NPRL3 loss alters neuronal morphology, mTOR localization, cortical lamination and seizure threshold.

Mutations in nitrogen permease regulator-like 3 (NPRL3), a component of the GATOR1 complex within the mTOR pathway, are associated with epilepsy and malformations of cortical development. Little is known about the effects of NPRL3 loss on neuronal mTOR signalling and morphology, or cerebral cortical development and seizure susceptibility. We report the clinical phenotypic spectrum of a founder NPRL3 pedigree (c.349delG, p.Glu117LysFS; n = 133) among Old Order Mennonites dating to 1727. Next, as a strategy to define the role of NPRL3 in cortical development, CRISPR/Cas9 Nprl3 knockout in Neuro2a cells in vitro and in foetal mouse brain in vivo was used to assess the effects of Nprl3 knockout on mTOR activation, subcellular mTOR localization, nutrient signalling, cell morphology and aggregation, cerebral cortical cytoarchitecture and network integrity. The NPRL3 pedigree exhibited an epilepsy penetrance of 28% and heterogeneous clinical phenotypes with a range of epilepsy semiologies, i.e. focal or generalized onset, brain imaging abnormalities, i.e. polymicrogyria, focal cortical dysplasia or normal imaging, and EEG findings, e.g. focal, multi-focal or generalized spikes, focal or generalized slowing. Whole exome analysis comparing a seizure-free group (n = 37) to those with epilepsy (n = 24) to search for gene modifiers for epilepsy did not identify a unique genetic modifier that explained the variability in seizure penetrance in this cohort. Nprl3 knockout in vitro caused mTOR pathway hyperactivation, cell soma enlargement and the formation of cellular aggregates seen in time-lapse videos that were prevented with the mTOR inhibitors rapamycin or torin1. In Nprl3 knockout cells, mTOR remained localized on the lysosome in a constitutively active conformation, as evidenced by phosphorylation of ribosomal S6 and 4E-BP1 proteins, even under nutrient starvation (amino acid-free) conditions, demonstrating that Nprl3 loss decouples mTOR activation from neuronal metabolic state. To model human malformations of cortical development associated with NPRL3 variants, we created a focal Nprl3 knockout in foetal mouse cortex by in utero electroporation and found altered cortical lamination and white matter heterotopic neurons, effects which were prevented with rapamycin treatment. EEG recordings showed network hyperexcitability and reduced seizure threshold to pentylenetetrazol treatment. NPRL3 variants are linked to a highly variable clinical phenotype which we propose results from mTOR-dependent effects on cell structure, cortical development and network organization.

Factors Influencing Migraine Recurrence After Infusion and Inpatient Migraine Treatment in Children and Adolescents.

OBJECTIVE: To evaluate factors that influence migraine recurrence after outpatient infusion or inpatient treatment for intractable migraine. BACKGROUND: Recurrence of migraine after acute treatment in an infusion center or an inpatient setting is not well documented in children and adolescents. Given the multifactorial pathogenesis of migraines, multiple factors may influence migraine recurrence. It has been reported that treatment with steroids may reduce the risk of migraine recurrence. The efficacy of steroids as a therapeutic adjunct has not been established. Studies in the adult population have yielded conflicting results. METHODS: This study is a retrospective chart review of patients presenting for treatment of an intractable migraine to the outpatient infusion unit or inpatient unit at Cincinnati Children's Hospital Medical Center (CCHMC). Data collected included: age, gender, location of treatment (outpatient, inpatient), migraine duration, diagnosis, severity, the addition of steroids to treatment protocols, and recurrence of migraine at 48 and 72 hours after discharge. Data were analyzed using Fisher's exact tests, logistic regression with backward elimination for variable selection, and least squares means slicing with associated odds ratios. RESULTS: Charts from 207 pediatric patients were analyzed. Using logistic regression analysis: location, gender, diagnosis, and age were all found to be significant predictors of migraine recurrence (P < .05). Patients treated in the inpatient setting were significantly less likely to experience recurrence compared to patients treated in an outpatient infusion unit (OR = 0.32; 95% CI 0.17-0.61, P = .0002). Male patients with a diagnosis of episodic migraine were significantly less likely to experience recurrence than male patients with chronic migraine (OR 0.17; 95% CI 0.04-0.73; P = .0074). The inclusion of steroids in this study population showed no significant reduction in migraine recurrence. The probability of recurrence decreased with age for episodic migraine patients, while the probability increased with age for chronic migraine patients. CONCLUSIONS: Recurrence is an important consideration when treating intractable migraines. Age, gender, diagnosis, and location of treatment correlate with migraine recurrence, but the inclusion of steroids does not. Considering these factors in the management of migraines may improve the outcome of these patients and reduce the risk of recurrence.