Background and ObjectivesClinical manifestations in STXBP1 developmental and epileptic encephalopathy (DEE) vary in severity and outcome, and the genotypic spectrum is diverse. We aim to trace the neurodevelopmental trajectories in individuals with STXBP1-DEE and dissect the relationship between neurodevelopment and epilepsy.MethodsRetrospective standardized clinical data were collected through international collaboration. A composite neurodevelopmental score system compared the developmental trajectories in STXBP1-DEE.ResultsForty-eight patients with de novo STXBP1 variants and a history of epilepsy were included (age range at the time of the study: 10 months to 35 years, mean 8.5 years). At the time of inclusion, 65% of individuals (31/48) had active epilepsy, whereas 35% (17/48) were seizure free, and 76% of those (13/17) achieved remission within the first year of life. Twenty-two individuals (46%) showed signs of developmental impairment and/or neurologic abnormalities before epilepsy onset. Age at seizure onset correlated with severity of developmental outcome and the developmental milestones achieved, with a later seizure onset associated with better developmental outcome. In contrast, age at seizure remission and epilepsy duration did not affect neurodevelopmental outcomes. Overall, we did not observe a clear genotype-phenotype correlation, but monozygotic twins with de novo STXBP1 variant showed similar phenotype and parallel disease course.DiscussionThe disease course in STXBP1-DEE presents with 2 main trajectories, with either early seizure remission or drug-resistant epilepsy, and a range of neurodevelopmental outcomes from mild to profound intellectual disability. Age at seizure onset is the only epilepsy-related feature associated with neurodevelopment outcome. These findings can inform future dedicated natural history studies and trial design.

Summary Objective Pathogenic variants in SCN8A have been associated with a wide spectrum of epilepsy phenotypes, ranging from benign familial infantile seizures (BFIS) to epileptic encephalopathies with variable severity. Furthermore, a few patients with intellectual disability (ID) or movement disorders without epilepsy have been reported. The vast majority of the published SCN8A patients suffer from severe developmental and epileptic encephalopathy (DEE). In this study, we aimed to provide further insight on the spectrum of milder SCN8A‐related epilepsies. Methods A cohort of 1095 patients were screened using a next generation sequencing panel. Further patients were ascertained from a network of epilepsy genetics clinics. Patients with severe DEE and BFIS were excluded from the study. Results We found 36 probands who presented with an SCN8A‐related epilepsy and normal intellect (33%) or mild (61%) to moderate ID (6%). All patients presented with epilepsy between age 1.5 months and 7 years (mean = 13.6 months), and 58% of these became seizure‐free, two‐thirds on monotherapy. Neurological disturbances included ataxia (28%) and hypotonia (19%) as the most prominent features. Interictal electroencephalogram was normal in 41%. Several recurrent variants were observed, including Ile763Val, Val891Met, Gly1475Arg, Gly1483Lys, Phe1588Leu, Arg1617Gln, Ala1650Val/Thr, Arg1872Gln, and Asn1877Ser. Significance With this study, we explore the electroclinical features of an intermediate SCN8A‐related epilepsy with mild cognitive impairment, which is for the majority a treatable epilepsy.

Background The detection of antibodies to myelin oligodendrocyte glycoprotein (MOG) is fundamental for the identification of MOG antibody-associated disorders (MOGAD), and the differential diagnosis of acquired demyelinating syndromes of the CNS, among which multiple sclerosis (MS). We compared the diagnostic performance of four cell-based assays (CBAs) for their detection. Methods Consecutive sera from 204 patients with 'possible MOGAD' (55), MS (112), and other neurological disorders (OND, 37) were tested for MOG-IgG with a live-CBA with anti-heavy-and-light chain secondary-antibody (LCBA-IgG H+L ), and a live-CBA for IgG 1 (LCBA-IgG 1 ). A subgroup of 71 patients was additionally tested with a live-CBA with anti-Fcγ secondary-antibody (LCBA-IgG Fcγ ), and a commercial fixed-CBA with anti-Fcγ secondary-antibody (FCBA-IgG Fcγ ) . Results Fifty-seven/204 patients (27.9%) were MOG-IgG-positive. Sensitivity was 89.1% (CI:77.8-95.9) and specificity 93.3% (CI:88.0-96.7) for LCBA-IgG H+L , and 74.6% (CI:61.0-85.3) and 100% (CI:97.6-100) for LCBA-IgG 1 . Eighteen of 57 (31%) samples showed discrepant results (all negative on LCBA-IgG 1 ); of these, three with 'possible MOGAD' showed high-titer MOG-IgG (≥ 1:640), and positivity for MOG-IgG 2 , whereas 15/18 had low-titer MOG-IgG (1:160/1:320) and mixed diagnoses (5 'possible MOGAD', 6 MS, 4 OND). In the subgroup analysis, sensitivity was 92.3% (CI:79.1-98.4) and specificity 97.0% (CI:83.8-99.9) for LCBA-IgG Fcγ , and 87.2% (CI:72.6-95.7) and 97.0% (CI:83.8-99.9) for FCBA-IgG Fcγ . Conclusions LCBA-IgG 1 showed the highest specificity but can miss MOG-IgG 2 reactivities, whose meaning warrants further investigations. Titration of samples tested with LCBA-IgG H+L / IgG Fcγ is important for meaningful interpretation of the results. In the subgroup analysis, LCBA-IgG Fcγ yielded the highest accuracy, and FCBA-IgG Fcγ good specificity, but it was at risk of false-negative results.

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Background Childhood epilepsies are a heterogeneous group of conditions differing in diagnostic criteria, management, and outcome. Late-infantile neuronal ceroid lipofuscinosis type 2 (CLN2) is a neurodegenerative condition caused by biallelic TPP1 variants. This disorder presents with subtle and relatively non-specific symptoms, mimicking those observed in more common paediatric epilepsies and followed by rapid psychomotor deterioration and drug-resistant epilepsy. A prompt diagnosis is essential to adopt appropriate treatment and disease management strategies. Methods This is a prospective, multicentre study on the efficiency of targeted re-sequencing in the early identification of the genetic causes of childhood epilepsy, with particular regard to CLN2. After phenotypic characterization, a 283-gene Next Generation Sequencing panel was performed in 21 Italian children with neurodevelopmental abnormalities, aged between 24 and 60 months, experiencing first unprovoked seizure after 2 years of age. Results The average age at enrolment was 39.9 months, with a mean age at seizure onset of 30.9 months and a mean time interval between seizure onset and targeted resequencing of 9 months. Genetic confirmation was achieved in 4 out of 21 patients, with a diagnostic yield of 19%. In one case, the homozygous splice acceptor variant c.509-1G > C in TPP1 was identified, leading to a CLN2 diagnosis. Three pathogenic variants in MECP2 were also detected in three patients, including the frameshift variant c.1157_1186delinsA (p.Leu386Hisfs*9) in a girl with negative single gene sequencing. Variants of unknown significance (VUS) were found in 11 out of 21 (52.4%) individuals, whereas no clinically significant variants were observed in the remaining 6 subjects. Conclusions Our findings support the efficacy of target re-sequencing in the identification of the genetic causes of childhood epilepsy and suggest that this technique might prove successful in the early detection of CLN2 as well as other neurodevelopmental conditions.

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BackgroundIgG antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) define a subset of associated disorders (myelin oligodendrocyte glycoprotein associated disorders (MOGAD)) that can have a relapsing course. However, information on relapse predictors is scarce. The utility of retesting MOG-IgG over time and measuring their titres is uncertain. We aimed to evaluate the clinical relevance of longitudinal MOG-IgG titre measurement to predict relapses in patients with MOGAD.MethodsIn this retrospective multicentre Italian cohort study, we recruited patients with MOGAD and available longitudinal samples (at least one >3 months after disease onset) and tested them with a live cell-based assay with endpoint titration (1:160 cut-off). Samples were classified as ‘attack’ (within 30 days since a disease attack (n=59, 17%)) and ‘remission’ (≥31 days after attack (n=295, 83%)).ResultsWe included 102 patients with MOGAD (57% adult and 43% paediatric) with a total of 354 samples (83% from remission and 17% from attack). Median titres were higher during attacks (1:1280 vs 1:640, p=0.001). Median onset titres did not correlate with attack-related disability, age or relapses. Remission titres were higher in relapsing patients (p=0.02). When considering the first remission sample available for each patient, titres >1:2560 were predictors of relapsing course in survival (log rank, p<0.001) and multivariate analysis (p<0.001, HR: 10.9, 95% CI 3.4 to 35.2). MOG-IgG seroconversion to negative was associated with a 95% relapse incidence rate reduction (incidence rate ratio: 0.05, p<0.001).ConclusionsPersistent MOG-IgG positivity and high remission titres are associated with an increased relapse risk. Longitudinal MOG-IgG titres could be useful to stratify patients to be treated with long term immunosuppression.