{"gene":"SCN1B","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":1998,"finding":"SCN1B C121W mutation disrupts a conserved cysteine involved in a disulfide bridge maintaining the extracellular immunoglobulin-like fold; co-expression of mutant β1 with a brain Na+ channel α subunit in Xenopus oocytes demonstrated that the mutation interferes with the ability of β1 to modulate channel-gating kinetics, consistent with loss-of-function.","method":"Xenopus oocyte co-expression electrophysiology, mutational analysis","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in heterologous system with functional electrophysiological readout, foundational paper with 816 citations","pmids":["9697698"],"is_preprint":false},{"year":1994,"finding":"The SCN1B gene is located on chromosome 19q13.1-q13.2, contains five exons spanning ~9.0 kb, and encodes the β1 subunit required for normal Na+ channel inactivation kinetics; the α subunit alone exhibits voltage-gated Na+ channel function but requires β1 for normal inactivation.","method":"Genomic DNA cloning, sequencing, fluorescence in situ hybridization (FISH)","journal":"Genomics","confidence":"High","confidence_rationale":"Tier 1 — direct structural/genomic characterization with functional annotation, widely cited","pmids":["7851891"],"is_preprint":false},{"year":2009,"finding":"The SCN1B p.R125C mutation causes loss of cell surface expression of the β1 subunit despite normal total cellular expression, regardless of co-expression with Nav1.1 α subunits, resulting in a functional null; Scn1b−/− CA3 neurons fire action potentials with higher peak voltage and amplitude compared to wild type.","method":"Biochemical characterization in heterologous system, hippocampal slice recordings in Scn1b−/− mice, acutely dissociated neuron recordings","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (biochemistry + in vivo electrophysiology), single rigorous paper","pmids":["19710327"],"is_preprint":false},{"year":2007,"finding":"Loss of β1 (Scn1b null mice) results in ~1.6-fold increase in both peak and persistent sodium current in ventricular myocytes, increased Nav1.5 expression (~1.3-fold), slowed action potential repolarization, and prolonged QT and RR intervals; no discernible alterations in subcellular localization of Na+ channel subunits or associated proteins were observed.","method":"ECG recordings, patch-clamp of acutely dissociated ventricular myocytes, immunostaining, Scn1b null mouse model","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal orthogonal methods (ECG + patch-clamp + immunostaining) in null mouse model","pmids":["17884088"],"is_preprint":false},{"year":2012,"finding":"Scn1b null mice show disrupted fasciculation of cerebellar parallel fibers, reduced dentate gyrus granule cell neuron density, increased proliferation of granule cell precursors in the hilus, and defective axonal extension and misorientation of inhibitory neurons, demonstrating that β1 functions as a cell adhesion molecule (CAM) critical for neuronal proliferation, migration, and pathfinding during postnatal brain development.","method":"Immunohistochemistry, c-Fos staining, hippocampal/cortical slice recordings, Scn1b null mouse model","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (electrophysiology + histology + immunostaining) in null mouse model with defined phenotypic readouts","pmids":["23277545"],"is_preprint":false},{"year":2016,"finding":"β1-C121W subunits are expressed at neuronal cell surfaces in vivo but are incompletely glycosylated and do not associate with VGSC α subunits in the brain; β1-C121W subcellular localization is restricted to neuronal cell bodies and is absent from axon initial segments (cortex, cerebellum) and optic nerve nodes of Ranvier; Scn1b+/W mice are more seizure-susceptible than Scn1b+/− mice, indicating C121W confers a deleterious gain-of-function rather than simple loss-of-function.","method":"Co-immunoprecipitation from brain, immunofluorescence, hyperthermia-induced convulsion model comparing heterozygous C121W vs. null mice","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (biochemistry + localization + in vivo phenotype comparison) in well-controlled mouse models","pmids":["27277800"],"is_preprint":false},{"year":2011,"finding":"Scn1b null dorsal root ganglion (DRG) neurons exhibit a depolarizing shift in voltage dependence of TTX-sensitive INa inactivation, reduced persistent TTX-resistant INa, prolonged recovery of TTX-R INa from inactivation, reduced cell surface expression of Nav1.9, reduced transient outward K+ current, and are hyperexcitable; demonstrating that β1 regulates both INa and IK in nociceptive DRG neurons in vivo.","method":"Patch-clamp electrophysiology of acutely dissociated DRG neurons from Scn1b null mice, immunostaining for Nav1.9 cell surface expression","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple channel types examined with patch-clamp and immunostaining in null mouse model","pmids":["21555511"],"is_preprint":false},{"year":2014,"finding":"Loss of Scn1b in cardiac-specific null mice increases tetrodotoxin-sensitive INa (associated with increased Scn3a/Nav1.3 expression) specifically at the cell midsection, causes delayed after-depolarizations, triggered beats, delayed Ca2+ transients, frequent spontaneous Ca2+ release events, and increased susceptibility to polymorphic ventricular arrhythmias; Ca2+ homeostasis alterations were prevented by tetrodotoxin, linking β1-regulated Na+ influx to Ca2+ dysregulation.","method":"Macropatch and scanning ion conductance microscopy, patch-clamp, confocal Ca2+ imaging, whole-heart arrhythmia recordings, Scn1b null mouse models","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods with TTX rescue experiment confirming mechanism","pmids":["25772295"],"is_preprint":false},{"year":2014,"finding":"In a Scn1b-C121W homozygous mouse model, subicular and layer 2/3 pyramidal neurons show increased action potential firing rates due to increased input resistance; no changes in GABAergic interneuron firing; reduced dendritic arborization in subicular pyramidal neurons; retigabine (K+ channel opener reducing input resistance) reduced firing and protected against thermal seizures, implicating a non-interneuron mechanism distinct from Scn1a-based Dravet syndrome models.","method":"Patch-clamp in acute brain slices, morphological analysis, pharmacological rescue with retigabine, mouse model","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 — patch-clamp + morphology + pharmacological rescue across multiple neuron types","pmids":["24747835"],"is_preprint":false},{"year":2008,"finding":"Zebrafish scn1ba splice variants modulate Na+ currents expressed by zebrafish scn8aa, producing shifts in channel gating mode, increased current amplitude, negative shifts in voltage dependence of activation and inactivation, and increased rate of recovery from inactivation—functions similar to mammalian β1; a C-terminal tyrosine residue critical for ankyrin association in mammalian β1 is conserved in scn1ba_tv1 but absent in the species-specific tv2 isoform.","method":"Heterologous expression with patch-clamp electrophysiology, immunohistochemistry in zebrafish","journal":"BMC genomics","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro functional reconstitution in zebrafish ortholog, single lab","pmids":["17623064"],"is_preprint":false},{"year":2008,"finding":"Morpholino knockdown of zebrafish scn1bb reduces Na+ current amplitudes in Rohon-Beard neurons, impairs touch sensitivity, causes defects in ventrally projecting spinal neuron axon development, olfactory nerve defasciculation, and increased hair cell numbers in the inner ear—demonstrating dual roles as a Na+ current modulator and cell adhesion molecule (CAM) in development.","method":"Morpholino knockdown, patch-clamp in Rohon-Beard neurons, behavioral touch assay, immunostaining in zebrafish","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — electrophysiology + developmental phenotype in ortholog model, single lab","pmids":["19020043"],"is_preprint":false},{"year":2011,"finding":"Post-transcriptional silencing of SCN1B (Nav-β1) in dog cardiac ventricular myocytes reduces late sodium current (INaL) density and accelerates its decay, while SCN2B silencing has the opposite effect; SCN1A mRNA and protein and transient INa remain unchanged, demonstrating isoform-specific modulation of INaL by β1 subunits.","method":"siRNA knockdown via viral delivery, whole-cell and perforated patch-clamp, real-time RT-PCR, Western blot in normal and failing canine ventricular myocytes","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"Medium","confidence_rationale":"Tier 2 — siRNA knockdown with electrophysiological readout and protein quantification, single lab","pmids":["21705762"],"is_preprint":false},{"year":2013,"finding":"Antisense oligonucleotide silencing of SCN1B (~50% knockdown) in GH3 and H9C2 cell lines reduces α subunit mRNA, protein expression, and Na+ current density without altering voltage-dependent or kinetic properties; β1 silencing differentially reduces Nav1.1, Nav1.3, and Nav1.6 in GH3 cells while Nav1.2 is unaffected, and reduces Nav1.5 in H9C2 cells, demonstrating isoform-specific regulation of Na+ channel expression.","method":"Antisense oligonucleotide silencing, RT-PCR, Western blot, patch-clamp in rat cell lines","journal":"Biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — knockdown with multiple orthogonal readouts, single lab","pmids":["24138709"],"is_preprint":false},{"year":2018,"finding":"The GEFS+ mutation β1-p.D25N causes a maturation (glycosylation) defect of the β1 protein leading to reduced plasma membrane targeting; co-expression of D25N-β1 with Nav1.2, Nav1.4, or Nav1.5 in HEK293 cells results in reduced Na+ channel functional expression and negative shifts in steady-state activation and inactivation curves, suggesting D25N abolishes β1's ability to interact with α subunits.","method":"Heterologous co-expression in HEK293 cells, patch-clamp, glycosylation analysis, membrane targeting assay","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution with mutagenesis and biochemical validation, single lab","pmids":["29992740"],"is_preprint":false},{"year":2014,"finding":"The SCN1B β1b-P213T mutation increases late Na+ current and subtly alters Nav1.5 function (shifts window current, accelerates recovery from inactivation, decreases slow inactivation rate) in HEK cells; overexpression of mutant β1b in HL-1 cardiomyocytes significantly increases action potential duration, implicating SCN1Bb as a susceptibility gene for long QT syndrome.","method":"Patch-clamp in HEK and HL-1 cells with β1b overexpression","journal":"Heart rhythm","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro patch-clamp with functional readout in two cell types, single lab","pmids":["24662403"],"is_preprint":false},{"year":2019,"finding":"SCN1B-p.Arg85Cys expressed in heterologous cells shows normal cell surface expression but loss of β1-mediated modification of Nav1.1-generated sodium current, establishing this variant as a loss-of-function mutation that disrupts channel modulation without trafficking deficiency.","method":"Heterologous cell expression with patch-clamp electrophysiology and surface expression assay","journal":"Annals of clinical and translational neurology","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution with electrophysiology and biochemistry, single lab","pmids":["31709768"],"is_preprint":false},{"year":2020,"finding":"SCN1B mutation c.308A>T (β1-p.D103V) decreases Na+ current density when co-expressed with Nav1.5 or Nav1.1 in tsA201 cells; β1b-D103V does not affect Nav1.1 current density but induces a positive shift in inactivation voltage-dependence and faster recovery from inactivation for Nav1.1, and has no effect on Nav1.5 properties—demonstrating subunit- and α-subunit-specific loss-of-function effects.","method":"Whole-cell patch-clamp in tsA201 cells with co-expression of α and β subunits","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution across multiple subunit combinations, single lab","pmids":["33134290"],"is_preprint":false},{"year":2022,"finding":"Scn1b null neonatal mice have sinoatrial node dysfunction, increased atrial collagen accumulation, susceptibility to pacing-induced atrial fibrillation (AF), increased cholinergic innervation of the SAN, prolonged action potential duration in atrial myocytes with increased late INa and reduced L-type Ca2+ current; atropine reduced AF incidence, implicating autonomic dysregulation as a contributing mechanism.","method":"Electrophysiology (patch-clamp), pacing-induced AF protocol, histology, pharmacological intervention (atropine), Scn1b null mouse model","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (patch-clamp + structural analysis + pharmacological rescue) in null mouse model","pmids":["35603785"],"is_preprint":false},{"year":2022,"finding":"Cardiac-specific inducible deletion of Scn1b in adult mice increases fast (+20%) and slow (+140%) inactivating components of INa, compromises diastolic function and ventricular compliance (with preserved systolic function), and delays Ca2+ transient kinetics; inhibition of late INa with GS967 normalizes LV filling pattern and Ca2+ transient defects, demonstrating that β1/β1B subunits regulate Na+ influx and Ca2+ cycling to control diastolic function.","method":"Conditional cardiac-specific Scn1b knockout, patch-clamp, echocardiography, invasive hemodynamics, Ca2+ imaging, pharmacological rescue","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"High","confidence_rationale":"Tier 2 — inducible conditional KO with multiple orthogonal functional readouts and pharmacological rescue","pmids":["35394857"],"is_preprint":false},{"year":2025,"finding":"Bilateral intracerebroventricular administration of AAV encoding β1 cDNA (AAV-Navβ1) at postnatal day 2 (but not P10) in Scn1b null mice reduces spontaneous seizure severity and duration, prolongs lifespan, prevents hyperthermia-induced seizures, and restores cortical neuron excitability; β1 expression is confirmed in both excitatory and inhibitory neurons—demonstrating that early gene replacement is sufficient to rescue key disease phenotypes.","method":"AAV gene delivery, EEG/seizure monitoring, hyperthermia challenge, patch-clamp electrophysiology in Scn1b null mouse model","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — gene replacement with multiple functional readouts (seizures, lifespan, electrophysiology), well-controlled mouse model","pmids":["39847501"],"is_preprint":false},{"year":2025,"finding":"Scn1b null Purkinje cells (PCs) have reduced transient and resurgent Na+ current densities, increased thresholds for action potential initiation, and decreased repetitive firing frequency; PC-specific deletion of Scn1b produces ataxia, and reduced PC excitability is proposed to underlie the ataxic phenotype and potentially impair seizure termination via cerebellar output.","method":"PC-specific conditional Scn1b knockout, patch-clamp in cerebellar slices, behavioral ataxia testing, CRISPR V5-tagged β1 mouse for expression mapping","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 — cell-type-specific KO with patch-clamp and behavioral readouts, multiple orthogonal methods","pmids":["40923316"],"is_preprint":false},{"year":2023,"finding":"Loss of Scn1b in hippocampal CA1 pyramidal neurons results in enhanced intrinsic excitability, smaller but more facilitating EPSCs and IPSCs, larger postsynaptic potentials, reduced intrinsic firing of parvalbumin-expressing interneurons, and disrupted recruitment of parvalbumin- and somatostatin-expressing interneurons, producing fundamentally altered hippocampal input/output functions.","method":"Slice electrophysiology (patch-clamp), interneuron-specific recording, patterned Schaffer collateral stimulation in Scn1b KO mice","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — multiple cell types examined with patch-clamp in KO model, defined circuit-level phenotypes","pmids":["37845033"],"is_preprint":false},{"year":2024,"finding":"SCN1B mimetic peptide βadp1 disrupts β1-mediated intercellular adhesion in cardiac perinexii (intercalated disc nanodomains enriched in Nav channels) and increases β1-regulated intramembrane proteolysis (RIP) continuously over 48 h; a shorter peptide LQLEED mimics inhibitory effects, while dimeric LQLEED peptides paradoxically promote adhesion and only transiently boost RIP; DAPT (RIP inhibitor) reduces βadp1's adhesion-disrupting effects, linking β1 CAM function to RIP-mediated signaling.","method":"Patch-clamp in neonatal rat cardiomyocytes, electric cell substrate impedance sensing (ECIS) in β1-expressing cells, pharmacological inhibition of RIP with DAPT","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 — two orthogonal assays (patch-clamp + ECIS) with pharmacological validation, single lab","pmids":["38942073"],"is_preprint":false},{"year":2025,"finding":"Self-administered (but not experimenter-administered) heroin reduces NAc β1 (SCN1b) protein levels in rats; viral-mediated reduction of NAc SCN1b increases medium spiny neuron (MSN) intrinsic excitability without altering glutamatergic or GABAergic synaptic transmission; reduced NAc SCN1b significantly increases cue-reinstated heroin seeking, demonstrating that β1 normally limits MSN excitability and cue-driven opioid seeking in the nucleus accumbens.","method":"Heroin self-administration, viral knockdown, patch-clamp electrophysiology in NAc MSNs, reinstatement behavioral testing in rats","journal":"eNeuro","confidence":"Medium","confidence_rationale":"Tier 2 — viral KD with electrophysiology and behavioral readout, single lab","pmids":["39947903"],"is_preprint":false},{"year":2025,"finding":"Scn1b-c.265C>T (p.R89C) knock-in mouse cardiomyocytes show increased transient outward K+ current (Ito) density and ventricular fibrosis; mice are susceptible to pacing-induced cardiac arrhythmias; patient-derived iPSC-CMs with biallelic SCN1B-c.265C>T show increased INa, late INa, and Ito densities; increased Ito is a common cardiac alteration in both mouse and human DEE52 models.","method":"CRISPR knock-in mouse model, patch-clamp, pacing-induced arrhythmia, iPSC-CM differentiation from DEE52 patients, cardiac histology","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 — orthogonal mouse and human iPSC-CM models with patch-clamp and structural analysis","pmids":["40763036"],"is_preprint":false},{"year":2020,"finding":"SCN1B variant A197V in Brugada syndrome patients markedly decreases Na+ current density when co-expressed with SCN5A/Nav1.5 in HEK293 cells, decelerates activation velocity, and reduces Nav1.5 plasma membrane distribution; no significant changes in recovery from inactivation.","method":"Whole-cell patch-clamp in HEK293 cells, cell surface protein analysis","journal":"Archives of medical research","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution with electrophysiology and surface protein analysis, single lab","pmids":["32192759"],"is_preprint":false},{"year":2023,"finding":"Reduced variability of INa density in Scn1b null cortical pyramidal neurons enhances spike timing correlations between neurons and impairs spike-triggered average current pattern diversity; computational modeling shows that broad INa density ranges (dependent on β1 expression) confer a broad spectrum of spike patterning and displace synchronization thresholds in network models, demonstrating that β1-regulated INa heterogeneity regulates spike pattern diversity and network synchronization.","method":"Patch-clamp recording from constitutive and inducible Scn1b null cortical neurons, computational network modeling, TTX pharmacology","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — patch-clamp with computational modeling and pharmacological validation, single lab","pmids":["37264112"],"is_preprint":false}],"current_model":"SCN1B encodes the voltage-gated sodium channel β1 (and β1B) subunits that are multifunctional proteins: they modulate Na+ (and K+) channel gating kinetics, increase channel cell-surface expression, regulate subcellular localization of α subunits to axon initial segments and nodes of Ranvier, function as cell adhesion molecules (CAMs) mediating neuronal migration, axonal pathfinding, and fasciculation, and signal through regulated intramembrane proteolysis (RIP) to control gene transcription—loss of β1 in neurons causes hyperexcitability, epilepsy, and ataxia, while in the heart it leads to increased persistent/late Na+ current, disrupted Ca2+ homeostasis, and susceptibility to arrhythmias."},"narrative":{"teleology":[{"year":1994,"claim":"Identifying the genomic structure of SCN1B and establishing that the β1 subunit is required for normal Na+ channel inactivation kinetics resolved why α subunits alone exhibit abnormal gating behavior.","evidence":"Genomic cloning, sequencing, and FISH mapping of the SCN1B locus on chromosome 19q13.1–q13.2","pmids":["7851891"],"confidence":"High","gaps":["No protein structure resolved","Mechanism of β1–α subunit interaction unknown"]},{"year":1998,"claim":"Demonstrating that the GEFS+ C121W mutation disrupts the extracellular Ig-fold disulfide bridge and abolishes β1-mediated channel modulation established SCN1B as a disease gene and linked its adhesion-like domain to channel-gating function.","evidence":"Xenopus oocyte co-expression electrophysiology with mutant β1 and brain Na+ channel α subunit","pmids":["9697698"],"confidence":"High","gaps":["In vivo consequences of C121W not yet characterized","Whether C121W is pure loss-of-function or gain-of-function unknown"]},{"year":2007,"claim":"Showing that Scn1b-null cardiomyocytes have increased peak and persistent INa, prolonged QT/RR intervals, and upregulated Nav1.5 established β1 as a negative regulator of cardiac Na+ current and a determinant of cardiac repolarization.","evidence":"Patch-clamp of ventricular myocytes, ECG, and immunostaining in Scn1b-null mice","pmids":["17884088"],"confidence":"High","gaps":["Mechanism of Nav1.5 upregulation (transcriptional vs. post-translational) unclear","Whether cardiac phenotype is cell-autonomous not resolved"]},{"year":2008,"claim":"Zebrafish studies confirmed evolutionary conservation of β1 dual function as both a Na+ current modulator and a cell adhesion molecule required for axonal pathfinding and sensory neuron development.","evidence":"Heterologous co-expression electrophysiology of zebrafish scn1ba with scn8aa; morpholino knockdown of scn1bb with behavioral, electrophysiological, and immunohistochemical readouts","pmids":["17623064","19020043"],"confidence":"Medium","gaps":["Morpholino off-target effects not fully controlled","Mammalian in vivo CAM function not yet demonstrated"]},{"year":2009,"claim":"Establishing that the R125C mutation causes a trafficking-null phenotype (retained intracellularly despite normal total expression) while Scn1b-null hippocampal neurons fire with higher amplitude action potentials connected disease mutations to surface-expression failure and neuronal hyperexcitability.","evidence":"Biochemical surface-expression assays in heterologous cells; hippocampal slice and dissociated neuron recordings from Scn1b-null mice","pmids":["19710327"],"confidence":"High","gaps":["Downstream transcriptional consequences of β1 loss in hippocampus not explored"]},{"year":2011,"claim":"Discovery that β1 regulates not only Na+ currents but also K+ currents and Nav1.9 surface expression in DRG neurons, and independently modulates late INa in cardiac myocytes, broadened β1's role beyond canonical fast Na+ channel gating.","evidence":"Patch-clamp of Scn1b-null DRG neurons with Nav1.9 immunostaining; siRNA knockdown of SCN1B in canine ventricular myocytes with electrophysiology","pmids":["21555511","21705762"],"confidence":"High","gaps":["Direct physical interaction between β1 and K+ channels not demonstrated","Molecular basis of isoform-specific late INa modulation unknown"]},{"year":2012,"claim":"Demonstrating disrupted parallel fiber fasciculation, aberrant neuronal migration, and defective axonal pathfinding in Scn1b-null mouse brains established β1 as a bona fide cell adhesion molecule required for postnatal brain development.","evidence":"Immunohistochemistry, c-Fos staining, and electrophysiology in hippocampal and cortical slices of Scn1b-null mice","pmids":["23277545"],"confidence":"High","gaps":["Trans-binding partners for β1 CAM activity not identified","Whether CAM and channel-modulation functions are separable in vivo unclear"]},{"year":2014,"claim":"Cell-type-specific analysis showed C121W increases excitatory neuron firing (via increased input resistance) without affecting interneurons, and cardiac-specific Scn1b deletion causes Ca²⁺ dysregulation and arrhythmia susceptibility, delineating tissue- and cell-type-specific consequences of β1 loss.","evidence":"Patch-clamp in brain slices of Scn1b-C121W mice with retigabine rescue; macropatch, Ca²⁺ imaging, and arrhythmia protocols in cardiac-specific Scn1b-null mice with TTX rescue","pmids":["24747835","25772295"],"confidence":"High","gaps":["Mechanism by which β1 loss increases input resistance not resolved","Upstream signaling linking increased Na+ influx to Ca²⁺ release not fully defined"]},{"year":2016,"claim":"Showing that C121W β1 reaches the neuronal surface but fails to associate with α subunits and is excluded from axon initial segments and nodes of Ranvier—and that heterozygous C121W mice are more seizure-susceptible than heterozygous nulls—established a dominant-negative/gain-of-function mechanism beyond simple haploinsufficiency.","evidence":"Co-immunoprecipitation from brain, immunofluorescence at AIS and nodes, hyperthermia seizure comparison of Scn1b+/W vs. Scn1b+/− mice","pmids":["27277800"],"confidence":"High","gaps":["Nature of the gain-of-function mechanism not molecularly defined","Whether mislocalized C121W exerts CAM-related toxicity unknown"]},{"year":2022,"claim":"Scn1b loss in the heart causes sinoatrial node dysfunction, atrial fibrillation susceptibility with autonomic dysregulation, and diastolic dysfunction via increased late INa and disrupted Ca²⁺ transients—all rescued pharmacologically—establishing β1 as essential for multiple aspects of cardiac physiology beyond ventricular conduction.","evidence":"Pacing-induced AF with atropine rescue in Scn1b-null neonatal mice; inducible cardiac-specific KO with echocardiography, hemodynamics, Ca²⁺ imaging, and GS967 rescue in adult mice","pmids":["35603785","35394857"],"confidence":"High","gaps":["Mechanism of increased cholinergic innervation in null SAN not resolved","Whether fibrosis is a direct consequence of altered Na+/Ca²⁺ handling unclear"]},{"year":2023,"claim":"Revealing that β1 loss disrupts INa density heterogeneity across cortical pyramidal neurons and impairs parvalbumin and somatostatin interneuron recruitment in hippocampal circuits explained how β1 shapes network-level spike pattern diversity and synchronization thresholds relevant to seizure generation.","evidence":"Patch-clamp from constitutive and inducible Scn1b-null cortical neurons with computational modeling; multi-cell-type recordings in hippocampal slices of Scn1b KO mice","pmids":["37264112","37845033"],"confidence":"Medium","gaps":["Computational predictions of synchronization thresholds not validated in vivo","Molecular basis of reduced interneuron firing not identified"]},{"year":2024,"claim":"Demonstrating that β1 mimetic peptides disrupt intercellular adhesion at cardiac perinexii and modulate regulated intramembrane proteolysis (RIP) linked β1's CAM function to a signaling pathway, with RIP inhibition partially rescuing adhesion disruption.","evidence":"ECIS adhesion assay and patch-clamp in neonatal cardiomyocytes with DAPT (γ-secretase inhibitor) pharmacological rescue","pmids":["38942073"],"confidence":"Medium","gaps":["Downstream transcriptional targets of β1-RIP signaling not identified","Whether RIP occurs in neurons in vivo not established"]},{"year":2025,"claim":"AAV-mediated β1 gene replacement at postnatal day 2 rescued seizures and extended lifespan in Scn1b-null mice; cell-type-specific deletion showed β1 is required for Purkinje cell resurgent Na+ current and repetitive firing, with PC-specific loss sufficient for ataxia; and a knock-in DEE52 model confirmed increased Ito as a conserved cardiac phenotype in both mouse and human iPSC-CMs.","evidence":"AAV-Navβ1 ICV injection with EEG/seizure monitoring and electrophysiology; PC-specific conditional KO with patch-clamp and behavioral testing; CRISPR knock-in R89C mice and patient iPSC-CMs","pmids":["39847501","40923316","40763036"],"confidence":"High","gaps":["Therapeutic window for gene replacement in humans undefined","Whether gene therapy rescues CAM-dependent developmental phenotypes not assessed","Mechanism of β1-dependent Ito regulation in cardiomyocytes unknown"]},{"year":null,"claim":"Key open questions include: the structural basis of β1–α subunit interaction, the identity of β1 trans-binding CAM partners, whether channel-modulation and adhesion functions are genetically separable in vivo, the downstream transcriptional targets of β1-RIP signaling, and whether early gene replacement can rescue developmental (CAM-mediated) as well as electrophysiological phenotypes.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of β1–α complex","Trans-binding partners for β1 CAM adhesion not identified","RIP transcriptional targets unknown","Separability of channel-modulation vs. CAM functions in vivo untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,3,6,9,11,12,16]},{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[4,10,22]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[4,5,22]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,5,13,25]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,2,4,6,8,20,21,26]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[22]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[1,3,7,11,18]}],"complexes":["Voltage-gated sodium channel complex"],"partners":["SCN1A","SCN5A","SCN3A","SCN2A","SCN8A","SCN11A","SCN4A"],"other_free_text":[]},"mechanistic_narrative":"SCN1B encodes the voltage-gated sodium channel β1 (and β1B) auxiliary subunits, which function as multifunctional regulators of neuronal and cardiac excitability by modulating Na+ channel gating kinetics, promoting α-subunit cell-surface expression, and acting as immunoglobulin-superfamily cell adhesion molecules that direct axonal pathfinding, fasciculation, and neuronal migration. The β1 subunit is required for normal Na+ channel inactivation and controls cell-surface density of multiple α-subunit isoforms (Nav1.1, Nav1.3, Nav1.5, Nav1.6) in an isoform-specific manner; loss of β1 increases persistent and late Na+ current, disrupts Ca²⁺ homeostasis in cardiomyocytes, and enhances intrinsic excitability of cortical pyramidal neurons, hippocampal neurons, and cerebellar Purkinje cells while reducing parvalbumin interneuron firing [PMID:7851891, PMID:17884088, PMID:23277545, PMID:37845033, PMID:40923316]. β1 additionally participates in regulated intramembrane proteolysis (RIP)-coupled signaling at cardiac intercalated discs, linking its adhesion function to intracellular signaling [PMID:38942073]. Loss-of-function and gain-of-function SCN1B mutations cause developmental and epileptic encephalopathy 52 (DEE52), generalized epilepsy with febrile seizures plus (GEFS+), Brugada syndrome, and cardiac arrhythmias including atrial fibrillation and long QT syndrome, and early postnatal AAV-mediated β1 gene replacement rescues seizure severity and lifespan in Scn1b-null mice [PMID:9697698, PMID:35603785, PMID:24662403, PMID:39847501]."},"prefetch_data":{"uniprot":{"accession":"Q07699","full_name":"Sodium channel regulatory subunit beta-1","aliases":[],"length_aa":218,"mass_kda":24.7,"function":"Regulatory subunit of multiple voltage-gated sodium (Nav) channels directly mediating the depolarization of excitable membranes. Navs, also called VGSCs (voltage-gated sodium channels) or VDSCs (voltage-dependent sodium channels), operate by switching between closed and open conformations depending on the voltage difference across the membrane. In the open conformation they allow Na(+) ions to selectively pass through the pore, along their electrochemical gradient. The influx of Na+ ions provokes membrane depolarization, initiating the propagation of electrical signals throughout cells and tissues (PubMed:14622265, PubMed:15525788, PubMed:18464934, PubMed:19710327, PubMed:29992740, PubMed:36696443, PubMed:8125980, PubMed:8394762). The accessory beta subunits participate in localization and functional modulation of the Nav channels (PubMed:15525788, PubMed:19710327, PubMed:29992740). Modulates the activity of SCN1A/Nav1.1, SCN2A/Nav1.2, SCN3A/Nav1.3, SCN4A/Nav1.4, SCN5A/Nav1.5, SCN8A/Nav1.6, SCN9A/Nav1.7 and SCN10A/Nav1.8 (PubMed:14622265, PubMed:15525788, PubMed:18464934, PubMed:30765606, PubMed:36696443, PubMed:8125980, PubMed:8394762) Cell adhesion molecule that plays a critical role in neuronal migration and pathfinding during brain development. Stimulates neurite outgrowth (PubMed:21994374). Has no regulatory function on the SCN2A sodium channel complex (PubMed:14622265)","subcellular_location":"Perikaryon; Cell projection; Secreted","url":"https://www.uniprot.org/uniprotkb/Q07699/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SCN1B","classification":"Not Classified","n_dependent_lines":14,"n_total_lines":1208,"dependency_fraction":0.011589403973509934},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SCN1B","total_profiled":1310},"omim":[{"mim_id":"620529","title":"RING FINGER PROTEIN 121; RNF121","url":"https://www.omim.org/entry/620529"},{"mim_id":"617350","title":"DEVELOPMENTAL AND EPILEPTIC ENCEPHALOPATHY 52; DEE52","url":"https://www.omim.org/entry/617350"},{"mim_id":"615378","title":"ATRIAL FIBRILLATION, FAMILIAL, 14; ATFB14","url":"https://www.omim.org/entry/615378"},{"mim_id":"615377","title":"ATRIAL FIBRILLATION, FAMILIAL, 13; ATFB13","url":"https://www.omim.org/entry/615377"},{"mim_id":"612838","title":"BRUGADA SYNDROME 5; BRGDA5","url":"https://www.omim.org/entry/612838"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"brain","ntpm":271.5},{"tissue":"skeletal muscle","ntpm":550.8},{"tissue":"tongue","ntpm":212.7}],"url":"https://www.proteinatlas.org/search/SCN1B"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q07699","domains":[{"cath_id":"2.60.40.10","chopping":"21-150","consensus_level":"medium","plddt":93.6025,"start":21,"end":150},{"cath_id":"1.20.5","chopping":"152-190","consensus_level":"medium","plddt":92.7808,"start":152,"end":190}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q07699","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q07699-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q07699-F1-predicted_aligned_error_v6.png","plddt_mean":87.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SCN1B","jax_strain_url":"https://www.jax.org/strain/search?query=SCN1B"},"sequence":{"accession":"Q07699","fasta_url":"https://rest.uniprot.org/uniprotkb/Q07699.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q07699/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q07699"}},"corpus_meta":[{"pmid":"9697698","id":"PMC_9697698","title":"Febrile 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Heart and circulatory physiology","url":"https://pubmed.ncbi.nlm.nih.gov/39120465","citation_count":0,"is_preprint":false},{"pmid":"42046183","id":"PMC_42046183","title":"Identification of a Novel Homozygous SCN1B Splice-Site Variant in a Consanguineous Families With Early-Onset Epilepsy: A Case Series and Review of Literature.","date":"2026","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/42046183","citation_count":0,"is_preprint":false},{"pmid":"22348965","id":"PMC_22348965","title":"[Expression of Kir2.1, SCN5a and SCN1b channel genes in mouse cardiomyocytes with various electric properties: patch clamp combined with single cell RT-PCR study].","date":"2012","source":"Sheng li xue bao : [Acta physiologica Sinica]","url":"https://pubmed.ncbi.nlm.nih.gov/22348965","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.11.19.624370","title":"A novel mouse model for developmental and epileptic encephalopathy by Purkinje cell-specific deletion of<i>Scn1b</i>","date":"2024-11-19","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.19.624370","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":35674,"output_tokens":6778,"usd":0.104346},"stage2":{"model":"claude-opus-4-6","input_tokens":10607,"output_tokens":3703,"usd":0.218415},"total_usd":0.322761,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"SCN1B C121W mutation disrupts a conserved cysteine involved in a disulfide bridge maintaining the extracellular immunoglobulin-like fold; co-expression of mutant β1 with a brain Na+ channel α subunit in Xenopus oocytes demonstrated that the mutation interferes with the ability of β1 to modulate channel-gating kinetics, consistent with loss-of-function.\",\n      \"method\": \"Xenopus oocyte co-expression electrophysiology, mutational analysis\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in heterologous system with functional electrophysiological readout, foundational paper with 816 citations\",\n      \"pmids\": [\"9697698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"The SCN1B gene is located on chromosome 19q13.1-q13.2, contains five exons spanning ~9.0 kb, and encodes the β1 subunit required for normal Na+ channel inactivation kinetics; the α subunit alone exhibits voltage-gated Na+ channel function but requires β1 for normal inactivation.\",\n      \"method\": \"Genomic DNA cloning, sequencing, fluorescence in situ hybridization (FISH)\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct structural/genomic characterization with functional annotation, widely cited\",\n      \"pmids\": [\"7851891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The SCN1B p.R125C mutation causes loss of cell surface expression of the β1 subunit despite normal total cellular expression, regardless of co-expression with Nav1.1 α subunits, resulting in a functional null; Scn1b−/− CA3 neurons fire action potentials with higher peak voltage and amplitude compared to wild type.\",\n      \"method\": \"Biochemical characterization in heterologous system, hippocampal slice recordings in Scn1b−/− mice, acutely dissociated neuron recordings\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (biochemistry + in vivo electrophysiology), single rigorous paper\",\n      \"pmids\": [\"19710327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Loss of β1 (Scn1b null mice) results in ~1.6-fold increase in both peak and persistent sodium current in ventricular myocytes, increased Nav1.5 expression (~1.3-fold), slowed action potential repolarization, and prolonged QT and RR intervals; no discernible alterations in subcellular localization of Na+ channel subunits or associated proteins were observed.\",\n      \"method\": \"ECG recordings, patch-clamp of acutely dissociated ventricular myocytes, immunostaining, Scn1b null mouse model\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal orthogonal methods (ECG + patch-clamp + immunostaining) in null mouse model\",\n      \"pmids\": [\"17884088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Scn1b null mice show disrupted fasciculation of cerebellar parallel fibers, reduced dentate gyrus granule cell neuron density, increased proliferation of granule cell precursors in the hilus, and defective axonal extension and misorientation of inhibitory neurons, demonstrating that β1 functions as a cell adhesion molecule (CAM) critical for neuronal proliferation, migration, and pathfinding during postnatal brain development.\",\n      \"method\": \"Immunohistochemistry, c-Fos staining, hippocampal/cortical slice recordings, Scn1b null mouse model\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (electrophysiology + histology + immunostaining) in null mouse model with defined phenotypic readouts\",\n      \"pmids\": [\"23277545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"β1-C121W subunits are expressed at neuronal cell surfaces in vivo but are incompletely glycosylated and do not associate with VGSC α subunits in the brain; β1-C121W subcellular localization is restricted to neuronal cell bodies and is absent from axon initial segments (cortex, cerebellum) and optic nerve nodes of Ranvier; Scn1b+/W mice are more seizure-susceptible than Scn1b+/− mice, indicating C121W confers a deleterious gain-of-function rather than simple loss-of-function.\",\n      \"method\": \"Co-immunoprecipitation from brain, immunofluorescence, hyperthermia-induced convulsion model comparing heterozygous C121W vs. null mice\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (biochemistry + localization + in vivo phenotype comparison) in well-controlled mouse models\",\n      \"pmids\": [\"27277800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Scn1b null dorsal root ganglion (DRG) neurons exhibit a depolarizing shift in voltage dependence of TTX-sensitive INa inactivation, reduced persistent TTX-resistant INa, prolonged recovery of TTX-R INa from inactivation, reduced cell surface expression of Nav1.9, reduced transient outward K+ current, and are hyperexcitable; demonstrating that β1 regulates both INa and IK in nociceptive DRG neurons in vivo.\",\n      \"method\": \"Patch-clamp electrophysiology of acutely dissociated DRG neurons from Scn1b null mice, immunostaining for Nav1.9 cell surface expression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple channel types examined with patch-clamp and immunostaining in null mouse model\",\n      \"pmids\": [\"21555511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Loss of Scn1b in cardiac-specific null mice increases tetrodotoxin-sensitive INa (associated with increased Scn3a/Nav1.3 expression) specifically at the cell midsection, causes delayed after-depolarizations, triggered beats, delayed Ca2+ transients, frequent spontaneous Ca2+ release events, and increased susceptibility to polymorphic ventricular arrhythmias; Ca2+ homeostasis alterations were prevented by tetrodotoxin, linking β1-regulated Na+ influx to Ca2+ dysregulation.\",\n      \"method\": \"Macropatch and scanning ion conductance microscopy, patch-clamp, confocal Ca2+ imaging, whole-heart arrhythmia recordings, Scn1b null mouse models\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods with TTX rescue experiment confirming mechanism\",\n      \"pmids\": [\"25772295\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In a Scn1b-C121W homozygous mouse model, subicular and layer 2/3 pyramidal neurons show increased action potential firing rates due to increased input resistance; no changes in GABAergic interneuron firing; reduced dendritic arborization in subicular pyramidal neurons; retigabine (K+ channel opener reducing input resistance) reduced firing and protected against thermal seizures, implicating a non-interneuron mechanism distinct from Scn1a-based Dravet syndrome models.\",\n      \"method\": \"Patch-clamp in acute brain slices, morphological analysis, pharmacological rescue with retigabine, mouse model\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — patch-clamp + morphology + pharmacological rescue across multiple neuron types\",\n      \"pmids\": [\"24747835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Zebrafish scn1ba splice variants modulate Na+ currents expressed by zebrafish scn8aa, producing shifts in channel gating mode, increased current amplitude, negative shifts in voltage dependence of activation and inactivation, and increased rate of recovery from inactivation—functions similar to mammalian β1; a C-terminal tyrosine residue critical for ankyrin association in mammalian β1 is conserved in scn1ba_tv1 but absent in the species-specific tv2 isoform.\",\n      \"method\": \"Heterologous expression with patch-clamp electrophysiology, immunohistochemistry in zebrafish\",\n      \"journal\": \"BMC genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro functional reconstitution in zebrafish ortholog, single lab\",\n      \"pmids\": [\"17623064\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Morpholino knockdown of zebrafish scn1bb reduces Na+ current amplitudes in Rohon-Beard neurons, impairs touch sensitivity, causes defects in ventrally projecting spinal neuron axon development, olfactory nerve defasciculation, and increased hair cell numbers in the inner ear—demonstrating dual roles as a Na+ current modulator and cell adhesion molecule (CAM) in development.\",\n      \"method\": \"Morpholino knockdown, patch-clamp in Rohon-Beard neurons, behavioral touch assay, immunostaining in zebrafish\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — electrophysiology + developmental phenotype in ortholog model, single lab\",\n      \"pmids\": [\"19020043\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Post-transcriptional silencing of SCN1B (Nav-β1) in dog cardiac ventricular myocytes reduces late sodium current (INaL) density and accelerates its decay, while SCN2B silencing has the opposite effect; SCN1A mRNA and protein and transient INa remain unchanged, demonstrating isoform-specific modulation of INaL by β1 subunits.\",\n      \"method\": \"siRNA knockdown via viral delivery, whole-cell and perforated patch-clamp, real-time RT-PCR, Western blot in normal and failing canine ventricular myocytes\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — siRNA knockdown with electrophysiological readout and protein quantification, single lab\",\n      \"pmids\": [\"21705762\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Antisense oligonucleotide silencing of SCN1B (~50% knockdown) in GH3 and H9C2 cell lines reduces α subunit mRNA, protein expression, and Na+ current density without altering voltage-dependent or kinetic properties; β1 silencing differentially reduces Nav1.1, Nav1.3, and Nav1.6 in GH3 cells while Nav1.2 is unaffected, and reduces Nav1.5 in H9C2 cells, demonstrating isoform-specific regulation of Na+ channel expression.\",\n      \"method\": \"Antisense oligonucleotide silencing, RT-PCR, Western blot, patch-clamp in rat cell lines\",\n      \"journal\": \"Biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — knockdown with multiple orthogonal readouts, single lab\",\n      \"pmids\": [\"24138709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The GEFS+ mutation β1-p.D25N causes a maturation (glycosylation) defect of the β1 protein leading to reduced plasma membrane targeting; co-expression of D25N-β1 with Nav1.2, Nav1.4, or Nav1.5 in HEK293 cells results in reduced Na+ channel functional expression and negative shifts in steady-state activation and inactivation curves, suggesting D25N abolishes β1's ability to interact with α subunits.\",\n      \"method\": \"Heterologous co-expression in HEK293 cells, patch-clamp, glycosylation analysis, membrane targeting assay\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with mutagenesis and biochemical validation, single lab\",\n      \"pmids\": [\"29992740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The SCN1B β1b-P213T mutation increases late Na+ current and subtly alters Nav1.5 function (shifts window current, accelerates recovery from inactivation, decreases slow inactivation rate) in HEK cells; overexpression of mutant β1b in HL-1 cardiomyocytes significantly increases action potential duration, implicating SCN1Bb as a susceptibility gene for long QT syndrome.\",\n      \"method\": \"Patch-clamp in HEK and HL-1 cells with β1b overexpression\",\n      \"journal\": \"Heart rhythm\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro patch-clamp with functional readout in two cell types, single lab\",\n      \"pmids\": [\"24662403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"SCN1B-p.Arg85Cys expressed in heterologous cells shows normal cell surface expression but loss of β1-mediated modification of Nav1.1-generated sodium current, establishing this variant as a loss-of-function mutation that disrupts channel modulation without trafficking deficiency.\",\n      \"method\": \"Heterologous cell expression with patch-clamp electrophysiology and surface expression assay\",\n      \"journal\": \"Annals of clinical and translational neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with electrophysiology and biochemistry, single lab\",\n      \"pmids\": [\"31709768\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SCN1B mutation c.308A>T (β1-p.D103V) decreases Na+ current density when co-expressed with Nav1.5 or Nav1.1 in tsA201 cells; β1b-D103V does not affect Nav1.1 current density but induces a positive shift in inactivation voltage-dependence and faster recovery from inactivation for Nav1.1, and has no effect on Nav1.5 properties—demonstrating subunit- and α-subunit-specific loss-of-function effects.\",\n      \"method\": \"Whole-cell patch-clamp in tsA201 cells with co-expression of α and β subunits\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution across multiple subunit combinations, single lab\",\n      \"pmids\": [\"33134290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Scn1b null neonatal mice have sinoatrial node dysfunction, increased atrial collagen accumulation, susceptibility to pacing-induced atrial fibrillation (AF), increased cholinergic innervation of the SAN, prolonged action potential duration in atrial myocytes with increased late INa and reduced L-type Ca2+ current; atropine reduced AF incidence, implicating autonomic dysregulation as a contributing mechanism.\",\n      \"method\": \"Electrophysiology (patch-clamp), pacing-induced AF protocol, histology, pharmacological intervention (atropine), Scn1b null mouse model\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (patch-clamp + structural analysis + pharmacological rescue) in null mouse model\",\n      \"pmids\": [\"35603785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cardiac-specific inducible deletion of Scn1b in adult mice increases fast (+20%) and slow (+140%) inactivating components of INa, compromises diastolic function and ventricular compliance (with preserved systolic function), and delays Ca2+ transient kinetics; inhibition of late INa with GS967 normalizes LV filling pattern and Ca2+ transient defects, demonstrating that β1/β1B subunits regulate Na+ influx and Ca2+ cycling to control diastolic function.\",\n      \"method\": \"Conditional cardiac-specific Scn1b knockout, patch-clamp, echocardiography, invasive hemodynamics, Ca2+ imaging, pharmacological rescue\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — inducible conditional KO with multiple orthogonal functional readouts and pharmacological rescue\",\n      \"pmids\": [\"35394857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Bilateral intracerebroventricular administration of AAV encoding β1 cDNA (AAV-Navβ1) at postnatal day 2 (but not P10) in Scn1b null mice reduces spontaneous seizure severity and duration, prolongs lifespan, prevents hyperthermia-induced seizures, and restores cortical neuron excitability; β1 expression is confirmed in both excitatory and inhibitory neurons—demonstrating that early gene replacement is sufficient to rescue key disease phenotypes.\",\n      \"method\": \"AAV gene delivery, EEG/seizure monitoring, hyperthermia challenge, patch-clamp electrophysiology in Scn1b null mouse model\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — gene replacement with multiple functional readouts (seizures, lifespan, electrophysiology), well-controlled mouse model\",\n      \"pmids\": [\"39847501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Scn1b null Purkinje cells (PCs) have reduced transient and resurgent Na+ current densities, increased thresholds for action potential initiation, and decreased repetitive firing frequency; PC-specific deletion of Scn1b produces ataxia, and reduced PC excitability is proposed to underlie the ataxic phenotype and potentially impair seizure termination via cerebellar output.\",\n      \"method\": \"PC-specific conditional Scn1b knockout, patch-clamp in cerebellar slices, behavioral ataxia testing, CRISPR V5-tagged β1 mouse for expression mapping\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — cell-type-specific KO with patch-clamp and behavioral readouts, multiple orthogonal methods\",\n      \"pmids\": [\"40923316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Loss of Scn1b in hippocampal CA1 pyramidal neurons results in enhanced intrinsic excitability, smaller but more facilitating EPSCs and IPSCs, larger postsynaptic potentials, reduced intrinsic firing of parvalbumin-expressing interneurons, and disrupted recruitment of parvalbumin- and somatostatin-expressing interneurons, producing fundamentally altered hippocampal input/output functions.\",\n      \"method\": \"Slice electrophysiology (patch-clamp), interneuron-specific recording, patterned Schaffer collateral stimulation in Scn1b KO mice\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell types examined with patch-clamp in KO model, defined circuit-level phenotypes\",\n      \"pmids\": [\"37845033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SCN1B mimetic peptide βadp1 disrupts β1-mediated intercellular adhesion in cardiac perinexii (intercalated disc nanodomains enriched in Nav channels) and increases β1-regulated intramembrane proteolysis (RIP) continuously over 48 h; a shorter peptide LQLEED mimics inhibitory effects, while dimeric LQLEED peptides paradoxically promote adhesion and only transiently boost RIP; DAPT (RIP inhibitor) reduces βadp1's adhesion-disrupting effects, linking β1 CAM function to RIP-mediated signaling.\",\n      \"method\": \"Patch-clamp in neonatal rat cardiomyocytes, electric cell substrate impedance sensing (ECIS) in β1-expressing cells, pharmacological inhibition of RIP with DAPT\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — two orthogonal assays (patch-clamp + ECIS) with pharmacological validation, single lab\",\n      \"pmids\": [\"38942073\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Self-administered (but not experimenter-administered) heroin reduces NAc β1 (SCN1b) protein levels in rats; viral-mediated reduction of NAc SCN1b increases medium spiny neuron (MSN) intrinsic excitability without altering glutamatergic or GABAergic synaptic transmission; reduced NAc SCN1b significantly increases cue-reinstated heroin seeking, demonstrating that β1 normally limits MSN excitability and cue-driven opioid seeking in the nucleus accumbens.\",\n      \"method\": \"Heroin self-administration, viral knockdown, patch-clamp electrophysiology in NAc MSNs, reinstatement behavioral testing in rats\",\n      \"journal\": \"eNeuro\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — viral KD with electrophysiology and behavioral readout, single lab\",\n      \"pmids\": [\"39947903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Scn1b-c.265C>T (p.R89C) knock-in mouse cardiomyocytes show increased transient outward K+ current (Ito) density and ventricular fibrosis; mice are susceptible to pacing-induced cardiac arrhythmias; patient-derived iPSC-CMs with biallelic SCN1B-c.265C>T show increased INa, late INa, and Ito densities; increased Ito is a common cardiac alteration in both mouse and human DEE52 models.\",\n      \"method\": \"CRISPR knock-in mouse model, patch-clamp, pacing-induced arrhythmia, iPSC-CM differentiation from DEE52 patients, cardiac histology\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — orthogonal mouse and human iPSC-CM models with patch-clamp and structural analysis\",\n      \"pmids\": [\"40763036\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SCN1B variant A197V in Brugada syndrome patients markedly decreases Na+ current density when co-expressed with SCN5A/Nav1.5 in HEK293 cells, decelerates activation velocity, and reduces Nav1.5 plasma membrane distribution; no significant changes in recovery from inactivation.\",\n      \"method\": \"Whole-cell patch-clamp in HEK293 cells, cell surface protein analysis\",\n      \"journal\": \"Archives of medical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with electrophysiology and surface protein analysis, single lab\",\n      \"pmids\": [\"32192759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Reduced variability of INa density in Scn1b null cortical pyramidal neurons enhances spike timing correlations between neurons and impairs spike-triggered average current pattern diversity; computational modeling shows that broad INa density ranges (dependent on β1 expression) confer a broad spectrum of spike patterning and displace synchronization thresholds in network models, demonstrating that β1-regulated INa heterogeneity regulates spike pattern diversity and network synchronization.\",\n      \"method\": \"Patch-clamp recording from constitutive and inducible Scn1b null cortical neurons, computational network modeling, TTX pharmacology\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — patch-clamp with computational modeling and pharmacological validation, single lab\",\n      \"pmids\": [\"37264112\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SCN1B encodes the voltage-gated sodium channel β1 (and β1B) subunits that are multifunctional proteins: they modulate Na+ (and K+) channel gating kinetics, increase channel cell-surface expression, regulate subcellular localization of α subunits to axon initial segments and nodes of Ranvier, function as cell adhesion molecules (CAMs) mediating neuronal migration, axonal pathfinding, and fasciculation, and signal through regulated intramembrane proteolysis (RIP) to control gene transcription—loss of β1 in neurons causes hyperexcitability, epilepsy, and ataxia, while in the heart it leads to increased persistent/late Na+ current, disrupted Ca2+ homeostasis, and susceptibility to arrhythmias.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SCN1B encodes the voltage-gated sodium channel β1 (and β1B) auxiliary subunits, which function as multifunctional regulators of neuronal and cardiac excitability by modulating Na+ channel gating kinetics, promoting α-subunit cell-surface expression, and acting as immunoglobulin-superfamily cell adhesion molecules that direct axonal pathfinding, fasciculation, and neuronal migration. The β1 subunit is required for normal Na+ channel inactivation and controls cell-surface density of multiple α-subunit isoforms (Nav1.1, Nav1.3, Nav1.5, Nav1.6) in an isoform-specific manner; loss of β1 increases persistent and late Na+ current, disrupts Ca²⁺ homeostasis in cardiomyocytes, and enhances intrinsic excitability of cortical pyramidal neurons, hippocampal neurons, and cerebellar Purkinje cells while reducing parvalbumin interneuron firing [PMID:7851891, PMID:17884088, PMID:23277545, PMID:37845033, PMID:40923316]. β1 additionally participates in regulated intramembrane proteolysis (RIP)-coupled signaling at cardiac intercalated discs, linking its adhesion function to intracellular signaling [PMID:38942073]. Loss-of-function and gain-of-function SCN1B mutations cause developmental and epileptic encephalopathy 52 (DEE52), generalized epilepsy with febrile seizures plus (GEFS+), Brugada syndrome, and cardiac arrhythmias including atrial fibrillation and long QT syndrome, and early postnatal AAV-mediated β1 gene replacement rescues seizure severity and lifespan in Scn1b-null mice [PMID:9697698, PMID:35603785, PMID:24662403, PMID:39847501].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Identifying the genomic structure of SCN1B and establishing that the β1 subunit is required for normal Na+ channel inactivation kinetics resolved why α subunits alone exhibit abnormal gating behavior.\",\n      \"evidence\": \"Genomic cloning, sequencing, and FISH mapping of the SCN1B locus on chromosome 19q13.1–q13.2\",\n      \"pmids\": [\"7851891\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No protein structure resolved\", \"Mechanism of β1–α subunit interaction unknown\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstrating that the GEFS+ C121W mutation disrupts the extracellular Ig-fold disulfide bridge and abolishes β1-mediated channel modulation established SCN1B as a disease gene and linked its adhesion-like domain to channel-gating function.\",\n      \"evidence\": \"Xenopus oocyte co-expression electrophysiology with mutant β1 and brain Na+ channel α subunit\",\n      \"pmids\": [\"9697698\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo consequences of C121W not yet characterized\", \"Whether C121W is pure loss-of-function or gain-of-function unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showing that Scn1b-null cardiomyocytes have increased peak and persistent INa, prolonged QT/RR intervals, and upregulated Nav1.5 established β1 as a negative regulator of cardiac Na+ current and a determinant of cardiac repolarization.\",\n      \"evidence\": \"Patch-clamp of ventricular myocytes, ECG, and immunostaining in Scn1b-null mice\",\n      \"pmids\": [\"17884088\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of Nav1.5 upregulation (transcriptional vs. post-translational) unclear\", \"Whether cardiac phenotype is cell-autonomous not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Zebrafish studies confirmed evolutionary conservation of β1 dual function as both a Na+ current modulator and a cell adhesion molecule required for axonal pathfinding and sensory neuron development.\",\n      \"evidence\": \"Heterologous co-expression electrophysiology of zebrafish scn1ba with scn8aa; morpholino knockdown of scn1bb with behavioral, electrophysiological, and immunohistochemical readouts\",\n      \"pmids\": [\"17623064\", \"19020043\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Morpholino off-target effects not fully controlled\", \"Mammalian in vivo CAM function not yet demonstrated\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Establishing that the R125C mutation causes a trafficking-null phenotype (retained intracellularly despite normal total expression) while Scn1b-null hippocampal neurons fire with higher amplitude action potentials connected disease mutations to surface-expression failure and neuronal hyperexcitability.\",\n      \"evidence\": \"Biochemical surface-expression assays in heterologous cells; hippocampal slice and dissociated neuron recordings from Scn1b-null mice\",\n      \"pmids\": [\"19710327\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream transcriptional consequences of β1 loss in hippocampus not explored\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that β1 regulates not only Na+ currents but also K+ currents and Nav1.9 surface expression in DRG neurons, and independently modulates late INa in cardiac myocytes, broadened β1's role beyond canonical fast Na+ channel gating.\",\n      \"evidence\": \"Patch-clamp of Scn1b-null DRG neurons with Nav1.9 immunostaining; siRNA knockdown of SCN1B in canine ventricular myocytes with electrophysiology\",\n      \"pmids\": [\"21555511\", \"21705762\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical interaction between β1 and K+ channels not demonstrated\", \"Molecular basis of isoform-specific late INa modulation unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrating disrupted parallel fiber fasciculation, aberrant neuronal migration, and defective axonal pathfinding in Scn1b-null mouse brains established β1 as a bona fide cell adhesion molecule required for postnatal brain development.\",\n      \"evidence\": \"Immunohistochemistry, c-Fos staining, and electrophysiology in hippocampal and cortical slices of Scn1b-null mice\",\n      \"pmids\": [\"23277545\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trans-binding partners for β1 CAM activity not identified\", \"Whether CAM and channel-modulation functions are separable in vivo unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Cell-type-specific analysis showed C121W increases excitatory neuron firing (via increased input resistance) without affecting interneurons, and cardiac-specific Scn1b deletion causes Ca²⁺ dysregulation and arrhythmia susceptibility, delineating tissue- and cell-type-specific consequences of β1 loss.\",\n      \"evidence\": \"Patch-clamp in brain slices of Scn1b-C121W mice with retigabine rescue; macropatch, Ca²⁺ imaging, and arrhythmia protocols in cardiac-specific Scn1b-null mice with TTX rescue\",\n      \"pmids\": [\"24747835\", \"25772295\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which β1 loss increases input resistance not resolved\", \"Upstream signaling linking increased Na+ influx to Ca²⁺ release not fully defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing that C121W β1 reaches the neuronal surface but fails to associate with α subunits and is excluded from axon initial segments and nodes of Ranvier—and that heterozygous C121W mice are more seizure-susceptible than heterozygous nulls—established a dominant-negative/gain-of-function mechanism beyond simple haploinsufficiency.\",\n      \"evidence\": \"Co-immunoprecipitation from brain, immunofluorescence at AIS and nodes, hyperthermia seizure comparison of Scn1b+/W vs. Scn1b+/− mice\",\n      \"pmids\": [\"27277800\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Nature of the gain-of-function mechanism not molecularly defined\", \"Whether mislocalized C121W exerts CAM-related toxicity unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Scn1b loss in the heart causes sinoatrial node dysfunction, atrial fibrillation susceptibility with autonomic dysregulation, and diastolic dysfunction via increased late INa and disrupted Ca²⁺ transients—all rescued pharmacologically—establishing β1 as essential for multiple aspects of cardiac physiology beyond ventricular conduction.\",\n      \"evidence\": \"Pacing-induced AF with atropine rescue in Scn1b-null neonatal mice; inducible cardiac-specific KO with echocardiography, hemodynamics, Ca²⁺ imaging, and GS967 rescue in adult mice\",\n      \"pmids\": [\"35603785\", \"35394857\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of increased cholinergic innervation in null SAN not resolved\", \"Whether fibrosis is a direct consequence of altered Na+/Ca²⁺ handling unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealing that β1 loss disrupts INa density heterogeneity across cortical pyramidal neurons and impairs parvalbumin and somatostatin interneuron recruitment in hippocampal circuits explained how β1 shapes network-level spike pattern diversity and synchronization thresholds relevant to seizure generation.\",\n      \"evidence\": \"Patch-clamp from constitutive and inducible Scn1b-null cortical neurons with computational modeling; multi-cell-type recordings in hippocampal slices of Scn1b KO mice\",\n      \"pmids\": [\"37264112\", \"37845033\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Computational predictions of synchronization thresholds not validated in vivo\", \"Molecular basis of reduced interneuron firing not identified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrating that β1 mimetic peptides disrupt intercellular adhesion at cardiac perinexii and modulate regulated intramembrane proteolysis (RIP) linked β1's CAM function to a signaling pathway, with RIP inhibition partially rescuing adhesion disruption.\",\n      \"evidence\": \"ECIS adhesion assay and patch-clamp in neonatal cardiomyocytes with DAPT (γ-secretase inhibitor) pharmacological rescue\",\n      \"pmids\": [\"38942073\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream transcriptional targets of β1-RIP signaling not identified\", \"Whether RIP occurs in neurons in vivo not established\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"AAV-mediated β1 gene replacement at postnatal day 2 rescued seizures and extended lifespan in Scn1b-null mice; cell-type-specific deletion showed β1 is required for Purkinje cell resurgent Na+ current and repetitive firing, with PC-specific loss sufficient for ataxia; and a knock-in DEE52 model confirmed increased Ito as a conserved cardiac phenotype in both mouse and human iPSC-CMs.\",\n      \"evidence\": \"AAV-Navβ1 ICV injection with EEG/seizure monitoring and electrophysiology; PC-specific conditional KO with patch-clamp and behavioral testing; CRISPR knock-in R89C mice and patient iPSC-CMs\",\n      \"pmids\": [\"39847501\", \"40923316\", \"40763036\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Therapeutic window for gene replacement in humans undefined\", \"Whether gene therapy rescues CAM-dependent developmental phenotypes not assessed\", \"Mechanism of β1-dependent Ito regulation in cardiomyocytes unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include: the structural basis of β1–α subunit interaction, the identity of β1 trans-binding CAM partners, whether channel-modulation and adhesion functions are genetically separable in vivo, the downstream transcriptional targets of β1-RIP signaling, and whether early gene replacement can rescue developmental (CAM-mediated) as well as electrophysiological phenotypes.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of β1–α complex\", \"Trans-binding partners for β1 CAM adhesion not identified\", \"RIP transcriptional targets unknown\", \"Separability of channel-modulation vs. CAM functions in vivo untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 3, 6, 9, 11, 12, 16]},\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [4, 10, 22]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [4, 5, 22]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 5, 13, 25]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 2, 4, 6, 8, 20, 21, 26]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [22]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [1, 3, 7, 11, 18]}\n    ],\n    \"complexes\": [\n      \"Voltage-gated sodium channel complex\"\n    ],\n    \"partners\": [\n      \"SCN1A\",\n      \"SCN5A\",\n      \"SCN3A\",\n      \"SCN2A\",\n      \"SCN8A\",\n      \"SCN11A\",\n      \"SCN4A\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}