Seizure-driven brain damage in epilepsy accumulates over time, especially in the hippocampus, which can lead to sclerosis, cognitive decline, and death. Excitotoxicity is the prevalent model to explain ictal neurodegeneration. Current labeling technologies cannot distinguish between excitotoxicity and hypoxia, however, because they share common molecular mechanisms. This leaves open the possibility that undetected ischemic hypoxia, due to ictal blood flow restriction, could contribute to neurodegeneration previously ascribed to excitotoxicity. We tested this possibility with Confocal Laser Endomicroscopy (CLE) and novel stereological analyses in several models of epileptic mice. We found a higher number and magnitude of NG2+ mural-cell mediated capillary constrictions in the hippocampus of epileptic mice than in that of normal mice, in addition to spatial coupling between capillary constrictions and oxidative stressed neurons and neurodegeneration. These results reveal a role for hypoxia driven by capillary blood flow restriction in ictal neurodegeneration.

CRX is a transcription factor required for activating the expression of many photoreceptor-neuron genes. CRX may be mutated in three forms of human blindness; Leber congenital amaurosis (LCA), cone-rod degeneration (CRD) and retinitis pigmentosa (RP). The pathogenic mechanism in most cases is likely dominant negative, with gain of function. We report a novel, complete homozygous CRX deletion in LCA. We identified a Lebanese family with 3 affected LCA cases. The proband was sequenced by NGS. Quantitative PCR, array comparative genomic hybridization, and long range PCR were performed. Full eye examinations, OCT and photography were performed. We identified a homozygous 56,000 bp deletion of CRX, which co-segregates and is heterozygous in four parents, who report normal vision. The blind children with LCA manifest severe retinal degeneration, a phenotype typical for CRX and LCA. We hypothesized that a single copy of CRX (haplo-insufficiency) in the causes mild abnormal foveal development, but not LCA. Two parents had significant inner and outer foveal and photoreceptor abnormalities. This is the first reported case of a homozygous, complete CRX deletion. Nullizygosity of CRX thus causes LCA while haplo-insufficiency of CRX causes abnormal foveal development, but not LCA. Our data suggest a new disease mechanism for CRX.

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Hypothesis About 1% of patients clinically diagnosed as type 1 diabetes have non-autoimmune monogenic diabetes. The distinction has important therapeutic implications but, given the low prevalence and high cost of testing, selecting patients to test is important. We tested the hypothesis that low genetic risk for type 1 diabetes can substantially contribute to this selection. Methods As proof of principle, we examined by exome sequencing families with two or more children, recruited by the Type 1 Diabetes Genetics Consortium and selected for negativity for two autoantibodies and absence of risk HLA haplotypes. Results We examined 46 families that met the criteria. Of the 17 with an affected parent, seven (41.2%) had actionable monogenic variants. Of 29 families with no affected parent, 14 (48.3%) had such variants, including five with recessive pathogenic variants of WFS1 but no report of other features of Wolfram syndrome. Our approach diagnosed 55.8% of the estimated number of monogenic families in the entire T1DGC cohort, by sequencing only 11.1% of the autoantibody-negative ones. Conclusions Our findings justify proceeding to large-scale prospective screening studies using markers of autoimmunity, even in the absence of an affected parent. We also confirm that non-syndromic WFS1 variants are common among cases of monogenic diabetes misdiagnosed as type 1 diabetes.

Mutations in the neurite extension and migration factor (<i>NEXMIF</i>) gene are associated with X-linked intellectual disability. Thus far, all males reported with <i>NEXMIF</i> mutations have mild to profound intellectual disability with varying combinations of autistic features, poor or absent speech, epilepsy, facial dysmorphism, and strabismus. Affected females tend to have milder intellectual disability but severe, drug-resistant epilepsy. Here, we present a 32-month-old boy with a novel de novo frameshift <i>NEXMIF</i> pathogenic variant (p.Glu375ArgfsX21) who has mild motor delay, language delay, autistic features, and strabismus. In addition to these commonly described findings of <i>NEXMIF</i> mutations, his fundus exam revealed a very rare ophthalmologic abnormality, torpedo maculopathy. This finding has not previously been reported with <i>NEXMIF</i> mutation; however, on literature review, 7/15 males with <i>NEXMIF</i> mutations had other ophthalmologic abnormalities. This patient expands the phenotypic spectrum for males with <i>NEXMIF</i> mutations and suggests that NEXMIF may play an important role in ocular development.

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ObjectiveTo describe the thresholds of instability used by clinicians at reintubation and evaluate the accuracy of different combinations of criteria in predicting reintubation decisions.DesignSecondary analysis using data obtained from the prospective observational Automated Prediction of Extubation Readiness study (NCT01909947) between 2013 and 2018.SettingMulticentre (three neonatal intensive care units).PatientsInfants with birth weight ≤1250 g, mechanically ventilated and undergoing their first planned extubation were included.InterventionsAfter extubation, hourly O2requirements, blood gas values and occurrence of cardiorespiratory events requiring intervention were recorded for 14 days or until reintubation, whichever came first.Main outcome measuresThresholds at reintubation were described and grouped into four categories: increased O2, respiratory acidosis, frequent cardiorespiratory events and severe cardiorespiratory events (requiring positive pressure ventilation). An automated algorithm was used to generate multiple combinations of criteria from the four categories and compute their accuracies in capturing reintubated infants (sensitivity) without including non-reintubated infants (specificity).Results55 infants were reintubated (median gestational age 25.2 weeks (IQR 24.5–26.1 weeks), birth weight 750 g (IQR 640–880 g)), with highly variable thresholds at reintubation. After extubation, reintubated infants had significantly greater O2needs, lower pH, higher pCO2and more frequent and severe cardiorespiratory events compared with non-reintubated infants. After evaluating 123 374 combinations of reintubation criteria, Youden indices ranged from 0 to 0.46, suggesting low accuracy. This was primarily attributable to the poor agreement between clinicians on the number of cardiorespiratory events at which to reintubate.ConclusionsCriteria used for reintubation in clinical practice are highly variable, with no combination accurately predicting the decision to reintubate.