Juvenile Myoclonic Epilepsy

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Classifications

Harrison's Part

🔗

Mappings

MONDO

MONDO:0009696 juvenile myoclonic epilepsy

MONDO:0009696 is the juvenile myoclonic epilepsy concept.

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Discussions and Knowledge Gaps

3

Valproate is the most effective drug across all three JME seizure types but is teratogenic and generally contraindicated in women of childbearing potential. How well do the main alternatives (levetiracetam, lamotrigine) control myoclonic seizures specifically, and can a first-line non-valproate strategy achieve comparable seizure freedom without the teratogenic risk?

KNOWLEDGE GAP OPEN jme-valproate-vs-alternatives-women

Attached to

pathophysiology#Myoclonic and Generalized Seizures

JME predominantly affects adolescents and young adults, so the valproate-teratogenicity trade-off is a routine, high-stakes clinical decision. Levetiracetam is favored for women but head-to-head evidence on myoclonic-seizure control versus valproate is limited, and lamotrigine can aggravate myoclonus in some patients.

Proposed experiments

Non-valproate first-line strategy trial

jme-nonvalproate-trial

Randomized comparison of levetiracetam (and/or lamotrigine) versus valproate as first-line therapy in newly diagnosed JME, stratified by sex, with seizure-freedom and myoclonus-specific outcomes and long-term follow-up.

Readouts

Seizure freedom and myoclonus control by drug and sex

pathophysiology#Myoclonic and Generalized Seizures

Decision criterion

Comparable seizure freedom without teratogenic risk would support a non-valproate first-line strategy.

Would support

pathophysiology#Myoclonic and Generalized Seizures

Show evidence (1 reference)

PMID:35974938 SUPPORT Human Clinical

"Levetiracetam and sodium valproate have similar efficacy"

A randomized trial found levetiracetam and valproate similarly effective, supporting levetiracetam as a viable valproate-sparing option while leaving myoclonus-specific and long-term comparisons open.

JME has traditionally been considered a lifelong disorder requiring indefinite treatment, yet a subset of patients achieves durable seizure remission. Can clinical, EEG, or genetic markers reliably identify the patients in whom antiseizure medication can be safely withdrawn?

KNOWLEDGE GAP OPEN jme-lifelong-vs-remission-withdrawal

Attached to

pathophysiology#Myoclonic and Generalized Seizures

The lifelong-treatment assumption is increasingly questioned, and unnecessary lifelong medication carries real costs. Predicting safe withdrawal would change counseling and management, but robust predictors have not been established.

Proposed experiments

Prospective drug-withdrawal cohort

jme-withdrawal-cohort

Follow long-term seizure-free JME patients through a structured medication-withdrawal protocol, correlating relapse with clinical subtype, EEG normalization, and genetic background.

Readouts

Relapse rate versus candidate predictors

pathophysiology#Myoclonic and Generalized Seizures

Would support

pathophysiology#Genetic Susceptibility to JME

EFHC1 (myoclonin1) is a non-ion-channel protein linked to JME via effects on R-type calcium currents, neuronal migration, and cortical "microdysgenesis," but reports disagree on whether it is expressed in neurons or predominantly in motile ciliated cells, and mouse knockouts only partially recapitulate the human phenotype. How does EFHC1 dysfunction actually produce the human myoclonic phenotype, and how faithful are the current cellular and animal models?

HUMAN MODEL MISMATCH OPEN jme-efhc1-mechanism-fidelity

Attached to

pathophysiology#EFHC1-Related Neuronal Dysregulation

The cell type in which EFHC1 acts (neuron versus ciliated cell) and the fidelity of Efhc1-deficient mouse models to human JME are unresolved, so the mechanistic link between EFHC1 variants and the human phenotype - and the translational value of the models - remains uncertain even though variant pathogenicity is supported.

Proposed experiments

EFHC1 cell-type and model-fidelity study

jme-efhc1-celltype-mapping

Resolve EFHC1 expression and function across neuronal and ciliated cell types in human tissue and iPSC-derived neurons, and benchmark Efhc1-deficient animal models against the human electroclinical phenotype.

Readouts

EFHC1 cell-type expression and functional consequence

pathophysiology#EFHC1-Related Neuronal Dysregulation

Would support

pathophysiology#EFHC1-Related Neuronal Dysregulation

⚙

Pathophysiology

6

Genetic Susceptibility to JME

JME has a strong, usually complex (polygenic) genetic basis. Susceptibility variants affect GABA-A receptor subunits (GABRA1, GABRD), the EFHC1 (myoclonin) gene, and calcium-channel subunits (CACNB4), shifting the excitation-inhibition balance of cortical and thalamocortical circuits. This node captures the single concept of the predisposing genetic variation.

GABRA1 hgnc:4075

Downstream

Impaired GABAergic Cortical Inhibition GABA-A receptor subunit variants reduce inhibitory GABAergic signaling.

EFHC1-Related Neuronal Dysregulation EFHC1 variants perturb neuronal excitability and cortical development.

Impaired GABAergic Cortical Inhibition

Reduced GABA-A receptor-mediated inhibition (e.g., from GABRA1 or GABRD variants) lowers the inhibitory restraint on cortical neurons. This node captures the single concept of the inhibitory deficit and conforms to the shared epilepsy final common pathway.

GABAergic neuron CL:0000617

GABA signaling pathway GO:0007214 ↓ DECREASED

Downstream

Cortical and Thalamocortical Hyperexcitability Reduced inhibition disinhibits cortical and thalamocortical networks.

Show evidence (1 reference)

PMID:11992121 SUPPORT In Vitro

"GABA(A) receptors that contain the mutant subunit show a lesser amplitude of GABA-activated currents in vitro, indicating that seizures may result from loss of function of this inhibitory ligand-gated channel"

A JME-associated GABRA1 mutation reduces GABA-activated currents, evidencing loss of GABAergic inhibition as a mechanism.

Cortical and Thalamocortical Hyperexcitability

The motor cortex and the reciprocal thalamocortical network become hyperexcitable and prone to hypersynchronous discharge, with particular involvement of frontal/motor systems. This node captures the single concept of network hyperexcitability and conforms to the shared epilepsy final common pathway.

Neuron CL:0000540

Downstream

Generalized Polyspike-Wave Discharges Cortical/thalamocortical hypersynchrony produces generalized polyspike-wave discharges.

Generalized Polyspike-Wave Discharges

The hypersynchronous activity manifests on EEG as generalized, bilaterally synchronous polyspike-and-wave discharges (typically 4-6 Hz), often with photosensitivity. This node captures the single concept of the generalized epileptiform discharge.

Neuron CL:0000540

Downstream

Myoclonic and Generalized Seizures Generalized polyspike-wave discharges produce the clinical seizures.

Myoclonic and Generalized Seizures

The clinical seizures are early-morning myoclonic jerks (especially of the upper limbs, shortly after awakening), generalized tonic-clonic seizures, and typical absence seizures in a subset. Seizures are provoked by sleep deprivation, alcohol, and fatigue. This node captures the single concept of the seizure endpoint and conforms to the shared epilepsy final common pathway.

Neuron CL:0000540

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Pathograph

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

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Phenotypes

5

Nervous System 2

Myoclonic Jerks on Awakening Generalized myoclonic seizure HP:0002123

Generalized Tonic-Clonic Seizures Bilateral tonic-clonic seizure HP:0002069

Other 3

Typical Absence Seizures HP:0011147

Generalized Polyspike-Wave on EEG EEG with polyspike wave complexes HP:0002392

Photosensitivity Photosensitive myoclonic seizure HP:0001327

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Genetic Associations

4

EFHC1

Gene: EFHC1 hgnc:16406 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (2 references)

PMID:15258581 SUPPORT Human Clinical

"Mutation analyses identified five missense mutations in EFHC1 that cosegregated with epilepsy or EEG polyspike wave in affected members of six unrelated families with JME and did not occur in 382 control individuals"

Original report identifying cosegregating EFHC1 missense mutations across six JME families.

PMID:27467453 SUPPORT Human Clinical

"Nine variants were classified as "pathogenic," 14 as "likely pathogenic,""

A guideline-based (ACMG) reanalysis of EFHC1 epilepsy variants affirmed a substantial number as pathogenic or likely pathogenic.

GABRA1

Gene: GABRA1 hgnc:4075 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:11992121 SUPPORT Human Clinical

"Our results confirm that mutation of GABRA1 predisposes towards a common idiopathic generalized epilepsy syndrome in humans"

Establishes GABRA1 as a cause of an autosomal dominant JME / idiopathic generalized epilepsy phenotype.

CACNB4

Gene: CACNB4 hgnc:1404 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

GABRD

Gene: GABRD hgnc:4084 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

💊

Medical Actions

3

Valproate

Action: Pharmacotherapy NCIT:C15986

Agent: valproic acid CHEBI:39867

Valproic acid is highly effective across all three JME seizure types and is traditionally first-line; however, its teratogenicity means it is generally avoided in women of childbearing potential.

Show evidence (1 reference)

PMID:31440723 SUPPORT Human Clinical

"The response rate to valproate was highest among the five AEDs (42.7%)"

In a comparative-effectiveness study valproate had the highest response rate among antiseizure drugs in JME.

Levetiracetam

Action: Pharmacotherapy NCIT:C15986

Agent: levetiracetam CHEBI:6437

Levetiracetam is effective against myoclonic and generalized seizures and is a preferred first-line option, particularly in women of childbearing potential.

Show evidence (1 reference)

PMID:35974938 SUPPORT Human Clinical

"Levetiracetam can be a good alternative to sodium valproate, especially in women of childbearing age"

A double-blind randomized trial in JME found levetiracetam comparably effective to valproate and a good alternative, especially for women of childbearing age.

Lifestyle Measures (Trigger Avoidance)

Action: supportive care Ontology label: Supportive Care NCIT:C15747

Avoiding sleep deprivation, alcohol, and, when relevant, photic triggers reduces seizure frequency, since these are major provoking factors in JME.

📊

Prevalence

1

Juvenile Myoclonic Epilepsy (Norway, people <30 years)

Point Prevalence 56.0 per 100,000 1–9 per 10,000

Population-based Norwegian point prevalence of 5.6 per 10,000; JME constituted 9.3% of all epilepsies in the age group studied.

Show evidence (1 reference)

PMID:27861775 SUPPORT Human Clinical

"The point prevalence was estimated at 5.6/10,000. JME constituted 9.3% of all epilepsies in the age group we investigated."

Population-based study providing JME-specific prevalence in Norway.

{ }

Source YAML

click to show

name: Juvenile Myoclonic Epilepsy
creation_date: "2026-07-18T00:00:00Z"
category: Complex
description: >-
  Juvenile myoclonic epilepsy (JME) is the most common genetic (idiopathic)
  generalized epilepsy syndrome, typically beginning in adolescence. It is
  defined by early-morning myoclonic jerks of the upper limbs, generalized
  tonic-clonic seizures, and, in about a third of patients, typical absence
  seizures. Seizures are provoked by sleep deprivation, alcohol, and fatigue,
  and photosensitivity is common. The syndrome arises from a genetically
  influenced shift toward cortical (particularly motor-system) and
  thalamocortical hyperexcitability - reduced GABAergic inhibition together with
  susceptibility variants in genes such as GABRA1, EFHC1, CACNB4, and GABRD -
  producing generalized polyspike-and-wave discharges. Cognition is usually
  preserved and seizures generally respond well to medication, but the tendency
  to seizures is typically lifelong.
parents:
- Epilepsy
- Neurological Disease
synonyms:
- JME
- Janz syndrome
- Impulsive petit mal
disease_term:
  preferred_term: juvenile myoclonic epilepsy
  term:
    id: MONDO:0009696
    label: juvenile myoclonic epilepsy
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0009696
      label: juvenile myoclonic epilepsy
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
    mapping_justification: >-
      MONDO:0009696 is the juvenile myoclonic epilepsy concept.
classifications:
  harrisons_chapter:
  - classification_value: NEUROLOGIC
    evidence:
    - reference: PMID:35503716
      reference_title: "ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The goal of this paper is to delineate the four syndromes comprising the IGEs, namely childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic-clonic seizures alone."
      explanation: >-
        The ILAE Task Force on Nosology and Definitions places juvenile myoclonic
        epilepsy among the four idiopathic generalized epilepsy syndromes, an
        epilepsy nosology whose clinical home is the neurologic Part.
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:35503716
      reference_title: "ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In 2017, the International League Against Epilepsy (ILAE) Classification of Epilepsies described the \"genetic generalized epilepsies\" (GGEs), which contained the \"idiopathic generalized epilepsies\" (IGEs)."
      explanation: >-
        The ILAE classification nests the IGE syndromes, JME among them, inside
        the genetic generalized epilepsies, supporting a secondary genetic-basis
        Part alongside the primary neurologic placement.
    notes: >-
      Secondary Part only. JME susceptibility is complex/polygenic rather than
      Mendelian, so this tags the genetic axis of the syndrome, not a
      single-gene etiology.
pathophysiology:
- name: Genetic Susceptibility to JME
  description: >-
    JME has a strong, usually complex (polygenic) genetic basis. Susceptibility
    variants affect GABA-A receptor subunits (GABRA1, GABRD), the EFHC1
    (myoclonin) gene, and calcium-channel subunits (CACNB4), shifting the
    excitation-inhibition balance of cortical and thalamocortical circuits. This
    node captures the single concept of the predisposing genetic variation.
  role: trigger
  gene:
    preferred_term: GABRA1
    term:
      id: hgnc:4075
      label: GABRA1
  downstream:
  - target: Impaired GABAergic Cortical Inhibition
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      GABA-A receptor subunit variants reduce inhibitory GABAergic signaling.
  - target: EFHC1-Related Neuronal Dysregulation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      EFHC1 variants perturb neuronal excitability and cortical development.
- name: Impaired GABAergic Cortical Inhibition
  description: >-
    Reduced GABA-A receptor-mediated inhibition (e.g., from GABRA1 or GABRD
    variants) lowers the inhibitory restraint on cortical neurons. This node
    captures the single concept of the inhibitory deficit and conforms to the
    shared epilepsy final common pathway.
  role: mediator
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Ion Channel and Synaptic Dysfunction"
  cell_types:
  - preferred_term: GABAergic neuron
    term:
      id: CL:0000617
      label: GABAergic neuron
  biological_processes:
  - preferred_term: GABA signaling pathway
    term:
      id: GO:0007214
      label: gamma-aminobutyric acid signaling pathway
    modifier: DECREASED
  evidence:
  - reference: PMID:11992121
    reference_title: "Mutation of GABRA1 in an autosomal dominant form of juvenile myoclonic epilepsy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "GABA(A) receptors that contain the mutant subunit show a lesser amplitude of GABA-activated currents in vitro, indicating that seizures may result from loss of function of this inhibitory ligand-gated channel"
    explanation: >-
      A JME-associated GABRA1 mutation reduces GABA-activated currents,
      evidencing loss of GABAergic inhibition as a mechanism.
  downstream:
  - target: Cortical and Thalamocortical Hyperexcitability
    causal_link_type: DIRECT
    description: >-
      Reduced inhibition disinhibits cortical and thalamocortical networks.
- name: EFHC1-Related Neuronal Dysregulation
  description: >-
    EFHC1 (myoclonin1) influences neuronal calcium currents, division, and
    migration; JME-associated variants perturb cortical neuronal excitability
    and development. This node captures the single concept of the EFHC1 arm.
  role: mediator
  cell_types:
  - preferred_term: Neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: Regulation of membrane potential
    term:
      id: GO:0042391
      label: regulation of membrane potential
    modifier: ABNORMAL
  evidence:
  - reference: PMID:15258581
    reference_title: "Mutations in EFHC1 cause juvenile myoclonic epilepsy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "In patch-clamp analysis, EFHC1 specifically increased R-type Ca(2+) currents that were reversed by the mutations associated with JME"
    explanation: >-
      EFHC1 modulates R-type calcium currents, and JME mutations reverse this
      effect, linking EFHC1 to neuronal excitability regulation.
  downstream:
  - target: Cortical and Thalamocortical Hyperexcitability
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      EFHC1-related dysregulation contributes to cortical hyperexcitability.
- name: Cortical and Thalamocortical Hyperexcitability
  description: >-
    The motor cortex and the reciprocal thalamocortical network become
    hyperexcitable and prone to hypersynchronous discharge, with particular
    involvement of frontal/motor systems. This node captures the single concept
    of network hyperexcitability and conforms to the shared epilepsy final
    common pathway.
  role: central_effector
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Neuronal Hyperexcitability and Hypersynchrony"
  cell_types:
  - preferred_term: Neuron
    term:
      id: CL:0000540
      label: neuron
  downstream:
  - target: Generalized Polyspike-Wave Discharges
    causal_link_type: DIRECT
    description: >-
      Cortical/thalamocortical hypersynchrony produces generalized polyspike-wave
      discharges.
- name: Generalized Polyspike-Wave Discharges
  description: >-
    The hypersynchronous activity manifests on EEG as generalized, bilaterally
    synchronous polyspike-and-wave discharges (typically 4-6 Hz), often with
    photosensitivity. This node captures the single concept of the generalized
    epileptiform discharge.
  role: mediator
  cell_types:
  - preferred_term: Neuron
    term:
      id: CL:0000540
      label: neuron
  downstream:
  - target: Myoclonic and Generalized Seizures
    causal_link_type: DIRECT
    description: >-
      Generalized polyspike-wave discharges produce the clinical seizures.
- name: Myoclonic and Generalized Seizures
  description: >-
    The clinical seizures are early-morning myoclonic jerks (especially of the
    upper limbs, shortly after awakening), generalized tonic-clonic seizures,
    and typical absence seizures in a subset. Seizures are provoked by sleep
    deprivation, alcohol, and fatigue. This node captures the single concept of
    the seizure endpoint and conforms to the shared epilepsy final common
    pathway.
  role: consequence
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Recurrent Unprovoked Seizures"
  cell_types:
  - preferred_term: Neuron
    term:
      id: CL:0000540
      label: neuron
phenotypes:
- name: Myoclonic Jerks on Awakening
  description: >-
    Early-morning myoclonic jerks, especially of the upper limbs shortly after
    awakening, are the defining seizure type.
  phenotype_term:
    preferred_term: Generalized myoclonic seizure
    term:
      id: HP:0002123
      label: Generalized myoclonic seizure
- name: Generalized Tonic-Clonic Seizures
  description: >-
    Generalized tonic-clonic seizures, often occurring after a flurry of
    myoclonic jerks and provoked by sleep deprivation or alcohol, are common.
  phenotype_term:
    preferred_term: Bilateral tonic-clonic seizure
    term:
      id: HP:0002069
      label: Bilateral tonic-clonic seizure
- name: Typical Absence Seizures
  description: >-
    Typical absence seizures occur in roughly a third of patients.
  phenotype_term:
    preferred_term: Typical absence seizure
    term:
      id: HP:0011147
      label: Typical absence seizure
- name: Generalized Polyspike-Wave on EEG
  description: >-
    Interictal EEG shows generalized polyspike-and-wave complexes, often with a
    photoparoxysmal response.
  phenotype_term:
    preferred_term: EEG with polyspike wave complexes
    term:
      id: HP:0002392
      label: EEG with polyspike wave complexes
- name: Photosensitivity
  description: >-
    Photosensitivity (seizures provoked by flickering light) is common in JME.
  phenotype_term:
    preferred_term: Photosensitive myoclonic seizure
    term:
      id: HP:0001327
      label: Photosensitive myoclonic seizure
genetic:
- name: EFHC1
  gene_term:
    preferred_term: EFHC1
    term:
      id: hgnc:16406
      label: EFHC1
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >-
    EFHC1 (myoclonin1) was the first gene specifically associated with JME;
    variants perturb neuronal calcium currents and cortical development. A
    guideline-based reanalysis affirmed several EFHC1 variants as pathogenic or
    likely pathogenic.
  evidence:
  - reference: PMID:15258581
    reference_title: "Mutations in EFHC1 cause juvenile myoclonic epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mutation analyses identified five missense mutations in EFHC1 that cosegregated with epilepsy or EEG polyspike wave in affected members of six unrelated families with JME and did not occur in 382 control individuals"
    explanation: >-
      Original report identifying cosegregating EFHC1 missense mutations across
      six JME families.
  - reference: PMID:27467453
    reference_title: "EFHC1 variants in juvenile myoclonic epilepsy: reanalysis according to NHGRI and ACMG guidelines for assigning disease causality."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nine variants were classified as \"pathogenic,\" 14 as \"likely pathogenic,\""
    explanation: >-
      A guideline-based (ACMG) reanalysis of EFHC1 epilepsy variants affirmed a
      substantial number as pathogenic or likely pathogenic.
- name: GABRA1
  gene_term:
    preferred_term: GABRA1
    term:
      id: hgnc:4075
      label: GABRA1
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >-
    GABRA1 encodes the GABA-A receptor alpha-1 subunit; a loss-of-function
    variant causes autosomal dominant JME, linking reduced GABAergic inhibition
    to the phenotype.
  evidence:
  - reference: PMID:11992121
    reference_title: "Mutation of GABRA1 in an autosomal dominant form of juvenile myoclonic epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our results confirm that mutation of GABRA1 predisposes towards a common idiopathic generalized epilepsy syndrome in humans"
    explanation: >-
      Establishes GABRA1 as a cause of an autosomal dominant JME / idiopathic
      generalized epilepsy phenotype.
- name: CACNB4
  gene_term:
    preferred_term: CACNB4
    term:
      id: hgnc:1404
      label: CACNB4
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >-
    CACNB4 encodes a voltage-gated calcium channel beta-4 subunit implicated in
    idiopathic generalized epilepsy including JME.
- name: GABRD
  gene_term:
    preferred_term: GABRD
    term:
      id: hgnc:4084
      label: GABRD
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >-
    GABRD encodes the GABA-A receptor delta subunit; variants are associated
    with generalized epilepsy susceptibility including JME.
prevalence:
- population: Juvenile Myoclonic Epilepsy (Norway, people <30 years)
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_5_PER_10000
  rate_per_100000: 56.0
  notes: >-
    Population-based Norwegian point prevalence of 5.6 per 10,000; JME
    constituted 9.3% of all epilepsies in the age group studied.
  evidence:
  - reference: PMID:27861775
    reference_title: "Prevalence of juvenile myoclonic epilepsy in people <30 years of age-A population-based study in Norway."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The point prevalence was estimated at 5.6/10,000. JME constituted 9.3% of all epilepsies in the age group we investigated."
    explanation: Population-based study providing JME-specific prevalence in Norway.
treatments:
- name: Valproate
  description: >-
    Valproic acid is highly effective across all three JME seizure types and is
    traditionally first-line; however, its teratogenicity means it is generally
    avoided in women of childbearing potential.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: valproic acid
      term:
        id: CHEBI:39867
        label: valproic acid
  evidence:
  - reference: PMID:31440723
    reference_title: "Comparative effectiveness of antiepileptic drugs in juvenile myoclonic epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The response rate to valproate was highest among the five AEDs (42.7%)"
    explanation: >-
      In a comparative-effectiveness study valproate had the highest response
      rate among antiseizure drugs in JME.
- name: Levetiracetam
  description: >-
    Levetiracetam is effective against myoclonic and generalized seizures and is
    a preferred first-line option, particularly in women of childbearing
    potential.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: levetiracetam
      term:
        id: CHEBI:6437
        label: levetiracetam
  evidence:
  - reference: PMID:35974938
    reference_title: "Efficacy of levetiracetam, lamotrigine and sodium valproate on seizure attacks and EEG disorders in patients with juvenile myoclonic epilepsy: A double blind randomized clinical trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Levetiracetam can be a good alternative to sodium valproate, especially in women of childbearing age"
    explanation: >-
      A double-blind randomized trial in JME found levetiracetam comparably
      effective to valproate and a good alternative, especially for women of
      childbearing age.
- name: Lifestyle Measures (Trigger Avoidance)
  description: >-
    Avoiding sleep deprivation, alcohol, and, when relevant, photic triggers
    reduces seizure frequency, since these are major provoking factors in JME.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
datasets: []
discussions:
- discussion_id: jme-valproate-vs-alternatives-women
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - "pathophysiology#Myoclonic and Generalized Seizures"
  prompt: >-
    Valproate is the most effective drug across all three JME seizure types but
    is teratogenic and generally contraindicated in women of childbearing
    potential. How well do the main alternatives (levetiracetam, lamotrigine)
    control myoclonic seizures specifically, and can a first-line
    non-valproate strategy achieve comparable seizure freedom without the
    teratogenic risk?
  rationale: >-
    JME predominantly affects adolescents and young adults, so the
    valproate-teratogenicity trade-off is a routine, high-stakes clinical
    decision. Levetiracetam is favored for women but head-to-head evidence on
    myoclonic-seizure control versus valproate is limited, and lamotrigine can
    aggravate myoclonus in some patients.
  evidence:
  - reference: PMID:35974938
    reference_title: "Efficacy of levetiracetam, lamotrigine and sodium valproate on seizure attacks and EEG disorders in patients with juvenile myoclonic epilepsy: A double blind randomized clinical trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Levetiracetam and sodium valproate have similar efficacy"
    explanation: >-
      A randomized trial found levetiracetam and valproate similarly effective,
      supporting levetiracetam as a viable valproate-sparing option while
      leaving myoclonus-specific and long-term comparisons open.
  proposed_experiments:
  - experiment_id: jme-nonvalproate-trial
    name: Non-valproate first-line strategy trial
    description: >-
      Randomized comparison of levetiracetam (and/or lamotrigine) versus
      valproate as first-line therapy in newly diagnosed JME, stratified by sex,
      with seizure-freedom and myoclonus-specific outcomes and long-term
      follow-up.
    readouts:
    - name: Seizure freedom and myoclonus control by drug and sex
      target: "pathophysiology#Myoclonic and Generalized Seizures"
    decision_criterion: >-
      Comparable seizure freedom without teratogenic risk would support a
      non-valproate first-line strategy.
    would_support:
    - "pathophysiology#Myoclonic and Generalized Seizures"
- discussion_id: jme-lifelong-vs-remission-withdrawal
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - "pathophysiology#Myoclonic and Generalized Seizures"
  prompt: >-
    JME has traditionally been considered a lifelong disorder requiring
    indefinite treatment, yet a subset of patients achieves durable seizure
    remission. Can clinical, EEG, or genetic markers reliably identify the
    patients in whom antiseizure medication can be safely withdrawn?
  rationale: >-
    The lifelong-treatment assumption is increasingly questioned, and
    unnecessary lifelong medication carries real costs. Predicting safe
    withdrawal would change counseling and management, but robust predictors
    have not been established.
  proposed_experiments:
  - experiment_id: jme-withdrawal-cohort
    name: Prospective drug-withdrawal cohort
    description: >-
      Follow long-term seizure-free JME patients through a structured
      medication-withdrawal protocol, correlating relapse with clinical
      subtype, EEG normalization, and genetic background.
    readouts:
    - name: Relapse rate versus candidate predictors
      target: "pathophysiology#Myoclonic and Generalized Seizures"
    would_support:
    - "pathophysiology#Genetic Susceptibility to JME"
- discussion_id: jme-efhc1-mechanism-fidelity
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - "pathophysiology#EFHC1-Related Neuronal Dysregulation"
  prompt: >-
    EFHC1 (myoclonin1) is a non-ion-channel protein linked to JME via effects on
    R-type calcium currents, neuronal migration, and cortical "microdysgenesis,"
    but reports disagree on whether it is expressed in neurons or predominantly
    in motile ciliated cells, and mouse knockouts only partially recapitulate
    the human phenotype. How does EFHC1 dysfunction actually produce the human
    myoclonic phenotype, and how faithful are the current cellular and animal
    models?
  rationale: >-
    The cell type in which EFHC1 acts (neuron versus ciliated cell) and the
    fidelity of Efhc1-deficient mouse models to human JME are unresolved, so the
    mechanistic link between EFHC1 variants and the human phenotype - and the
    translational value of the models - remains uncertain even though variant
    pathogenicity is supported.
  proposed_experiments:
  - experiment_id: jme-efhc1-celltype-mapping
    name: EFHC1 cell-type and model-fidelity study
    description: >-
      Resolve EFHC1 expression and function across neuronal and ciliated cell
      types in human tissue and iPSC-derived neurons, and benchmark
      Efhc1-deficient animal models against the human electroclinical
      phenotype.
    readouts:
    - name: EFHC1 cell-type expression and functional consequence
      target: "pathophysiology#EFHC1-Related Neuronal Dysregulation"
    would_support:
    - "pathophysiology#EFHC1-Related Neuronal Dysregulation"

📚

References & Deep Research

Deep Research

1

Claude Code ▸

1. Disease Information

claude-haiku-4-5-20251001, claude-opus-4-8 17 citations 2026-07-18T10:55:35.876154

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	Type	Onset / course	Frequency	Suggested HPO
Myoclonic jerks (bilateral, arms/shoulders, on awakening, consciousness preserved)	Clinical sign / seizure	Onset ~12–18 y (mean ~15 y); recurrent, morning-predominant	~100% (defining)	`HP:0032794` Myoclonic seizure; `HP:0001336` Myoclonus
Generalized tonic-clonic seizures	Seizure	Typically months–years after myoclonus onset	~85–90%	`HP:0002069` Bilateral tonic-clonic seizure
Typical absence seizures	Seizure	Often earliest manifestation (ages 5–16), predates myoclonus	~20–40%	`HP:0011147` Typical absence seizure
Myoclonic-tonic-clonic (jerks building into GTCS)	Seizure	Variable	Subset	`HP:0002069` (best available)
EEG: 4–6 Hz polyspike-and-wave	Lab/electrophysiologic	Interictal; frontocentral	~ near-universal on sleep-deprived EEG	`HP:0011198` EEG with generalized epileptiform discharges; `HP:0002392`-family (polyspike)
Photoparoxysmal response / photosensitivity	Lab/reflex trait	Present from onset	~30–40%	`HP:0025186` Photosensitive seizure (verify label)
Praxis induction	Reflex trait	—	Subset	(no precise HPO; annotate as reflex trait)
Executive/frontal-lobe cognitive dysfunction (impulsivity, planning deficits)	Behavioral / neuropsychological	Subtle, often subclinical; present in unaffected siblings too	Common on testing	`HP:0000752` (attention), `HP:0031936`/executive terms
Psychiatric comorbidity (anxiety, mood disorders, cluster-B personality traits)	Behavioral	Elevated vs general population	~1/3 with personality features	`HP:0000739` Anxiety; `HP:0000716` Depression

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):

Gene	HGNC	Locus	Role	Variant / mechanism	Key reference
GABRA1	GABAA receptor α1 subunit	5q34	Monogenic AD (rare)	p.Ala322Asp (A322D) → reduced GABA-activated current amplitude (loss of inhibition)	Cossette et al. Nat Genet 2002;31:184-189. PMID: 11992121
EFHC1 (myoclonin-1)	EFHC1	6p12 (EJM1)	Susceptibility; reduced penetrance	Heterozygous missense variants; disrupts neuronal division & radial/tangential migration	Suzuki et al. Nat Genet 2004;36:842-849. PMID: 15258581
CACNB4	Ca channel β4 subunit	2q23	Rare	p.Arg482Ter (R482X) in a JME patient; C104F in praxis-induced/IGE families	Escayg et al. Am J Hum Genet 2000;66:1531-1539. PMID: 10762541
GABRD	GABAA receptor δ subunit	1p36	Polygenic susceptibility	Variants reduce GABA current (peri/extrasynaptic receptor)	Dibbens et al. Hum Mol Genet 2004;13:1315-1319. PMID: 15115768
BRD2 (RING3)	bromodomain transcription regulator	6p21.3	Susceptibility (common SNPs; AR families)	Promoter SNP alleles (OR ~6.5 in some cohorts); haploinsufficiency → GABAergic neuron deficit	Pal et al. Am J Hum Genet 2003;73:261-270. PMID: 12830434
CLCN2	chloride channel 2	3q27	Contested	Early reports of IGE association later questioned	Haug et al. Nat Genet 2003 (subsequently debated)
GJD2 (Cx36)	gap-junction δ2 / connexin-36	15q14	Susceptibility SNP	rs3743123 associations	(association studies)

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

Juvenile Myoclonic Epilepsy

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Summary of Key Ontology Anchors (for KB population)

Curation Notes & Caveats