GABRG2-Related Epilepsy

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Classifications

Harrison's Part

Channelopathy

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Mappings

MONDO

MONDO:0032725 developmental and epileptic encephalopathy, 74

MONDO:0032725 (developmental and epileptic encephalopathy, 74; OMIM:618396) is the MONDO class explicitly gene-associated with GABRG2 (RO:0004003 to HGNC:4087). It names the severe encephalopathic end of the GABRG2 allelic spectrum, so it is used here as the closest available anchor for this gene-anchored entry (predicate skos:narrowMatch because the entry additionally covers the milder febrile-seizure, GEFS+, and absence-epilepsy phenotypes of the same gene). The milder multi-gene familial syndrome maps to MONDO:0018214 (generalized epilepsy with febrile seizures plus), curated as a separate dismech entry.

MONDO:0005027 epilepsy DisMech

MONDO:0005027 (epilepsy) is the broad parent class used by the ClinGen Epilepsy Gene Curation Expert Panel for its Definitive GABRG2-epilepsy gene-disease validity assertion (autosomal dominant). It is recorded here as a skos:broadMatch because this gene-anchored entry is a specific subset (the GABRG2 allelic spectrum) of generic epilepsy.

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Inheritance

1

Autosomal dominant (frequently de novo) HP:0000006

GABRG2-related epilepsy is inherited in an autosomal dominant manner. In multiplex families with milder phenotypes (febrile seizures, GEFS+, childhood absence epilepsy) the variant is transmitted dominantly with variable expressivity, whereas the severe developmental and epileptic encephalopathy end is enriched for de novo variants. In a multicenter cohort of 35 patients with GABRG2 variants, the majority (22 of 35) were de novo.

Autosomal dominant inheritance

Show evidence (2 references)

PMID:35359574 SUPPORT Human Clinical

"In 35 patients with GABRG2 variants, 22 variants were de novo, and 18 variants were novel."

Documents that most GABRG2 epilepsy variants in a contemporary cohort arose de novo, supporting autosomal dominant inheritance with a large de novo contribution at the severe end.

PMID:16510738 SUPPORT In Vitro

"mutations in the gamma2 subunit have been monogenically associated with autosomal dominant transmission of febrile seizures."

Supports autosomal dominant transmission for the milder inherited (febrile-seizure) end of the GABRG2 spectrum.

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Subtypes

1

Developmental and Epileptic Encephalopathy 74 MONDO:0032725

The severe encephalopathic end of the GABRG2 spectrum (OMIM:618396), typically caused by de novo variants producing marked loss of surface GABA-A receptors, with early-onset, frequently drug-resistant seizures and developmental delay. In a multicenter GABRG2 cohort this severe end was a minority of the spectrum, which was dominated by milder febrile-seizure-plus and epilepsy-with-developmental-delay presentations.

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"Twelve patients were diagnosed with febrile seizures plus, eleven with epilepsy and developmental delay, two with Dravet syndrome, two with developmental and epileptic encephalopathy, two with focal epilepsy, two with febrile seizures, and four with unclassified epilepsy."

Provides the syndromic breakdown of a GABRG2 cohort, placing developmental and epileptic encephalopathy (DEE74) at the severe end of the spectrum alongside the milder febrile-seizure and absence phenotypes.

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Discussions and Knowledge Gaps

1

What determines where a given GABRG2 variant places a patient on the severity spectrum, from benign febrile seizures to severe developmental and epileptic encephalopathy: is it purely the quantitative degree of surface GABA-A receptor loss (trafficking and dominant-negative burden), or do variant location and residual channel function contribute independently?

KNOWLEDGE GAP OPEN gap_gabrg2_variant_class_phenotype_severity

Attached to

pathophysiology#Impaired GABA-A Receptor Assembly and Trafficking

GABRG2 variants span a wide phenotypic range within a single gene, and both trafficking-deficient missense variants and dominant-negative truncating variants reduce surface receptors, yet the mapping from molecular severity to clinical severity is incompletely resolved. A cohort study found that transmembrane-region missense variants were associated with developmental delay more often than extracellular-region variants, hinting that variant location adds information beyond simple loss of surface expression, but a predictive genotype-severity model is lacking and would directly aid prognostic counseling.

Proposed experiments

GABRG2 variant surface-expression versus clinical-severity mapping

genotype-function-severity correlation study

exp_gabrg2_genotype_function_severity_map

Across a graded GABRG2 allelic series spanning febrile seizures, GEFS+, absence epilepsy, Dravet-like, and encephalopathy phenotypes, quantify surface receptor expression, GABA-evoked current, and dominant-negative burden in a common assay background and test correlation with clinical severity and variant location.

Readouts

Surface receptor expression and GABA-gated current versus severity

pathophysiology#Impaired GABA-A Receptor Assembly and Trafficking

GABA-A receptor localization to the plasma membrane GO:0072659 ↓ DECREASED

patch-clamp electrophysiology cell-surface biotinylation assay

Direction: NEGATIVE

Controls

Wild-type GABRG2

Wild-type gamma-2 subunit assayed in the same background.

Decision criterion

A single quantitative axis is supported if clinical severity correlates monotonically with loss of surface receptor expression and current across the allelic series; an independent contribution of variant location is supported if residuals track with domain (extracellular versus transmembrane) after adjusting for surface-expression loss.

Would support

pathophysiology#Impaired GABA-A Receptor Assembly and Trafficking

Show evidence (1 reference)

PMID:27864268 SUPPORT In Vitro

"Compared with wild-type α1β2γ2L receptors, GABAA receptors containing a mutant γ2 subunit had reduced cell surface expression with altered subunit stoichiometry or decreased GABA-evoked whole-cell current amplitudes, but with different levels of reduction."

Shows that different GABRG2 encephalopathy variants reduce surface expression and current to different extents, framing the open question of how molecular severity maps to clinical severity.

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Pathophysiology

7

GABRG2 Variant and Gamma-2 Subunit Dysfunction

Heterozygous GABRG2 variants (missense, nonsense, frameshift, and splice-site classes) disrupt the GABA-A receptor gamma-2 subunit. The same gene produces a broad allelic spectrum: the founding K289M variant segregated in a family with a GEFS+-related phenotype, and across cohorts GABRG2 variants cause disease ranging from febrile seizures and GEFS+ to Dravet syndrome and severe developmental and epileptic encephalopathy.

GABAergic inhibitory interneuron CL:0000617

GABA-A receptor activity GO:0004890 ↓ DECREASED

brain UBERON:0000955

Downstream

Impaired GABA-A Receptor Assembly and Trafficking Gamma-2 subunit variants perturb receptor biogenesis, biasing pentamer assembly and surface delivery.

Show evidence (2 references)

PMID:11326274 SUPPORT Human Clinical

"We now report a K289M mutation in the GABA(A) receptor gamma2-subunit gene (GABRG2) that segregates in a family with a phenotype closely related to GEFS+"

Establishes GABRG2 gamma-2 subunit variation as the first genetic evidence of GABA-A receptor dysfunction in human epilepsy.

PMID:24480790 SUPPORT In Vitro

"Mutations in GABRG2, which encodes the γ2 subunit of GABAA receptors, can cause both genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome."

Documents the gene-anchored breadth of the GABRG2 phenotypic spectrum, from GEFS+ to Dravet syndrome.

Impaired GABA-A Receptor Assembly and Trafficking

Because the gamma-2 subunit is critical for GABA-A receptor assembly and trafficking, many variants reduce alpha-beta-gamma-2 receptor surface expression through impaired pentamer assembly, endoplasmic reticulum retention, and degradation. Truncating variants are frequently stably translated and exert dominant-negative effects on co-assembled wild-type subunits, amplifying the loss of surface receptors beyond simple haploinsufficiency.

GABAergic inhibitory interneuron CL:0000617

GABA-A receptor localization to the plasma membrane GO:0072659 ↓ DECREASED

Downstream

Reduced GABA-Gated Chloride Current and Phasic Inhibition Fewer surface GABA-A receptors reduce the postsynaptic chloride conductance available for phasic inhibition.

Temperature-Sensitive Receptor Trafficking The mistrafficked mutant receptors are additionally temperature-labile, so febrile-range temperature further depletes them from the cell surface.

Show evidence (4 references)

PMID:24798517 SUPPORT In Vitro

"The γ2(R82Q) and γ2(P83S) subunits had reduced α1β2γ2 receptor surface expression due to impaired assembly into pentamers, endoplasmic reticulum (ER) retention and degradation."

Directly demonstrates endoplasmic reticulum retention and reduced surface expression as the trafficking mechanism of GABRG2 epilepsy variants.

PMID:11748509 SUPPORT In Vitro

"fluorescent-microscopy studies have shown that receptors containing GFP-labeled gamma2(Q351X) protein are retained in the lumen of the endoplasmic reticulum."

Shows that the truncating Q351X variant causes endoplasmic reticulum retention of GABA-A receptors.

PMID:24480790 SUPPORT In Vitro

"Most GABRG2 truncating mutations associated with Dravet syndrome result in premature termination codons (PTCs) and are stably translated into mutant proteins with potential dominant-negative effects."

Establishes the dominant-negative mechanism whereby stably translated truncated gamma-2 subunits impair co-assembled wild-type receptors.

+ 1 more reference

Temperature-Sensitive Receptor Trafficking

A distinctive property of several GABRG2 variants is that their surface trafficking is temperature-sensitive: brief febrile-range temperature elevation dynamically reduces surface mutant receptors, while conversely lowering the temperature partially rescues surface expression. This provides a direct molecular link between the receptor-trafficking defect and the prominent fever-triggered seizures of GABRG2-related epilepsy.

GABAergic inhibitory interneuron CL:0000617

GABA-A receptor localization to the plasma membrane GO:0072659 ↓ DECREASED

Downstream

Febrile seizures Temperature-sensitive trafficking dynamically depletes surface mutant receptors during fever, lowering the seizure threshold.

Show evidence (2 references)

PMID:16510738 SUPPORT In Vitro

"suggesting that febrile seizures may be produced by a temperature-induced dynamic reduction of susceptible mutant surface GABAA receptors in response to fever."

Provides the temperature-sensitive-trafficking mechanism linking GABRG2 receptor mistrafficking to fever-triggered seizures.

PMID:24798517 SUPPORT In Vitro

"found increased surface and total levels of both wildtype and mutant γ2 subunits after decreasing the incubation temperature to 30°C for 24h, suggesting that lower temperatures increased GABAA receptor stability."

Demonstrates temperature-sensitive trafficking: lower temperature rescues surface GABA-A receptor expression, the converse of fever-driven surface receptor loss.

Reduced GABA-Gated Chloride Current and Phasic Inhibition

Reduced surface GABA-A receptors and altered channel gating decrease the GABA-gated chloride current, weakening fast phasic inhibitory neurotransmission. Functional studies of GABRG2 variants show decreased GABA-activated current amplitudes and, for some variants, abolished benzodiazepine (diazepam) sensitivity, consistent with loss of inhibitory receptor function.

GABAergic inhibitory interneuron CL:0000617

Chloride transmembrane transport GO:1902476 ↓ DECREASED GABAergic synaptic transmission GO:0051932 ↓ DECREASED

GABA-gated chloride ion channel activity GO:0022851 ↓ DECREASED

Downstream

Excitation-Inhibition Imbalance Loss of phasic inhibition shifts the cortical and thalamocortical excitation-inhibition balance toward net excitation.

Show evidence (3 references)

PMID:11326274 SUPPORT In Vitro

"Analysis of the mutated and wild-type alleles in Xenopus laevis oocytes confirmed the predicted effect of the mutation, a decrease in the amplitude of GABA-activated currents."

Direct electrophysiological evidence that a GABRG2 variant reduces GABA-activated (chloride) current.

PMID:24480790 SUPPORT In Vitro

"Electrophysiological studies with the reconstituted GABAA receptors in HEK cells showed reduced GABA-induced currents when mutated γ2 DNA was cotransfected with wild-type α1 and β2 subunits."

Confirms reduced GABA-induced current when the mutant gamma-2 subunit is co-expressed with wild-type subunits (dominant-negative functional effect).

PMID:11326275 SUPPORT In Vitro

"the mutation in GABRG2 (encoding the gamma2-subunit) abolished in vitro sensitivity to diazepam"

Demonstrates loss of benzodiazepine modulation of the mutant GABA-A receptor, a functional readout of impaired inhibitory receptor function.

Excitation-Inhibition Imbalance

Because GABA-A receptors mediate most fast synaptic inhibition in the brain, diminished GABAergic tone shifts the balance between excitatory (glutamatergic) and inhibitory (GABAergic) signaling toward net excitation across cortical and thalamocortical circuits, the conserved amplifier step of the epilepsy excitation-inhibition-imbalance pathway.

GABAergic inhibitory interneuron CL:0000617

GABA signaling pathway GO:0007214 ↓ DECREASED

Downstream

Neuronal Hyperexcitability and Hypersynchrony Net excitatory bias drives neuronal hyperexcitability and hypersynchrony.

Show evidence (1 reference)

PMID:16510738 SUPPORT Other

"Pentameric GABAA receptors mediate the majority of fast synaptic inhibition in the brain"

Establishes that GABA-A receptors carry most fast synaptic inhibition, so their loss of function tips the excitation-inhibition balance toward excitation. Evidence source is OTHER because this is a general background statement rather than a disease-specific experimental finding.

Neuronal Hyperexcitability and Hypersynchrony

The net excitatory bias produces a hyperexcitable, hypersynchronous neuronal state that lowers the seizure threshold and generates the seizures that define the disorder. GABRG2 loss of inhibitory function directly disinhibits excitatory networks.

Excitatory pyramidal neuron CL:0000598

Membrane depolarization GO:0051899 ↑ INCREASED

Downstream

Febrile seizures Network hyperexcitability produces fever-triggered seizures in early childhood.

Generalized tonic-clonic seizures Hyperexcitable networks generate bilateral tonic-clonic seizures.

Focal-onset seizures GABRG2 network hyperexcitability can present with focal-onset seizures.

Absence seizures Thalamocortical disinhibition produces generalized non-motor (absence) seizures.

Myoclonic seizures Network hyperexcitability generates generalized myoclonic seizures, more prominent toward the Dravet-like end of the spectrum.

Impaired Neurodevelopment Severe, early, and frequent GABRG2 loss-of-inhibition manifests as developmental and epileptic encephalopathy at the severe end of the spectrum.

Show evidence (1 reference)

PMID:11326274 SUPPORT Human Clinical

"We thus provide the first genetic evidence that a GABA(A) receptor is directly involved in human idiopathic epilepsy."

Links GABA-A receptor dysfunction directly to the human epilepsy phenotype.

Impaired Neurodevelopment

At the severe end of the GABRG2 spectrum, de novo variants causing marked loss of surface GABA-A receptors present as developmental and epileptic encephalopathy: early-onset, frequently medication-resistant seizures accompanied by developmental delay and intellectual disability. Developmental delay was reported in nearly half of a GABRG2 cohort, and de novo GABRG2 variants are recurrently identified in epileptic encephalopathy series.

neuron CL:0000540

Nervous system development GO:0007399 ⚠ ABNORMAL

Downstream

Developmental delay Severe early-onset GABRG2 encephalopathy is accompanied by developmental delay and intellectual disability.

Epileptic encephalopathy The severe de novo end of the GABRG2 spectrum presents clinically as a developmental and epileptic encephalopathy.

Show evidence (2 references)

PMID:27864268 SUPPORT Human Clinical

"Many epileptic encephalopathies have a genetic aetiology and are often associated with de novo mutations in genes mediating synaptic transmission, including GABAA receptor subunit genes."

Establishes de novo GABA-A receptor subunit (including GABRG2) variants as a cause of epileptic encephalopathy with poor developmental outcome.

PMID:35359574 SUPPORT Human Clinical

"Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%)."

Quantifies developmental delay in a GABRG2 epilepsy cohort, supporting the neurodevelopmental outcome node.

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Pathograph

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Phenotypes

7

Nervous System 6

Febrile seizures VERY_FREQUENT Febrile seizure (within the age range of 3 months to 6 years) HP:0002373

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%)."

Supports fever-sensitive (febrile) seizures as a very frequent (91.4%) feature of GABRG2-related epilepsy.

Focal-onset seizures FREQUENT HP:0007359

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%)."

Documents focal seizures as frequent (68.6%) in a GABRG2 epilepsy cohort.

Generalized tonic-clonic seizures FREQUENT Bilateral tonic-clonic seizure HP:0002069

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%)."

Documents generalized tonic-clonic seizures as frequent (60%) in a GABRG2 epilepsy cohort.

Absence seizures OCCASIONAL Generalized non-motor (absence) seizure HP:0002121

Show evidence (2 references)

PMID:11326275 SUPPORT Human Clinical

"The two main phenotypes were childhood absence epilepsy (CAE) and febrile seizures (FS)."

Establishes childhood absence epilepsy as a core GABRG2 (R43Q) phenotype.

PMID:35359574 SUPPORT Human Clinical

"Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%)."

Supports absence seizures as an occasional (11.4%) seizure type in a GABRG2 cohort.

Myoclonic seizures OCCASIONAL Generalized myoclonic seizure HP:0002123

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%)."

Documents myoclonic seizures as occasional (14.3%) in a GABRG2 epilepsy cohort.

Developmental delay FREQUENT Global developmental delay HP:0001263

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%)."

Documents developmental delay as frequent (45.7%) in a GABRG2 epilepsy cohort.

Other 1

Epileptic encephalopathy HP:0200134

Show evidence (1 reference)

PMID:27864268 SUPPORT Human Clinical

"Recently, we performed next generation sequencing on patients with a spectrum of epileptic encephalopathy phenotypes, and we identified five novel (A106T, I107T, P282S, R323W and F343L) and one known (R323Q) de novo GABRG2 pathogenic variants (mutations) in eight patients."

Human-clinical evidence that de novo GABRG2 variants were identified by next-generation sequencing in patients across the epileptic encephalopathy phenotypic spectrum.

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Genetic Associations

1

GABRG2 (GABRG2 encodes the GABA-A receptor gamma-2 subunit and is the most commonly implicated GABA-A receptor subunit gene in epilepsy. Missense, nonsense, frameshift, and splice-site variants reduce surface receptor expression via endoplasmic reticulum retention and dominant-negative effects or alter channel gating, producing a spectrum from febrile seizures and GEFS+ through childhood absence epilepsy to Dravet syndrome and developmental and epileptic encephalopathy.)

Gene: GABRG2 hgnc:4087 relationship_type: CAUSATIVE

Autosomal dominant (frequently de novo)

Show evidence (4 references)

PMID:11326274 SUPPORT Human Clinical

"We now report a K289M mutation in the GABA(A) receptor gamma2-subunit gene (GABRG2) that segregates in a family with a phenotype closely related to GEFS+"

Original identification of a causative GABRG2 gamma-2 subunit variant in familial epilepsy.

PMID:11748509 SUPPORT Human Clinical

"This mutation lies in the intracellular loop between the third and fourth transmembrane domains of the GABA(A)-receptor gamma2 subunit and introduces a premature stop codon at Q351 in the mature protein."

Documents a causative truncating (Q351X) GABRG2 variant at the severe (severe myoclonic epilepsy of infancy) end of the spectrum.

PMID:35359574 SUPPORT Human Clinical

"Phenotypes of GABRG2-related epilepsy were ranged from mild febrile seizures to severe epileptic encephalopathies."

Summarizes the gene-anchored breadth of GABRG2-related epilepsy across a multicenter cohort.

+ 1 more reference

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Medical Actions

4

Anti-seizure medication (valproate and levetiracetam)

Action: Anticonvulsant Therapy NCIT:C64172

Agent: valproic acid CHEBI:39867 levetiracetam CHEBI:6437

Broad-spectrum anti-seizure medication is the mainstay of treatment. In a GABRG2-related epilepsy cohort most patients achieved seizure control, and the great majority of controlled seizures responded to valproate and/or levetiracetam.

Mechanism Target:

INHIBITS Neuronal Hyperexcitability and Hypersynchrony — Broad-spectrum anti-seizure medications (valproate, levetiracetam) suppress network hyperexcitability and hypersynchronous firing, raising the seizure threshold.

Show evidence (2 references)

PMID:35359574 SUPPORT Human Clinical

"92% of their seizures were controlled by valproate and/or levetiracetam."

Supports valproate and levetiracetam as effective anti-seizure treatments in GABRG2-related epilepsy.

PMID:35359574 SUPPORT Human Clinical

"Valproate and levetiracetam were effective treatments for most patients."

Directly states that valproate and levetiracetam are effective for most GABRG2-related epilepsy patients.

Benzodiazepines (acute and cluster-seizure control)

Action: Anticonvulsant Therapy NCIT:C64172

Agent: diazepam CHEBI:49575

Benzodiazepines are positive allosteric modulators of the GABA-A receptor used for acute seizures, status epilepticus, and cluster seizures in GABRG2-related epilepsy. Their efficacy can be attenuated for variants that reduce the benzodiazepine sensitivity of the mutant receptor, so response is variant-dependent.

Mechanism Target:

INHIBITS Neuronal Hyperexcitability and Hypersynchrony — As GABA-A positive allosteric modulators, benzodiazepines enhance residual inhibitory tone to suppress network hyperexcitability.

Show evidence (1 reference)

PMID:11326275 SUPPORT In Vitro

"the mutation in GABRG2 (encoding the gamma2-subunit) abolished in vitro sensitivity to diazepam"

Documents that a GABRG2 (R43Q) variant abolishes benzodiazepine (diazepam) sensitivity of the mutant receptor, a pharmacogenetic caveat that can limit benzodiazepine efficacy for some variants.

Ketogenic diet

Action: ketogenic diet Ontology label: Dietary Intervention NCIT:C15447

The ketogenic diet is a recognized non-pharmacological option for drug-resistant epilepsy, including the severe developmental and epileptic encephalopathy end of the GABRG2 spectrum, when seizures remain refractory to anti-seizure medication.

Genetic counseling

Action: Genetic Counseling NCIT:C15240

Genetic counseling is indicated given autosomal dominant inheritance with a large de novo contribution; counseling addresses recurrence risk, which differs between inherited (dominant transmission) and de novo presentations.

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"In 35 patients with GABRG2 variants, 22 variants were de novo, and 18 variants were novel."

The high de novo fraction informs recurrence-risk counseling for families.

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Diagnosis

1

Gene-panel or exome sequencing (GABRG2)

Molecular diagnosis is by identification of a heterozygous pathogenic GABRG2 variant, typically via a targeted epilepsy gene panel or exome/genome sequencing. GABRG2 is included among the GABA-A receptor subunit genes sequenced in early-onset epilepsy and epileptic encephalopathy work-ups; many variants are de novo.

Show evidence (1 reference)

PMID:27864268 SUPPORT Human Clinical

"Many epileptic encephalopathies have a genetic aetiology and are often associated with de novo mutations in genes mediating synaptic transmission, including GABAA receptor subunit genes."

Supports next-generation sequencing detection of de novo GABA-A receptor subunit (GABRG2) variants in the diagnostic work-up of epileptic encephalopathy.

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Progression

1

Onset

Age: Infancy to early childhood

Onset is usually in infancy or early childhood, frequently with fever-sensitive seizures. The course is strongly variant- and phenotype-dependent: milder febrile-seizure, GEFS+, and childhood absence presentations often have a good prognosis with seizure control, whereas the de novo developmental and epileptic encephalopathy end has early-onset, frequently drug-resistant seizures with developmental delay. In one cohort, seizures were controlled in most patients.

Show evidence (1 reference)

PMID:35359574 SUPPORT Human Clinical

"The clinical features of GABRG2-related epilepsy included seizure onset, usually in infancy, and seizures were fever-sensitive."

Documents the typical infantile onset and fever sensitivity of GABRG2-related epilepsy.

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Prevalence

1

Worldwide

Unknown Rare

GABRG2 is the most commonly implicated GABA-A receptor subunit gene in epilepsy, but GABRG2-related epilepsy is individually rare and no firm population prevalence has been established; reports are cohort- and case-series-based rather than population-based. The severe developmental and epileptic encephalopathy end (DEE74, OMIM:618396) is ultra-rare.

🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from GABRG2-Related Epilepsy:

Generalized epilepsy with febrile seizures plus (GEFS+)

Overlapping Features GEFS+ is a familial multi-gene epilepsy syndrome in which GABRG2 is one of several loci (alongside SCN1A, SCN1B, SCN9A, GABRD, and STX1B). It is curated as a separate dismech entry. This gene-anchored GABRG2 entry instead spans the full GABRG2 allelic spectrum, including the childhood absence epilepsy, Dravet-like, and severe developmental and epileptic encephalopathy presentations that fall outside the classic GEFS+ definition.

Distinguishing Features

GEFS+ is defined at the syndrome/family level and is genetically heterogeneous (sodium-channel, GABA-A receptor, and SNARE genes), whereas this entry is anchored on the single gene GABRG2 and its receptor-trafficking mechanism.
GABRG2 variants also cause phenotypes beyond GEFS+, including childhood absence epilepsy, Dravet syndrome, and severe developmental and epileptic encephalopathy.

Show evidence (1 reference)

PMID:24480790 SUPPORT In Vitro

"Mutations in GABRG2, which encodes the γ2 subunit of GABAA receptors, can cause both genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome."

Documents that GABRG2 causes both GEFS+ and Dravet syndrome, justifying a gene-anchored entry distinct from the GEFS+ syndrome entry.

{ }

Source YAML

click to show

name: GABRG2-Related Epilepsy
creation_date: "2026-07-25T00:00:00Z"
category: Mendelian
description: >-
  GABRG2-related epilepsy is a gene-anchored, phenotypically heterogeneous
  epilepsy spectrum caused by heterozygous variants in GABRG2, which encodes the
  gamma-2 subunit of the GABA-A receptor, the heteropentameric chloride channel
  that mediates most fast synaptic (phasic) inhibition in the brain. The
  gamma-2 subunit has a special role in GABA-A receptor assembly, trafficking,
  clustering, and synaptic maintenance, so many missense and truncating variants
  reduce surface receptor expression through endoplasmic reticulum retention and
  degradation and exert dominant-negative effects on co-assembled wild-type
  subunits, while other variants alter channel gating. All routes converge on
  reduced GABA-gated chloride current and diminished inhibitory tone. The
  clinical spectrum ranges from simple febrile seizures, febrile seizures plus,
  and childhood absence epilepsy at the mild end, through generalized and focal
  epilepsies, to Dravet-like presentations and severe developmental and
  epileptic encephalopathy at the severe end. A distinctive feature is
  temperature-sensitive receptor trafficking, providing a mechanistic link to
  the prominent fever sensitivity of GABRG2-related seizures. This entry is
  deliberately gene-anchored on the GABRG2 receptor-trafficking mechanism across
  the whole allelic spectrum; the milder familial multi-gene GEFS+ syndrome (in
  which GABRG2 is one of several loci) is curated separately and listed here as
  a differential.
parents:
- Epilepsy
- Channelopathy
disease_term:
  preferred_term: GABRG2-related epilepsy
  term:
    id: MONDO:0032725
    label: developmental and epileptic encephalopathy, 74
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0032725
      label: developmental and epileptic encephalopathy, 74
    mapping_predicate: skos:narrowMatch
    mapping_source: MONDO
    mapping_justification: >-
      MONDO:0032725 (developmental and epileptic encephalopathy, 74; OMIM:618396)
      is the MONDO class explicitly gene-associated with GABRG2 (RO:0004003 to
      HGNC:4087). It names the severe encephalopathic end of the GABRG2 allelic
      spectrum, so it is used here as the closest available anchor for this
      gene-anchored entry (predicate skos:narrowMatch because the entry
      additionally covers the milder febrile-seizure, GEFS+, and absence-epilepsy
      phenotypes of the same gene). The milder multi-gene familial syndrome maps
      to MONDO:0018214 (generalized epilepsy with febrile seizures plus), curated
      as a separate dismech entry.
  - term:
      id: MONDO:0005027
      label: epilepsy
    mapping_predicate: skos:broadMatch
    mapping_source: MONDO
    mapping_justification: >-
      MONDO:0005027 (epilepsy) is the broad parent class used by the ClinGen
      Epilepsy Gene Curation Expert Panel for its Definitive GABRG2-epilepsy
      gene-disease validity assertion (autosomal dominant). It is recorded here
      as a skos:broadMatch because this gene-anchored entry is a specific subset
      (the GABRG2 allelic spectrum) of generic epilepsy.
classifications:
  channelopathy_category:
    classification_value: neurological channelopathy
  harrisons_chapter:
  - classification_value: NEUROLOGIC
synonyms:
- GABRG2-related epilepsy spectrum
- GABA-A receptor gamma-2 subunit epilepsy
- developmental and epileptic encephalopathy 74

references:
- reference: PMID:11326274
  title: "First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene."
- reference: PMID:35359574
  title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
- reference: PMID:27864268
  title: "De novo GABRG2 mutations associated with epileptic encephalopathies."

inheritance:
- name: Autosomal dominant (frequently de novo)
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    GABRG2-related epilepsy is inherited in an autosomal dominant manner. In
    multiplex families with milder phenotypes (febrile seizures, GEFS+, childhood
    absence epilepsy) the variant is transmitted dominantly with variable
    expressivity, whereas the severe developmental and epileptic encephalopathy
    end is enriched for de novo variants. In a multicenter cohort of 35 patients
    with GABRG2 variants, the majority (22 of 35) were de novo.
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In 35 patients with GABRG2 variants, 22 variants were de novo, and 18 variants were novel.
    explanation: >-
      Documents that most GABRG2 epilepsy variants in a contemporary cohort arose
      de novo, supporting autosomal dominant inheritance with a large de novo
      contribution at the severe end.
  - reference: PMID:16510738
    reference_title: "Why does fever trigger febrile seizures? GABAA receptor gamma2 subunit mutations associated with idiopathic generalized epilepsies have temperature-dependent trafficking deficiencies."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      mutations in the gamma2 subunit have been monogenically associated with autosomal dominant transmission of febrile seizures.
    explanation: >-
      Supports autosomal dominant transmission for the milder inherited
      (febrile-seizure) end of the GABRG2 spectrum.

prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: RARE
  notes: >-
    GABRG2 is the most commonly implicated GABA-A receptor subunit gene in
    epilepsy, but GABRG2-related epilepsy is individually rare and no firm
    population prevalence has been established; reports are cohort- and
    case-series-based rather than population-based. The severe developmental and
    epileptic encephalopathy end (DEE74, OMIM:618396) is ultra-rare.

has_subtypes:
- name: DEE74
  display_name: Developmental and Epileptic Encephalopathy 74
  subtype_term:
    preferred_term: developmental and epileptic encephalopathy, 74
    term:
      id: MONDO:0032725
      label: developmental and epileptic encephalopathy, 74
  description: >-
    The severe encephalopathic end of the GABRG2 spectrum (OMIM:618396),
    typically caused by de novo variants producing marked loss of surface
    GABA-A receptors, with early-onset, frequently drug-resistant seizures and
    developmental delay. In a multicenter GABRG2 cohort this severe end was a
    minority of the spectrum, which was dominated by milder febrile-seizure-plus
    and epilepsy-with-developmental-delay presentations.
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Twelve patients were diagnosed with febrile seizures plus, eleven with epilepsy and developmental delay, two with Dravet syndrome, two with developmental and epileptic encephalopathy, two with focal epilepsy, two with febrile seizures, and four with unclassified epilepsy.
    explanation: >-
      Provides the syndromic breakdown of a GABRG2 cohort, placing developmental
      and epileptic encephalopathy (DEE74) at the severe end of the spectrum
      alongside the milder febrile-seizure and absence phenotypes.

pathophysiology:
- name: GABRG2 Variant and Gamma-2 Subunit Dysfunction
  role: trigger
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Ion Channel and Synaptic Dysfunction"
  biological_scale: MOLECULAR
  description: >-
    Heterozygous GABRG2 variants (missense, nonsense, frameshift, and splice-site
    classes) disrupt the GABA-A receptor gamma-2 subunit. The same gene produces
    a broad allelic spectrum: the founding K289M variant segregated in a family
    with a GEFS+-related phenotype, and across cohorts GABRG2 variants cause
    disease ranging from febrile seizures and GEFS+ to Dravet syndrome and severe
    developmental and epileptic encephalopathy.
  cell_types:
  - preferred_term: GABAergic inhibitory interneuron
    term:
      id: CL:0000617
      label: GABAergic neuron
  molecular_functions:
  - preferred_term: GABA-A receptor activity
    term:
      id: GO:0004890
      label: GABA-A receptor activity
    modifier: DECREASED
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:11326274
    reference_title: "First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We now report a K289M mutation in the GABA(A) receptor gamma2-subunit gene (GABRG2) that segregates in a family with a phenotype closely related to GEFS+
    explanation: >-
      Establishes GABRG2 gamma-2 subunit variation as the first genetic evidence
      of GABA-A receptor dysfunction in human epilepsy.
  - reference: PMID:24480790
    reference_title: "Association of nonsense mutation in GABRG2 with abnormal trafficking of GABAA receptors in severe epilepsy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Mutations in GABRG2, which encodes the γ2 subunit of GABAA receptors, can cause both genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome.
    explanation: >-
      Documents the gene-anchored breadth of the GABRG2 phenotypic spectrum, from
      GEFS+ to Dravet syndrome.
  downstream:
  - target: Impaired GABA-A Receptor Assembly and Trafficking
    description: >-
      Gamma-2 subunit variants perturb receptor biogenesis, biasing pentamer
      assembly and surface delivery.
    causal_link_type: DIRECT

- name: Impaired GABA-A Receptor Assembly and Trafficking
  role: intermediate
  biological_scale: MOLECULAR
  description: >-
    Because the gamma-2 subunit is critical for GABA-A receptor assembly and
    trafficking, many variants reduce alpha-beta-gamma-2 receptor surface
    expression through impaired pentamer assembly, endoplasmic reticulum
    retention, and degradation. Truncating variants are frequently stably
    translated and exert dominant-negative effects on co-assembled wild-type
    subunits, amplifying the loss of surface receptors beyond simple
    haploinsufficiency.
  cell_types:
  - preferred_term: GABAergic inhibitory interneuron
    term:
      id: CL:0000617
      label: GABAergic neuron
  biological_processes:
  - preferred_term: GABA-A receptor localization to the plasma membrane
    term:
      id: GO:0072659
      label: protein localization to plasma membrane
    modifier: DECREASED
  evidence:
  - reference: PMID:24798517
    reference_title: "Three epilepsy-associated GABRG2 missense mutations at the γ+/β- interface disrupt GABAA receptor assembly and trafficking by similar mechanisms but to different extents."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The γ2(R82Q) and γ2(P83S) subunits had reduced α1β2γ2 receptor surface expression due to impaired assembly into pentamers, endoplasmic reticulum (ER) retention and degradation.
    explanation: >-
      Directly demonstrates endoplasmic reticulum retention and reduced surface
      expression as the trafficking mechanism of GABRG2 epilepsy variants.
  - reference: PMID:11748509
    reference_title: "Truncation of the GABA(A)-receptor gamma2 subunit in a family with generalized epilepsy with febrile seizures plus."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      fluorescent-microscopy studies have shown that receptors containing GFP-labeled gamma2(Q351X) protein are retained in the lumen of the endoplasmic reticulum.
    explanation: >-
      Shows that the truncating Q351X variant causes endoplasmic reticulum
      retention of GABA-A receptors.
  - reference: PMID:24480790
    reference_title: "Association of nonsense mutation in GABRG2 with abnormal trafficking of GABAA receptors in severe epilepsy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Most GABRG2 truncating mutations associated with Dravet syndrome result in premature termination codons (PTCs) and are stably translated into mutant proteins with potential dominant-negative effects.
    explanation: >-
      Establishes the dominant-negative mechanism whereby stably translated
      truncated gamma-2 subunits impair co-assembled wild-type receptors.
  - reference: PMID:39143639
    reference_title: "GABRG2 mutations in genetic epilepsy with febrile seizures plus: structure, roles, and molecular genetics."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The γ2 subunit plays a special role in receptor trafficking and is closely related to its structural specificity.
    explanation: >-
      A 2024 review affirms the special role of the gamma-2 subunit in GABA-A
      receptor trafficking, the mechanism perturbed by GABRG2 variants. Evidence
      source is OTHER because this is a review article.
  downstream:
  - target: Reduced GABA-Gated Chloride Current and Phasic Inhibition
    description: >-
      Fewer surface GABA-A receptors reduce the postsynaptic chloride
      conductance available for phasic inhibition.
    causal_link_type: DIRECT
  - target: Temperature-Sensitive Receptor Trafficking
    description: >-
      The mistrafficked mutant receptors are additionally temperature-labile, so
      febrile-range temperature further depletes them from the cell surface.
    causal_link_type: DIRECT

- name: Temperature-Sensitive Receptor Trafficking
  role: intermediate
  biological_scale: MOLECULAR
  description: >-
    A distinctive property of several GABRG2 variants is that their surface
    trafficking is temperature-sensitive: brief febrile-range temperature
    elevation dynamically reduces surface mutant receptors, while conversely
    lowering the temperature partially rescues surface expression. This provides a
    direct molecular link between the receptor-trafficking defect and the
    prominent fever-triggered seizures of GABRG2-related epilepsy.
  cell_types:
  - preferred_term: GABAergic inhibitory interneuron
    term:
      id: CL:0000617
      label: GABAergic neuron
  biological_processes:
  - preferred_term: GABA-A receptor localization to the plasma membrane
    term:
      id: GO:0072659
      label: protein localization to plasma membrane
    modifier: DECREASED
  evidence:
  - reference: PMID:16510738
    reference_title: "Why does fever trigger febrile seizures? GABAA receptor gamma2 subunit mutations associated with idiopathic generalized epilepsies have temperature-dependent trafficking deficiencies."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      suggesting that febrile seizures may be produced by a temperature-induced dynamic reduction of susceptible mutant surface GABAA receptors in response to fever.
    explanation: >-
      Provides the temperature-sensitive-trafficking mechanism linking GABRG2
      receptor mistrafficking to fever-triggered seizures.
  - reference: PMID:24798517
    reference_title: "Three epilepsy-associated GABRG2 missense mutations at the γ+/β- interface disrupt GABAA receptor assembly and trafficking by similar mechanisms but to different extents."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      found increased surface and total levels of both wildtype and mutant γ2 subunits after decreasing the incubation temperature to 30°C for 24h, suggesting that lower temperatures increased GABAA receptor stability.
    explanation: >-
      Demonstrates temperature-sensitive trafficking: lower temperature rescues
      surface GABA-A receptor expression, the converse of fever-driven surface
      receptor loss.
  downstream:
  - target: Febrile seizures
    description: >-
      Temperature-sensitive trafficking dynamically depletes surface mutant
      receptors during fever, lowering the seizure threshold.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:16510738
      reference_title: "Why does fever trigger febrile seizures? GABAA receptor gamma2 subunit mutations associated with idiopathic generalized epilepsies have temperature-dependent trafficking deficiencies."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        suggesting that febrile seizures may be produced by a temperature-induced dynamic reduction of susceptible mutant surface GABAA receptors in response to fever.
      explanation: >-
        Provides the temperature-sensitive-trafficking mechanism linking GABRG2
        receptor mistrafficking to fever-triggered seizures.

- name: Reduced GABA-Gated Chloride Current and Phasic Inhibition
  role: intermediate
  biological_scale: CELLULAR
  description: >-
    Reduced surface GABA-A receptors and altered channel gating decrease the
    GABA-gated chloride current, weakening fast phasic inhibitory
    neurotransmission. Functional studies of GABRG2 variants show decreased
    GABA-activated current amplitudes and, for some variants, abolished
    benzodiazepine (diazepam) sensitivity, consistent with loss of inhibitory
    receptor function.
  cell_types:
  - preferred_term: GABAergic inhibitory interneuron
    term:
      id: CL:0000617
      label: GABAergic neuron
  molecular_functions:
  - preferred_term: GABA-gated chloride ion channel activity
    term:
      id: GO:0022851
      label: GABA-gated chloride ion channel activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: Chloride transmembrane transport
    term:
      id: GO:1902476
      label: chloride transmembrane transport
    modifier: DECREASED
  - preferred_term: GABAergic synaptic transmission
    term:
      id: GO:0051932
      label: synaptic transmission, GABAergic
    modifier: DECREASED
  evidence:
  - reference: PMID:11326274
    reference_title: "First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Analysis of the mutated and wild-type alleles in Xenopus laevis oocytes confirmed the predicted effect of the mutation, a decrease in the amplitude of GABA-activated currents.
    explanation: >-
      Direct electrophysiological evidence that a GABRG2 variant reduces
      GABA-activated (chloride) current.
  - reference: PMID:24480790
    reference_title: "Association of nonsense mutation in GABRG2 with abnormal trafficking of GABAA receptors in severe epilepsy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Electrophysiological studies with the reconstituted GABAA receptors in HEK cells showed reduced GABA-induced currents when mutated γ2 DNA was cotransfected with wild-type α1 and β2 subunits.
    explanation: >-
      Confirms reduced GABA-induced current when the mutant gamma-2 subunit is
      co-expressed with wild-type subunits (dominant-negative functional effect).
  - reference: PMID:11326275
    reference_title: "Mutant GABA(A) receptor gamma2-subunit in childhood absence epilepsy and febrile seizures."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the mutation in GABRG2 (encoding the gamma2-subunit) abolished in vitro sensitivity to diazepam
    explanation: >-
      Demonstrates loss of benzodiazepine modulation of the mutant GABA-A
      receptor, a functional readout of impaired inhibitory receptor function.
  downstream:
  - target: Excitation-Inhibition Imbalance
    description: >-
      Loss of phasic inhibition shifts the cortical and thalamocortical
      excitation-inhibition balance toward net excitation.
    causal_link_type: DIRECT

- name: Excitation-Inhibition Imbalance
  role: intermediate
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Excitation-Inhibition Imbalance"
  biological_scale: CELLULAR
  description: >-
    Because GABA-A receptors mediate most fast synaptic inhibition in the brain,
    diminished GABAergic tone shifts the balance between excitatory
    (glutamatergic) and inhibitory (GABAergic) signaling toward net excitation
    across cortical and thalamocortical circuits, the conserved amplifier step of
    the epilepsy excitation-inhibition-imbalance pathway.
  cell_types:
  - preferred_term: GABAergic inhibitory interneuron
    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:16510738
    reference_title: "Why does fever trigger febrile seizures? GABAA receptor gamma2 subunit mutations associated with idiopathic generalized epilepsies have temperature-dependent trafficking deficiencies."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Pentameric GABAA receptors mediate the majority of fast synaptic inhibition in the brain
    explanation: >-
      Establishes that GABA-A receptors carry most fast synaptic inhibition, so
      their loss of function tips the excitation-inhibition balance toward
      excitation. Evidence source is OTHER because this is a general background
      statement rather than a disease-specific experimental finding.
  downstream:
  - target: Neuronal Hyperexcitability and Hypersynchrony
    description: >-
      Net excitatory bias drives neuronal hyperexcitability and hypersynchrony.
    causal_link_type: DIRECT

- name: Neuronal Hyperexcitability and Hypersynchrony
  role: intermediate
  conforms_to: "epilepsy_excitation_inhibition_imbalance#Neuronal Hyperexcitability and Hypersynchrony"
  biological_scale: CELLULAR
  description: >-
    The net excitatory bias produces a hyperexcitable, hypersynchronous neuronal
    state that lowers the seizure threshold and generates the seizures that define
    the disorder. GABRG2 loss of inhibitory function directly disinhibits
    excitatory networks.
  cell_types:
  - preferred_term: Excitatory pyramidal neuron
    term:
      id: CL:0000598
      label: pyramidal neuron
  biological_processes:
  - preferred_term: Membrane depolarization
    term:
      id: GO:0051899
      label: membrane depolarization
    modifier: INCREASED
  evidence:
  - reference: PMID:11326274
    reference_title: "First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We thus provide the first genetic evidence that a GABA(A) receptor is directly involved in human idiopathic epilepsy.
    explanation: >-
      Links GABA-A receptor dysfunction directly to the human epilepsy phenotype.
  downstream:
  - target: Febrile seizures
    description: Network hyperexcitability produces fever-triggered seizures in early childhood.
    causal_link_type: DIRECT
  - target: Generalized tonic-clonic seizures
    description: Hyperexcitable networks generate bilateral tonic-clonic seizures.
    causal_link_type: DIRECT
  - target: Focal-onset seizures
    description: GABRG2 network hyperexcitability can present with focal-onset seizures.
    causal_link_type: DIRECT
  - target: Absence seizures
    description: Thalamocortical disinhibition produces generalized non-motor (absence) seizures.
    causal_link_type: DIRECT
  - target: Myoclonic seizures
    description: >-
      Network hyperexcitability generates generalized myoclonic seizures, more
      prominent toward the Dravet-like end of the spectrum.
    causal_link_type: DIRECT
  - target: Impaired Neurodevelopment
    description: >-
      Severe, early, and frequent GABRG2 loss-of-inhibition manifests as
      developmental and epileptic encephalopathy at the severe end of the
      spectrum.
    causal_link_type: DIRECT

- name: Impaired Neurodevelopment
  role: outcome
  biological_scale: ORGANISM
  description: >-
    At the severe end of the GABRG2 spectrum, de novo variants causing marked
    loss of surface GABA-A receptors present as developmental and epileptic
    encephalopathy: early-onset, frequently medication-resistant seizures
    accompanied by developmental delay and intellectual disability. Developmental
    delay was reported in nearly half of a GABRG2 cohort, and de novo GABRG2
    variants are recurrently identified in epileptic encephalopathy series.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: Nervous system development
    term:
      id: GO:0007399
      label: nervous system development
    modifier: ABNORMAL
  evidence:
  - reference: PMID:27864268
    reference_title: "De novo GABRG2 mutations associated with epileptic encephalopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Many epileptic encephalopathies have a genetic aetiology and are often associated with de novo mutations in genes mediating synaptic transmission, including GABAA receptor subunit genes.
    explanation: >-
      Establishes de novo GABA-A receptor subunit (including GABRG2) variants as
      a cause of epileptic encephalopathy with poor developmental outcome.
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%).
    explanation: >-
      Quantifies developmental delay in a GABRG2 epilepsy cohort, supporting the
      neurodevelopmental outcome node.
  downstream:
  - target: Developmental delay
    description: >-
      Severe early-onset GABRG2 encephalopathy is accompanied by developmental
      delay and intellectual disability.
    causal_link_type: DIRECT
  - target: Epileptic encephalopathy
    description: >-
      The severe de novo end of the GABRG2 spectrum presents clinically as a
      developmental and epileptic encephalopathy.
    causal_link_type: DIRECT

phenotypes:
- name: Febrile seizures
  description: >-
    Fever-triggered seizures in early childhood are a hallmark of GABRG2-related
    epilepsy; fever-sensitive seizures were reported in the large majority of a
    GABRG2 cohort, consistent with the temperature-sensitive trafficking
    mechanism.
  phenotype_term:
    preferred_term: Febrile seizure
    term:
      id: HP:0002373
      label: Febrile seizure (within the age range of 3 months to 6 years)
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%).
    explanation: >-
      Supports fever-sensitive (febrile) seizures as a very frequent (91.4%)
      feature of GABRG2-related epilepsy.
- name: Focal-onset seizures
  description: >-
    Focal-onset seizures are the most common seizure type in GABRG2-related
    epilepsy cohorts.
  phenotype_term:
    preferred_term: Focal-onset seizure
    term:
      id: HP:0007359
      label: Focal-onset seizure
  frequency: FREQUENT
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%).
    explanation: >-
      Documents focal seizures as frequent (68.6%) in a GABRG2 epilepsy cohort.
- name: Generalized tonic-clonic seizures
  description: >-
    Afebrile or fever-associated bilateral tonic-clonic seizures occur across the
    GABRG2 spectrum.
  phenotype_term:
    preferred_term: Generalized tonic-clonic seizure
    term:
      id: HP:0002069
      label: Bilateral tonic-clonic seizure
  frequency: FREQUENT
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%).
    explanation: >-
      Documents generalized tonic-clonic seizures as frequent (60%) in a GABRG2
      epilepsy cohort.
- name: Absence seizures
  description: >-
    Generalized non-motor (absence) seizures occur in GABRG2-related epilepsy;
    childhood absence epilepsy was one of the two main phenotypes in the family
    carrying the R43Q variant.
  phenotype_term:
    preferred_term: Absence seizure
    term:
      id: HP:0002121
      label: Generalized non-motor (absence) seizure
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:11326275
    reference_title: "Mutant GABA(A) receptor gamma2-subunit in childhood absence epilepsy and febrile seizures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The two main phenotypes were childhood absence epilepsy (CAE) and febrile seizures (FS).
    explanation: >-
      Establishes childhood absence epilepsy as a core GABRG2 (R43Q) phenotype.
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%).
    explanation: >-
      Supports absence seizures as an occasional (11.4%) seizure type in a GABRG2
      cohort.
- name: Myoclonic seizures
  description: >-
    Generalized myoclonic seizures occur in a minority of GABRG2 patients, more
    prominent toward the Dravet-like and encephalopathic end of the spectrum.
  phenotype_term:
    preferred_term: Myoclonic seizure
    term:
      id: HP:0002123
      label: Generalized myoclonic seizure
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Seizure types included focal seizures (68.6%), generalized tonic-clonic seizures (60%), myoclonic seizures (14.3%), and absence seizures (11.4%).
    explanation: >-
      Documents myoclonic seizures as occasional (14.3%) in a GABRG2 epilepsy
      cohort.
- name: Developmental delay
  description: >-
    Developmental delay affects a substantial subset of GABRG2 patients,
    especially those with transmembrane-region missense variants and the severe
    encephalopathic phenotype.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  frequency: FREQUENT
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other clinical features included fever-sensitive seizures (91.4%), cluster seizures (57.1%), and developmental delay (45.7%).
    explanation: >-
      Documents developmental delay as frequent (45.7%) in a GABRG2 epilepsy
      cohort.
- name: Epileptic encephalopathy
  category: Clinical
  description: >-
    The severe end of the GABRG2 spectrum is a developmental and epileptic
    encephalopathy with early-onset, often drug-resistant seizures and impaired
    development, caused by de novo variants producing marked loss of surface
    GABA-A receptors.
  phenotype_term:
    preferred_term: Developmental and epileptic encephalopathy
    term:
      id: HP:0200134
      label: Epileptic encephalopathy
  evidence:
  - reference: PMID:27864268
    reference_title: "De novo GABRG2 mutations associated with epileptic encephalopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Recently, we performed next generation sequencing on patients with a spectrum of epileptic encephalopathy phenotypes, and we identified five novel (A106T, I107T, P282S, R323W and F343L) and one known (R323Q) de novo GABRG2 pathogenic variants (mutations) in eight patients.
    explanation: >-
      Human-clinical evidence that de novo GABRG2 variants were identified by
      next-generation sequencing in patients across the epileptic encephalopathy
      phenotypic spectrum.

genetic:
- name: GABRG2
  gene_term:
    preferred_term: GABRG2
    term:
      id: hgnc:4087
      label: GABRG2
  association: >-
    GABRG2 encodes the GABA-A receptor gamma-2 subunit and is the most commonly
    implicated GABA-A receptor subunit gene in epilepsy. Missense, nonsense,
    frameshift, and splice-site variants reduce surface receptor expression via
    endoplasmic reticulum retention and dominant-negative effects or alter
    channel gating, producing a spectrum from febrile seizures and GEFS+ through
    childhood absence epilepsy to Dravet syndrome and developmental and epileptic
    encephalopathy.
  relationship_type: CAUSATIVE
  inheritance:
  - name: Autosomal dominant (frequently de novo)
  evidence:
  - reference: PMID:11326274
    reference_title: "First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We now report a K289M mutation in the GABA(A) receptor gamma2-subunit gene (GABRG2) that segregates in a family with a phenotype closely related to GEFS+
    explanation: >-
      Original identification of a causative GABRG2 gamma-2 subunit variant in
      familial epilepsy.
  - reference: PMID:11748509
    reference_title: "Truncation of the GABA(A)-receptor gamma2 subunit in a family with generalized epilepsy with febrile seizures plus."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This mutation lies in the intracellular loop between the third and fourth transmembrane domains of the GABA(A)-receptor gamma2 subunit and introduces a premature stop codon at Q351 in the mature protein.
    explanation: >-
      Documents a causative truncating (Q351X) GABRG2 variant at the severe
      (severe myoclonic epilepsy of infancy) end of the spectrum.
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Phenotypes of GABRG2-related epilepsy were ranged from mild febrile seizures to severe epileptic encephalopathies.
    explanation: >-
      Summarizes the gene-anchored breadth of GABRG2-related epilepsy across a
      multicenter cohort.
  - reference: CGGV:assertion_3a3176e9-ac0c-41fe-ae40-0750726c33d8-2020-01-21T170000.000Z
    reference_title: "GABRG2 / epilepsy (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      GABRG2 | HGNC:4087 | epilepsy | MONDO:0005027 | AD | Definitive | SOP7 | Epilepsy Gene Curation Expert Panel | 2020-01-21T17:00:00.000Z
    explanation: >-
      ClinGen's Epilepsy Gene Curation Expert Panel classifies the
      GABRG2-epilepsy gene-disease relationship as Definitive (autosomal
      dominant), the authoritative gene-disease validity statement anchoring this
      gene-scoped entry.

diagnosis:
- name: Gene-panel or exome sequencing (GABRG2)
  description: >-
    Molecular diagnosis is by identification of a heterozygous pathogenic GABRG2
    variant, typically via a targeted epilepsy gene panel or exome/genome
    sequencing. GABRG2 is included among the GABA-A receptor subunit genes
    sequenced in early-onset epilepsy and epileptic encephalopathy work-ups; many
    variants are de novo.
  evidence:
  - reference: PMID:27864268
    reference_title: "De novo GABRG2 mutations associated with epileptic encephalopathies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Many epileptic encephalopathies have a genetic aetiology and are often associated with de novo mutations in genes mediating synaptic transmission, including GABAA receptor subunit genes.
    explanation: >-
      Supports next-generation sequencing detection of de novo GABA-A receptor
      subunit (GABRG2) variants in the diagnostic work-up of epileptic
      encephalopathy.

differential_diagnoses:
- name: Generalized epilepsy with febrile seizures plus (GEFS+)
  description: >-
    GEFS+ is a familial multi-gene epilepsy syndrome in which GABRG2 is one of
    several loci (alongside SCN1A, SCN1B, SCN9A, GABRD, and STX1B). It is curated
    as a separate dismech entry. This gene-anchored GABRG2 entry instead spans the
    full GABRG2 allelic spectrum, including the childhood absence epilepsy,
    Dravet-like, and severe developmental and epileptic encephalopathy
    presentations that fall outside the classic GEFS+ definition.
  distinguishing_features:
  - >-
    GEFS+ is defined at the syndrome/family level and is genetically
    heterogeneous (sodium-channel, GABA-A receptor, and SNARE genes), whereas this
    entry is anchored on the single gene GABRG2 and its receptor-trafficking
    mechanism.
  - >-
    GABRG2 variants also cause phenotypes beyond GEFS+, including childhood
    absence epilepsy, Dravet syndrome, and severe developmental and epileptic
    encephalopathy.
  evidence:
  - reference: PMID:24480790
    reference_title: "Association of nonsense mutation in GABRG2 with abnormal trafficking of GABAA receptors in severe epilepsy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Mutations in GABRG2, which encodes the γ2 subunit of GABAA receptors, can cause both genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome.
    explanation: >-
      Documents that GABRG2 causes both GEFS+ and Dravet syndrome, justifying a
      gene-anchored entry distinct from the GEFS+ syndrome entry.
- name: SCN1A-related Dravet syndrome
  description: >-
    Dravet syndrome is most commonly caused by SCN1A loss-of-function variants.
    GABRG2 truncating variants can produce a clinically overlapping Dravet-like
    presentation, so SCN1A testing is part of the differential at the severe end.
  distinguishing_features:
  - >-
    Molecular testing distinguishes SCN1A sodium-channel Dravet syndrome from
    GABRG2 GABA-A receptor Dravet-like presentations; sodium-channel-blocking
    anti-seizure medications are specifically contraindicated in SCN1A Dravet
    syndrome.

progression:
- phase: Onset
  age_range: Infancy to early childhood
  notes: >-
    Onset is usually in infancy or early childhood, frequently with
    fever-sensitive seizures. The course is strongly variant- and
    phenotype-dependent: milder febrile-seizure, GEFS+, and childhood absence
    presentations often have a good prognosis with seizure control, whereas the
    de novo developmental and epileptic encephalopathy end has early-onset,
    frequently drug-resistant seizures with developmental delay. In one cohort,
    seizures were controlled in most patients.
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The clinical features of GABRG2-related epilepsy included seizure onset, usually in infancy, and seizures were fever-sensitive.
    explanation: >-
      Documents the typical infantile onset and fever sensitivity of
      GABRG2-related epilepsy.

treatments:
- name: Anti-seizure medication (valproate and levetiracetam)
  description: >-
    Broad-spectrum anti-seizure medication is the mainstay of treatment. In a
    GABRG2-related epilepsy cohort most patients achieved seizure control, and the
    great majority of controlled seizures responded to valproate and/or
    levetiracetam.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Anticonvulsant Therapy
    term:
      id: NCIT:C64172
      label: Anticonvulsant Therapy
    therapeutic_agent:
    - preferred_term: valproic acid
      term:
        id: CHEBI:39867
        label: valproic acid
    - preferred_term: levetiracetam
      term:
        id: CHEBI:6437
        label: levetiracetam
  target_mechanisms:
  - target: Neuronal Hyperexcitability and Hypersynchrony
    treatment_effect: INHIBITS
    description: >-
      Broad-spectrum anti-seizure medications (valproate, levetiracetam) suppress
      network hyperexcitability and hypersynchronous firing, raising the seizure
      threshold.
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      92% of their seizures were controlled by valproate and/or levetiracetam.
    explanation: >-
      Supports valproate and levetiracetam as effective anti-seizure treatments in
      GABRG2-related epilepsy.
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Valproate and levetiracetam were effective treatments for most patients.
    explanation: >-
      Directly states that valproate and levetiracetam are effective for most
      GABRG2-related epilepsy patients.
- name: Benzodiazepines (acute and cluster-seizure control)
  description: >-
    Benzodiazepines are positive allosteric modulators of the GABA-A receptor
    used for acute seizures, status epilepticus, and cluster seizures in
    GABRG2-related epilepsy. Their efficacy can be attenuated for variants that
    reduce the benzodiazepine sensitivity of the mutant receptor, so response is
    variant-dependent.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Anticonvulsant Therapy
    term:
      id: NCIT:C64172
      label: Anticonvulsant Therapy
    therapeutic_agent:
    - preferred_term: diazepam
      term:
        id: CHEBI:49575
        label: diazepam
  target_mechanisms:
  - target: Neuronal Hyperexcitability and Hypersynchrony
    treatment_effect: INHIBITS
    description: >-
      As GABA-A positive allosteric modulators, benzodiazepines enhance residual
      inhibitory tone to suppress network hyperexcitability.
  evidence:
  - reference: PMID:11326275
    reference_title: "Mutant GABA(A) receptor gamma2-subunit in childhood absence epilepsy and febrile seizures."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the mutation in GABRG2 (encoding the gamma2-subunit) abolished in vitro sensitivity to diazepam
    explanation: >-
      Documents that a GABRG2 (R43Q) variant abolishes benzodiazepine (diazepam)
      sensitivity of the mutant receptor, a pharmacogenetic caveat that can limit
      benzodiazepine efficacy for some variants.
- name: Ketogenic diet
  description: >-
    The ketogenic diet is a recognized non-pharmacological option for
    drug-resistant epilepsy, including the severe developmental and epileptic
    encephalopathy end of the GABRG2 spectrum, when seizures remain refractory to
    anti-seizure medication.
  treatment_term:
    preferred_term: ketogenic diet
    term:
      id: NCIT:C15447
      label: Dietary Intervention
- name: Genetic counseling
  description: >-
    Genetic counseling is indicated given autosomal dominant inheritance with a
    large de novo contribution; counseling addresses recurrence risk, which
    differs between inherited (dominant transmission) and de novo presentations.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:35359574
    reference_title: "Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In 35 patients with GABRG2 variants, 22 variants were de novo, and 18 variants were novel.
    explanation: >-
      The high de novo fraction informs recurrence-risk counseling for families.

datasets: []

notes: >-
  This entry is intentionally gene-anchored on GABRG2 and its GABA-A receptor
  gamma-2 subunit trafficking mechanism across the whole allelic spectrum. The
  overlapping but distinct multi-gene familial syndrome, generalized epilepsy
  with febrile seizures plus (GEFS+, MONDO:0018214), is curated as a separate
  dismech entry in which GABRG2 is one of several contributing loci; it is listed
  here as a differential rather than duplicated. Founding GABRG2 variants include
  K289M (Baulac 2001), R43Q (childhood absence epilepsy and febrile seizures,
  Wallace 2001), and the truncating Q351X (Harkin 2002).

discussions:
- discussion_id: gap_gabrg2_variant_class_phenotype_severity
  prompt: >-
    What determines where a given GABRG2 variant places a patient on the severity
    spectrum, from benign febrile seizures to severe developmental and epileptic
    encephalopathy: is it purely the quantitative degree of surface GABA-A
    receptor loss (trafficking and dominant-negative burden), or do variant
    location and residual channel function contribute independently?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Impaired GABA-A Receptor Assembly and Trafficking
  rationale: >-
    GABRG2 variants span a wide phenotypic range within a single gene, and both
    trafficking-deficient missense variants and dominant-negative truncating
    variants reduce surface receptors, yet the mapping from molecular severity to
    clinical severity is incompletely resolved. A cohort study found that
    transmembrane-region missense variants were associated with developmental
    delay more often than extracellular-region variants, hinting that variant
    location adds information beyond simple loss of surface expression, but a
    predictive genotype-severity model is lacking and would directly aid
    prognostic counseling.
  evidence:
  - reference: PMID:27864268
    reference_title: "De novo GABRG2 mutations associated with epileptic encephalopathies."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Compared with wild-type α1β2γ2L receptors, GABAA receptors containing a mutant γ2 subunit had reduced cell surface expression with altered subunit stoichiometry or decreased GABA-evoked whole-cell current amplitudes, but with different levels of reduction.
    explanation: >-
      Shows that different GABRG2 encephalopathy variants reduce surface
      expression and current to different extents, framing the open question of
      how molecular severity maps to clinical severity.
  proposed_experiments:
  - experiment_id: exp_gabrg2_genotype_function_severity_map
    name: GABRG2 variant surface-expression versus clinical-severity mapping
    description: >-
      Across a graded GABRG2 allelic series spanning febrile seizures, GEFS+,
      absence epilepsy, Dravet-like, and encephalopathy phenotypes, quantify
      surface receptor expression, GABA-evoked current, and dominant-negative
      burden in a common assay background and test correlation with clinical
      severity and variant location.
    experiment_type:
      preferred_term: genotype-function-severity correlation study
    readouts:
    - name: Surface receptor expression and GABA-gated current versus severity
      target: pathophysiology#Impaired GABA-A Receptor Assembly and Trafficking
      biological_processes:
      - preferred_term: GABA-A receptor localization to the plasma membrane
        term:
          id: GO:0072659
          label: protein localization to plasma membrane
        modifier: DECREASED
      assays:
      - preferred_term: patch-clamp electrophysiology
      - preferred_term: cell-surface biotinylation assay
      direction: NEGATIVE
    controls:
    - name: Wild-type GABRG2
      description: Wild-type gamma-2 subunit assayed in the same background.
    decision_criterion: >-
      A single quantitative axis is supported if clinical severity correlates
      monotonically with loss of surface receptor expression and current across
      the allelic series; an independent contribution of variant location is
      supported if residuals track with domain (extracellular versus
      transmembrane) after adjusting for surface-expression loss.
    would_support:
    - pathophysiology#Impaired GABA-A Receptor Assembly and Trafficking

📚

References & Deep Research

References

3

PMID:11326274

First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene.

No top-level findings curated for this source.

PMID:35359574

Phenotypic Spectrum and Prognosis of Epilepsy Patients With GABRG2 Variants.

No top-level findings curated for this source.

PMID:27864268

De novo GABRG2 mutations associated with epileptic encephalopathies.

No top-level findings curated for this source.

GABRG2-Related Epilepsy

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