| Mechanism class | Representative genes | Typical functional consequence | Causal chain to phenotype | Representative precision-management implication | Evidence type / limitations |
|---|---|---|---|---|---|
| Voltage-gated sodium channelopathy | SCN1A, SCN2A, SCN8A | Variant-specific; can be loss-of-function (LOF) or gain-of-function (GOF), so effect must be interpreted per gene/variant rather than assumed | Altered sodium current changes neuronal excitability during early brain development, contributing to recurrent seizures, epileptiform activity, and downstream developmental slowing/regression; SCN1A-related Dravet syndrome is a key example (pqac-00000003, pqac-00000004, pqac-00000010) | Precision management depends on mechanism: activity-boosting strategies for LOF versus inhibitory strategies for GOF; SCN1A-positive Dravet syndrome has AAV9 transcriptional activation trials (ETX101) designed to increase SCN1A expression in presumed LOF disease (pqac-00000010, pqac-00000014, pqac-00000015) | Human umbrella reviews plus gene-specific trials and mouse studies support this class, but not every variant in these genes behaves identically and treatment generalization across sodium-channel genes is unsafe (pqac-00000003, pqac-00000012, pqac-00000014) |
| Potassium channelopathy | KCNQ2, KCNT1, KCNH5 | Variant-specific GOF or LOF; functional direction is clinically important and should be established where possible | Disordered potassium conductance impairs membrane repolarization and network stability, producing neonatal/infantile seizures and, in severe cases, DEE with developmental impairment (pqac-00000008, pqac-00000010) | Mechanism-guided therapy is conceptually important: inhibitor approach for some GOF states versus function-supporting approach for LOF states; emerging gene/RNA strategies are under study broadly in DEE, but robust variant-level treatment rules remain incomplete (pqac-00000010, pqac-00000006) | Evidence is strong for inclusion of potassium-channel genes among major DEE causes, but the gathered evidence is mostly review-level and does not provide uniform variant-specific response data for all genes in this class (pqac-00000008, pqac-00000010) |
| Synaptic vesicle / synaptic signaling dysfunction | STXBP1, SYNGAP1, PCDH19, NBEA | Often reduced or altered synaptic function; exact consequence is gene- and variant-specific | Impaired vesicle release or synaptic signaling disrupts circuit formation and excitatory/inhibitory balance, leading to seizures, developmental delay/intellectual disability, and frequent movement/behavioral comorbidity (pqac-00000009, pqac-00000010) | Supportive precision approach is mainly diagnosis-led today; STXBP1 has an early interventional gene-therapy program (CAP-002) in pediatrics, but efficacy is not established (pqac-00000018) | Evidence comes from multicenter human cohorts and reviews; STXBP1 trial evidence is preliminary, and mechanistic heterogeneity across synaptic genes limits direct extrapolation from one gene to another (pqac-00000009, pqac-00000018) |
| Glutamatergic receptor / excitatory synapse dysfunction | GRIN2A and broader GRIN family | Variant-specific receptor dysfunction, potentially GOF or LOF depending on variant | Abnormal NMDA receptor signaling disturbs synaptic maturation and excitatory circuit development, contributing to epileptiform activity plus language/cognitive impairment characteristic of some DEEs (pqac-00000000, pqac-00000010) | Precision implication is mechanism-first interpretation rather than syndrome-first treatment; receptor dysfunction supports rationale for targeted pathway modulation, but gene-specific standardized therapies were not established in the gathered clinical evidence (pqac-00000010) | Evidence is mainly review-level in the gathered set; mechanistic plausibility is strong, but variant-level therapeutic evidence is comparatively limited here (pqac-00000000, pqac-00000010) |
| mTOR-pathway dysregulation / cortical developmental pathology | MTOR, TSC1, TSC2 | Typically pathway overactivation in relevant disorders, though exact molecular consequence depends on lesion/gene context | mTOR overactivation in the developing cortex can drive malformations of cortical development, network hyperexcitability, infantile spasms/epilepsy, and developmental impairment (pqac-00000005, pqac-00000010, pqac-00000012) | mTOR is a representative actionable pathway in DEE; pathway-oriented treatment logic is stronger here than in many other classes, although the gathered evidence emphasizes translational rationale more than new 2024 trial outcomes (pqac-00000005, pqac-00000012) | Supported by authoritative reviews and pathway-oriented discussion; however, not all mTOR-related epilepsies are identical and some evidence cited is translational rather than direct comparative clinical efficacy data (pqac-00000005, pqac-00000012) |
| Metabolic / vitamin-responsive causes within early-infantile DEE differential | GLDC, SAMHD1; biotinidase deficiency noted in cohort-level metabolic testing | Mechanistically heterogeneous; some are potentially treatable metabolic defects rather than classic ion-channel DEEs | Metabolic dysfunction can produce early seizures and encephalopathy; in early-infantile cohorts, vitamin-responsive etiologies had better seizure control than genetic/unknown groups, showing the importance of separating treatable metabolic causes from monogenic DEE (pqac-00000009, pqac-00000020) | Precision implication is urgent metabolic evaluation because some early-infantile epilepsies are vitamin responsive and clinically more treatable than most monogenic DEEs (pqac-00000020) | Strong practical message from prospective human cohort, but this row spans heterogeneous disorders and should not be collapsed into a single molecular DEE mechanism (pqac-00000020) |
| Chromatin / transcriptional regulation defects | CHD2, KMT2A, HNRNPU, CDKL5 | Often dosage-sensitive or loss-of-function/haploinsufficiency-like effects, but not uniformly so across genes | Disrupted transcriptional or chromatin regulation alters neuronal differentiation and network development, yielding treatment-resistant epilepsy, developmental delay/intellectual disability, autism/behavioral features, and possible regression (pqac-00000009, pqac-00000006) | Current precision-management value is highest for diagnosis, prognosis, and trial readiness; CHD2 is highlighted as dosage sensitive with model systems under development, but no established targeted therapy yet (pqac-00000006) | Human cohort and roadmap/model evidence support this class; important limitation is that some animal models fail to recapitulate seizures, underscoring translational gaps (pqac-00000006) |


*Table: This table summarizes major mechanistic categories represented in genetic developmental and epileptic encephalopathies, linking gene classes to variant effects, disease biology, and current precision-management implications. It is useful as a compact knowledge-base scaffold because DEE is genetically heterogeneous and treatment logic often depends on variant-specific gain- versus loss-of-function.*