{"gene":"SCN1B","run_date":"2026-06-10T07:46:29","timeline":{"discoveries":[{"year":1998,"finding":"SCN1B encodes a β1 subunit that modulates Na+ channel-gating kinetics; the C121W mutation disrupts a conserved cysteine that maintains an extracellular immunoglobulin-like disulfide bridge, abolishing β1-mediated modulation of channel gating when co-expressed with a brain Na+ channel α subunit in Xenopus oocytes, consistent with a loss-of-function allele.","method":"Co-expression of mutant β1 with brain Na+ channel α subunit in Xenopus laevis oocytes; electrophysiology","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with functional electrophysiological readout; foundational study replicated across multiple subsequent labs","pmids":["9697698"],"is_preprint":false},{"year":1994,"finding":"The human SCN1B gene consists of five exons spanning ~9 kb of genomic DNA and maps to chromosome 19q13.1-q13.2 by fluorescence in situ hybridization.","method":"Genomic DNA cloning, intron-exon boundary sequencing, FISH","journal":"Genomics","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct experimental mapping by FISH and genomic sequencing; foundational structural determination","pmids":["7851891"],"is_preprint":false},{"year":2007,"finding":"Loss of β1 (Scn1b null mice) increases both peak and persistent ventricular sodium current (~1.6-fold) and Nav1.5 protein expression (~1.3-fold), prolongs action potential repolarization, and results in extended QTc and RR intervals, demonstrating that β1 is required for normal cardiac excitability.","method":"Scn1b null mouse model; patch-clamp electrophysiology in acutely dissociated ventricular myocytes; ECG recording; immunostaining","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cellular phenotype, multiple orthogonal methods (ECG, patch-clamp, Western blot), single lab","pmids":["17884088"],"is_preprint":false},{"year":2009,"finding":"The SCN1B p.R125C recessive mutation causes near-absent cell surface expression of β1 despite normal total cellular protein levels, regardless of co-expression with Nav1.1 α subunits. In Scn1b null CA3 neurons, action potentials have higher peak voltage and greater amplitude than wild type, but sodium current density is unchanged.","method":"Heterologous expression with cell surface biotinylation; hippocampal slice recordings in Scn1b−/− vs +/+ mice","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (biochemical surface expression assay, electrophysiology in heterologous and native systems), replicated finding linking mutation to functional null","pmids":["19710327"],"is_preprint":false},{"year":2011,"finding":"Scn1b regulates nociceptive DRG neuron excitability in vivo: Scn1b null neurons show a depolarizing shift in TTX-S INa inactivation, reduced persistent TTX-R INa and reduced cell-surface Nav1.9 expression, reduced transient outward K+ current, and resulting neuronal hyperexcitability.","method":"Patch-clamp electrophysiology and cell surface biotinylation in acutely dissociated DRG neurons from Scn1b null mice vs. WT","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KO with multiple orthogonal electrophysiological and biochemical readouts, single lab","pmids":["21555511"],"is_preprint":false},{"year":2012,"finding":"Scn1b deletion disrupts neuronal pathfinding during early postnatal brain development (P5): null cerebella show disrupted parallel fiber fasciculation, reduced dentate gyrus neuron density, increased granule cell precursor proliferation in the hilus, and defective axonal extension and misorientation of inhibitory neurons, preceding hyperexcitability (onset ~P16).","method":"Histological and immunofluorescence analysis of Scn1b null mouse brain at P5 and P16; c-Fos immunostaining; hippocampal/cortical slice electrophysiology","journal":"Proceedings of the National Academy of Sciences","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KO with multiple cellular phenotype readouts and temporal dissection of pathfinding vs. hyperexcitability, single lab","pmids":["23277545"],"is_preprint":false},{"year":2014,"finding":"Scn1b deletion in cardiac-specific null mice increases tetrodotoxin-sensitive INa (attributable to increased Nav1.3 protein at the cell midsection), causes delayed after-depolarizations, triggered beats, delayed Ca2+ transients, spontaneous Ca2+ release events, and increased susceptibility to polymorphic ventricular arrhythmias; most Ca2+ homeostasis alterations were prevented by 100 nM TTX.","method":"Cardiac-specific Scn1b null mouse; macropatch and scanning ion conductance microscopy; action potential and Ca2+ transient recordings; whole-heart arrhythmia induction","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — cardiac-specific KO with multiple orthogonal methods, pharmacological rescue with TTX, single lab","pmids":["25772295"],"is_preprint":false},{"year":2014,"finding":"In an Scn1b-C121W knock-in mouse model, β1-C121W subunits are expressed at neuronal cell bodies but are incompletely glycosylated, do not associate with VGSC α subunits in brain, and are absent from axon initial segments and nodes of Ranvier. Heterozygous Scn1b+/W mice are more susceptible to hyperthermia-induced seizures than heterozygous null (Scn1b+/−) mice, demonstrating the C121W mutation confers a deleterious gain-of-function rather than simple loss-of-function.","method":"Scn1b-C121W knock-in mouse; co-immunoprecipitation; immunofluorescence; hyperthermia seizure threshold assay","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo knock-in model with biochemical (Co-IP, surface expression) and behavioral readouts, direct comparison to null allele, single lab","pmids":["27277800"],"is_preprint":false},{"year":2014,"finding":"In a mouse model bearing the human Scn1b-C121W mutation (homozygous), subicular and layer 2/3 pyramidal neurons have increased action potential firing rates due to increased input resistance, with increased spontaneous synaptic activity in the subiculum but not CA1; no changes were seen in GABAergic interneuron firing, contrasting with Scn1a-based Dravet models. Retigabine (a K+ channel opener reducing input resistance) dampened firing and protected against thermal seizures.","method":"Scn1b-C121W homozygous mouse model; patch-clamp electrophysiology in brain slices; thermal seizure threshold; pharmacological intervention","journal":"Brain","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple cell types analyzed, pharmacological rescue with mechanism-based drug, defined circuit phenotype, single lab","pmids":["24747835"],"is_preprint":false},{"year":2011,"finding":"Post-transcriptional silencing of SCN1B (>80% reduction) in cardiac myocytes reduces late sodium current (INaL) density and accelerates its decay, while siRNA against SCN2B has the opposite effect, demonstrating β1 and β2 subunits exert oppositely directed modulation of INaL in both normal and failing heart myocytes.","method":"siRNA-mediated knockdown via viral delivery; whole-cell and perforated patch-clamp; Western blot and RT-PCR in isolated dog ventricular cardiomyocytes","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional siRNA knockdown with electrophysiological readout in native cardiomyocytes, single lab","pmids":["21705762"],"is_preprint":false},{"year":2013,"finding":"Antisense-mediated silencing of SCN1B reduces α subunit mRNA, protein expression and sodium current density in GH3 and H9C2 cells in an isoform-specific manner: Nav1.1, Nav1.3, and Nav1.6 are reduced in GH3 cells, Nav1.5 is reduced in H9C2 cells, while Nav1.2 is unaffected, without altering channel gating kinetics.","method":"Antisense oligonucleotide knockdown; RT-PCR; Western blot; whole-cell patch-clamp in rat GH3 and H9C2 cell lines","journal":"Biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with both mRNA/protein and functional readouts, multiple cell lines, single lab","pmids":["24138709"],"is_preprint":false},{"year":2007,"finding":"Zebrafish scn1ba splice variants modulate Na+ currents expressed by scn8aa: both produce negative shifts in voltage dependence of activation and inactivation, increased current amplitude, and faster recovery from inactivation, consistent with mammalian β1 subunit function. The C-terminus tyrosine critical for ankyrin association in mammalian β1 is conserved in scn1ba_tv1 but absent in tv2.","method":"Heterologous co-expression in Xenopus oocytes or cell lines; electrophysiology; immunohistochemistry in zebrafish tissue","journal":"BMC genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional reconstitution in heterologous system with multiple electrophysiological parameters, structural domain analysis","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 defective development of ventrally projecting spinal neuron axons, defasciculation of the olfactory nerve, and increased inner ear hair cell numbers, demonstrating dual roles as a Na+ current modulator and cell adhesion molecule in vivo.","method":"Morpholino knockdown in zebrafish; patch-clamp in Rohon-Beard neurons; behavioral touch assay; morphological analysis","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KD with multiple orthogonal phenotypic readouts (electrophysiology, behavior, morphology), single lab","pmids":["19020043"],"is_preprint":false},{"year":2014,"finding":"The SCN1B β1b-P213T mutation increases late sodium current and subtly alters Nav1.5 gating (shifts window current, accelerates recovery from inactivation, decreases slow inactivation) and significantly prolongs action potential duration in HL-1 cells, identifying SCN1Bb as a susceptibility gene for Long QT syndrome.","method":"Whole-cell patch-clamp in HEK cells and HL-1 cardiomyocytes co-expressing β1b-P213T with Nav1.5","journal":"Heart rhythm","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patch-clamp with multiple gating parameters in two cell systems, single lab, single mutation","pmids":["24662403"],"is_preprint":false},{"year":2018,"finding":"The SCN1B-D25N mutation causes a glycosylation (maturation) defect that reduces targeting of β1 to the plasma membrane, abolishes β1-dependent modulation of gating kinetics when co-expressed with Nav1.2, Nav1.4, or Nav1.5 in HEK293 cells, and impairs interaction with the α subunit.","method":"Heterologous co-expression in HEK293 cells; whole-cell patch-clamp; Western blot for glycosylation state; cell surface biotinylation","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (biochemistry and electrophysiology), multiple α subunit isoforms tested, single lab","pmids":["29992740"],"is_preprint":false},{"year":2019,"finding":"The SCN1B-p.Arg85Cys variant shows normal cell surface expression but loss of β1-mediated modification of Nav1.1-generated sodium current in heterologous cells, establishing it as a loss-of-function variant through a gating modulation defect rather than a trafficking defect.","method":"Heterologous expression in HEK cells; whole-cell patch-clamp; surface expression assay","journal":"Annals of clinical and translational neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patch-clamp with surface expression assay, mechanistically informative distinction from trafficking vs. gating defect, single lab","pmids":["31709768"],"is_preprint":false},{"year":2020,"finding":"The SCN1B mutation β1-D103V (c.308A>T) decreases sodium current density when co-expressed with Nav1.5 or Nav1.1, while β1b-D103V does not affect Nav1.1 current density but causes a positive shift in voltage dependence of inactivation and faster recovery from inactivation, demonstrating isoform-specific effects on cardiac (Nav1.5) and brain (Nav1.1) sodium currents.","method":"Whole-cell patch-clamp in tsA201 cells co-expressing mutant β1 or β1b with Nav1.5 or Nav1.1","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional patch-clamp with two α subunits and two β isoforms, single lab, single mutation","pmids":["33134290"],"is_preprint":false},{"year":2022,"finding":"Scn1b deletion increases fast (+20%) and slow (+140%) inactivating components of INa in adult mouse cardiomyocytes, compromises diastolic function and ventricular compliance without affecting systolic function; pharmacological inhibition of late INa with GS967 normalized left ventricular filling and isovolumic relaxation time, linking β1/β1B subunits to diastolic function through control of Na+ influx and Ca2+ cycling.","method":"Adult cardiac-specific inducible Scn1b knockout mouse; patch-clamp; echocardiography; invasive hemodynamics; Ca2+ imaging; pharmacological rescue with GS967","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional/inducible KO with multiple orthogonal methods (electrophysiology, imaging, in vivo hemodynamics, pharmacological rescue), single lab","pmids":["35394857"],"is_preprint":false},{"year":2022,"finding":"Scn1b null neonatal mice develop sinoatrial node dysfunction, atrial fibrillation (AF), atrial collagen accumulation, and increased cholinergic innervation of the SAN. Null atrial myocytes have prolonged action potential duration, increased late sodium current, and reduced L-type calcium current. Atropine reduced AF incidence, indicating that increased cholinergic tone contributes to AF.","method":"Scn1b null neonatal mouse model; ECG; pacing-induced AF protocol; histology; patch-clamp; gene expression analysis; atropine pharmacological intervention","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KO with multiple orthogonal methods (electrophysiology, histology, pharmacology, gene expression), single lab","pmids":["35603785"],"is_preprint":false},{"year":2023,"finding":"In Scn1b null mice, reduced sodium current (INa) density heterogeneity between cortical layer 6 and subicular pyramidal neurons enhances spike timing correlations and impairs spike-pattern diversity. Low-concentration TTX phenocopies this effect, demonstrating that INa variability between neurons, regulated by β1, decorrelates spiking and suppresses network synchronization.","method":"Constitutive and inducible Scn1b null mice; patch-clamp in cortical pyramidal neurons; computational modeling; TTX pharmacological experiments","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO with electrophysiology and pharmacological validation, computational modeling, single lab","pmids":["37264112"],"is_preprint":false},{"year":2023,"finding":"Scn1b null mice display ataxia; Purkinje cells (PCs) and cerebellar interneurons in null cerebellar slices have increased thresholds for AP initiation and decreased repetitive firing frequency, associated with reduced transient and resurgent sodium current densities in PCs. Cerebellar output hypoexcitability is proposed to underlie ataxia and to exacerbate seizure severity.","method":"Scn1b null mouse behavioral (rotarod, gait); cerebellar slice patch-clamp; sodium current recordings; CRISPR-V5 tagged β1 mouse for localization","journal":"JCI insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with behavioral, electrophysiological, and localization experiments, single lab","pmids":["40923316"],"is_preprint":false},{"year":2023,"finding":"In Scn1b null hippocampal CA1, pyramidal neurons have enhanced intrinsic excitability, smaller facilitating EPSCs and IPSCs but larger postsynaptic potentials, and parvalbumin and somatostatin interneuron recruitment is disrupted; together these result in greatly amplified input/output functions upon patterned Schaffer collateral stimulation.","method":"Scn1b null mouse; CA1 slice patch-clamp electrophysiology; patterned stimulation protocols; interneuron-specific recordings","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with multiple cell-type recordings and synaptic/intrinsic analysis, single lab","pmids":["37845033"],"is_preprint":false},{"year":2025,"finding":"AAV-mediated delivery of 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 protein was expressed in both excitatory and inhibitory neurons, confirming that early restoration of β1 in brain is sufficient to rescue the DEE52 phenotype.","method":"AAV gene therapy in Scn1b null mice; intracerebroventricular injection at P2 vs P10; EEG; seizure scoring; cortical neuron patch-clamp; Western blot","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Moderate — proof-of-principle rescue experiment with multiple orthogonal readouts (EEG, survival, behavior, electrophysiology), single lab but rigorous design","pmids":["39847501"],"is_preprint":false},{"year":2025,"finding":"Self-administered heroin reduces NAc β1 (SCN1b) protein levels in rats. Viral-mediated reduction of NAc SCN1b increases MSN intrinsic excitability without altering synaptic transmission, and increases cue-reinstated heroin seeking, demonstrating that NAc β1 limits cue-induced drug seeking by modulating MSN excitability.","method":"Heroin self-administration in rats; Western blot for SCN1b protein; viral-mediated knockdown; patch-clamp electrophysiology in NAc MSNs; cue-reinstatement behavioral assay","journal":"eNeuro","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo viral KD with electrophysiological and behavioral readouts, single lab","pmids":["39947903"],"is_preprint":false},{"year":2025,"finding":"Purkinje cell-specific deletion of Scn1b in mice causes marked decrements in Purkinje cell physiology (increased AP threshold, reduced repetitive firing) and motor, social, and cognitive dysfunction without early mortality, establishing cerebellar Purkinje cells as a critical node for SCN1B-related DEE neurological disabilities.","method":"Conditional Purkinje cell-specific Scn1b knockout mouse; cerebellar slice patch-clamp; behavioral tests (motor, social, cognitive)","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-type-specific KO with electrophysiological and behavioral readouts, single lab","pmids":["41162148"],"is_preprint":false},{"year":2025,"finding":"Scn1b-C89/C89 (DEE52 variant p.R89C knock-in) mouse cardiomyocytes show increased transient outward K+ current (Ito) and ventricular fibrosis; patient-derived iPSC-CMs with biallelic SCN1B-c.265C>T show increased peak INa, late INa, and Ito. Both models show susceptibility to cardiac arrhythmias, supporting a cardiac contribution to SUDEP in DEE52.","method":"Scn1b-p.R89C knock-in mouse; iPSC-CMs from DEE52 patients; patch-clamp; histology; pacing-induced arrhythmia protocol","journal":"JCI insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two complementary models (mouse and human iPSC-CM) with electrophysiological and structural readouts, single lab","pmids":["40763036"],"is_preprint":false},{"year":2024,"finding":"Loss of Scn1b compromises mitochondrial energetics and ROS-scavenging capacity: cardiomyocytes from Scn1b null mice die faster, accumulate more ROS under oxidative challenge (diamide), and have increased glutathione peroxidase protein expression and activity; intact Scn1b null hearts show higher arrhythmia scores under oxidative stress.","method":"Scn1b null mouse; isolated cardiomyocytes and hearts; oxidative challenge with diamide; ROS imaging; enzyme activity assays; gene expression","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean KO with multiple biochemical and functional readouts but novel link (ROS/arrhythmia) tested in single lab study","pmids":["39120465"],"is_preprint":false},{"year":2024,"finding":"A SCN1B mimetic peptide (βadp1) disrupts β1-mediated intercellular adhesion in cardiac perinexii and increases β1-regulated intramembrane proteolysis (RIP) over 48 h; inhibition of RIP with DAPT reduces βadp1's effect on adhesion. Dimeric agonist peptides (containing LQLEED repeats) acutely promote adhesion and transiently boost RIP, establishing a mechanistic link between β1 adhesion function and RIP-mediated transcriptional signaling.","method":"Patch-clamp in neonatal rat cardiomyocytes; electric cell substrate impedance sensing (ECIS); RIP assay; DAPT pharmacological inhibition","journal":"Journal of molecular and cellular cardiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — peptide pharmacology with functional adhesion and signaling readouts in cardiomyocytes, two orthogonal assay systems, single lab","pmids":["38942073"],"is_preprint":false},{"year":2017,"finding":"A synonymous SCN1B variant (c.492T>C, p.Tyr164Tyr) disrupts a splicing silencer sequence and causes splicing imbalance between wild-type and mutant exons, confirmed by in vitro splicing assay, contributing to Benign Familial Infantile Epilepsy.","method":"Genome-wide linkage analysis; whole exome sequencing; in vitro splicing assay; in silico splicing analysis","journal":"European journal of paediatric neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro splicing assay confirms in silico prediction, single lab","pmids":["28566192"],"is_preprint":false},{"year":2031,"finding":"In Scn1b-p.R89C knock-in mice, β1-p.R89C polypeptides are expressed at normal brain levels and localize to the plasma membrane with intact regulated intramembrane proteolysis, but produce α subunit subtype-specific effects on sodium current in heterologous cells. Scn1b somatosensory cortex shows increased Scn2a, Scn3a, Scn5a, and Scn1b mRNA; Scn1b null cortex is haploinsufficient for Scn1a, indicating an additive disease mechanism.","method":"CRISPR knock-in mouse; heterologous electrophysiology; RT-qPCR; surface biotinylation; RIP assay; hyperthermia seizure threshold; EEG","journal":"Brain communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR knock-in with multiple orthogonal methods, single lab","pmids":["38425576"],"is_preprint":false}],"current_model":"SCN1B encodes voltage-gated sodium channel β1 and β1B subunits that function as multifunctional proteins: they modulate the gating kinetics and cell-surface expression of multiple Nav α subunit isoforms (Nav1.1–Nav1.6) in neurons and cardiomyocytes; act as cell adhesion molecules (CAMs) that mediate trans-homophilic interactions, axonal fasciculation, neuronal migration, and pathfinding; undergo regulated intramembrane proteolysis (RIP) that drives downstream gene transcription; and regulate K+ currents, Ca2+ homeostasis, and network synchronization in the brain. Loss-of-function—whether by missense mutations disrupting the extracellular immunoglobulin-like disulfide bridge, trafficking defects, or null alleles—reduces Nav α subunit surface expression, abolishes β1-mediated channel gating modulation, impairs neuronal pathfinding, and produces cardiac arrhythmias, epilepsy, and SUDEP in mouse models and human patients."},"narrative":{"mechanistic_narrative":"SCN1B encodes the voltage-gated sodium channel β1 subunit (and the splice variant β1B), a multifunctional protein that modulates the gating kinetics and surface expression of multiple Nav α subunit isoforms and acts as a cell-adhesion molecule governing neuronal pathfinding [PMID:9697698, PMID:23277545, PMID:19020043]. β1 modulation of channel gating depends on a conserved extracellular immunoglobulin-like disulfide bridge; the C121W mutation that disrupts this bridge abolishes β1-mediated gating modulation of co-expressed brain Nav α subunits [PMID:9697698]. β1 regulates Nav α subunits in an isoform-specific manner, controlling surface density of Nav1.1, Nav1.3, Nav1.5, Nav1.6 and Nav1.9 across brain, cardiac and sensory tissues [PMID:21555511, PMID:24138709, PMID:33134290]. Loss of β1 increases sodium current — including persistent/late INa — and raises Nav protein levels, producing cardiac phenotypes spanning prolonged repolarization and QTc, atrial fibrillation with sinoatrial node dysfunction, impaired diastolic function, and arrhythmia susceptibility rescued pharmacologically by late-INa or muscarinic blockade [PMID:17884088, PMID:35394857, PMID:35603785, PMID:25772295]. In the brain, β1 deletion disrupts early postnatal axonal fasciculation and neuronal pathfinding before driving network hyperexcitability, with region- and cell-type-specific effects on pyramidal neuron and cerebellar Purkinje cell firing that underlie epilepsy and ataxia [PMID:23277545, PMID:24747835, PMID:40923316, PMID:41162148]. β1 additionally undergoes regulated intramembrane proteolysis that is mechanistically coupled to its trans-adhesion function [PMID:38942073]. Human loss-of-function and splicing variants cause epilepsy phenotypes including benign familial infantile epilepsy and the developmental and epileptic encephalopathy DEE52, and AAV-mediated restoration of β1 in neonatal Scn1b-null brain rescues seizures and excitability, establishing β1 deficiency as the disease driver [PMID:31709768, PMID:28566192, PMID:39847501].","teleology":[{"year":1994,"claim":"Establishing the genomic structure and chromosomal location of SCN1B provided the molecular foundation for linking the gene to inherited disease.","evidence":"Genomic DNA cloning, intron-exon boundary sequencing and FISH mapping to 19q13.1-q13.2","pmids":["7851891"],"confidence":"High","gaps":["Does not address protein function","No isoform/splice-variant catalog"]},{"year":1998,"claim":"The first functional study showed β1 modulates Nav α subunit gating and that the epilepsy-associated C121W mutation disrupts an extracellular disulfide bridge to abolish this modulation, defining a loss-of-function disease mechanism.","evidence":"Co-expression of mutant β1 with brain Nav α subunit in Xenopus oocytes with electrophysiology","pmids":["9697698"],"confidence":"High","gaps":["Heterologous oocyte system, not native neurons","Single mutation; in vivo consequences untested"]},{"year":2007,"claim":"Cardiac null mice revealed β1 is required for normal cardiac excitability, restraining peak and persistent sodium current and Nav1.5 levels.","evidence":"Scn1b null mouse with ventricular myocyte patch-clamp, ECG and immunostaining","pmids":["17884088"],"confidence":"High","gaps":["Mechanism of increased Nav1.5 expression unresolved","Constitutive KO confounds developmental vs acute roles"]},{"year":2009,"claim":"A recessive human mutation (R125C) was shown to act as a functional null via abolished surface trafficking, while native CA3 recordings dissociated β1's gating effects from sodium current density.","evidence":"Heterologous surface biotinylation plus hippocampal slice recordings in Scn1b-null mice","pmids":["19710327"],"confidence":"High","gaps":["Trafficking machinery for β1 not identified","Unchanged current density vs altered AP not fully reconciled"]},{"year":2011,"claim":"Studies in sensory and cardiac systems established β1 as an isoform-selective regulator of sodium and potassium currents, with opposite-direction modulation of late INa relative to β2.","evidence":"DRG patch-clamp/biotinylation in Scn1b null mice and siRNA knockdown in dog ventricular cardiomyocytes","pmids":["21555511","21705762"],"confidence":"Medium","gaps":["Molecular basis of β1 vs β2 opposite effects unknown","K+ current modulation mechanism unclear"]},{"year":2012,"claim":"β1 was shown to control early postnatal neuronal pathfinding and fasciculation, a developmental role preceding network hyperexcitability and distinguishing its adhesion function from channel modulation.","evidence":"Histology, immunofluorescence and slice electrophysiology of Scn1b null mouse brain at P5 and P16","pmids":["23277545"],"confidence":"High","gaps":["Adhesion partners mediating pathfinding not identified here","Causal link between pathfinding defects and later seizures untested"]},{"year":2013,"claim":"Knockdown across cell lines demonstrated β1 sets α subunit mRNA, protein and current density in an isoform-specific way without changing gating, separating its trafficking/expression role from its gating role.","evidence":"Antisense knockdown with RT-PCR, Western blot and patch-clamp in GH3 and H9C2 cells","pmids":["24138709"],"confidence":"Medium","gaps":["Mechanism of isoform selectivity unknown","Cell-line context may not reflect native neurons"]},{"year":2014,"claim":"Multiple in vivo and heterologous models showed the C121W mutation is a deleterious gain-of-function with mislocalized, under-glycosylated β1, and defined circuit-level (pyramidal vs interneuron) drivers of seizure susceptibility distinct from Scn1a-based Dravet models.","evidence":"Scn1b-C121W knock-in and homozygous mice with Co-IP, immunofluorescence, slice patch-clamp, thermal seizure assays and retigabine rescue; cardiac-specific KO with Ca2+ imaging and arrhythmia induction","pmids":["27277800","24747835","25772295"],"confidence":"High","gaps":["Molecular nature of the C121W gain-of-function unresolved","Link between glycosylation defect and mislocalization mechanistically incomplete"]},{"year":2018,"claim":"Disease variants were resolved into distinct mechanistic classes — glycosylation/trafficking defects versus pure gating-modulation defects with normal surface expression.","evidence":"Heterologous co-expression of D25N and R85C variants with multiple Nav α subunits, patch-clamp, glycosylation Westerns and surface biotinylation","pmids":["29992740","31709768"],"confidence":"Medium","gaps":["Structural basis distinguishing trafficking vs gating effects not defined","Patient genotype-phenotype correlation limited"]},{"year":2020,"claim":"β1 and β1B were shown to produce divergent, isoform-specific effects on cardiac (Nav1.5) versus brain (Nav1.1) sodium currents, explaining how single variants can produce mixed cardiac and neurological phenotypes.","evidence":"Whole-cell patch-clamp in tsA201 cells co-expressing mutant β1/β1B with Nav1.5 or Nav1.1","pmids":["33134290"],"confidence":"Medium","gaps":["Single mutation tested","In vivo relevance of β1 vs β1B divergence untested"]},{"year":2022,"claim":"Conditional and developmental cardiac KO models linked β1 loss to late-INa-driven diastolic dysfunction and to atrial fibrillation with sinoatrial node dysfunction and increased cholinergic tone, with pharmacological rescue confirming the late-INa and muscarinic mechanisms.","evidence":"Inducible and neonatal cardiac Scn1b KO with patch-clamp, echocardiography, hemodynamics, histology and GS967/atropine rescue","pmids":["35394857","35603785"],"confidence":"High","gaps":["Source of increased cholinergic innervation unclear","Fibrosis trigger downstream of β1 loss undefined"]},{"year":2023,"claim":"Brain network and cerebellar studies established that β1 tunes intrinsic excitability and inter-neuronal sodium current heterogeneity, with loss decorrelating spiking, amplifying hippocampal input/output, and causing cerebellar hypoexcitability and ataxia.","evidence":"Constitutive/inducible Scn1b null mice with cortical, CA1 and cerebellar slice patch-clamp, computational modeling, TTX experiments and CRISPR-V5 localization","pmids":["37264112","37845033","40923316"],"confidence":"Medium","gaps":["Causal chain from cellular excitability to behavior incomplete","Cell-type-specific contributions not fully separated in constitutive KO"]},{"year":2024,"claim":"β1 trans-adhesion was mechanistically coupled to regulated intramembrane proteolysis, and β1 loss was linked to compromised mitochondrial energetics and ROS handling in cardiomyocytes, broadening its roles beyond channel modulation.","evidence":"Mimetic/agonist peptide pharmacology with ECIS adhesion and RIP assays plus DAPT inhibition in cardiomyocytes; oxidative challenge, ROS imaging and enzyme assays in Scn1b null hearts","pmids":["38942073","39120465"],"confidence":"Medium","gaps":["Transcriptional targets of β1 RIP not identified","Mechanism linking β1 to mitochondrial/ROS function unknown"]},{"year":2025,"claim":"Gene-replacement, knock-in and patient-derived models established that early restoration of β1 rescues the DEE52 phenotype and that variant β1 produces additive α-subunit dysregulation plus a cardiac contribution to SUDEP.","evidence":"Neonatal AAV-β1 delivery with EEG/survival/patch-clamp; R89C knock-in mice and DEE52 iPSC-cardiomyocytes; Purkinje-specific KO with behavior; NAc viral knockdown in heroin self-administration rats","pmids":["39847501","40763036","41162148","39947903","38425576"],"confidence":"Medium","gaps":["Therapeutic window narrow (P2 vs P10) and human translation untested","Additive transcriptional dysregulation mechanism not fully defined"]},{"year":null,"claim":"How β1's adhesion-coupled regulated intramembrane proteolysis controls specific downstream gene programs, and which trans-homophilic and α-subunit binding interfaces mediate isoform-selective trafficking versus gating, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No RIP transcriptional target identified in the corpus","No structural model of β1–α subunit or β1–β1 adhesion interfaces","Mechanism of isoform-selective α subunit regulation unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,10,16]},{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[12,27]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,4]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,7,14]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[5,8,21]},{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[2,6,17]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[5,12]}],"complexes":["voltage-gated sodium channel complex"],"partners":["SCN1A","SCN5A","SCN2A","SCN3A","SCN8A","SCN2B"],"other_free_text":[]}},"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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Japanese.","date":"2010","source":"International journal of clinical pharmacology and therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/20137763","citation_count":4,"is_preprint":false},{"pmid":"18175077","id":"PMC_18175077","title":"GEFS+ is not related to the most common mutations of SCN1B, SCN1A and GABRG2 in two Tunisian families.","date":"2008","source":"Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/18175077","citation_count":4,"is_preprint":false},{"pmid":"40763036","id":"PMC_40763036","title":"Altered cardiac excitability and arrhythmia in models of SCN1B-linked developmental and epileptic encephalopathy.","date":"2025","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/40763036","citation_count":3,"is_preprint":false},{"pmid":"40923316","id":"PMC_40923316","title":"Ataxia and cerebellar hypoexcitability in a mouse model of SCN1B-linked Dravet syndrome.","date":"2025","source":"JCI insight","url":"https://pubmed.ncbi.nlm.nih.gov/40923316","citation_count":3,"is_preprint":false},{"pmid":"26877851","id":"PMC_26877851","title":"SCN1A and SCN1B gene polymorphisms and their association with plasma concentrations of carbamazepine and carbamazepine 10, 11 epoxide in Iranian epileptic patients.","date":"2015","source":"Iranian journal of basic medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/26877851","citation_count":3,"is_preprint":false},{"pmid":"16157473","id":"PMC_16157473","title":"Involvement of Scn1b and Kcna1 ion channels in audiogenic seizures and PTZ-induced epilepsy.","date":"2005","source":"Epilepsy research","url":"https://pubmed.ncbi.nlm.nih.gov/16157473","citation_count":3,"is_preprint":false},{"pmid":"37264112","id":"PMC_37264112","title":"Heterogeneity of voltage gated sodium current density between neurons decorrelates spiking and suppresses network synchronization in Scn1b null mouse models.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/37264112","citation_count":3,"is_preprint":false},{"pmid":"37845033","id":"PMC_37845033","title":"Complex Synaptic and Intrinsic Interactions Disrupt Input/Output Functions in the Hippocampus of Scn1b Knock-Out Mice.","date":"2023","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/37845033","citation_count":2,"is_preprint":false},{"pmid":"27896052","id":"PMC_27896052","title":"Mutation analysis of the candidate genes SCN1B-4B, FHL1, and LMNA in patients with arrhythmogenic right ventricular cardiomyopathy.","date":"2012","source":"Applied & translational genomics","url":"https://pubmed.ncbi.nlm.nih.gov/27896052","citation_count":2,"is_preprint":false},{"pmid":"39947903","id":"PMC_39947903","title":"Heroin Regulates the Voltage-Gated Sodium Channel Auxiliary Subunit, SCN1b, to Modulate Nucleus Accumbens Medium Spiny Neuron Intrinsic Excitability and Cue-Induced Heroin Seeking.","date":"2025","source":"eNeuro","url":"https://pubmed.ncbi.nlm.nih.gov/39947903","citation_count":1,"is_preprint":false},{"pmid":"41162148","id":"PMC_41162148","title":"A Novel Mouse Model for Developmental and Epileptic Encephalopathy by Purkinje Cell-Specific Deletion of Scn1b.","date":"2025","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/41162148","citation_count":0,"is_preprint":false},{"pmid":"39605540","id":"PMC_39605540","title":"A novel mouse model for developmental and epileptic encephalopathy by Purkinje cell-specific deletion of Scn1b.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39605540","citation_count":0,"is_preprint":false},{"pmid":"37163033","id":"PMC_37163033","title":"Complex synaptic and intrinsic interactions disrupt input/output functions in the hippocampus of Scn1b knockout mice.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/37163033","citation_count":0,"is_preprint":false},{"pmid":"39120465","id":"PMC_39120465","title":"Decreased ability to manage increases in reactive oxygen species may underlie susceptibility to arrhythmias in mice lacking Scn1b.","date":"2024","source":"American journal of physiology. Heart and circulatory physiology","url":"https://pubmed.ncbi.nlm.nih.gov/39120465","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":"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":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":36401,"output_tokens":7650,"usd":0.111977,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":17275,"output_tokens":4720,"usd":0.102188,"stage2_stop_reason":"end_turn"},"total_usd":0.214165,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"SCN1B encodes a β1 subunit that modulates Na+ channel-gating kinetics; the C121W mutation disrupts a conserved cysteine that maintains an extracellular immunoglobulin-like disulfide bridge, abolishing β1-mediated modulation of channel gating when co-expressed with a brain Na+ channel α subunit in Xenopus oocytes, consistent with a loss-of-function allele.\",\n      \"method\": \"Co-expression of mutant β1 with brain Na+ channel α subunit in Xenopus laevis oocytes; electrophysiology\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with functional electrophysiological readout; foundational study replicated across multiple subsequent labs\",\n      \"pmids\": [\"9697698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"The human SCN1B gene consists of five exons spanning ~9 kb of genomic DNA and maps to chromosome 19q13.1-q13.2 by fluorescence in situ hybridization.\",\n      \"method\": \"Genomic DNA cloning, intron-exon boundary sequencing, FISH\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct experimental mapping by FISH and genomic sequencing; foundational structural determination\",\n      \"pmids\": [\"7851891\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Loss of β1 (Scn1b null mice) increases both peak and persistent ventricular sodium current (~1.6-fold) and Nav1.5 protein expression (~1.3-fold), prolongs action potential repolarization, and results in extended QTc and RR intervals, demonstrating that β1 is required for normal cardiac excitability.\",\n      \"method\": \"Scn1b null mouse model; patch-clamp electrophysiology in acutely dissociated ventricular myocytes; ECG recording; immunostaining\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cellular phenotype, multiple orthogonal methods (ECG, patch-clamp, Western blot), single lab\",\n      \"pmids\": [\"17884088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The SCN1B p.R125C recessive mutation causes near-absent cell surface expression of β1 despite normal total cellular protein levels, regardless of co-expression with Nav1.1 α subunits. In Scn1b null CA3 neurons, action potentials have higher peak voltage and greater amplitude than wild type, but sodium current density is unchanged.\",\n      \"method\": \"Heterologous expression with cell surface biotinylation; hippocampal slice recordings in Scn1b−/− vs +/+ mice\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (biochemical surface expression assay, electrophysiology in heterologous and native systems), replicated finding linking mutation to functional null\",\n      \"pmids\": [\"19710327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Scn1b regulates nociceptive DRG neuron excitability in vivo: Scn1b null neurons show a depolarizing shift in TTX-S INa inactivation, reduced persistent TTX-R INa and reduced cell-surface Nav1.9 expression, reduced transient outward K+ current, and resulting neuronal hyperexcitability.\",\n      \"method\": \"Patch-clamp electrophysiology and cell surface biotinylation in acutely dissociated DRG neurons from Scn1b null mice vs. WT\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with multiple orthogonal electrophysiological and biochemical readouts, single lab\",\n      \"pmids\": [\"21555511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Scn1b deletion disrupts neuronal pathfinding during early postnatal brain development (P5): null cerebella show disrupted parallel fiber fasciculation, reduced dentate gyrus neuron density, increased granule cell precursor proliferation in the hilus, and defective axonal extension and misorientation of inhibitory neurons, preceding hyperexcitability (onset ~P16).\",\n      \"method\": \"Histological and immunofluorescence analysis of Scn1b null mouse brain at P5 and P16; c-Fos immunostaining; hippocampal/cortical slice electrophysiology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with multiple cellular phenotype readouts and temporal dissection of pathfinding vs. hyperexcitability, single lab\",\n      \"pmids\": [\"23277545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Scn1b deletion in cardiac-specific null mice increases tetrodotoxin-sensitive INa (attributable to increased Nav1.3 protein at the cell midsection), causes delayed after-depolarizations, triggered beats, delayed Ca2+ transients, spontaneous Ca2+ release events, and increased susceptibility to polymorphic ventricular arrhythmias; most Ca2+ homeostasis alterations were prevented by 100 nM TTX.\",\n      \"method\": \"Cardiac-specific Scn1b null mouse; macropatch and scanning ion conductance microscopy; action potential and Ca2+ transient recordings; whole-heart arrhythmia induction\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cardiac-specific KO with multiple orthogonal methods, pharmacological rescue with TTX, single lab\",\n      \"pmids\": [\"25772295\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In an Scn1b-C121W knock-in mouse model, β1-C121W subunits are expressed at neuronal cell bodies but are incompletely glycosylated, do not associate with VGSC α subunits in brain, and are absent from axon initial segments and nodes of Ranvier. Heterozygous Scn1b+/W mice are more susceptible to hyperthermia-induced seizures than heterozygous null (Scn1b+/−) mice, demonstrating the C121W mutation confers a deleterious gain-of-function rather than simple loss-of-function.\",\n      \"method\": \"Scn1b-C121W knock-in mouse; co-immunoprecipitation; immunofluorescence; hyperthermia seizure threshold assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo knock-in model with biochemical (Co-IP, surface expression) and behavioral readouts, direct comparison to null allele, single lab\",\n      \"pmids\": [\"27277800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"In a mouse model bearing the human Scn1b-C121W mutation (homozygous), subicular and layer 2/3 pyramidal neurons have increased action potential firing rates due to increased input resistance, with increased spontaneous synaptic activity in the subiculum but not CA1; no changes were seen in GABAergic interneuron firing, contrasting with Scn1a-based Dravet models. Retigabine (a K+ channel opener reducing input resistance) dampened firing and protected against thermal seizures.\",\n      \"method\": \"Scn1b-C121W homozygous mouse model; patch-clamp electrophysiology in brain slices; thermal seizure threshold; pharmacological intervention\",\n      \"journal\": \"Brain\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple cell types analyzed, pharmacological rescue with mechanism-based drug, defined circuit phenotype, single lab\",\n      \"pmids\": [\"24747835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Post-transcriptional silencing of SCN1B (>80% reduction) in cardiac myocytes reduces late sodium current (INaL) density and accelerates its decay, while siRNA against SCN2B has the opposite effect, demonstrating β1 and β2 subunits exert oppositely directed modulation of INaL in both normal and failing heart myocytes.\",\n      \"method\": \"siRNA-mediated knockdown via viral delivery; whole-cell and perforated patch-clamp; Western blot and RT-PCR in isolated dog ventricular cardiomyocytes\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional siRNA knockdown with electrophysiological readout in native cardiomyocytes, single lab\",\n      \"pmids\": [\"21705762\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Antisense-mediated silencing of SCN1B reduces α subunit mRNA, protein expression and sodium current density in GH3 and H9C2 cells in an isoform-specific manner: Nav1.1, Nav1.3, and Nav1.6 are reduced in GH3 cells, Nav1.5 is reduced in H9C2 cells, while Nav1.2 is unaffected, without altering channel gating kinetics.\",\n      \"method\": \"Antisense oligonucleotide knockdown; RT-PCR; Western blot; whole-cell patch-clamp in rat GH3 and H9C2 cell lines\",\n      \"journal\": \"Biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with both mRNA/protein and functional readouts, multiple cell lines, single lab\",\n      \"pmids\": [\"24138709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Zebrafish scn1ba splice variants modulate Na+ currents expressed by scn8aa: both produce negative shifts in voltage dependence of activation and inactivation, increased current amplitude, and faster recovery from inactivation, consistent with mammalian β1 subunit function. The C-terminus tyrosine critical for ankyrin association in mammalian β1 is conserved in scn1ba_tv1 but absent in tv2.\",\n      \"method\": \"Heterologous co-expression in Xenopus oocytes or cell lines; electrophysiology; immunohistochemistry in zebrafish tissue\",\n      \"journal\": \"BMC genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional reconstitution in heterologous system with multiple electrophysiological parameters, structural domain analysis\",\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 defective development of ventrally projecting spinal neuron axons, defasciculation of the olfactory nerve, and increased inner ear hair cell numbers, demonstrating dual roles as a Na+ current modulator and cell adhesion molecule in vivo.\",\n      \"method\": \"Morpholino knockdown in zebrafish; patch-clamp in Rohon-Beard neurons; behavioral touch assay; morphological analysis\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KD with multiple orthogonal phenotypic readouts (electrophysiology, behavior, morphology), single lab\",\n      \"pmids\": [\"19020043\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The SCN1B β1b-P213T mutation increases late sodium current and subtly alters Nav1.5 gating (shifts window current, accelerates recovery from inactivation, decreases slow inactivation) and significantly prolongs action potential duration in HL-1 cells, identifying SCN1Bb as a susceptibility gene for Long QT syndrome.\",\n      \"method\": \"Whole-cell patch-clamp in HEK cells and HL-1 cardiomyocytes co-expressing β1b-P213T with Nav1.5\",\n      \"journal\": \"Heart rhythm\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patch-clamp with multiple gating parameters in two cell systems, single lab, single mutation\",\n      \"pmids\": [\"24662403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The SCN1B-D25N mutation causes a glycosylation (maturation) defect that reduces targeting of β1 to the plasma membrane, abolishes β1-dependent modulation of gating kinetics when co-expressed with Nav1.2, Nav1.4, or Nav1.5 in HEK293 cells, and impairs interaction with the α subunit.\",\n      \"method\": \"Heterologous co-expression in HEK293 cells; whole-cell patch-clamp; Western blot for glycosylation state; cell surface biotinylation\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (biochemistry and electrophysiology), multiple α subunit isoforms tested, single lab\",\n      \"pmids\": [\"29992740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The SCN1B-p.Arg85Cys variant shows normal cell surface expression but loss of β1-mediated modification of Nav1.1-generated sodium current in heterologous cells, establishing it as a loss-of-function variant through a gating modulation defect rather than a trafficking defect.\",\n      \"method\": \"Heterologous expression in HEK cells; whole-cell patch-clamp; surface expression assay\",\n      \"journal\": \"Annals of clinical and translational neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patch-clamp with surface expression assay, mechanistically informative distinction from trafficking vs. gating defect, single lab\",\n      \"pmids\": [\"31709768\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The SCN1B mutation β1-D103V (c.308A>T) decreases sodium current density when co-expressed with Nav1.5 or Nav1.1, while β1b-D103V does not affect Nav1.1 current density but causes a positive shift in voltage dependence of inactivation and faster recovery from inactivation, demonstrating isoform-specific effects on cardiac (Nav1.5) and brain (Nav1.1) sodium currents.\",\n      \"method\": \"Whole-cell patch-clamp in tsA201 cells co-expressing mutant β1 or β1b with Nav1.5 or Nav1.1\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional patch-clamp with two α subunits and two β isoforms, single lab, single mutation\",\n      \"pmids\": [\"33134290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Scn1b deletion increases fast (+20%) and slow (+140%) inactivating components of INa in adult mouse cardiomyocytes, compromises diastolic function and ventricular compliance without affecting systolic function; pharmacological inhibition of late INa with GS967 normalized left ventricular filling and isovolumic relaxation time, linking β1/β1B subunits to diastolic function through control of Na+ influx and Ca2+ cycling.\",\n      \"method\": \"Adult cardiac-specific inducible Scn1b knockout mouse; patch-clamp; echocardiography; invasive hemodynamics; Ca2+ imaging; pharmacological rescue with GS967\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional/inducible KO with multiple orthogonal methods (electrophysiology, imaging, in vivo hemodynamics, pharmacological rescue), single lab\",\n      \"pmids\": [\"35394857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Scn1b null neonatal mice develop sinoatrial node dysfunction, atrial fibrillation (AF), atrial collagen accumulation, and increased cholinergic innervation of the SAN. Null atrial myocytes have prolonged action potential duration, increased late sodium current, and reduced L-type calcium current. Atropine reduced AF incidence, indicating that increased cholinergic tone contributes to AF.\",\n      \"method\": \"Scn1b null neonatal mouse model; ECG; pacing-induced AF protocol; histology; patch-clamp; gene expression analysis; atropine pharmacological intervention\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with multiple orthogonal methods (electrophysiology, histology, pharmacology, gene expression), single lab\",\n      \"pmids\": [\"35603785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Scn1b null mice, reduced sodium current (INa) density heterogeneity between cortical layer 6 and subicular pyramidal neurons enhances spike timing correlations and impairs spike-pattern diversity. Low-concentration TTX phenocopies this effect, demonstrating that INa variability between neurons, regulated by β1, decorrelates spiking and suppresses network synchronization.\",\n      \"method\": \"Constitutive and inducible Scn1b null mice; patch-clamp in cortical pyramidal neurons; computational modeling; TTX pharmacological experiments\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with electrophysiology and pharmacological validation, computational modeling, single lab\",\n      \"pmids\": [\"37264112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Scn1b null mice display ataxia; Purkinje cells (PCs) and cerebellar interneurons in null cerebellar slices have increased thresholds for AP initiation and decreased repetitive firing frequency, associated with reduced transient and resurgent sodium current densities in PCs. Cerebellar output hypoexcitability is proposed to underlie ataxia and to exacerbate seizure severity.\",\n      \"method\": \"Scn1b null mouse behavioral (rotarod, gait); cerebellar slice patch-clamp; sodium current recordings; CRISPR-V5 tagged β1 mouse for localization\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with behavioral, electrophysiological, and localization experiments, single lab\",\n      \"pmids\": [\"40923316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Scn1b null hippocampal CA1, pyramidal neurons have enhanced intrinsic excitability, smaller facilitating EPSCs and IPSCs but larger postsynaptic potentials, and parvalbumin and somatostatin interneuron recruitment is disrupted; together these result in greatly amplified input/output functions upon patterned Schaffer collateral stimulation.\",\n      \"method\": \"Scn1b null mouse; CA1 slice patch-clamp electrophysiology; patterned stimulation protocols; interneuron-specific recordings\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with multiple cell-type recordings and synaptic/intrinsic analysis, single lab\",\n      \"pmids\": [\"37845033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"AAV-mediated delivery of 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 protein was expressed in both excitatory and inhibitory neurons, confirming that early restoration of β1 in brain is sufficient to rescue the DEE52 phenotype.\",\n      \"method\": \"AAV gene therapy in Scn1b null mice; intracerebroventricular injection at P2 vs P10; EEG; seizure scoring; cortical neuron patch-clamp; Western blot\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proof-of-principle rescue experiment with multiple orthogonal readouts (EEG, survival, behavior, electrophysiology), single lab but rigorous design\",\n      \"pmids\": [\"39847501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Self-administered heroin reduces NAc β1 (SCN1b) protein levels in rats. Viral-mediated reduction of NAc SCN1b increases MSN intrinsic excitability without altering synaptic transmission, and increases cue-reinstated heroin seeking, demonstrating that NAc β1 limits cue-induced drug seeking by modulating MSN excitability.\",\n      \"method\": \"Heroin self-administration in rats; Western blot for SCN1b protein; viral-mediated knockdown; patch-clamp electrophysiology in NAc MSNs; cue-reinstatement behavioral assay\",\n      \"journal\": \"eNeuro\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo viral KD with electrophysiological and behavioral readouts, single lab\",\n      \"pmids\": [\"39947903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Purkinje cell-specific deletion of Scn1b in mice causes marked decrements in Purkinje cell physiology (increased AP threshold, reduced repetitive firing) and motor, social, and cognitive dysfunction without early mortality, establishing cerebellar Purkinje cells as a critical node for SCN1B-related DEE neurological disabilities.\",\n      \"method\": \"Conditional Purkinje cell-specific Scn1b knockout mouse; cerebellar slice patch-clamp; behavioral tests (motor, social, cognitive)\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-type-specific KO with electrophysiological and behavioral readouts, single lab\",\n      \"pmids\": [\"41162148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Scn1b-C89/C89 (DEE52 variant p.R89C knock-in) mouse cardiomyocytes show increased transient outward K+ current (Ito) and ventricular fibrosis; patient-derived iPSC-CMs with biallelic SCN1B-c.265C>T show increased peak INa, late INa, and Ito. Both models show susceptibility to cardiac arrhythmias, supporting a cardiac contribution to SUDEP in DEE52.\",\n      \"method\": \"Scn1b-p.R89C knock-in mouse; iPSC-CMs from DEE52 patients; patch-clamp; histology; pacing-induced arrhythmia protocol\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two complementary models (mouse and human iPSC-CM) with electrophysiological and structural readouts, single lab\",\n      \"pmids\": [\"40763036\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of Scn1b compromises mitochondrial energetics and ROS-scavenging capacity: cardiomyocytes from Scn1b null mice die faster, accumulate more ROS under oxidative challenge (diamide), and have increased glutathione peroxidase protein expression and activity; intact Scn1b null hearts show higher arrhythmia scores under oxidative stress.\",\n      \"method\": \"Scn1b null mouse; isolated cardiomyocytes and hearts; oxidative challenge with diamide; ROS imaging; enzyme activity assays; gene expression\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean KO with multiple biochemical and functional readouts but novel link (ROS/arrhythmia) tested in single lab study\",\n      \"pmids\": [\"39120465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A SCN1B mimetic peptide (βadp1) disrupts β1-mediated intercellular adhesion in cardiac perinexii and increases β1-regulated intramembrane proteolysis (RIP) over 48 h; inhibition of RIP with DAPT reduces βadp1's effect on adhesion. Dimeric agonist peptides (containing LQLEED repeats) acutely promote adhesion and transiently boost RIP, establishing a mechanistic link between β1 adhesion function and RIP-mediated transcriptional signaling.\",\n      \"method\": \"Patch-clamp in neonatal rat cardiomyocytes; electric cell substrate impedance sensing (ECIS); RIP assay; DAPT pharmacological inhibition\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — peptide pharmacology with functional adhesion and signaling readouts in cardiomyocytes, two orthogonal assay systems, single lab\",\n      \"pmids\": [\"38942073\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"A synonymous SCN1B variant (c.492T>C, p.Tyr164Tyr) disrupts a splicing silencer sequence and causes splicing imbalance between wild-type and mutant exons, confirmed by in vitro splicing assay, contributing to Benign Familial Infantile Epilepsy.\",\n      \"method\": \"Genome-wide linkage analysis; whole exome sequencing; in vitro splicing assay; in silico splicing analysis\",\n      \"journal\": \"European journal of paediatric neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro splicing assay confirms in silico prediction, single lab\",\n      \"pmids\": [\"28566192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2031,\n      \"finding\": \"In Scn1b-p.R89C knock-in mice, β1-p.R89C polypeptides are expressed at normal brain levels and localize to the plasma membrane with intact regulated intramembrane proteolysis, but produce α subunit subtype-specific effects on sodium current in heterologous cells. Scn1b somatosensory cortex shows increased Scn2a, Scn3a, Scn5a, and Scn1b mRNA; Scn1b null cortex is haploinsufficient for Scn1a, indicating an additive disease mechanism.\",\n      \"method\": \"CRISPR knock-in mouse; heterologous electrophysiology; RT-qPCR; surface biotinylation; RIP assay; hyperthermia seizure threshold; EEG\",\n      \"journal\": \"Brain communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR knock-in with multiple orthogonal methods, single lab\",\n      \"pmids\": [\"38425576\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SCN1B encodes voltage-gated sodium channel β1 and β1B subunits that function as multifunctional proteins: they modulate the gating kinetics and cell-surface expression of multiple Nav α subunit isoforms (Nav1.1–Nav1.6) in neurons and cardiomyocytes; act as cell adhesion molecules (CAMs) that mediate trans-homophilic interactions, axonal fasciculation, neuronal migration, and pathfinding; undergo regulated intramembrane proteolysis (RIP) that drives downstream gene transcription; and regulate K+ currents, Ca2+ homeostasis, and network synchronization in the brain. Loss-of-function—whether by missense mutations disrupting the extracellular immunoglobulin-like disulfide bridge, trafficking defects, or null alleles—reduces Nav α subunit surface expression, abolishes β1-mediated channel gating modulation, impairs neuronal pathfinding, and produces cardiac arrhythmias, epilepsy, and SUDEP in mouse models and human patients.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SCN1B encodes the voltage-gated sodium channel β1 subunit (and the splice variant β1B), a multifunctional protein that modulates the gating kinetics and surface expression of multiple Nav α subunit isoforms and acts as a cell-adhesion molecule governing neuronal pathfinding [#0, #5, #12]. β1 modulation of channel gating depends on a conserved extracellular immunoglobulin-like disulfide bridge; the C121W mutation that disrupts this bridge abolishes β1-mediated gating modulation of co-expressed brain Nav α subunits [#0]. β1 regulates Nav α subunits in an isoform-specific manner, controlling surface density of Nav1.1, Nav1.3, Nav1.5, Nav1.6 and Nav1.9 across brain, cardiac and sensory tissues [#4, #10, #16]. Loss of β1 increases sodium current — including persistent/late INa — and raises Nav protein levels, producing cardiac phenotypes spanning prolonged repolarization and QTc, atrial fibrillation with sinoatrial node dysfunction, impaired diastolic function, and arrhythmia susceptibility rescued pharmacologically by late-INa or muscarinic blockade [#2, #17, #18, #6]. In the brain, β1 deletion disrupts early postnatal axonal fasciculation and neuronal pathfinding before driving network hyperexcitability, with region- and cell-type-specific effects on pyramidal neuron and cerebellar Purkinje cell firing that underlie epilepsy and ataxia [#5, #8, #20, #24]. β1 additionally undergoes regulated intramembrane proteolysis that is mechanistically coupled to its trans-adhesion function [#27]. Human loss-of-function and splicing variants cause epilepsy phenotypes including benign familial infantile epilepsy and the developmental and epileptic encephalopathy DEE52, and AAV-mediated restoration of β1 in neonatal Scn1b-null brain rescues seizures and excitability, establishing β1 deficiency as the disease driver [#15, #28, #22].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Establishing the genomic structure and chromosomal location of SCN1B provided the molecular foundation for linking the gene to inherited disease.\",\n      \"evidence\": \"Genomic DNA cloning, intron-exon boundary sequencing and FISH mapping to 19q13.1-q13.2\",\n      \"pmids\": [\"7851891\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address protein function\", \"No isoform/splice-variant catalog\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"The first functional study showed β1 modulates Nav α subunit gating and that the epilepsy-associated C121W mutation disrupts an extracellular disulfide bridge to abolish this modulation, defining a loss-of-function disease mechanism.\",\n      \"evidence\": \"Co-expression of mutant β1 with brain Nav α subunit in Xenopus oocytes with electrophysiology\",\n      \"pmids\": [\"9697698\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Heterologous oocyte system, not native neurons\", \"Single mutation; in vivo consequences untested\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Cardiac null mice revealed β1 is required for normal cardiac excitability, restraining peak and persistent sodium current and Nav1.5 levels.\",\n      \"evidence\": \"Scn1b null mouse with ventricular myocyte patch-clamp, ECG and immunostaining\",\n      \"pmids\": [\"17884088\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of increased Nav1.5 expression unresolved\", \"Constitutive KO confounds developmental vs acute roles\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"A recessive human mutation (R125C) was shown to act as a functional null via abolished surface trafficking, while native CA3 recordings dissociated β1's gating effects from sodium current density.\",\n      \"evidence\": \"Heterologous surface biotinylation plus hippocampal slice recordings in Scn1b-null mice\",\n      \"pmids\": [\"19710327\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trafficking machinery for β1 not identified\", \"Unchanged current density vs altered AP not fully reconciled\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Studies in sensory and cardiac systems established β1 as an isoform-selective regulator of sodium and potassium currents, with opposite-direction modulation of late INa relative to β2.\",\n      \"evidence\": \"DRG patch-clamp/biotinylation in Scn1b null mice and siRNA knockdown in dog ventricular cardiomyocytes\",\n      \"pmids\": [\"21555511\", \"21705762\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of β1 vs β2 opposite effects unknown\", \"K+ current modulation mechanism unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"β1 was shown to control early postnatal neuronal pathfinding and fasciculation, a developmental role preceding network hyperexcitability and distinguishing its adhesion function from channel modulation.\",\n      \"evidence\": \"Histology, immunofluorescence and slice electrophysiology of Scn1b null mouse brain at P5 and P16\",\n      \"pmids\": [\"23277545\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Adhesion partners mediating pathfinding not identified here\", \"Causal link between pathfinding defects and later seizures untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Knockdown across cell lines demonstrated β1 sets α subunit mRNA, protein and current density in an isoform-specific way without changing gating, separating its trafficking/expression role from its gating role.\",\n      \"evidence\": \"Antisense knockdown with RT-PCR, Western blot and patch-clamp in GH3 and H9C2 cells\",\n      \"pmids\": [\"24138709\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of isoform selectivity unknown\", \"Cell-line context may not reflect native neurons\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Multiple in vivo and heterologous models showed the C121W mutation is a deleterious gain-of-function with mislocalized, under-glycosylated β1, and defined circuit-level (pyramidal vs interneuron) drivers of seizure susceptibility distinct from Scn1a-based Dravet models.\",\n      \"evidence\": \"Scn1b-C121W knock-in and homozygous mice with Co-IP, immunofluorescence, slice patch-clamp, thermal seizure assays and retigabine rescue; cardiac-specific KO with Ca2+ imaging and arrhythmia induction\",\n      \"pmids\": [\"27277800\", \"24747835\", \"25772295\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular nature of the C121W gain-of-function unresolved\", \"Link between glycosylation defect and mislocalization mechanistically incomplete\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Disease variants were resolved into distinct mechanistic classes — glycosylation/trafficking defects versus pure gating-modulation defects with normal surface expression.\",\n      \"evidence\": \"Heterologous co-expression of D25N and R85C variants with multiple Nav α subunits, patch-clamp, glycosylation Westerns and surface biotinylation\",\n      \"pmids\": [\"29992740\", \"31709768\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis distinguishing trafficking vs gating effects not defined\", \"Patient genotype-phenotype correlation limited\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"β1 and β1B were shown to produce divergent, isoform-specific effects on cardiac (Nav1.5) versus brain (Nav1.1) sodium currents, explaining how single variants can produce mixed cardiac and neurological phenotypes.\",\n      \"evidence\": \"Whole-cell patch-clamp in tsA201 cells co-expressing mutant β1/β1B with Nav1.5 or Nav1.1\",\n      \"pmids\": [\"33134290\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single mutation tested\", \"In vivo relevance of β1 vs β1B divergence untested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Conditional and developmental cardiac KO models linked β1 loss to late-INa-driven diastolic dysfunction and to atrial fibrillation with sinoatrial node dysfunction and increased cholinergic tone, with pharmacological rescue confirming the late-INa and muscarinic mechanisms.\",\n      \"evidence\": \"Inducible and neonatal cardiac Scn1b KO with patch-clamp, echocardiography, hemodynamics, histology and GS967/atropine rescue\",\n      \"pmids\": [\"35394857\", \"35603785\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Source of increased cholinergic innervation unclear\", \"Fibrosis trigger downstream of β1 loss undefined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Brain network and cerebellar studies established that β1 tunes intrinsic excitability and inter-neuronal sodium current heterogeneity, with loss decorrelating spiking, amplifying hippocampal input/output, and causing cerebellar hypoexcitability and ataxia.\",\n      \"evidence\": \"Constitutive/inducible Scn1b null mice with cortical, CA1 and cerebellar slice patch-clamp, computational modeling, TTX experiments and CRISPR-V5 localization\",\n      \"pmids\": [\"37264112\", \"37845033\", \"40923316\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal chain from cellular excitability to behavior incomplete\", \"Cell-type-specific contributions not fully separated in constitutive KO\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"β1 trans-adhesion was mechanistically coupled to regulated intramembrane proteolysis, and β1 loss was linked to compromised mitochondrial energetics and ROS handling in cardiomyocytes, broadening its roles beyond channel modulation.\",\n      \"evidence\": \"Mimetic/agonist peptide pharmacology with ECIS adhesion and RIP assays plus DAPT inhibition in cardiomyocytes; oxidative challenge, ROS imaging and enzyme assays in Scn1b null hearts\",\n      \"pmids\": [\"38942073\", \"39120465\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcriptional targets of β1 RIP not identified\", \"Mechanism linking β1 to mitochondrial/ROS function unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Gene-replacement, knock-in and patient-derived models established that early restoration of β1 rescues the DEE52 phenotype and that variant β1 produces additive α-subunit dysregulation plus a cardiac contribution to SUDEP.\",\n      \"evidence\": \"Neonatal AAV-β1 delivery with EEG/survival/patch-clamp; R89C knock-in mice and DEE52 iPSC-cardiomyocytes; Purkinje-specific KO with behavior; NAc viral knockdown in heroin self-administration rats\",\n      \"pmids\": [\"39847501\", \"40763036\", \"41162148\", \"39947903\", \"38425576\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Therapeutic window narrow (P2 vs P10) and human translation untested\", \"Additive transcriptional dysregulation mechanism not fully defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How β1's adhesion-coupled regulated intramembrane proteolysis controls specific downstream gene programs, and which trans-homophilic and α-subunit binding interfaces mediate isoform-selective trafficking versus gating, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No RIP transcriptional target identified in the corpus\", \"No structural model of β1–α subunit or β1–β1 adhesion interfaces\", \"Mechanism of isoform-selective α subunit regulation unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 10, 16]},\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [12, 27]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 7, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [5, 8, 21]},\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [2, 6, 17]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [5, 12]}\n    ],\n    \"complexes\": [\"voltage-gated sodium channel complex\"],\n    \"partners\": [\"SCN1A\", \"SCN5A\", \"SCN2A\", \"SCN3A\", \"SCN8A\", \"SCN2B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}