Pathogenic KCNQ2 variants are the most common genetic cause of neonatal-onset epilepsies, with phenotypes ranging from self-limited (familial) neonatal epilepsy (SeL(F)NE) to severe developmental and epileptic encephalopathy (KCNQ2-DEE). Sodium channel blockers (SCBs) have shown promise for seizure control in these disorders, but their impact on neurodevelopmental outcomes and possible relationship with timing of initiation remain incompletely understood. We leveraged a large, multicentre international cohort comprising 282 individuals with pathogenic KCNQ2 variants to retrospectively assess the effectiveness of antiseizure medications (ASMs), particularly SCBs, on seizure control and neurodevelopment. Individuals were grouped according to the predicted variant-specific functional effects: loss-of-function (LOF) variants known to be associated with SeL(F)NE or DEE respectively, and gain-of-function (GOF) variants. Epilepsy course, ASM effectiveness, and neurodevelopmental milestones were systematically collected and analysed, including time-to-event and adjusted outcome analyses. SCBs, especially carbamazepine (CBZ) and oxcarbazepine (OXC), emerged as the most effective ASMs in both LOF groups. In LOF KCNQ2-DEE, time-to-event analyses showed that early SCB initiation (≤1 month) was associated with earlier seizure offset. Early SCB initiation was also associated with significantly more favourable neurodevelopmental outcomes, including higher rates of attaining major motor milestones. This association remained significant after adjustment for seizure control by 1 month and total ASM burden. Considerable phenotypic variability persisted, with some individuals experiencing severe impairment despite early seizure control and SCB initiation, suggesting that variant severity and additional genetic or biological modifiers contribute to outcome heterogeneity.Our results support the use of SCBs, particularly CBZ and OXC, as first-line therapy in (LOF) KCNQ2-DEE and SeL(F)NE. Earlier SCB initiation was associated with earlier seizure offset and more favourable developmental outcomes, underscoring the importance of early genetic diagnosis and timely SCB therapy. We however emphasise that early treatment is not universally transformative and further prospective work, including exploration of targeted therapies and standardised neurodevelopmental assessments, is needed to optimise long-term outcomes in this heterogeneous population.
C. Millevert, M. Hairabedian, Samuel Dahan et al.· Brain : a journal of neurolo...· 0 citations
In a clinical setting, exome sequencing (ES) with copy number variant (CNV) analysis is currently the most effective approach for developmental and epileptic encephalopathies (DEE). However, trio-based ES is often not feasible in adults, its costs remain prohibitive in certain health care settings, and computational tools for CNV calling still lack sufficient accuracy. Chromosomal microarray (CMA) is indicated as a first-tier test for CNV detection in patients with DEE, dysmorphisms, and comorbidities. We investigate the role of CNVs in the etiology of DEE in an adult cohort, to define the most appropriate diagnostic approach in this population. A total of 219 patients (male/female: 104/115) with undiagnosed DEE underwent array-based comparative genomic hybridization/single nucleotide polymorphism arrays as adults. Causative CNVs were identified in 18 patients (8.2%); 14 were deletions (mean size ≈ 2.96 Mb), and four were duplications/triplications (mean size ≈ 3.63 Mb). Thirteen were responsible for known deletion/microduplication syndromes, and four were deletions involving haploinsufficient genes associated with epilepsy/neurodevelopmental disorders. For one deletion, population evidence, reports with overlapping deletions, and clinical databases support a likely pathogenic role. The mean age at CMA diagnosis was 32.4 ± 13 years. An additional 46 patients (21%) then received a molecular diagnosis through alternative approaches. Despite a diagnostic delay of 24.2 ± 14.5 years, CMA enabled a genetic diagnosis in 8.2% of our adult DEE patients, especially in those with dysmorphisms. The diagnostic yield rises to 10.4% when excluding patients diagnosed using other methods. A total of 66.7% of solved cases had direct implications from the diagnosis, supporting the clinical utility of CNV analysis inclusion in the diagnostic workflow for adult patients with DEE.
L. Licchetta, G. Bruschi, T. Giangregorio et al.· Epilepsia· 1 citation
The electroclinical and developmental features of three patients carrying truncating TANC2 variants identified through trio‐exome sequencing within the European collaborative platform NETRE are described, expanding the known clinical spectrum of TANC2‐related disorders and suggesting that selected patients may have a more favorable seizure course than expected.
L. Perilli, Carlotta Stipa, Gianmichele Villano et al.· Epilepsia Open· 0 citations