Juvenile Myoclonic Epilepsy

1. Disease Information

Overview. Juvenile Myoclonic Epilepsy (JME) is the most common of the idiopathic (genetic) generalized epilepsy syndromes. It's a lifelong, adolescence-onset epilepsy in otherwise neurologically and cognitively normal young people, defined by a clinical triad: myoclonic jerks (brief, involuntary muscle twitches, classically of the arms/shoulders shortly after waking), generalized tonic-clonic seizures (GTCS), and, in a minority, typical absence seizures. The interictal EEG signature is bilateral, symmetric 4–6 Hz polyspike-and-wave discharges with frontocentral predominance. Brain MRI is normal on routine visual inspection. It is a genetic disease with complex (mostly polygenic, occasionally monogenic) inheritance.

Key identifiers: - MONDO: MONDO:0009696 (juvenile myoclonic epilepsy) — sits under the grouping class MONDO:0100577 (myoclonic epilepsy). (Verified via Monarch Initiative.) - OMIM: #254770 — "EPILEPSY, MYOCLONIC JUVENILE; EJM" (also labeled EJM1). Additional susceptibility loci are catalogued as EJM2–EJM9 across other OMIM entries. - Orphanet: ORPHA:307 (Juvenile myoclonic epilepsy). - ICD-10: G40.3 (Generalized idiopathic epilepsy and epileptic syndromes). ICD-11: 8A61 range (Generalized epilepsies) / specifically the idiopathic generalized epilepsy entries. - MeSH: "Myoclonic Epilepsy, Juvenile" (D020190). - UMLS/CUI: C0270853.

Synonyms / alternative names: Janz syndrome; Janz-Christian syndrome; impulsive petit mal; myoclonic epilepsy of adolescence; EJM. (Note the eponym "Janz" — Dieter Janz described the syndrome in 1957.)

Data source type: Information here is drawn from aggregated disease-level resources (OMIM, Orphanet, MONDO, ILAE consensus statements, cohort studies, and mechanistic reviews) rather than individual EHR-level patient records.

Anchor citation: Hirsch E, French J, Scheffer IE, et al. "ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions." Epilepsia. 2022;63(6):1475-1499. PMID: 35503716. Quote: "...the four syndromes comprising the idiopathic generalized epilepsies (IGEs): childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic–clonic seizures alone."

2. Etiology

Primary causal factors. JME is a genetic epilepsy. In most patients the genetic architecture is complex/polygenic (many common variants of small effect), with a minority of families showing monogenic, autosomal-dominant transmission. There is no acquired structural, infectious, or metabolic cause in classic JME — its presence should prompt reconsideration of the diagnosis (e.g., progressive myoclonus epilepsy).

Genetic risk factors: - Rare high-penetrance variants in monogenic families: GABRA1, EFHC1, CACNB4, GABRD, CLCN2 (contested), ICK, CASR. - Common susceptibility variants / association signals: BRD2 (RING3) promoter/SNP alleles, GJD2 (connexin-36/Cx36), ME2. - Copy-number variants: recurrent microdeletions at 15q13.3, 15q11.2, and 16p13.11 are enriched in genetic generalized epilepsies including JME. - Common polygenic burden captured by GWAS of the generalized epilepsies (see §4).

Environmental / non-genetic risk & precipitating factors (these trigger seizures rather than cause the disease): - Sleep deprivation (the single most consistent precipitant). - Alcohol (and alcohol withdrawal). - Photic stimulation (flickering light, screens) — 30–40% are photosensitive. - Fatigue, emotional stress, anxiety. - Menstrual cycle (catamenial exacerbation in some women). - Praxis induction — seizures provoked by complex cognitive-motor tasks (calculation, writing, spatial tasks) — a reflex trait relatively specific to JME. - Family history of epilepsy (present in ~50% of probands).

Protective factors: No well-established genetic protective alleles are described. Behaviorally, adequate/regular sleep, alcohol avoidance, and photic-trigger avoidance reduce seizure frequency; these are management levers rather than disease-prevention factors.

Gene-environment interactions. The classic example is the photoparoxysmal / praxis-induced reflex trait interacting with genetic background: reflex ictogenic mechanisms (photosensitivity, praxis induction) segregate with the core JME phenotype and correlate with executive dysfunction and worse prognosis, suggesting the same thalamofrontal circuit vulnerability underlies both the genetic substrate and the trigger sensitivity.

Search source: MedlinePlus Genetics — "The genetics of juvenile myoclonic epilepsy are complex and not completely understood... mutations in one of several genes can cause or increase susceptibility."

3. Phenotypes

For each phenotype: type, characteristics, frequency, and suggested HPO term.

Phenotype characteristics summary: - Age of onset: adolescent/juvenile (HP:0003621 Juvenile onset); range ~5–34 y, peak 12–18 y. - Severity: variable; most patients are well-controlled on medication, but a drug-resistant minority (~15–35% depending on definition) persists. - Progression: chronic and lifelong but non-degenerative — seizure burden often lessens after age ~40; myoclonus may persist even when GTCS remit. - Circadian pattern: morning predominance is a hallmark.

Quality-of-life impact: Driving restrictions, medication burden and teratogenicity concerns (especially valproate in women), sleep-and-alcohol lifestyle constraints, and psychosocial impact of unpredictable jerks/GTCS. Executive dysfunction and psychiatric comorbidity independently worsen QoL and social adjustment.

Cognitive endophenotype source: Wandschneider et al./others — patients with combined praxis-induction + photosensitivity show greater executive dysfunction, higher rates of persistent myoclonia, polytherapy, and psychiatric comorbidity. See "Cognitive performance in juvenile myoclonic epilepsy patients with specific endophenotypes," Seizure 2016. PMID: 27343727.

4. Genetic / Molecular Information

Causal / susceptibility genes (with landmark citations):

Variant classification & functional consequences. - Most JME variants are missense in ion-channel/receptor subunits producing loss of function of inhibitory (GABAergic) signaling or altered channel gating; EFHC1 acts through a non-channel, neurodevelopmental route (cell division, neuroblast migration, dendrite/synapse formation). - Many reported "causal" variants have incomplete penetrance and appear in unaffected relatives — consistent with polygenic/oligogenic contribution rather than strict Mendelian causation. A 2016 reanalysis under ACMG/NHGRI guidelines downgraded several historical EFHC1 claims, so treat single-gene attributions cautiously. - Allele frequencies: the classic monogenic variants are rare (private to specific families); common susceptibility SNPs (BRD2, GJD2) are polymorphic in the general population. Origin is germline.

GWAS / polygenic architecture. The ILAE Consortium on Complex Epilepsies genome-wide mega-analysis (15,212 cases, 29,677 controls) found 16 loci (11 novel), with signal concentrated in the genetic generalized epilepsies; implicated genes code for ion-channel subunits, transcription factors, and a vitamin-B6 metabolism enzyme, with enrichment for AED targets and brain epigenetic regulation.

Nat Commun. 2018;9:5269. DOI: 10.1038/s41467-018-07524-z (PMID ~30531953 — confirm on fetch). Quote: "...16 genome-wide significant loci, of which 11 are novel... 21 most likely epilepsy genes... coding for ion-channel subunits, transcription factors and a vitamin-B6 metabolism enzyme."

Modifier genes: trigger/severity modifiers overlap with the reflex-trait loci; no cleanly validated single modifier established.

Epigenetics: BRD2 is itself a chromatin-reading bromodomain protein, so its haploinsufficiency implicates transcriptional/epigenetic dysregulation of GABAergic neuron development; the GWAS also flagged brain epigenetic regulation. No JME-specific methylation signature is established.

Chromosomal abnormalities: recurrent CNVs at 15q13.3 (incl. CHRNA7), 15q11.2, 16p13.11 confer risk across IGE/GGE including JME.

5. Environmental Information

• Environmental/toxic factors: No causative toxin or pollutant. Alcohol is the main exogenous seizure precipitant.
• Lifestyle factors: Sleep deprivation and irregular sleep-wake schedules are the dominant modifiable precipitants; alcohol use, and to a lesser degree caffeine/stimulant use and stress. Screen-mediated photic exposure matters in the photosensitive subgroup.
• Infectious agents: Not applicable — JME is not infectious or post-infectious.

6. Mechanism / Pathophysiology

The core network hypothesis (upstream). Modern multimodal MRI reframes JME as a thalamocortical / "thalamofrontal" network disorder rather than a truly diffuse "generalized" epilepsy. Converging structural and functional data show thalamic volume loss, increased mesiofrontal/frontobasal gray-matter concentration, microstructural damage in frontal white-matter tracts (corona radiata, corpus callosum), and abnormal thalamocortical connectivity, plus extrafrontal involvement of basal ganglia and hippocampus — a striatum-thalamus-frontal circuit.

O'Muircheartaigh et al. "Abnormal thalamocortical structural and functional connectivity in juvenile myoclonic epilepsy," Brain 2012;135(12):3635. Also see topographic structural/microstructural analysis, Epilepsy Behav/ Seizure 2015, PMID: 26216697.

Molecular pathways / cellular mechanism. The unifying theme is an excitation–inhibition imbalance from impaired GABAergic inhibition: 1. GABAergic hypofunction — loss-of-function GABAA-receptor subunit variants (GABRA1 α1, GABRD δ) reduce inhibitory postsynaptic currents; BRD2 haploinsufficiency reduces the GABAergic interneuron population during development. 2. Altered ion-channel gating — CACNB4 (Ca²⁺) and CLCN2 (Cl⁻) variants perturb neuronal excitability and thalamocortical rhythmicity. 3. Neurodevelopmental miswiring — EFHC1/myoclonin-1 dysfunction disrupts neuroblast division and radial/tangential migration, plausibly producing the subtle cortical microdysgenesis and network abnormalities. 4. Network output — the resulting hyperexcitable, hypersynchronous thalamocortical loop generates polyspike-wave discharges and the clinical myoclonus/absence/GTCS spectrum.

Causal chain (upstream → downstream): GABAergic/channel gene variant or GABAergic interneuron deficit → reduced cortical inhibition + abnormal thalamocortical/frontal connectivity → cortical/thalamocortical hyperexcitability & hypersynchrony → excitation–inhibition imbalance (epileptogenesis) → paroxysmal polyspike-wave discharges → myoclonic jerks / absences / GTCS

This maps directly onto the dismech module epilepsy_excitation_inhibition_imbalance — JME is a strong candidate to declare conforms_to: "epilepsy_excitation_inhibition_imbalance#Excitation-Inhibition Imbalance", substituting GABAergic subunit LOF as the disease-specific channel/synaptic lesion.

Protein dysfunction: GABAA α1/δ subunit misassembly and reduced surface expression (A322D causes asymmetric, position-dependent current reduction and lower α1 protein); channel-gating alterations for CACNB4/CLCN2.

Cell types & compartments: - Cell types (CL): cortical GABAergic interneurons (CL:0000617 GABAergic neuron; CL:0010011 cerebral cortex GABAergic interneuron), pyramidal/cortical excitatory neurons (CL:0000598), thalamic relay neurons, generic neuron (CL:0000540). - Subcellular (GO CC): postsynaptic membrane (GO:0045211), GABA-A receptor complex (GO:1902711), plasma membrane.

GO biological processes: GO:0007214 gamma-aminobutyric acid signaling pathway; GO:0051932 synaptic transmission, GABAergic; GO:0042391 regulation of membrane potential; GO:0001764 neuron migration; GO:0070588 calcium ion transmembrane transport; GO:1902476 chloride transmembrane transport.

Metabolic / immune involvement: Not a metabolic or autoimmune epilepsy in the classic form (contrast progressive myoclonus epilepsies and autoimmune encephalitides in the differential). The GWAS vitamin-B6-metabolism-enzyme signal is a population-level hint, not a JME-specific metabolic defect.

Tissue-damage mechanism: None — JME is non-lesional and non-degenerative; the imaging changes reflect developmental network abnormality, not progressive tissue destruction.

Molecular profiling: Human transcriptomic/proteomic/metabolomic signatures specific to JME are not established; mechanistic evidence is dominated by functional electrophysiology of variant channels (IN_VITRO) and neuroimaging (HUMAN_CLINICAL), plus mouse/cell models of EFHC1 and BRD2 (MODEL_ORGANISM / IN_VITRO).

7. Anatomical Structures Affected

• Organ level: Central nervous system (brain) — nervous system is the sole primary system. No systemic organ involvement.
• Regions (UBERON):
• Cerebral cortex UBERON:0000956, with frontal cortex/lobe emphasis (UBERON:0016525 frontal cortex).
• Thalamus UBERON:0001897 (dorsal thalamus) — core node.
• Corpus callosum UBERON:0002336 and frontal white-matter tracts / corona radiata.
• Basal ganglia / striatum UBERON:0002420 and hippocampus UBERON:0002421 (extended network).
• Tissue/cell level: nervous tissue; cortical GABAergic interneurons and thalamocortical projection neurons (see §6, CL terms).
• Subcellular: neuronal postsynaptic membrane / GABA-A receptor complex.
• Lateralization: bilateral and symmetric (a defining electroclinical feature), though myoclonus can appear asymmetric clinically.

8. Temporal Development

• Onset: Adolescent/juvenile, typically 12–18 years (mean ~15), range ~5–34 y. Absences, when present, may precede myoclonus by several years. Onset pattern is insidious/subacute — myoclonic jerks are frequently unreported until a first GTCS brings the patient to attention.
• Progression: Chronic, lifelong, non-progressive in terms of neurological deterioration. Seizure burden is usually stable-to-improving, often decreasing after ~40 years of age. Course is best described as chronic with episodic seizures modulated by triggers.
• Remission patterns: Pharmacological (treatment-induced) control is the norm; spontaneous drug-free remission is uncommon and relapse on withdrawal is high (see §11).
• Critical periods: Adolescence is the vulnerability window for onset; the therapeutic "critical decision" window is around medication-withdrawal attempts (higher success with older age at withdrawal and sustained GTCS control).

9. Inheritance and Population

Epidemiology: - Prevalence: JME accounts for ~5–10% of all epilepsies and up to ~18–26% of the idiopathic/genetic generalized epilepsies. A population-based Norwegian study estimated prevalence in people <30 years.

"Prevalence of juvenile myoclonic epilepsy in people <30 years of age—A population-based study in Norway." PMID: 27861775. - Incidence: approximately 1 per 100,000 per year (order-of-magnitude; varies by ascertainment). - Sex ratio: Roughly equal, with a modest female predominance reported in several series (~1.5:1).

Genetic epidemiology: - Inheritance pattern: predominantly complex/polygenic (multifactorial); a minority show autosomal dominant (e.g., GABRA1) or autosomal recessive (some BRD2-associated NY families) transmission. - Penetrance: incomplete and age-dependent — unaffected carriers of "causal" variants are common. - Expressivity: variable — the same family can show myoclonus-only, GTCS-predominant, or full-triad phenotypes; overlaps with other IGE syndromes (CAE/JAE/GTCS-alone). - Genetic anticipation: not a feature (JME is not a repeat-expansion disorder). - Founder effects / population variation: EFHC1 variants occur in ~9–20% of Mexican-American JME families but only ~3% of Japanese families, illustrating population heterogeneity. - Consanguinity: relevant for the rare autosomal-recessive susceptibility families. - Family history: positive in ~50% of probands.

Demographics: No strong ethnic restriction; geographic variation is in the genetic contributors (above) more than in overall prevalence.

10. Diagnostics

Clinical/electrophysiologic tests: - EEG (cornerstone): interictal 4–6 Hz generalized polyspike-and-wave, frontocentrally predominant; ictal ~10–16 Hz polyspike bursts time-locked to myoclonus. Sleep-deprived EEG and photic stimulation markedly increase yield — abnormalities appear in nearly all patients under provocation even when routine EEG is normal. LOINC/electrophysiology annotation: EEG study. - Brain MRI: typically normal on visual inspection (used to exclude structural/other causes); quantitative MRI shows the network changes in §6 but is a research tool. - Laboratory: no diagnostic blood/urine biomarker; labs used to exclude mimics (e.g., progressive myoclonus epilepsy work-up if red flags: cognitive decline, ataxia, drug resistance, atypical EEG).

Genetic testing: - Not required for routine diagnosis (diagnosis is electroclinical). Genetic testing (epilepsy gene panels, WES, occasionally chromosomal microarray for CNVs) is reserved for atypical presentations, strong family history, or research. Panels may include GABRA1, GABRD, EFHC1, CACNB4, CLCN2; CMA detects the 15q/16p CNVs. Single-gene testing has low diagnostic yield given polygenicity.

Clinical diagnostic criteria (ILAE 2022, Hirsch et al., PMID 35503716): mandatory myoclonic seizures (bilateral, predominantly on awakening, preserved awareness) with typical generalized spike/polyspike-wave EEG, onset in the compatible age window, normal development/cognition, and normal MRI; GTCS and absences are supportive.

Differential diagnosis: - Other IGE syndromes (juvenile absence epilepsy, epilepsy with GTCS alone, childhood absence epilepsy). - Progressive myoclonus epilepsies (Unverricht-Lundborg, Lafora, sialidosis, MERRF) — distinguished by progressive cognitive/motor decline, ataxia, drug resistance, and atypical EEG. - Focal epilepsy with secondary generalization, non-epileptic myoclonus, and physiologic hypnic jerks.

Screening: No population newborn/carrier screening (polygenic, adult-quality-of-life impact). Family counseling rather than cascade genetic screening is standard.

11. Outcome / Prognosis

• Seizure control: Good in the majority — a large fraction achieve seizure freedom on appropriate medication (valproate historically controls all seizure types in a high proportion).
• Survival/mortality: Life expectancy is near-normal; the principal excess-mortality concern is SUDEP (sudden unexpected death in epilepsy) and seizure-related accidents, both tied to uncontrolled GTCS — an argument for maintaining control.
• Relapse on withdrawal (the defining prognostic fact): ~70–90% relapse after antiseizure-medication withdrawal — JME is generally considered to require lifelong treatment. Older age at withdrawal and complete GTCS remission improve the odds of staying seizure-free.

  Long-term cohort: 5-year terminal remission ~65%; at mean 44.6-year follow-up ~59% seizure-free ≥5 years, but most still on medication. See "Juvenile myoclonic epilepsy: Long-term prognosis and risk factors," J Neurol Sci 2021. PMID: 33781581.

• Prognostic factors (worse outcome): presence of absence seizures, all three seizure types, photoparoxysmal response, praxis induction, psychiatric comorbidity, and poor lifestyle-trigger control. Drug resistance affects a substantial minority.

  Practical stratified-medicine definition & prognosis variation: BIOJUME Consortium, "Variation in prognosis and treatment outcome in juvenile myoclonic epilepsy," Brain Commun 2023;5(3):fcad182.

• Morbidity/QoL: driving/employment restrictions, medication side effects, and the executive-function/psychiatric comorbidity load are the main non-seizure burdens.

12. Treatment

Suggested MAXO/NCIT + CHEBI annotations included.

First-line pharmacotherapy: - Valproic acid / sodium valproate — historically most effective broad-spectrum agent (controls myoclonus, absence, and GTCS; seizure freedom up to ~90% in some series). Major caveat: teratogenicity and neurodevelopmental risk — avoid in people who can become pregnant where possible. - treatment_term: Pharmacotherapy NCIT:C15986; therapeutic_agent: valproic acid CHEBI:39867; therapeutic_modality: SMALL_MOLECULE. - Levetiracetam — strong RCT/meta-analytic support against myoclonic and generalized seizures; preferred alternative, especially in women of childbearing potential. CHEBI:6437. - Lamotrigine — effective for GTCS/absence and useful in women, but can worsen myoclonus in a subset. CHEBI:6367.

Other useful agents: - Topiramate (CHEBI:9581), zonisamide (CHEBI:10127) — broad-spectrum adjuncts. - Clonazepam (CHEBI:3756) — targeted control of myoclonic jerks. - Ethosuximide (CHEBI:4887) — for absence component only (does not cover GTCS/myoclonus). - Perampanel, brivaracetam — newer options for refractory cases.

Drugs to AVOID (can aggravate myoclonus/absence — clinically important): carbamazepine (CHEBI:3387), oxcarbazepine, phenytoin, gabapentin, pregabalin, vigabatrin, tiagabine, and (per some sources) phenobarbital/primidone. Misclassifying JME as focal epilepsy and starting a sodium-channel blocker is a classic, avoidable error.

Comparative efficacy: valproate highest response (~42.7%), levetiracetam comparable (~37.1%); lamotrigine/carbamazepine/topiramate lower. See comparative-effectiveness and RCT sources (PMC6698679; double-blind RCT PMC9348222).

Advanced/interventional: Drug-resistant JME may be managed with rational polytherapy and, in selected cases, vagus nerve stimulation (VNS) — resective surgery is generally not applicable (generalized network disorder). Gene/RNA/cell therapies are not in clinical use for JME.

Pharmacogenomics: No JME-specific pharmacogenomic guideline, but general AED considerations apply (e.g., HLA-B*15:02 and carbamazepine SJS/TEN risk — and carbamazepine is contraindicated in JME anyway).

Supportive / non-pharmacologic (high-value): sleep hygiene / regular sleep (MAXO lifestyle/behavioral intervention), alcohol avoidance, photic-trigger avoidance, medication adherence counseling — these directly reduce seizure frequency. Genetic counseling (MAXO:0000079) for family planning, and preconception counseling re: valproate.

Treatment strategy / personalization: Choice pivots on sex/childbearing potential (valproate-sparing in women), seizure-type profile, and trigger sensitivity; BIOJUME's stratified-medicine framing aims to individualize this.

Suggested treatment-action MAXO/NCIT: Pharmacotherapy (NCIT:C15986), dietary/lifestyle counseling, genetic counseling (MAXO:0000079), VNS as a device/neurostimulation action.

13. Prevention

• Primary prevention: Not available — JME is genetic and cannot be prevented at the population level. "Prevention" in practice = seizure prevention via trigger control (sleep regularity, alcohol avoidance, photic-trigger avoidance) and adherence.
• Secondary prevention: early recognition (don't dismiss morning jerks; ask about them explicitly) → prompt correct AED selection prevents GTCS and SUDEP risk. Sleep-deprived/photic EEG improves early detection.
• Tertiary prevention: avoiding aggravating AEDs, managing psychiatric comorbidity, and sustaining control to reduce injury/SUDEP.
• Immunization / public health / environmental / prophylaxis: Not applicable.
• Genetic counseling: appropriate for affected individuals and families — quantifying the ~50% family-history background and the polygenic, incompletely penetrant risk to relatives; prenatal/preimplantation testing is generally not applicable given polygenicity and good prognosis.

14. Other Species / Natural Disease

• Taxonomy: Human — Homo sapiens, NCBITaxon:9606.
• Natural animal disease: No well-recognized naturally occurring homolog of JME specifically in companion animals or wildlife (idiopathic/genetic generalized epilepsies occur in dogs, but not a validated JME counterpart).
• Orthologous genes (for modeling): Gabra1, Efhc1, Cacnb4 (the mouse lethargic mutant lh is a Cacnb4 model of absence/ataxia), Gabrd, Brd2 — all conserved in mouse and other vertebrates.
• Comparative biology: The Cacnb4 lethargic mouse links β4-subunit dysfunction to spike-wave/absence phenotypes across species, supporting evolutionary conservation of the thalamocortical mechanism. Zoonosis/cross-species transmission: not applicable (non-infectious).

15. Model Organisms

• Mouse (primary mammalian model):
• Cacnb4 "lethargic" (lh) mouse — spontaneous β4 loss-of-function; absence-like spike-wave discharges + ataxia (classic IGE model).
• Efhc1 knockout / knockdown — used to show myoclonin-1's role in cell division and radial/tangential neuroblast migration; supports the neurodevelopmental arm of JME. > "Mutations of EFHC1... disrupt radial and tangential migrations during brain development." (PMC3490517)
• Brd2 haploinsufficient mice — reduced GABAergic neurons and seizure susceptibility; supports the GABAergic-interneuron-deficit hypothesis. > "GABAergic Neuron Deficit As An Idiopathic Generalized Epilepsy Mechanism: BRD2 Haploinsufficiency..." (PLoS One, PMC3161054).
• Gabra1/Gabrd variant knock-in / in-vitro expression — electrophysiology showing reduced GABA currents (functional validation of human variants).
• Model types available: knockout, knock-in (humanized variant), spontaneous mutant (lethargic), and heterologous cell-expression systems (Xenopus oocytes / HEK cells) for channel electrophysiology.
• Phenotype recapitulation: Models reproduce discrete features — spike-wave discharges/absence (Cacnb4), GABAergic deficit/seizure susceptibility (Brd2), migration defects (Efhc1) — but no single model reproduces the full human JME triad (morning myoclonus + adolescent onset + full EEG signature).
• Model limitations (flag as HUMAN_MODEL_MISMATCH candidates): the age-specific adolescent onset, morning-myoclonus circadian pattern, praxis-induction reflex trait, and human-specific frontal-executive phenotype are poorly captured; polygenic human risk is hard to model with single-gene rodents. Human validity of the migration-defect mechanism is still an open translational question.
• Resources: MGI (mouse), IMPC/KOMP (knockouts), Alliance of Genome Resources (orthology), Cellosaurus (cell lines).

Summary of Key Ontology Anchors (for KB population)

• Disease: MONDO:0009696; OMIM #254770; Orphanet ORPHA:307.
• Module conformance candidate: epilepsy_excitation_inhibition_imbalance#Excitation-Inhibition Imbalance.
• Phenotypes (HP): HP:0032794 (myoclonic seizure), HP:0002069 (bilateral tonic-clonic seizure), HP:0011147 (typical absence seizure), HP:0011198 (generalized epileptiform EEG), HP:0003621 (juvenile onset), HP:0000739 (anxiety).
• Genes (HGNC, lowercase prefix): GABRA1, EFHC1, CACNB4, GABRD, BRD2, CLCN2, GJD2.
• GO BP: GO:0007214, GO:0051932, GO:0042391, GO:0001764.
• CL: CL:0010011 (cortical GABAergic interneuron), CL:0000598 (pyramidal neuron).
• UBERON: UBERON:0001897 (thalamus), UBERON:0016525 (frontal cortex), UBERON:0002336 (corpus callosum).
• CHEBI (treatments): valproic acid CHEBI:39867, levetiracetam CHEBI:6437, lamotrigine CHEBI:6367, clonazepam CHEBI:3756, ethosuximide CHEBI:4887; carbamazepine CHEBI:3387 (contraindicated).
• MAXO/NCIT: Pharmacotherapy NCIT:C15986; genetic counseling MAXO:0000079.

Curation Notes & Caveats

• NEC preflight cleared conceptually: the literature consistently keys on the GABAergic/channel gene set (GABRA1, EFHC1, CACNB4) and OMIM #254770 for juvenile myoclonic epilepsy — distinct from infantile (MONDO:0011506) and adult myoclonic epilepsy. Confirm against runoak -i sqlite:obo:mondo info MONDO:0009696 -O obo before committing.
• Verify before use: every PMID/snippet above must be re-fetched via just fetch-reference PMID:XXXX and substring-validated — the GWAS PMID in particular I've given as a DOI (10.1038/s41467-018-07524-z) because I confirmed the DOI but not the exact PMID; the CLCN2 association is genuinely contested in the literature, so cite it as susceptibility-with-caveat, not causal.
• Two evidence-source flavors to keep distinct: channel-variant electrophysiology = IN_VITRO; mouse Efhc1/Brd2/lethargic work = MODEL_ORGANISM; imaging/cohort/epidemiology = HUMAN_CLINICAL.

Primary sources used (URLs): - ILAE IGE definition — Hirsch 2022, Epilepsia (PMID 35503716) - Cossette 2002, GABRA1 — Nat Genet (PMID 11992121) - Suzuki 2004, EFHC1 — Nat Genet (PMID 15258581) - Escayg 2000, CACNB4 — Am J Hum Genet (PMID 10762541) - Dibbens 2004, GABRD — Hum Mol Genet (PMID 15115768) - Pal 2003, BRD2 — Am J Hum Genet (PMID 12830434) - ILAE Consortium GWAS 2018 — Nat Commun (DOI 10.1038/s41467-018-07524-z) - StatPearls: Juvenile Myoclonic Epilepsy - OMIM #254770 - MONDO:0009696 — Monarch Initiative - Long-term prognosis — PMID 33781581 - BIOJUME stratified definition — Brain Communications 2023 - Thalamocortical connectivity — Brain 2012 - Cognitive endophenotypes — PMID 27343727 - Prevalence, Norway — PMID 27861775 - EFHC1 migration defects — PMC3490517 - BRD2 haploinsufficiency/GABAergic deficit — PMC3161054