-
    A markedly prolonged QTc, usually >500 msec in JLNS, supports the
    cardiac component of the diagnosis.
  diagnosis_term:
    preferred_term: clinical assessment
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  notes: >-
    NCIT does not provide an ECG-specific diagnostic term here, so the
    preferred term is narrowed in the name and description.
  evidence:
  - reference: DOI:10.3390/children11050582
    reference_title: "Congenital Long QT Syndrome in Children and Adolescents: A General Overview"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "characterized by a prolongation of QTc interval on ECG"
    explanation: >-
      A 2024 congenital LQTS review states that ECG-measured QTc
      prolongation is the defining diagnostic feature of the QT-prolongation
      component shared by all congenital LQTS subtypes, including JLNS.
clinical_trials:
- name: NCT06534671
  phase: PHASE_IV
  status: COMPLETED
  description: >-
    A single-participant Vanderbilt University Medical Center trial testing
    the acute effect of a single intravenous dose of diltiazem, a calcium
    channel blocker, on the QT interval in a genetically confirmed JLNS
    patient. The trial's public summary does not specify whether the
    participant carried KCNQ1 or KCNE1 variants, so it is recorded here as
    JLNS-wide (not confirmed JLNS2-specific) evidence.
  target_phenotypes:
  - preferred_term: Prolonged QT interval
    term:
      id: HP:0001657
      label: Prolonged QT interval
  evidence:
  - reference: clinicaltrials:NCT06534671
    reference_title: "Diltiazem in Jervell and Lange-Nielsen Syndrome"
    supports: SUPPORT
    snippet: "This study will test the effect of diltiazem, a calcium channel blocking drug, on the QT interval in patients with Jervell and Lange-Nielsen syndrome. This will be a single IV dose and acute effects (within minutes) will be observed."
    explanation: >-
      ClinicalTrials.gov summary of the only identified JLNS-specific
      interventional trial testing a candidate acute QT-shortening agent.
  notes: >-
    Completed October 2024 with a single enrolled participant; no
    peer-reviewed efficacy results have been identified. Experimental, not a
    standard-of-care treatment; not added to the treatments section pending
    published results.
datasets: []
references:
- reference: PMID:20301579
  title: Jervell and Lange-Nielsen Syndrome.
  tags:
  - GeneReviews
  findings: []
📚

References & Deep Research

References

1
Jervell and Lange-Nielsen Syndrome.
No top-level findings curated for this source.

Deep Research

1
Falcon
Disease Characteristics Research Template
Edison Scientific Literature 18 citations 2026-08-17T21:18:40.900844

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

  • Disease Name: Jervell and Lange-Nielsen Syndrome 2
  • MONDO ID: (if available)
  • Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Jervell and Lange-Nielsen Syndrome 2 covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.


1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

  • What is the disease? Provide a concise overview.
  • What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
  • What are the common synonyms and alternative names?
  • Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

  • Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
  • Risk Factors:

    Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases

  • Genetic risk factors (causal variants, susceptibility loci, modifier genes)
  • Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
  • Protective Factors:

    Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases

  • Genetic protective factors (protective variants, modifier alleles)
  • Environmental protective factors (diet, lifestyle, exposures that reduce risk)
  • Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

    Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

  • Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

    Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene

  • Pathogenic Variants:
  • Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
  • Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
  • Variant type/class (missense, frameshift, nonsense, splice-site, structural)
  • Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
  • Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
  • Functional consequences (loss of function, gain of function, dominant negative)
  • Modifier Genes: Genes that modify disease severity or expression
  • Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

    Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

  • Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

    Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases

  • Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

    Search first: CDC databases, WHO, PubMed, NHANES

  • Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

    Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

  • Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

    Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc

  • Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

    Search first: Gene Ontology (GO), Reactome, KEGG, PubMed

  • Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

    Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold

  • Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

    Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA

  • Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

    Search first: ImmPort, Immunome Database, IEDB, Gene Ontology

  • Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

    Search first: PubMed, Gene Ontology, Reactome

  • Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

    Search first: BRENDA, UniProt, KEGG, OMIM, PubMed

  • Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Molecular Profiling (if available):
  • Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
  • Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
  • Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
  • Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
  • Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
  • Advanced Technologies (if applicable):
  • Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
  • Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
  • Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
  • Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

  • Organ Level:
  • Primary organs directly affected
  • Secondary organ involvement (complications, secondary effects)
  • Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

    Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT

  • Tissue and Cell Level:
  • Specific tissue types affected (epithelial, connective, muscle, nervous)
  • Specific cell populations targeted (with Cell Ontology terms)

    Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB

  • Subcellular Level:
  • Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

    Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas

  • Localization:
  • Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
  • Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

  • Onset:
  • Typical age of onset (congenital, pediatric, adult, geriatric)
  • Onset pattern (acute, subacute, chronic, insidious)

    Search first: OMIM, Orphanet, HPO, PubMed

  • Progression:
  • Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
  • Progression rate (rapid, slow, variable)
  • Disease course pattern (episodic, relapsing-remitting, progressive, stable)
  • Disease duration (self-limited, chronic lifelong)

    Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM

  • Patterns:
  • Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
  • Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

  • Epidemiology:
  • Prevalence (cases per 100,000 at given time)
  • Incidence (new cases per 100,000 per year)

    Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries

  • For Genetic Etiology:
  • Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
  • Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
  • Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
  • Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
  • Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
  • Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
  • Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
  • Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
  • Population Demographics:
  • Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
  • Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
  • Geographic distribution of specific variants
  • Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
  • Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

  • Clinical Tests:
  • Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
  • Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
  • Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
  • Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
  • Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
  • Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
  • Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
  • Genetic Testing:

    Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen

  • Overview of recommended genetic testing approach
  • Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
  • Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
  • Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
  • Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
  • Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
  • Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
  • FISH > Search first: ClinVar, cytogenetics databases, PubMed
  • Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
  • Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
  • Omics-Based Diagnostics (if applicable):
  • RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
  • Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
  • Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
  • Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
  • Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
  • Clinical Criteria:
  • Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
  • Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
  • Screening:
  • Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

  • Survival and Mortality:
  • Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
  • Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
  • Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
  • Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
  • Morbidity and Function:
  • Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
  • Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
  • Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
  • Disease Course:
  • Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
  • Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
  • Prediction:
  • Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
  • Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

  • Pharmacotherapy:
  • Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
  • Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
  • Advanced Therapeutics:
  • Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
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  • Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
  • Surgical and Interventional:
  • Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
  • Supportive and Rehabilitative:
  • Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
  • Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
  • Experimental:
  • Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
  • Treatment Outcomes:
  • Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
  • Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
  • Treatment Strategy:
  • Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
  • Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
  • Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest NCIT (NCI Thesaurus) clinical-intervention terms where applicable.

13. Prevention

  • Prevention Levels:
  • Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
  • Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
  • Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
  • Immunization: Vaccine strategies (if applicable)

    Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database

  • Screening and Early Detection:
  • Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
  • Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
  • Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
  • Behavioral Interventions: Lifestyle modifications to reduce risk

    Search first: CDC, WHO, behavioral intervention databases, Cochrane Library

  • Counseling: Genetic counseling (risk assessment, family planning guidance)

    Search first: NSGC resources, ACMG guidelines, GeneReviews

  • Public Health:
  • Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
  • Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
  • Prophylaxis: Preventive medications or procedures

    Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

  • Taxonomy: Species affected (with NCBI Taxon identifiers)

    Search first: NCBI Taxonomy

  • Breed: Specific breeds affected (with VBO identifiers if applicable)

    Search first: VBO (Vertebrate Breed Ontology)

  • Gene: Orthologous genes in other species (with NCBI Gene IDs)

    Search first: NCBI Gene

  • Natural Disease:
  • Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
  • Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
  • Comparative Biology:
  • Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
  • Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
  • Transmission (if applicable):
  • Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
  • Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

  • Model Types:
  • Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
  • Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
  • Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
  • Genetic Models:
  • Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
  • Model Characteristics:
  • Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
  • Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
  • Applications:
  • Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
  • Resources:
  • Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic and clinical claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes from abstracts where possible to support key statements
  • Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, NCIT, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (NCIT terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Jervell and Lange-Nielsen syndrome 2: disease-characteristics report

Executive summary and evidence scope

Jervell and Lange-Nielsen syndrome 2 (JLNS2) is an exceptionally rare, severe, autosomal-recessive cardio-auditory channelopathy caused by biallelic pathogenic loss-of-function variants in KCNE1. Its defining combination is congenital, usually profound bilateral sensorineural hearing loss and long-QT syndrome (LQTS), which predisposes to torsades de pointes, ventricular fibrillation, syncope, seizure-like episodes, cardiac arrest, and sudden death. It must be distinguished from JLNS1, caused by biallelic KCNQ1 variants, and from autosomal-dominant KCNE1-related Romano-Ward syndrome/LQT5, which lacks congenital deafness. The strongest JLNS2-specific clinical evidence remains small family series rather than large cohorts; therefore, numerical prognosis and most treatment recommendations necessarily derive from JLNS overall or congenital LQTS guidance and are labeled accordingly. (faridi2019mutationalandphenotypic pages 9-11, faridi2019mutationalandphenotypic pages 8-9, faridi2019mutationalandphenotypic pages 1-3)

Domain Database-ready summary Key ontology / identifiers Evidence type Key citations
Identity Jervell and Lange-Nielsen syndrome 2 (JLNS2) is a rare cardio-auditory channelopathy defined by congenital profound bilateral sensorineural hearing loss plus long-QT syndrome with risk of ventricular arrhythmia and sudden death; it is distinct from JLNS1, which is caused by biallelic KCNQ1 variants. OMIM: 612347; MONDO: disease-level JLNS available as MONDO_0002441; HPO candidates: congenital sensorineural hearing impairment, long QT interval Human clinical families; disease-gene curation (faridi2019mutationalandphenotypic pages 1-3, OpenTargets Search: Jervell and Lange-Nielsen syndrome-KCNE1)
Causal gene / inheritance Cause: biallelic loss-of-function variants in KCNE1, encoding the potassium voltage-gated channel subfamily E regulatory subunit 1, an accessory subunit for KCNQ1/Kv7.1. Inheritance is autosomal recessive; heterozygous loss-of-function carriers may have normal hearing and normal QT, while some heterozygous missense alleles can cause Romano-Ward syndrome via dominant-negative effects. Gene: KCNE1; HGNC-approved symbol: KCNE1; HPO candidate: autosomal recessive inheritance Human clinical genetics; mechanistic interpretation (faridi2019mutationalandphenotypic pages 1-3, faridi2019mutationalandphenotypic pages 8-9, faridi2019mutationalandphenotypic pages 9-11)
Cardinal phenotypes Core phenotype is congenital, severe-to-profound, bilateral sensorineural deafness with prolonged QTc. Reported JLNS2 families had QTcF about 487-495 ms and QTcB about 503-518 ms; syncopal events may be absent in some genetically confirmed cases, so hearing-loss-first presentation is possible. HPO candidates: profound sensorineural hearing impairment; bilateral hearing impairment; long QT interval; syncope; sudden cardiac death Human clinical families (faridi2019mutationalandphenotypic pages 8-9, faridi2019mutationalandphenotypic pages 1-3)
Mechanism / pathophysiology Upstream defect: KCNE1 deficiency impairs the IKs channel complex with KCNQ1. In heart, reduced repolarizing current delays ventricular repolarization, prolonging QT and increasing torsades/ventricular arrhythmia risk. In inner ear stria vascularis, KCNE1/KCNQ1 dysfunction disrupts K+ secretion into endolymph and collapses the endocochlear potential required for hair-cell depolarization, causing deafness; paralog compensation appears insufficient in inner ear. GO candidates: potassium ion transmembrane transport; regulation of cardiac action potential repolarization; sensory perception of sound; CL candidate: strial marginal cell; UBERON candidate: stria vascularis, cochlea, heart ventricle Human molecular genetics; animal model; auditory cell biology (faridi2019mutationalandphenotypic pages 9-11, faridi2019mutationalandphenotypic pages 3-4)
Diagnostic anchors Diagnostic confirmation rests on syndromic phenotype plus ECG and molecular testing. Contemporary congenital LQTS anchors: QTc ≥480 ms, or modified Schwartz score >3; in symptomatic patients, QTc ≥460 ms can suffice. Because a proportion of gene-confirmed LQTS can have normal-range resting QTc, KCNE1-inclusive NGS panels/exome testing are important in deaf children or families with cardio-auditory findings. HPO candidates: abnormal electrocardiogram, long QT interval; test concepts: ECG, molecular genetic testing Human clinical guidelines/review; human genetic diagnosis (balestra2024congenitallongqt pages 4-5, balestra2024congenitallongqt pages 5-8, qiu2020jervellandlangenielsen pages 1-2)
Standard management Management is largely extrapolated from congenital LQTS/JLNS practice: nonselective beta-blockers (nadolol or propranolol) are first-line; avoidance of QT-prolonging drugs and trigger management are standard. ICD is recommended after cardiac arrest and considered for persistent symptoms despite beta-blockers; left cardiac sympathetic denervation is used when events recur or ICD is unsuitable. Cochlear implantation can improve hearing, but peri-anesthetic arrhythmia risk requires careful planning and monitoring. NCIT candidates: Beta Adrenergic Receptor Blocking Agent Therapy; Implantable Cardioverter Defibrillator; Sympathectomy; Cochlear Implantation Guidelines/review; case report real-world implementation (balestra2024congenitallongqt pages 5-8, balestra2024congenitallongqt pages 8-9, qiu2020jervellandlangenielsen pages 5-7)
Emerging research / latest developments Recent work emphasizes precision medicine in congenital LQTS using patient-specific iPSC-derived cardiomyocytes, CRISPR-enabled variant validation, and high-throughput drug testing. A completed 2024 phase 4 JLNS trial tested acute IV diltiazem effects on QT interval in 1 genetically confirmed adult participant; results were submitted for publication after trial completion. Research concepts: iPSC disease modeling; CRISPR genome editing; ClinicalTrials.gov NCT06534671 In vitro precision-medicine review; clinical trial (yu2023precisionmedicinefor pages 1-2, yu2023precisionmedicinefor pages 7-8, NCT06534671 chunk 1)
Major evidence gaps JLNS2-specific epidemiology, penetrance, carrier frequency, founder-variant frequencies, longitudinal survival, quality-of-life metrics, and genotype-specific treatment outcomes remain sparse because published evidence is limited to few families/case-based data. No confident JLNS2-specific epigenomic, transcriptomic, proteomic, metabolomic, or large natural-history datasets were identified in the retrieved evidence. No supported disease-specific ontology additions beyond above Evidence-gap synthesis (faridi2019mutationalandphenotypic pages 1-3, faridi2019mutationalandphenotypic pages 8-9, NCT06534671 chunk 1)

Table: This table summarizes the most actionable database-ready facts for Jervell and Lange-Nielsen syndrome 2, including identity, gene, mechanism, diagnosis, management, recent research, and explicit evidence gaps. It is designed to support structured knowledge-base entry creation while avoiding unsupported identifiers.

1. Disease information

Definition and identifiers

  • Preferred name: Jervell and Lange-Nielsen syndrome 2
  • Synonyms: JLNS2; Jervell and Lange-Nielsen syndrome type 2; KCNE1-related Jervell–Lange-Nielsen syndrome; autosomal-recessive long-QT syndrome with deafness caused by KCNE1.
  • OMIM: 612347.
  • MONDO: The retrieved disease-level record is MONDO:0002441, Jervell and Lange-Nielsen syndrome. A securely verified subtype-specific MONDO identifier for JLNS2 was not recovered; the knowledge base should not substitute the JLNS1 record MONDO:0024540.
  • Orphanet: JLNS is represented as a rare syndromic long-QT disorder, but a securely verified type-2-specific ORPHA identifier was not recovered in this search.
  • ICD-10/ICD-11: No dedicated JLNS2 code was identified. Coding generally combines congenital long-QT syndrome/cardiac arrhythmia and sensorineural hearing-loss concepts.
  • MeSH: No securely verified JLNS2-specific descriptor was identified; “Long QT Syndrome” and “Hearing Loss, Sensorineural” are appropriate indexing concepts.

Open Targets identifies KCNE1 (ENSG00000180509) as the principal evidence-supported target for the general JLNS record, with an association score of 0.804 and supporting literature including PMID 30461122. Low-scoring neighboring-gene associations in that resource should not be interpreted as additional causal JLNS2 genes. (OpenTargets Search: Jervell and Lange-Nielsen syndrome-KCNE1)

The information here is aggregated disease-level evidence from literature, disease resources, and trial registries. Individual-patient evidence appears only in published family/case reports and is not derived from an accessible EHR cohort.

2. Etiology, risk, and protective factors

Primary cause

JLNS2 results from germline biallelic KCNE1 pathogenic variants, usually homozygous in consanguineous families or compound heterozygous. KCNE1 encodes the minK regulatory β-subunit of the KCNQ1/Kv7.1 potassium channel complex. Biallelic loss reduces the slow delayed-rectifier potassium current, I(Ks). (faridi2019mutationalandphenotypic pages 9-11, faridi2019mutationalandphenotypic pages 1-3)

The key publication states directly: “Both KCNE1 and KCNQ1 are necessary for normal hearing and cardiac ventricular repolarization” and that “biallelic null alleles are associated with JLNS2.” This is human clinical-genetic evidence from Faridi et al., Human Mutation, published December 2019, PMID 30461122, DOI: https://doi.org/10.1002/humu.23689. (faridi2019mutationalandphenotypic pages 1-3)

Genetic risk factors

  • Two pathogenic/likely pathogenic alleles in trans are the defining risk factor.
  • Published homozygous nonsense alleles include NM_000219:c.50G>A (p.Trp17Ter), c.51G>A (p.Trp17Ter), and c.138C>A (p.Tyr46Ter). These are predicted null alleles producing severe N-terminal truncation. (faridi2019mutationalandphenotypic pages 8-9, faridi2019mutationalandphenotypic pages 1-3)
  • Missense, splice, frameshift, and other truncating variants can be disease-causing, but each should be classified under current ACMG/AMP and ClinGen specifications rather than assumed pathogenic solely because it occurs in KCNE1.
  • Heterozygous relatives carrying a null allele may have normal hearing and normal QT. Conversely, some heterozygous missense variants produce autosomal-dominant LQTS/Romano-Ward syndrome through a dominant-negative effect. Thus, dosage, variant mechanism, and functional evidence matter. (faridi2019mutationalandphenotypic pages 8-9, faridi2019mutationalandphenotypic pages 1-3)
  • The common KCNE1 p.Asp85Asn allele can modify repolarization in broader LQTS populations, but it is not by itself an established cause of recessive JLNS2 in the evidence reviewed.

Population allele frequencies must be retrieved variant-by-variant from the current gnomAD release. A single JLNS2-wide carrier frequency cannot be assigned from the available evidence. Causal alleles are expected to be individually rare; variants too common for a severe recessive cardio-auditory disorder require reassessment.

Modifiers, environment, and protection

No JLNS2-specific modifier gene has been validated. Variability among individuals with KCNE1 deficiency implies additional genetic, physiologic, treatment, or exposure modifiers, but the evidence is insufficient for a curated modifier annotation. The apparent capacity of other KCNE paralogs to compensate partially in heart—but not in inner ear—is a mechanistic hypothesis, not a clinically validated protective genotype. (faridi2019mutationalandphenotypic pages 8-9, faridi2019mutationalandphenotypic pages 3-4)

Environmental factors do not cause JLNS2, but can expose its arrhythmia substrate. Relevant triggers include exertion, swimming, emotional stress, sudden auditory stimuli, fever, electrolyte depletion, anesthesia, and QT-prolonging medication. Maintaining normal potassium and magnesium, avoiding QT-prolonging drugs, adherence to β-blockade, and trigger-specific precautions reduce event risk but do not prevent congenital deafness or remove the genotype. (balestra2024congenitallongqt pages 5-8, balestra2024congenitallongqt pages 4-5, qiu2020jervellandlangenielsen pages 5-7)

Smoking, diet, alcohol, infection, pollution, radiation, and occupational exposure have no established etiologic role. Infection matters only indirectly through fever, dehydration, electrolyte disturbance, or exposure to QT-prolonging antimicrobials.

3. Phenotypes

Cardinal manifestations

Phenotype Type and course Frequency/evidence Suggested HPO term
Congenital bilateral sensorineural deafness Physical/functional; present at birth, severe-to-profound and generally permanent Defining feature in reported JLNS2; homozygous null families had severe-to-profound deafness Congenital sensorineural hearing impairment; profound sensorineural hearing impairment; bilateral hearing impairment
Long QT interval ECG abnormality; congenital substrate, magnitude can vary over time and with rate/exposure Defining cardiac feature; reported QTcF 487–495 ms and QTcB 503–518 ms HP:0001657 Long QT interval
Ventricular tachyarrhythmia/torsades Episodic, potentially fatal Recognized disease risk; sparse JLNS2-specific frequency data Ventricular tachycardia; torsade de pointes
Syncope Episodic, often triggered; may begin in childhood Variable; absent in some molecularly confirmed null-allele individuals HP:0001279 Syncope
Seizure-like episodes Symptom, usually cerebral hypoperfusion rather than primary epilepsy Reported in JLNS and frequently causes diagnostic delay Seizure; episodic loss of consciousness
Cardiac arrest/sudden cardiac death Acute complication Major untreated risk, but no reliable JLNS2-only percentage Cardiac arrest; sudden cardiac death
Vestibular dysfunction Clinical sign; variable Supported in JLNS and Kcne1-null animals, but JLNS2 human frequency is unknown Vestibular dysfunction

The Faridi families show why symptoms cannot be used to exclude disease: individuals with profound deafness and QTcB 503–518 ms reported no syncope. (faridi2019mutationalandphenotypic pages 8-9)

Quality of life

Profound prelingual deafness affects language acquisition, education, communication, social participation, and caregiver burden. Cardiac risk imposes medication, exercise, medication-screening, emergency-planning, and procedural-anesthesia burdens. ICD shocks and activity restriction may add psychological morbidity. No JLNS2-specific EQ-5D, SF-36, PROMIS, or disease-specific quality-of-life dataset was found.

4. Genetic and molecular information

  • Gene: KCNE1; approved name potassium voltage-gated channel subfamily E regulatory subunit 1; Ensembl ENSG00000180509.
  • Disease locus: chromosome 21q22 region.
  • Origin: germline; somatic variation is not a recognized cause.
  • Inheritance: autosomal recessive.
  • Functional class: predominantly loss of function; null alleles produce absence or severe deficiency of functional KCNE1. Some heterozygous missense alleles have a distinct dominant-negative mechanism and should be annotated as Romano-Ward/LQT5 rather than JLNS2 unless a second pathogenic allele is present. (faridi2019mutationalandphenotypic pages 9-11, faridi2019mutationalandphenotypic pages 8-9)
  • Chromosomal abnormalities: no recurrent aneuploidy, translocation, inversion, or copy-number syndrome was established as a typical cause. Exon-level deletion/duplication analysis remains relevant when sequence analysis finds one or no allele.
  • Epigenetics: no reproducible JLNS2-specific DNA methylation, histone, or chromatin signature was found.
  • Anticipation: not expected and not reported.
  • Mosaicism: no characteristic germline-mosaic pattern is established; low residual recurrence from parental germline mosaicism is theoretically possible in apparently de novo cases.

Penetrance for congenital deafness appears high with biallelic null variants, whereas cardiac severity and events show variable expressivity. Precise age-dependent penetrance estimates are unavailable.

5. Environmental and lifestyle information

JLNS2 is not infectious, toxic, nutritional, occupational, or lifestyle-caused. Clinically important interactions are mainly arrhythmia triggers:

  1. adrenergic surges from vigorous exercise or emotional stress;
  2. swimming, especially unsupervised;
  3. fever, vomiting, diarrhea, fasting, or other causes of electrolyte disturbance;
  4. medications listed as QT-prolonging or torsadogenic;
  5. perioperative stress and anesthetic drugs/interactions.

A published cochlear-implant case with biallelic KCNQ1—therefore JLNS1, not JLNS2—developed life-threatening arrhythmia around anesthesia. It demonstrates a clinically plausible JLNS-wide procedural hazard but cannot establish a JLNS2-specific event rate. Defibrillation capability, continuous monitoring, electrolyte optimization, continuation/planning of cardiac medication, and coordination among electrophysiology, anesthesia, and otology teams are prudent. (qiu2020jervellandlangenielsen pages 5-7, qiu2020jervellandlangenielsen pages 1-2)

6. Mechanism and pathophysiology

Causal chain in heart

Biallelic KCNE1 loss → deficient KCNE1–KCNQ1 channel complex → reduced/altered I(Ks) → impaired phase-3 ventricular repolarization and reduced repolarization reserve → prolonged action potential and QTc → early afterdepolarizations and spatial dispersion → torsades de pointes/ventricular fibrillation → syncope, hypoxic convulsion, cardiac arrest, or sudden death.

Relevant cells are ventricular cardiomyocytes. Suggested terms include CL:0000746 cardiac muscle cell/cardiomyocyte, GO “potassium ion transmembrane transport,” “regulation of cardiac muscle cell action potential,” “cardiac muscle cell action potential involved in contraction,” and “membrane repolarization during cardiac action potential.” The relevant subcellular compartment is the plasma membrane and voltage-gated potassium-channel complex.

Causal chain in inner ear

Biallelic KCNE1 loss → defective apical KCNQ1/KCNE1 current in strial marginal cells → impaired potassium secretion into scala-media endolymph → loss of the positive endocochlear potential and potassium homeostasis → failure of hair-cell depolarization plus secondary Reissner-membrane collapse/hair-cell degeneration → congenital profound sensorineural deafness. KCNE paralogs apparently do not compensate adequately in the inner ear. (faridi2019mutationalandphenotypic pages 9-11, faridi2019mutationalandphenotypic pages 3-4)

Suggested annotations are GO “potassium ion transport,” “sensory perception of sound,” and “inner ear development”; CL “strial marginal cell,” “inner hair cell,” and “outer hair cell”; and UBERON “cochlea,” “stria vascularis,” “scala media,” “endolymph,” “organ of Corti,” and “Reissner membrane.”

There is no established primary immune, inflammatory, fibrotic, neoplastic, or metabolic mechanism. Tissue injury in the cochlea is downstream of ionic failure rather than autoimmunity or infection.

Molecular profiling and advanced technologies

No disease-defining JLNS2 transcriptomic, proteomic, metabolomic, lipidomic, single-cell, spatial-transcriptomic, or multi-omic signature was identified. Current LQTS precision research uses patient-specific induced pluripotent stem cell-derived cardiomyocytes, whole-genome sequencing, CRISPR correction/engineering, machine learning, and high-throughput drug testing. These platforms can test causality and variant-specific responses, but they are research tools rather than validated JLNS2 diagnostics or treatments. The 2023 review’s abstract states that “Deep phenotyping and high-throughput drug testing using LQTS patient-specific cardiomyocytes herald the upcoming precision medicine in LQTS.” Publication: January 2023; DOI: https://doi.org/10.1017/erm.2022.43. (yu2023precisionmedicinefor pages 1-2, yu2023precisionmedicinefor pages 7-8)

7. Anatomical structures affected

  • Primary organ systems: cardiovascular and auditory/vestibular systems.
  • Heart: ventricular myocardium/electrical conduction at the cardiomyocyte-membrane level; the heart is generally structurally normal.
  • Inner ear: bilateral cochleae, especially stria vascularis and scala-media ionic environment; secondary organ-of-Corti hair-cell degeneration may occur.
  • Vestibular labyrinth: possible involvement through analogous potassium-secreting dark cells.
  • Secondary brain effects: transient cerebral hypoperfusion during arrhythmia can cause syncope or convulsive movements; primary epilepsy is not intrinsic to JLNS2.
  • Lateralization: auditory involvement is typically bilateral, not unilateral or asymmetric.

Suggested UBERON terms: heart, cardiac ventricle, ventricular myocardium, inner ear, cochlea, cochlear duct, stria vascularis, organ of Corti, and vestibular labyrinth. Suggested GO cellular components: plasma membrane, voltage-gated potassium-channel complex, and KCNQ1–KCNE1 complex where supported.

8. Temporal development

The molecular defect is present from conception. Hearing loss is congenital and lifelong. QT prolongation is congenital or detectable in infancy/childhood, although resting QTc and clinical expression can fluctuate. Arrhythmic events are episodic and trigger-dependent rather than steadily progressive. The disorder itself is lifelong; there is no spontaneous remission of the genotype or deafness.

Critical windows are:

  • newborn/early-childhood hearing assessment, before language delay;
  • the first ECG after detection of congenital profound deafness;
  • initiation and adherence to β-blockade before a sentinel arrhythmia;
  • illness, electrolyte disturbance, swimming/exertion, and perioperative periods;
  • cascade testing after identification of a proband.

QTc above 500 ms is generally high risk and above 600 ms extremely high risk in congenital LQTS. Syncope before age seven predicts recurrent events despite β-blockade in broader LQTS data. (balestra2024congenitallongqt pages 4-5)

9. Inheritance and population

JLNS2 is autosomal recessive: for two carrier parents, each pregnancy has a 25% probability of an affected child, 50% probability of a heterozygous child, and 25% probability of inheriting neither familial allele. Both sexes should be affected equally.

JLNS overall has been estimated at roughly 1 per 200,000 to 1 per 1,000,000, but this range is not JLNS2-specific and likely varies with consanguinity and founder effects. Approximately 90% of JLNS in some series is attributed to KCNQ1, making KCNE1-related JLNS2 the minority subtype. (faridi2019mutationalandphenotypic pages 1-3, qiu2020jervellandlangenielsen pages 1-2)

Consanguinity increases the probability that two relatives carry the same rare allele; the reported p.Trp17Ter and p.Tyr46Ter homozygotes were found in consanguineous Pakistani families. This is ascertainment evidence, not proof of restriction to any ancestry. (faridi2019mutationalandphenotypic pages 8-9)

No robust JLNS2-specific incidence, prevalence, sex ratio, carrier frequency, geographic distribution, or founder-allele frequency was identified. Such fields should be recorded as unknown, not populated using all-JLNS or all-LQTS estimates.

10. Diagnostics

Clinical work-up

  1. History: congenital deafness, exertional/emotional/sudden-noise syncope, apparent seizures, resuscitated arrest, unexplained drowning, sudden death, medication exposure, and three-generation pedigree.
  2. ECG: manual QT measurement and heart-rate correction, preferably serial studies. Contemporary congenital LQTS criteria include QTc ≥480 ms or modified Schwartz score >3; QTc ≥460 ms can support diagnosis in a patient with arrhythmic syncope or cardiac arrest. (balestra2024congenitallongqt pages 4-5)
  3. Additional electrophysiology: Holter/event monitoring and exercise/recovery ECG can reveal dynamic abnormalities. Echocardiography helps exclude structural disease but is usually not diagnostic.
  4. Audiology: newborn auditory brainstem response, otoacoustic emissions, pure-tone audiometry when developmentally appropriate, speech/language assessment, and cochlear-implant evaluation.
  5. Laboratory testing: potassium, magnesium, calcium, renal function, and thyroid studies identify acquired contributors; there is no diagnostic serum biomarker or enzyme assay.

A normal resting QTc does not exclude inherited LQTS: recent reviews estimate 20–25%, and in some selected genetically confirmed series up to approximately 40%, may have normal-range resting QTc. These differing figures reflect study populations and should not be treated as a JLNS2-specific frequency. (balestra2024congenitallongqt pages 5-8, yu2023precisionmedicinefor pages 1-2, yu2023precisionmedicinefor pages 2-2)

Genetic testing

The preferred approach is a validated hereditary arrhythmia or combined hearing-loss/cardio-auditory panel including at minimum KCNE1 and *KCNQ1*, with deletion/duplication analysis. A broad hearing-loss panel that omits arrhythmia genes can miss the life-threatening diagnosis. If panel testing is negative or the phenotype is atypical, exome or genome sequencing with copy-number and splice-aware analysis is appropriate. Sanger sequencing is useful for confirmation and segregation.

CMA, karyotype, FISH, mitochondrial sequencing, and repeat-expansion testing are not first-line unless other clinical findings suggest an alternative disorder. RNA analysis may clarify suspected splice variants but is not routine. Variant interpretation must incorporate allele frequency, segregation, phenotype, functional data, and ACMG/AMP criteria; a VUS does not independently confirm JLNS2.

Differential diagnosis

  • JLNS1: identical cardinal phenotype, but biallelic KCNQ1 variants.
  • Romano-Ward/LQT5: heterozygous KCNE1 variant, long QT without congenital profound deafness.
  • Other congenital LQTS subtypes plus unrelated genetic deafness.
  • Acquired QT prolongation from medication, hypokalemia, hypomagnesemia, hypocalcemia, or bradycardia.
  • Nonsyndromic hearing loss, including GJB2, STRC, or other causes, without intrinsic long QT.
  • Pendred syndrome, Usher syndrome, mitochondrial deafness, and congenital infection.
  • Epilepsy when convulsive syncope is the true mechanism.

Screening

All infants with severe/profound congenital hearing loss should receive an ECG or prompt cardiac assessment where JLNS is plausible. Once familial variants are known, targeted cascade testing is more efficient than repeated broad sequencing. At-risk relatives need ECG assessment even when hearing is normal because heterozygous missense effects and incomplete cardiac expression can complicate segregation. Prenatal diagnosis and preimplantation genetic testing are technically possible for known familial pathogenic variants.

11. Outcome and prognosis

Untreated JLNS is one of the highest-risk congenital LQTS presentations, but JLNS2-only survival and mortality curves are unavailable. Profound deafness does not spontaneously recover. Arrhythmia risk is lifelong but can be substantially reduced by early recognition, trigger avoidance, nonselective β-blockade, and escalation to device or surgical therapy when indicated.

In broader symptomatic congenital LQTS, β-blockers reportedly reduced annual mortality from approximately 60% to below 2% over the ten years after an arrhythmic event; this historical statistic is not a JLNS2-specific response rate. (balestra2024congenitallongqt pages 5-8)

Adverse prognostic features include prior cardiac arrest, recurrent syncope on therapy, very prolonged QTc, early-childhood events, poor adherence, electrolyte disturbance, QT-prolonging medication, and potentially a second arrhythmia-associated variant. Absence of previous syncope is not reassuring enough to omit treatment because molecularly confirmed JLNS2 can be asymptomatic despite QTc above 500 ms. (faridi2019mutationalandphenotypic pages 8-9, balestra2024congenitallongqt pages 4-5)

12. Treatment and current implementation

Cardiac treatment

  • Nonselective β-blockers: first-line, usually nadolol or propranolol. A recent pediatric LQTS review gives propranolol 2–3 mg/kg/day or nadolol 1–1.5 mg/kg/day, divided according to regimen. Dosing is individualized by electrophysiology specialists. β1-selective agents are generally less favored for congenital LQTS. Suggested NCIt concept: beta-adrenergic receptor blocking-agent therapy. (balestra2024congenitallongqt pages 5-8)
  • ICD: recommended after resuscitated cardiac arrest and considered for recurrent arrhythmic syncope or ventricular arrhythmia despite optimized therapy. In small children, device complications and inappropriate shocks require careful balancing. NCIt: implantable cardioverter-defibrillator procedure/device. (balestra2024congenitallongqt pages 8-9)
  • Left cardiac sympathetic denervation: appropriate when events recur despite medication, when an ICD is contraindicated/not feasible, or to reduce recurrent shocks. NCIt: sympathectomy/left cardiac sympathetic denervation. (balestra2024congenitallongqt pages 8-9, yu2023precisionmedicinefor pages 7-8)
  • Pacing: may be considered in selected patients with severe bradycardia, pause-dependent events, or as part of an individualized high-risk strategy; it is not universal JLNS2 therapy.
  • Electrolytes: promptly correct potassium and magnesium depletion. Routine potassium supplementation requires clinical supervision.
  • Avoidance: use a current QT-risk resource when prescribing; avoid unsupervised swimming and individualize exercise participation through specialist shared decision-making.

Mexiletine is genotype-directed mainly for sodium-channel LQTS3 and is not established targeted treatment for KCNE1-JLNS2. No validated pharmacogenomic dosing rule specific to KCNE1 was found.

Hearing and supportive care

Hearing aids may provide limited benefit when loss is profound. Cochlear implantation can provide useful auditory access, coupled with early speech-language therapy, educational support, and Deaf-community/family-centered communication planning. Surgery requires a JLNS-aware anesthesia protocol and continuous postoperative monitoring. The strongest retrieved procedural case was KCNQ1-related JLNS1, so efficacy and anesthesia precautions are extrapolated to JLNS2 on syndrome-wide grounds. (qiu2020jervellandlangenielsen pages 5-7)

Experimental treatment and 2023–2024 developments

No approved gene, RNA, cell, or CRISPR therapy corrects JLNS2. Patient-specific iPSC cardiomyocytes and CRISPR-based isogenic controls are being developed for functional variant adjudication and individualized drug testing, but remain preclinical. (yu2023precisionmedicinefor pages 1-2, yu2023precisionmedicinefor pages 7-8)

NCT06534671, “Diltiazem in Jervell and Lange-Nielsen Syndrome,” was a completed Phase 4 Vanderbilt study in 2024. One genetically confirmed adult received IV diltiazem 0.25 mg/kg, with a possible 0.35 mg/kg second dose, and ECG/telemetry assessment for acute QT shortening. Enrollment was one, completion was October 23, 2024, and no efficacy conclusion should be drawn without posted peer-reviewed results. Diltiazem is therefore experimental, not standard JLNS2 treatment. (NCT06534671 chunk 1)

13. Prevention

Primary prevention of the genotype is possible only through informed reproductive choices: carrier testing in at-risk relatives, genetic counseling, prenatal diagnosis, donor gametes, or preimplantation genetic testing. There is no vaccine or environmental primary prevention.

Secondary prevention consists of newborn hearing screening followed by ECG/genetic evaluation, cascade testing, early β-blockade, and identification of concealed disease. Tertiary prevention includes medication adherence, QT-drug avoidance, electrolyte management, emergency action plans, supervised exercise decisions, ICD/LCSD where indicated, and safe anesthesia planning.

Families should be counseled about autosomal-recessive recurrence, variable cardiac expression, CPR/AED access, recognition of arrhythmic syncope, and informing schools, dentists, surgeons, and anesthesiologists. Public-health sanitation or infectious-disease control is not relevant.

14. Other species and natural disease

No well-established naturally occurring veterinary syndrome equivalent to human JLNS2 was identified. There is no zoonotic potential or cross-species transmission because this is an inherited channelopathy.

Orthologous Kcne1 is conserved in laboratory mouse, Mus musculus, NCBI Taxonomy 10090. The relevant comparative biology is experimental rather than a common spontaneous veterinary disease. A spontaneous mouse nonsense allele, Kcne1^pkr (“punk rocker,” p.Arg67Ter), produces an auditory/vestibular phenotype. (faridi2019mutationalandphenotypic pages 9-11)

15. Model organisms

Three Kcne1-null mouse alleles are reported: two engineered coding-exon deletions and the spontaneous p.Arg67Ter punk-rocker allele. Homozygous animals are deaf; heterozygotes have normal hearing. Cochlear findings include collapsed Reissner membrane and hair-cell degeneration, and punk-rocker mice display head tossing consistent with vestibular dysfunction. These findings strongly recapitulate the recessive inner-ear component of human JLNS2. (faridi2019mutationalandphenotypic pages 9-11)

Cardiac recapitulation is inconsistent: one line showed longer QT at slow rates and shorter QT at fast rates, another increased inducible arrhythmia, and another no ECG difference. A major limitation is the mouse resting heart rate of approximately 500–700 beats/minute, which complicates QT measurement and makes the model less faithful for human ventricular repolarization. Mouse inner-ear architecture is much more suitable for studying the auditory mechanism. (faridi2019mutationalandphenotypic pages 9-11)

Suggested model annotations include mammalian genetic knockout, homozygous null, nonsense knock-in/spontaneous mutant, auditory brainstem response, ECG/telemetry, cochlear histopathology, strial marginal cell, hair cell, and vestibular dark cell. Patient-derived iPSC cardiomyocytes are the leading human cellular model for variant causality and drug testing, although a large JLNS2-specific iPSC dataset was not identified. (yu2023precisionmedicinefor pages 1-2)

Evidence limitations and curation cautions

  1. JLNS2 is much rarer than KCNQ1-related JLNS1; disease-wide JLNS numbers must not be assigned automatically to JLNS2.
  2. Much treatment evidence comes from congenital LQTS or JLNS overall rather than randomized JLNS2 trials.
  3. Individual variants require current ClinVar/gnomAD review; literature-level pathogenicity should not replace laboratory reclassification.
  4. No reliable JLNS2-specific incidence, carrier frequency, survival curve, quality-of-life scale, molecular-omics signature, protective allele, or approved precision therapy was found.
  5. A retrieved 2020 cochlear-implant report is JLNS1 because its patient carried biallelic KCNQ1; it supports syndrome-wide procedural practice but must not be mislabeled as genotype-confirmed JLNS2. (qiu2020jervellandlangenielsen pages 5-7, qiu2020jervellandlangenielsen pages 1-2)

References

  1. (faridi2019mutationalandphenotypic pages 9-11): Rabia Faridi, Risa Tona, Alessandra Brofferio, Michael Hoa, Rafal Olszewski, Isabelle Schrauwen, Muhammad Z.K. Assir, Akhtar A. Bandesha, Asma A. Khan, Atteeq U. Rehman, Carmen Brewer, Wasim Ahmed, Suzanne M. Leal, Sheikh Riazuddin, Steven E. Boyden, and Thomas B. Friedman. Mutational and phenotypic spectra of kcne1 deficiency in jervell and lange‐nielsen syndrome and romano‐ward syndrome. Human Mutation, 40:162-176, Dec 2019. URL: https://doi.org/10.1002/humu.23689, doi:10.1002/humu.23689. This article has 47 citations and is from a domain leading peer-reviewed journal.

  2. (faridi2019mutationalandphenotypic pages 8-9): Rabia Faridi, Risa Tona, Alessandra Brofferio, Michael Hoa, Rafal Olszewski, Isabelle Schrauwen, Muhammad Z.K. Assir, Akhtar A. Bandesha, Asma A. Khan, Atteeq U. Rehman, Carmen Brewer, Wasim Ahmed, Suzanne M. Leal, Sheikh Riazuddin, Steven E. Boyden, and Thomas B. Friedman. Mutational and phenotypic spectra of kcne1 deficiency in jervell and lange‐nielsen syndrome and romano‐ward syndrome. Human Mutation, 40:162-176, Dec 2019. URL: https://doi.org/10.1002/humu.23689, doi:10.1002/humu.23689. This article has 47 citations and is from a domain leading peer-reviewed journal.

  3. (faridi2019mutationalandphenotypic pages 1-3): Rabia Faridi, Risa Tona, Alessandra Brofferio, Michael Hoa, Rafal Olszewski, Isabelle Schrauwen, Muhammad Z.K. Assir, Akhtar A. Bandesha, Asma A. Khan, Atteeq U. Rehman, Carmen Brewer, Wasim Ahmed, Suzanne M. Leal, Sheikh Riazuddin, Steven E. Boyden, and Thomas B. Friedman. Mutational and phenotypic spectra of kcne1 deficiency in jervell and lange‐nielsen syndrome and romano‐ward syndrome. Human Mutation, 40:162-176, Dec 2019. URL: https://doi.org/10.1002/humu.23689, doi:10.1002/humu.23689. This article has 47 citations and is from a domain leading peer-reviewed journal.

  4. (OpenTargets Search: Jervell and Lange-Nielsen syndrome-KCNE1): Open Targets Query (Jervell and Lange-Nielsen syndrome-KCNE1, 8 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  5. (faridi2019mutationalandphenotypic pages 3-4): Rabia Faridi, Risa Tona, Alessandra Brofferio, Michael Hoa, Rafal Olszewski, Isabelle Schrauwen, Muhammad Z.K. Assir, Akhtar A. Bandesha, Asma A. Khan, Atteeq U. Rehman, Carmen Brewer, Wasim Ahmed, Suzanne M. Leal, Sheikh Riazuddin, Steven E. Boyden, and Thomas B. Friedman. Mutational and phenotypic spectra of kcne1 deficiency in jervell and lange‐nielsen syndrome and romano‐ward syndrome. Human Mutation, 40:162-176, Dec 2019. URL: https://doi.org/10.1002/humu.23689, doi:10.1002/humu.23689. This article has 47 citations and is from a domain leading peer-reviewed journal.

  6. (balestra2024congenitallongqt pages 4-5): Elia Balestra, Marco Bobbo, Marco Cittar, Daniela Chicco, Biancamaria D’Agata Mottolese, Egidio Barbi, and Thomas Caiffa. Congenital long qt syndrome in children and adolescents: a general overview. Children, 11:582, May 2024. URL: https://doi.org/10.3390/children11050582, doi:10.3390/children11050582. This article has 20 citations.

  7. (balestra2024congenitallongqt pages 5-8): Elia Balestra, Marco Bobbo, Marco Cittar, Daniela Chicco, Biancamaria D’Agata Mottolese, Egidio Barbi, and Thomas Caiffa. Congenital long qt syndrome in children and adolescents: a general overview. Children, 11:582, May 2024. URL: https://doi.org/10.3390/children11050582, doi:10.3390/children11050582. This article has 20 citations.

  8. (qiu2020jervellandlangenielsen pages 1-2): Yue Qiu, Sen Chen, Xia Wu, Wen-Juan Zhang, Wen Xie, Yuan Jin, Le Xie, Kai Xu, Xue Bai, Hui-Min Zhang, Xiao-Zhou Liu, Xiao-Hui Wang, Yu Sun, and Wei-Jia Kong. Jervell and lange-nielsen syndrome due to a novel compound heterozygous kcnq1 mutation in a chinese family. Neural Plasticity, 2020:1-8, May 2020. URL: https://doi.org/10.1155/2020/3569359, doi:10.1155/2020/3569359. This article has 14 citations and is from a peer-reviewed journal.

  9. (balestra2024congenitallongqt pages 8-9): Elia Balestra, Marco Bobbo, Marco Cittar, Daniela Chicco, Biancamaria D’Agata Mottolese, Egidio Barbi, and Thomas Caiffa. Congenital long qt syndrome in children and adolescents: a general overview. Children, 11:582, May 2024. URL: https://doi.org/10.3390/children11050582, doi:10.3390/children11050582. This article has 20 citations.

  10. (qiu2020jervellandlangenielsen pages 5-7): Yue Qiu, Sen Chen, Xia Wu, Wen-Juan Zhang, Wen Xie, Yuan Jin, Le Xie, Kai Xu, Xue Bai, Hui-Min Zhang, Xiao-Zhou Liu, Xiao-Hui Wang, Yu Sun, and Wei-Jia Kong. Jervell and lange-nielsen syndrome due to a novel compound heterozygous kcnq1 mutation in a chinese family. Neural Plasticity, 2020:1-8, May 2020. URL: https://doi.org/10.1155/2020/3569359, doi:10.1155/2020/3569359. This article has 14 citations and is from a peer-reviewed journal.

  11. (yu2023precisionmedicinefor pages 1-2): Yang Yu, Isabelle Deschenes, and Ming-Tao Zhao. Precision medicine for long qt syndrome: patient-specific ipscs take the lead. Expert Reviews in Molecular Medicine, Jan 2023. URL: https://doi.org/10.1017/erm.2022.43, doi:10.1017/erm.2022.43. This article has 23 citations and is from a peer-reviewed journal.

  12. (yu2023precisionmedicinefor pages 7-8): Yang Yu, Isabelle Deschenes, and Ming-Tao Zhao. Precision medicine for long qt syndrome: patient-specific ipscs take the lead. Expert Reviews in Molecular Medicine, Jan 2023. URL: https://doi.org/10.1017/erm.2022.43, doi:10.1017/erm.2022.43. This article has 23 citations and is from a peer-reviewed journal.

  13. (NCT06534671 chunk 1): Prince Joseph Kannankeril. Diltiazem in Jervell and Lange-Nielsen Syndrome. Vanderbilt University Medical Center. 2024. ClinicalTrials.gov Identifier: NCT06534671

  14. (yu2023precisionmedicinefor pages 2-2): Yang Yu, Isabelle Deschenes, and Ming-Tao Zhao. Precision medicine for long qt syndrome: patient-specific ipscs take the lead. Expert Reviews in Molecular Medicine, Jan 2023. URL: https://doi.org/10.1017/erm.2022.43, doi:10.1017/erm.2022.43. This article has 23 citations and is from a peer-reviewed journal.

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