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The Okur-Chung neurodevelopmental syndrome, or OCNDS, is a newly discovered rare neurodevelopmental disorder. It is characterized by developmental delay, intellectual disability, behavioral problems (hyperactivity, repetitive movements and social interaction deficits), hypotonia, epilepsy and language/verbalization deficits. OCNDS is linked to de novo mutations in CSNK2A1, that lead to missense or deletion/truncating variants in the encoded protein, the protein kinase CK2α. Eighteen different missense CK2α mutations have been identified to date; however, no biochemical or cell biological studies have yet been performed to clarify the functional impact of such mutations. Here, we show that 15 different missense CK2α mutations lead to varying degrees of loss of kinase activity as recombinant purified proteins and when mutants are ectopically expressed in mammalian cells. We further detect changes in the phosphoproteome of three patient-derived fibroblast lines and show that the subcellular localization of CK2α is altered for some of the OCNDS-linked variants and in patient-derived fibroblasts. Our data argue that reduced kinase activity and abnormal localization of CK2α may underlie the OCNDS phenotype.

Here we present a novel statistical approach to splicing outlier and differential splicing detection, implemented in a software package called Bisbee. We leverage Bisbee’s prediction of protein level effects to benchmark using matched RNAseq and mass spectrometry data from normal tissues. Bisbee exhibits improved sensitivity and specificity over existing approaches. We applied Bisbee to confirm a pathogenic splicing event in a rare disease and to identify tumor-specific splice isoforms associated with an oncogenic splice factor mutation. We also identified common tumor associated splice isoforms replicated in an independent dataset, demonstrating the utility of Bisbee in discovering disease relevant splice variants.

Selective pericyte loss, the histological hallmark of early diabetic retinopathy (DR), enhances the breakdown of the blood-retinal barrier (BRB) in diabetes. However, the role of pericytes on BRB alteration in diabetes and the signaling pathways involved in their effects are currently unknown. To understand the role of diabetes-induced molecular alteration of pericytes, we performed transcriptomic analysis of sorted retinal pericytes from mice model of diabetes. Retinal tissue from non-diabetic and diabetic (duration 3 months) mouse eyes (n = 10 in each group) were used to isolate pericytes through fluorescent activated cell sorting (FACS) using pericyte specific fluorescent antibodies, PDGFRb-APC. For RNA sequencing and qPCR analysis, a cDNA library was generated using template switching oligo and the resulting libraries were sequenced using paired-end Illumina sequencing. Molecular functional pathways were analyzed using differentially expressed genes (DEGs). Differential expression analysis revealed 217 genes significantly upregulated and 495 genes downregulated, in pericytes isolated from diabetic animals. These analyses revealed a core set of differentially expressed genes that could potentially contribute to the pericyte dysfunction in diabetes and highlighted the pattern of functional connectivity between key candidate genes and blood retinal barrier alteration mechanisms. The top up-regulated gene list included: Ext2, B3gat3, Gpc6, Pip5k1c and Pten and down-regulated genes included: Notch3, Xbp1, Gpc4, Atp1a2 and AKT3. Out of these genes, we further validated one of the down regulated genes, Notch 3 and its role in BRB alteration in diabetic retinopathy. We confirmed the downregulation of Notch3 expression in human retinal pericytes exposed to Advanced Glycation End-products (AGEs) treatment mimicking the chronic hyperglycemia effect. Exploration of pericyte-conditioned media demonstrated that loss of NOTCH3 in pericyte led to increased permeability of endothelial cell monolayers. Collectively, we identify a role for NOTCH3 in pericyte dysfunction in diabetes. Further validation of other DEGs to identify cell specific molecular change through whole transcriptomic approach in diabetic retina will provide novel insight into the pathogenesis of DR and novel therapeutic targets.

Although there is strong clinical evidence that the control of blood glucose, blood pressure, and lipid level can prevent and slow down the progression of diabetic retinopathy (DR) as shown by landmark clinical trials, it has been shown that these factors only account for 10% of the risk for developing this disease. This suggests that other factors, such as genetics, may play a role in the development and progression of DR. Clinical evidence shows that some diabetics, despite the long duration of their diabetes (25 years or more) do not show any sign of DR or show minimal non-proliferative diabetic retinopathy (NPDR). Similarly, not all diabetics develop proliferative diabetic retinopathy (PDR). So far, linkage analysis, candidate gene studies, and genome-wide association studies (GWAS) have not produced any statistically significant results. We recently initiated a genomics study, the Diabetic Retinopathy Genetics (DRGen) Study, to examine the contribution of rare and common variants in the development of different phenotypes of DR, as well as their responsiveness to anti-VEGF treatment in diabetic macular edema (DME). Our preliminary findings reveal a novel set of genetic variants involved in the angiogenesis and inflammatory pathways that contribute to DR progression or protection. Further investigation of variants can help to develop novel biomarkers and lead to new therapeutic targets in DR.

Pelizaeus-Merzbacher-like disease (PMLD) is an autosomal recessive hypomyelinating leukodystrophy, which is clinically and radiologically similar to X-linked Pelizaeus-Merzbacher disease (PMD). PMLD is characterized by early-onset nystagmus, delayed development (motor delay, speech delay and dysarthria), dystonia, hypotonia typically evolving into spasticity, ataxia, seizures, optic atrophy, and diffuse leukodystrophy on magnetic resonance imaging (MRI). We identified a 12-year-old Caucasian/Hispanic male with the classical clinical characteristics of PMLD with lack of myelination of the subcortical white matter, and absence of the splenium of corpus callosum. Exome sequencing in the trio revealed novel compound heterozygous pathogenic mutations in SNAP29 (p.Leu119AlafsX15, c.354DupG and p.0?, c.2T > C). Quantitative analysis of the patient’s blood cells through RNA sequencing identified a significant decrease in SNAP29 mRNA expression, while western blot analysis on fibroblast cells revealed a lack of protein expression compared to parental and control cells. Mutations in SNAP29 have previously been associated with cerebral dysgenesis, neuropathy, ichthyosis, and keratoderma (CEDNIK) syndrome. Typical skin features described in CEDNIK syndrome, such as generalized ichthyosis and keratoderma, were absent in our patient. Moreover, the early onset nystagmus and leukodystrophy were consistent with a PMLD diagnosis. These findings suggest that loss of SNAP29 function, which was previously associated with CEDNIK syndrome, is also associated with PMLD. Overall, our study expands the genetic spectrum of PMLD.

Objective Description of a new variant of the glutamine-fructose-6-phosphate transaminase 1 (GFPT1) gene causing congenital myasthenic syndrome (CMS) in 3 children from 2 unrelated families. Methods Muscle biopsies, EMG, and whole-exome sequencing were performed. Results All 3 patients presented with congenital hypotonia, muscle weakness, respiratory insufficiency, head lag, areflexia, and gastrointestinal dysfunction. Genetic analysis identified a homozygous frameshift insertion in the GFPT1 gene (NM_001244710.1: c.686dupC; p.Arg230Ter) that was shared by all 3 patients. In one of the patients, inheritance of the variant was through uniparental disomy (UPD) with maternal origin. Repetitive nerve stimulation and single-fiber EMG was consistent with the clinical diagnosis of CMS with a postjunctional defect. Ultrastructural evaluation of the muscle biopsy from one of the patients showed extremely attenuated postsynaptic folds at neuromuscular junctions and extensive autophagic vacuolar pathology. Conclusions These results expand on the spectrum of known loss-of-function GFPT1 mutations in CMS12 and in one family demonstrate a novel mode of inheritance due to UPD.

International audience; The human RNA helicase DDX6 is an essential component of membrane-less organelles called processing bodies (PBs). PBs are involved in mRNA metabolic processes including translational repression via coordinated storage of mRNAs. Previous studies in human cell lines have implicated altered DDX6 in molecular and cellular dysfunction, but clinical consequences and pathogenesis in humans have yet to be described. Here, we report the identification of five rare de novo missense variants in DDX6 in probands presenting with intellectual disability, developmental delay, and similar dysmorphic features including telecanthus, epicanthus, arched eyebrows, and low-set ears. All five missense variants (p.His372Arg, p.Arg373Gln, p.Cys390Arg, p.Thr391Ile, and p.Thr391Pro) are located in two conserved motifs of the RecA-2 domain of DDX6 involved in RNA binding, helicase activity, and protein-partner binding. We use functional studies to demonstrate that the first variants identified (p.Arg373Gln and p.Cys390Arg) cause significant defects in PB assembly in primary fibroblast and model human cell lines. These variants' interactions with several protein partners were also disrupted in immunoprecipitation assays. Further investigation via complementation assays included the additional variants p.Thr391Ile and p.Thr391Pro, both of which, similarly to p.Arg373Gln and p.Cys390Arg, demonstrated significant defects in P-body assembly. Complementing these molecular findings, modeling of the variants on solved protein structures showed distinct spatial clustering near known protein binding regions. Collectively, our clinical and molecular data describe a neurodevelopmental syndrome associated with pathogenic missense variants in DDX6. Additionally, we suggest DDX6 join the DExD/H-box genes DDX3X and DHX30 in an emerging class of neurodevelopmental disorders involving RNA helicases.

ObjectiveDescription of a new variant of the glutamine-fructose-6-phosphate transaminase 1 (GFPT1) gene causing congenital myasthenic syndrome (CMS) in 3 children from 2 unrelated families.MethodsMuscle biopsies, EMG, and whole-exome sequencing were performed.ResultsAll 3 patients presented with congenital hypotonia, muscle weakness, respiratory insufficiency, head lag, areflexia, and gastrointestinal dysfunction. Genetic analysis identified a homozygous frameshift insertion in the GFPT1 gene (NM_001244710.1: c.686dupC; p.Arg230Ter) that was shared by all 3 patients. In one of the patients, inheritance of the variant was through uniparental disomy (UPD) with maternal origin. Repetitive nerve stimulation and single-fiber EMG was consistent with the clinical diagnosis of CMS with a postjunctional defect. Ultrastructural evaluation of the muscle biopsy from one of the patients showed extremely attenuated postsynaptic folds at neuromuscular junctions and extensive autophagic vacuolar pathology.ConclusionsThese results expand on the spectrum of known loss-of-function GFPT1 mutations in CMS12 and in one family demonstrate a novel mode of inheritance due to UPD.

Epileptic encephalopathies are childhood brain disorders characterized by a variety of severe epilepsy syndromes that differ by the age of onset and seizure type. Until recently, the cause of many epileptic encephalopathies was unknown. Whole exome or whole genome sequencing has led to the identification of several causal genes in individuals with epileptic encephalopathy, and the list of genes has now expanded greatly. Genetic testing with epilepsy gene panels is now done quite early in the evaluation of children with epilepsy, following brain imaging, electroencephalogram, and metabolic profile. Early infantile epileptic encephalopathy (EIEE1; OMIM #308350) is the earliest of these age-dependent encephalopathies, manifesting as tonic spasms, myoclonic seizures, or partial seizures, with severely abnormal electroencephalogram, often showing a suppression-burst pattern. In this case study, we describe a 33-month-old female child with severe, neonatal onset epileptic encephalopathy. An infantile epilepsy gene panel test revealed 2 novel heterozygous variants in the MECP2 gene; a 70-bp deletion resulting in a frameshift and truncation (p.Lys377ProfsX9) thought to be pathogenic, and a 6-bp in-frame deletion (p.His371_372del), designated as a variant of unknown significance. Based on this test result, the diagnosis of atypical Rett syndrome (RTT) was made. Family-based targeted testing and segregation analysis, however, raised questions about the pathogenicity of these specific MECP2 variants. Whole exome sequencing was performed in this family trio, leading to the discovery of a rare, de novo, missense mutation in GNAO1 (p. Leu284Ser). De novo, heterozygous mutations in GNAO1 have been reported to cause early infantile epileptic encephalopathy-17 (EIEE17; OMIM 615473). The child's severe phenotype, the family history and segregation analysis of variants and prior reports of GNAO1-linked disease allowed us to conclude that the GNAO1 mutation, and not the MECP2 variants, was the cause of this child's neurological disease. With the increased use of genetic panels and whole exome sequencing, we will be confronted with lists of gene variants suspected to be pathogenic or of unknown significance. It is important to integrate clinical information, genetic testing that includes family members and correlates this with the published clinical and scientific literature, to help one arrive at the correct genetic diagnosis.

Diabetic macular edema (DME) is the major cause of vision loss in diabetic persons. Alteration of the blood–retinal barrier is the hallmark of this disease, characterized by pericyte loss and endothelial cell–cell junction breakdown. Recent animal and clinical studies strongly indicate that DME is an inflammatory disease. Multiple cytokines and chemokines are involved in the pathogenesis of DME, with multiple cellular involvement affecting the neurovascular unit. With the introduction of anti–vascular endothelial growth factor (VEGF) agents, the treatment of DME has been revolutionized, and the indication for laser therapy has been limited. However, the response to anti-VEGF drugs in DME is not as robust as in proliferative diabetic retinopathy, and many patients with DME do not show complete resolution of fluid despite multiple intravitreal injections. Potential novel therapies targeting molecules other than VEGF and using new drug-delivery systems currently are being developed and evaluated in clinical trials.

Chromosome 1q41-q42 deletions have recently been associated with a recognizable neurodevelopmental syndrome of early childhood (OMIM 612530). Within this group, a predominant phenotype of developmental delay (DD), intellectual disability (ID), epilepsy, distinct dysmorphology, and brain anomalies on magnetic resonance imaging/computed tomography has emerged. Previous reports of patients with de novo deletions at 1q41-q42 have led to the identification of an evolving smallest region of overlap which has included several potentially causal genes including DISP1, TP53BP2, and FBXO28. In a recent report, a cohort of patients with de novo mutations in WDR26 was described that shared many of the clinical features originally described in the 1q41-q42 microdeletion syndrome (MDS). Here, we describe a novel germline FBXO28 frameshift mutation in a 3-year-old girl with intractable epilepsy, ID, DD, and other features which overlap those of the 1q41-q42 MDS. Through a familial whole-exome sequencing study, we identified a de novo FBXO28 c.972_973delACinsG (p.Arg325GlufsX3) frameshift mutation in the proband. The frameshift and resulting premature nonsense mutation have not been reported in any genomic database. This child does not have a large 1q41-q42 deletion, nor does she harbor a WDR26 mutation. Our case joins a previously reported patient also in whom FBXO28 was affected but WDR26 was not. These findings support the idea that FBXO28 is a monogenic disease gene and contributes to the complex neurodevelopmental phenotype of the 1q41-q42 gene deletion syndrome.

Aim: To explore differential DNA methylation (DNAm) in Aicardi syndrome (AIC), a severe neurodevelopmental disorder with largely unknown etiology. Patients & methods: We characterized DNAm in AIC female patients and parents using the Illumina 450 K array. Differential DNAm was assessed using the local outlier factor algorithm, and results were validated via qPCR in a larger set of AIC female patients, parents and unrelated young female controls. Functional epigenetic modules analysis was used to detect pathways integrating both genome-wide DNAm and RNA-seq data. Results & conclusion: We detected differential methylation patterns in AIC patients in several neurodevelopmental and/or neuroimmunological networks. These networks may be part of the underlying pathogenic mechanisms involved in the disease.

Epigenetic marks are modifications of DNA and histones. They are considered to be permanent within a single cell during development, and are heritable across cell division. Programming of neurons through epigenetic mechanisms is believed to be critical in neural development. Disruption or alteration in this process causes an array of neurodevelopmental disorders, including autism spectrum disorders (ASDs). Recent studies have provided evidence for an altered epigenetic landscape in ASDs and demonstrated the central role of epigenetic mechanisms in their pathogenesis. Many of the genes linked to the ASDs encode proteins that are involved in transcriptional regulation and chromatin remodeling. In this review we highlight selected neurodevelopmental disorders in which epigenetic dysregulation plays an important role. These include Rett syndrome, fragile X syndrome, Prader–Willi syndrome, Angelman syndrome, and Kabuki syndrome. For each of these disorders, we discuss how advances in our understanding of epigenetic mechanisms may lead to novel therapeutic approaches.

Background The controlled recruitment of monocytes from the circulation to the site of injury and their differentiation into tissue macrophages are critical events in the reconstitution of tissue integrity. Subsets of monocytes/macrophages have been implicated in the pathogenesis of atherosclerosis and tumor vascularity; however, the significance of monocyte heterogeneity in physiologic neovascularization is just emerging. Materials and methods A cranial-based, peninsular-shaped myocutaneous flap was surgically created on the dorsum of wild-type mice (C57BL6) and populations of mice with genetic deletion of subset-specific chemokine ligand-receptor axes important in monocyte trafficking and function (CCL2−/− and CX3CR1−/−) (n = 36 total; 12 mice per group, nine with flap and three unoperated controls). Planimetric analysis of digital photographic images was utilized to determine flap surface viability in wild-type and knockout mice. Real-time myocutaneous flap perfusion and functional revascularization was determined by laser speckle contrast imaging. Image analysis of CD-31 immunostained sections confirmed flap microvascular density and anatomy. Macrophage quantification and localization in flap tissues was determined by F4/80 gene and protein expression. Quantitative reverse transcription-polymerase chain reaction was performed on nonoperative back skin and postoperative flap tissue specimens to determine local gene expression. Results Myocutaneous flaps created on wild type and CX3CR1−/− mice were engrafted to the recipient site, resulting in viability. In contrast, distal full thickness cutaneous necrosis and resultant flap dehiscence was evident by d 10 in CCL2−/− mice. Over 10 d, laser speckle contrast imaging documented immediate graded flap ischemia in all three groups of mice, functional flap revascularization in wild type and CX3CR1−/− mice, and lack of distal flap reperfusion in CCL2−/− mice. Immunostaining of serial histologic specimens confirmed marked increases in microvascular density and number of macrophages in wild type mice, intermediate increases in CX3CR1−/− mice, and no significant change in vessel count or macrophage quantity in CCL2−/− mice over the study interval. Finally, quantitative reverse transcriptase polymerase chain reaction demonstrated that the loss of function of chemokine ligand and receptor genes influenced the transcription of local genes involved in monocyte chemotaxis and wound angiogenesis. Conclusions In a graded-ischemia wound healing model, monocyte recruitment was severely impaired in CCL2−/− mice, resulting in failure of flap revascularization and concomitant cutaneous necrosis. Analysis of CX3CR1-deficient mice revealed adequate monocyte recruitment and revascularization for flap survival; however, the myeloid cell response and magnitude of neovascularization were dampened compared with wild type mice.

Young onset type 2 diabetes patients (T2DM-Y) have been shown to possess an increased risk of developing microvascular complications particularly diabetic retinopathy. However, the molecular mechanisms are not clearly understood. In this study, we investigated the serum levels of monocyte chemotactic protein 1 (MCP-1) and cathepsin-D in patients with T2DM-Y without and with diabetic retinopathy.In this case-control study, participants comprised individuals with normal glucose tolerance (NGT=40), patients with type 2 diabetes mellitus (T2DM=35), non-proliferative diabetic retinopathy (NPDR=35) and proliferative diabetic retinopathy (PDR=35). Clinical characterization of the study subjects was done by standard procedures and MCP-1 and cathepsin-D were measured by ELISA.Compared to control individuals, patients with T2DM-Y, NPDR and PDR exhibited significantly (p0.001) higher levels of MCP-1. Cathepsin-D levels were also significantly (p0.001) higher in patients with T2DM-Y without and with diabetic retinopathy. Correlation analysis revealed a positive association (p0.001) between MCP-1 and cathepsin-D levels. There was also a significant negative correlation of MCP1/cathepsin-D with C-peptide levels. The association of increased levels of MCP-1/cathepsin-D in patients with DR persisted even after adjusting for all the confounding factors.As both MCP-1 and cathepsin-D are molecular signatures of cellular senescence, we suggest that these biomarkers might be useful to predict the development of retinopathy in T2DM-Y patients.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutation in the X-linked MECP2 gene, encoding methyl-CpG-binding protein 2. We have created a mouse model (Mecp2 A140V “knock-in” mutant) expressing the recurrent human MECP2 A140V mutation linked to an X-linked mental retardation/Rett syndrome phenotype. Morphological analyses focused on quantifying soma and nucleus size were performed on primary hippocampus and cerebellum granule neuron (CGN) cultures from mutant (Mecp2A140V/y) and wild type (Mecp2+/y) male mice. Cultured hippocampus and cerebellar granule neurons from mutant animals were significantly smaller than neurons from wild type animals. We also examined soma size in hippocampus neurons from individual female transgenic mice that express both a mutant (maternal allele) and a wild type Mecp2 gene linked to an eGFP transgene (paternal allele). In cultures from such doubly heterozygous female mice, the size of neurons expressing the mutant (A140V) allele also showed a significant reduction compared to neurons expressing wild type MeCP2, supporting a cell-autonomous role for MeCP2 in neuronal development. IGF-1 (insulin growth factor-1) treatment of neuronal cells from Mecp2 mutant mice rescued the soma size phenotype. We also found that Mecp2 mutation leads to down-regulation of the mTOR signaling pathway, known to be involved in neuronal size regulation. Our results suggest that i) reduced neuronal size is an important in vitro cellular phenotype of Mecp2 mutation in mice, and ii) MeCP2 might play a critical role in the maintenance of neuronal structure by modulation of the mTOR pathway. The definition of a quantifiable cellular phenotype supports using neuronal size as a biomarker in the development of a high-throughput, in vitro assay to screen for compounds that rescue small neuronal phenotype (“phenotypic assay”).

OBJECTIVE—Zinc transporter eight (SLC30A8) is a major target of autoimmunity in human type 1A diabetes and is implicated in type 2 diabetes in genome-wide association studies. The type 2 diabetes nonsynonymous single nucleotide polymorphism (SNP) affecting aa325 lies within the region of highest ZnT8 autoantibody (ZnT8A) binding, prompting an investigation of its relationship to type 1 diabetes. RESEARCH DESIGN AND METHODS—ZnT8A radioimmunoprecipitation assays were performed in 421 new-onset type 1 diabetic Caucasians using COOH-terminal constructs incorporating the known human aa325 variants (Trp, Arg, and Gln). Genotypes were determined by PCR-based SNP analysis. RESULTS—Sera from 224 subjects (53%) were reactive to Arg325 probes, from 185 (44%) to Trp325probes, and from 142 (34%) to Gln325probes. Sixty subjects reacted only with Arg325 constructs, 31 with Trp325 only, and 1 with Gln325 only. The restriction to either Arg325 or Trp325 corresponded with inheritance of the respective C- or T-alleles. A strong gene dosage effect was also evident because both Arg- and Trp-restricted ZnT8As were less prevalent in heterozygous than homozygous individuals. The SLC30A8 SNP allele frequency (75% C and 25% T) varied little with age of type 1 diabetes onset or the presence of other autoantibodies. CONCLUSIONS—The finding that diabetes autoimmunity can be defined by a single polymorphic residue has not previously been documented. It argues against ZnT8 autoimmunity arising from molecular mimicry and suggests a mechanistic link between the two major forms of diabetes. It has implications for antigen-based therapeutic interventions because the response to ZnT8 administration could be protective or immunogenic depending on an individual's genotype.

Incontinentia pigmenti (IP; Bloch-Sulzberger syndrome; OMIM #308300) is an X-linked dominant neurocutaneous disorder with presumed male lethality. It is usually diagnosed in female newborns based on skin features (erythematous, vesicular, or bullous eruption in linear streaks). The skin lesions evolve into a verrucous stage, followed by atrophy and scarring, leaving linear areas of hypopigmentation and hyperpigmented macules in bizarre patterns following Blaschko's lines. Systemic and neurologic complications include focal seizures and hemorrhagic cerebral infarction in infants, and retinal vasculopathy leading to blindness. Hypodontia, conical or pegged teeth, and linear areas of alopecia persist into adulthood. IP is caused by mutation of the IKBKG/NEMO gene on Xq28. Deletion of exons 4 to 10 (NEMOΔ4-10) accounts for about 80% of cases (familial and sporadic). NEMO mutation leads to loss of function of NF-κB, a critical protein that modulates cellular proliferation, apoptosis, and response to proinflammatory factors, leading to the characteristic features of IP. In female carriers, selective loss of cells expressing the mutant X-chromosome results in completely skewed X-inactivation in the majority of cases. Study of mouse models in which various components of the NF-κB pathway (including NEMO) have been knocked out has contributed significantly to our understanding of disease pathogenesis.

Incontinentia pigmenti (IP; Bloch-Sulzberger syndrome; OMIM #308300) is an X-linked dominant neurocutaneous disorder with presumed male lethality. It is usually diagnosed in female newborns based on skin features (erythematous, vesicular, or bullous eruption in linear streaks). The skin lesions evolve into a verrucous stage, followed by atrophy and scarring, leaving linear areas of hypopigmentation and hyperpigmented macules in bizarre patterns following Blaschko's lines. Systemic and neurologic complications include focal seizures and hemorrhagic cerebral infarction in infants, and retinal vasculopathy leading to blindness. Hypodontia, conical or pegged teeth, and linear areas of alopecia persist into adulthood. IP is caused by mutation of the IKBKG/NEMO gene on Xq28. Deletion of exons 4 to 10 (NEMOΔ4-10) accounts for about 80% of cases (familial and sporadic). NEMO mutation leads to loss of function of NF-κB, a critical protein that modulates cellular proliferation, apoptosis, and response to proinflammatory factors, leading to the characteristic features of IP. In female carriers, selective loss of cells expressing the mutant X-chromosome results in completely skewed X-inactivation in the majority of cases. Study of mouse models in which various components of the NF-κB pathway (including NEMO) have been knocked out has contributed significantly to our understanding of disease pathogenesis.

Mutations disrupting presynaptic protein TBC1D24 are associated with a variable neurological phenotype, including DOORS syndrome, myoclonic epilepsy, early-infantile epileptic encephalopathy, and non-syndromic hearing loss. In this report, we describe a family segregating autosomal dominant epilepsy, and a 37-year-old Caucasian female with a severe neurological phenotype including epilepsy, Parkinsonism, psychosis, visual and auditory hallucinations, gait ataxia and intellectual disability. Whole exome sequencing revealed two missense mutations in the TBC1D24 gene segregating within this family (c.1078C>T; p.Arg360Cys and c.404C>T; p.Pro135Leu). The female proband who presents with a severe neurological phenotype carries both of these mutations in a compound heterozygous state. The p.Pro135Leu variant, however, is present in the proband’s mother and sibling as well, and is consistent with an autosomal dominant pattern linked to tonic-clonic and myoclonic epilepsy. In conclusion, we describe a single family in which TBC1D24 mutations cause expanded dominant and recessive phenotypes. In addition, we discuss and highlight that some variants in TBC1D24 might cause a dominant susceptibility to epilepsy

Diabetic retinopathy is the major cause of vision loss in middle-aged adults. Alteration of the blood-retinal barrier (BRB) is the hallmark of diabetic retinopathy and, subsequently, hypoxia may result in retinal neovascularization. Tight control of systemic factors such as blood glucose, blood pressure and blood lipids is essential in the management of this disease. Vascular endothelial growth factor (VEGF) is one of the most important factors responsible for alteration of the BRB. The introduction of anti-VEGF agents has revolutionized the therapeutic strategies used in people with diabetic retinopathy, and the use of laser therapy has been modified. In the present article, we examine the clinical features and pathophysiology of diabetic retinopathy and review the current status of new treatment recommendations for this disease, and also explore some possible future therapies.

Diabetes mellitus is a metabolic disease caused by both genetic and environmental factors. The pathogenic mechanism(s) of diabetes are complex, and the complicated networks related to this disease involve distinct signaling pathways. Evidence has recently been provided that ER stress might be involved in the pathogenesis of diabetes and its complications. Early steps in the maturation of secretory proteins take place in the ER, for example, the folding of the nascent polypeptide chains and posttranslational modifications important for proper folding and function of the protein. At a stage (due to several metabolic disturbances), when unfolded polypeptide exceeds the folding and/or processing capacity of the ER, cells are susceptible to a phenomenon referred to as “ER stress.” Under these conditions, specific signaling pathways, termed the unfolded protein response (UPR), are activated to return the ER to its normal physiological state. Prolonged activation of the ER stress and the UPR can lead to cell pathology and subsequent tissue dysfunction. There is now ample evidence that the UPR is chronically activated in many disease states including diabetes and its complications. Therefore, a better understanding of the pathways regulating ER stress and UPR is warranted in order to be instrumental for the design of novel therapies for diabetes and its complications. In this focused issue of the journal, we have assembled several invited reviews, from well-recognized experts in their fields, as well as original research articles. These reviews provide state-of-the-art knowledge dealing with several mechanisms not only related to the genesis of diabetes but also to its progression to diabetic complications, all of which potentially originate or converge from chronic ER stress. In addition, several excellent original research articles demonstrate novel pathophysiologic aspects of diabetes with mechanistic studies central to ER stress and give hope and directionality for identifying new drug targets and developing newer therapeutic measures. Of all the professional secretory cells we possess, β-cells are the most sensitive to ER stress because of the large fluctuations in protein synthesis (including insulin) they face daily. M.-K. Kim et al. have reviewed how this “protein quality-control machinery” of the cell is responsible for appropriate insulin biosynthesis and how ER stress plays an important role in the impairment of insulin biosynthesis. J. Zhong et al. have summarized the status on how ER stress plays an essential role in autoimmune-mediated β-cell destruction and also pointed out how ER stress regulates the functionality of immune cells relevant to autoimmune progression during Type 1 diabetes development. In an attempt to improve islet transplantation in humans, the molecular mechanism of apoptosis in β cells of islets in the transplantation setting needs to be clearly understood. In this context, M. Wang et al. have discussed their original research work on human islets subjected to multiple stressors and delineated several apoptotic pathways originating from oxidative stress, autophagy, and ER stress. While ER stress is emerging as a unifying paradigm in diabetes and its complications, several recent studies, emphasized a definite role of ER stress in retinal, podocyte, and neuronal cell apoptosis. G. Jing et al. have summarized the recent progress on ER stress and apoptosis in retinal diseases, focusing on various proapoptotic and antiapoptotic pathways that are activated by the UPR and discussed how these pathways contribute to ER stress-induced apoptosis in retinal cells. Considering the fact that ER stress is initially an adaptive response, studying ER stress-related factors appear to unravel novel drug targets to prevent and treat diabetic retinopathy. In this connection, W. -K. Hu et al. have explained the role of P58IPK and ER-associated degradation (ERAD) of unfolded protein which prevents ER stress and reduce retinal vascular leakage under high-glucose conditions. While thioredoxin interacting protein (TXNIP) has been recently identified as an early response gene highly induced by diabetes and hyperglycemia, its role in the pathogenesis of diabetic retinopathy is not clearly understood. Using appropriate animal model and retinal Muller cell line and several molecular biology techniques, T. S. Devi et al. have described how upregulation of TXNIP evokes a program of cellular defense and survival mechanism(s) that ultimately lead to oxidative stress, ER-stress, inflammation, and apoptosis. Despite a great deal of research, the mechanisms that may link high-glucose concentrations to the molecular and cellular pathways of diabetic atherogenesis are not fully understood. D. R. Beriault and G. H. Werstuck have summarized the current state of our knowledge of pathways and mechanisms that may link diabetes and hyperglycemia to atherogenesis highlighting the recent work from their lab (and others) that supports a role for ER stress in these processes. Although recent studies have shown that perturbations in lipid metabolism cause an ER stress response, very little is known about the mechanism of UPR activation by perturbations in glucose and lipid metabolism. Moreover, it has been demonstrated that 4-phenylbutyrate (4-PBA) and tauroursodeoxycholic acid (TUDCA), which are two different chemical structures having chemical chaperone activity in common, relieve ER stress. Using THP-1 human monocytes as a surrogate cell model and utilizing several molecular biology techniques, R. Lenin et al. have demonstrated that monocytes subjected to glucolipotoxicity exhibited increased UPR responses (as evidenced by increased mRNA expression of several ER stress markers) along with increased oxidative stress and apoptosis. Interestingly, ER stress inducted by glucolipotoxicity was shown resisted by PBA. These observations constitute an important proof of principle that manipulation of the ER system to decrease ER stress by chemical agents may have therapeutic implications for diabetes and its complications. Lastly, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased in parallel with the epidemics of obesity and type 2 diabetes, which are risk factors for NAFLD. Whereas the association of type 2 diabetes with microvascular complications and macrovascular disease is well established, the association of type 2 diabetes with NAFLD is only recently recognized and so are the inter-related pathogenic mechanisms. Using steatohepatitis animal model and HepB3 cells, M. K. Chae et al. have demonstrated that Pentoxifylline (a known anti-inflammatory agent) attenuates methionine and choline-1-deficient diet-induced steatohepatitis by suppressing ER stress. These papers, hopefully, will provide better understanding of ER stress and UPR pathway involvement in the pathogenesis of diabetes and its complications and bring forward new and innovative ideas with respect to the development of efficient and adjuvant treatment modalities. Considering the involvement of ER stress in multiple tissues and their convergence in multiple pathogenic pathways (oxidative stress, inflammation, apoptosis, autophagy, and proteasomal degradation), targeting the ER stress pathway appears as a promising therapeutic strategy. The significant side effects with existing drugs and the demand for newer molecules with improved safety and a different mode of action justifies this directionality. In fact, it has been reported that chemical ER chaperones can reduce ER stress, suggesting that small molecules can affect ER stress signaling in disease states. There is also much hope in investigating the traditional plant principles of medicinal claims to see whether they act as beneficial ER stress modulators. Given the possible development of novel UPR-targeted therapies for diabetes and its complications, it is essential to know which components of the ER stress response to target and which particular disease stage will be most amenable to therapy. Although there is an enormous progress in studying the ER stress aspects, the list of unresolved queries in the stress mediated pathway of ER dysfunction in diabetes and its complications warrant continued research efforts. Obviously not all aspects of this exciting ER stress field could be addressed in one issue and we extend our apologies to many contributors of this field whose work has not been covered. We thank all the authors who contributed to this special issue of EDR and the reviewers for the highly constructive and helpful comments. Muthuswamy Balasubramanyam Lalit P. Singh Sampathkumar Rangasamy

Most anti-vascular endothelial growth factor (VEGF) therapies in diabetic macular edema are not as robust as in proliferative diabetic retinopathy. Although the VEGF appears to be a good target in diabetic macular edema, the anti-VEGF therapies appear to be of transient benefit as the edema recurs within a few weeks, and repeated injections are necessary. There is new evidence that indicates 'retinal inflammation' as an important player in the pathogenesis of diabetic retinopathy. There are common sets of inflammatory cytokines that are upregulated in both the serum and vitreous and aqueous samples, in subjects with diabetic retinopathy, and these cytokines can have multiple interactions to impact the pathogenesis of the disease. The key inflammatory events involved in the blood retinal barrier (BRB) alteration appear to be: (1) Increased expression of endothelial adhesion molecules such as ICAM1, VCAM1, PECAM-1, and P-selectin, (2) adhesion of leukocytes to the endothelium, (3) release of inflammatory chemokines, cytokines, and vascular permeability factors, (4) alteration of adherens and tight junctional proteins between the endothelial cells, and (5) infiltration of leukocytes into the neuro-retina, resulting in the alteration of the blood retinal barrier (diapedesis). VEGF inhibition itself may not achieve neutralization of other inflammatory molecules involved in the inflammatory cascade of the breakdown of the BRB. It is possible that the novel selective inhibitors of the inflammatory cascade (like angiopoietin-2, TNFα, and chemokines) may be useful therapeutic agents in the treatment of diabetic macular edema (DME), either alone or in combination with the anti-VEGF drugs.

The human retinal structure along with the neuronal component develops from a single layer of undifferentiated neuroepithelial cells during embryonic ontogenesis. During this process, retinal vasculature develops to form an elaborate vascular tree that matches the metabolic need of tissues. Retinal vascular development involves a complex process of vasculogenesis and angiogenesis. Vasculogenesis describes the de novo formation of vessels from vascular endothelial precursor cells (angioblasts), which migrate to or differentiate at the location of future vessels, coalesce into cords, and differentiate into endothelial cells leading to the formation of ultimate vessels.

Objective— The mechanisms that regulate the physical interaction of pericytes and endothelial cells and the effects of these interactions on interendothelial cell junctions are not well understood. We determined the extent to which vascular pericytes could regulate pericyte-endothelial adhesion and the consequences that this disruption might have on the function of the endothelial barrier. Methods and Results— Human retinal microvascular endothelial cells were cocultured with pericytes, and the effect on the monolayer resistance of endothelial cells and expression of the cell junction molecules N-cadherin and VE-cadherin were measured. The molecules responsible for the effect of pericytes or pericyte-conditioned media on the endothelial resistance and cell junction molecules were further analyzed. Our results indicate that pericytes increase the barrier properties of endothelial cell monolayers. This barrier function is maintained through the secretion of pericyte-derived sphingosine 1-phosphate. Sphingosine 1-phosphate aids in maintenance of microvascular stability by upregulating the expression of N-cadherin and VE-cadherin, and downregulating the expression of angiopoietin 2. Conclusion— Under normal circumstances, the retinal vascular pericytes maintain pericyte-endothelial contacts and vascular barrier function through the secretion of sphingosine 1-phosphate. Alteration of pericyte-derived sphingosine 1-phosphate production may be an important mechanism in the development of diseases characterized by vascular dysfunction and increased permeability.

PURPOSE. Aicardi syndrome (AIC) is a congenital neurodevelopmental disorder characterized by infantile spasms, agenesis of the corpus callosum, and chorioretinal lacunae. Variation in phenotype and disease severity is well documented, but chorioretinal lacunae represent the most constant pathological feature. Aicardi syndrome is believed to be an X-linked-dominant disorder occurring almost exclusively in females, although 46, XY males with AIC have been described. The purpose of this study is to identify genetic factors and pathways involved in AIC. METHODS. We performed exome/genome sequencing of 10 children diagnosed with AIC and their parents and performed RNA sequencing on blood samples from nine cases, their parents, and unrelated controls. RESULTS. We identified a de novo mutation in autosomal gene TEAD1, expressed in the retina and brain, in a patient with AIC. Mutations in TEAD1 have previously been associated with Sveinsson's chorioretinal atrophy, characterized by chorioretinal degeneration. This demonstrates that TEAD1 mutations can lead to different chorioretinal complications. In addition, we found that altered expression of genes associated with synaptic plasticity, neuronal development, retinal development, and cell cycle control/apoptosis is an important underlying potential pathogenic mechanism shared among cases. Last, we found a case with skewed X inactivation, supporting the idea that nonrandom X inactivation might be important in AIC. CONCLUSIONS. We expand the phenotype of TEAD1 mutations, demonstrate its importance in chorioretinal complications, and propose the first putative pathogenic mechanisms underlying AIC. Our data suggest that AIC is a genetically heterogeneous disease and is not restricted to the X chromosome, and that TEAD1 mutations may be present in male patients.

Diabetic retinopathy is the leading cause of visual impairment and blindness in diabetic patients in both developed and developing nations.1 One of the early events in diabetic retinopathy is the alteration of the blood–retinal barrier (BRB) leading to the increased permeability of blood vessels, resulting in diabetic macular edema. The development of macular edema is a progressive pathologic process characterized by hyperglycemia-induced damage to the vessel wall. The integrity of the BRB is maintained by the presence of specialized intracellular junctional molecules between adjacent endothelial cells as well as by adhesive interactions between endothelial cells and associated pericytes. Dysregulation of these junctions and the associated loss of cell–cell contact in response to hyperglycemia can lead to altered retinal vascular permeability.2 Vascular endothelial growth factor (VEGF) has been the primary factor implicated in the alteration of retinal vascular function leading to diabetic macular edema. This finding has led to several ongoing clinical trials of anti-VEGF treatments.3,4 Treatment with anti-VEGF appears to have limitations, as the improvement in retinal thickness is transient, and the edema tends to recur in most patients, suggesting that other factors play a role.5 Indeed, one such factor that has been suggested to play a role, along with VEGF, in the regulation of endothelial cell permeability is Ang-2.6 The angiopoietins are a family of growth factors that bind to the endothelial receptor tyrosine kinase Tie-2 and regulate vascular development and function.7 Angiopoietin (Ang)-1 and -2 share 60% amino acid identity and bind with similar affinity to Tie-2. The activity of Tie-2 is differentially regulated by the two ligands. Ang-1 is a strong agonist of the Tie-2 receptor, and Ang-2 acts as an agonist or antagonist in a context-dependent manner.8 The primary source of Ang-1 has been shown to be from nonendothelial cells, including pericytes (periendothelial cells), but little is known about its regulation of expression.9 Ang-2 is predominantly expressed in endothelial cells, stored in vesicles known as Weibel-Palade bodies, and is rapidly released in response to specific stimuli.10 Emerging evidence indicates that Ang-2 is upregulated in response to hyperglycemia and plays an important role in the pathogenesis of retinal diseases.11–16 A potential role for Ang-2 in altering vascular permeability, however, is not well understood. The cadherins are a family of proteins that mediate calcium-dependent homophilic adhesion between cells. Of particular importance to the endothelial cells of the vasculature is the vascular endothelial cadherin or (VE)-cadherin.17–19 The integrity of the VE-cadherin junctions between adjacent endothelial cells is considered to be critical for normal barrier function and is likely to involve interactions between VE-cadherin and the tight junction proteins occludin and claudin-5.20,21 Loss of VE-cadherin function by proteolysis or by phosphorylation has been implicated in the pathologic changes related to altered vascular permeability seen in diabetic retinopathy.22,23 Several factors have been shown to regulate the function of VE-cadherin; however, the role of Ang-2 as a mediator of altered VE-cadherin function has not been reported. In the present study, we hypothesized that Ang-2 may be an important mediator in the alteration of the blood–retinal barrier in diabetes. We examined the expression of Ang-2 in the diabetic retina and in human microvascular endothelial cells exposed to high glucose. The effect of Ang-2 on vascular permeability was assessed in vivo and in vitro using fluorescence-based assays. We also assessed the effect of Ang-2 on VE-cadherin by measuring the extent of tyrosine phosphorylation of this adherens junction protein.

International audience; PURPOSE: Lamb-Shaffer syndrome (LAMSHF) is a neurodevelopmental disorder described in just over two dozen patients with heterozygous genetic alterations involving SOX5, a gene encoding a transcription factor regulating cell fate and differentiation in neurogenesis and other discrete developmental processes. The genetic alterations described so far are mainly microdeletions. The present study was aimed at increasing our understanding of LAMSHF, its clinical and genetic spectrum, and the pathophysiological mechanisms involved.METHODS: Clinical and genetic data were collected through GeneMatcher and clinical or genetic networks for 41 novel patients harboring various types of SOX5 alterations. Functional consequences of selected substitutions were investigated.RESULTS: Microdeletions and truncating variants occurred throughout SOX5. In contrast, most missense variants clustered in the pivotal SOX-specific high-mobility-group domain. The latter variants prevented SOX5 from binding DNA and promoting transactivation in vitro, whereas missense variants located outside the high-mobility-group domain did not. Clinical manifestations and severity varied among patients. No clear genotype-phenotype correlations were found, except that missense variants outside the high-mobility-group domain were generally better tolerated.CONCLUSIONS:This study extends the clinical and genetic spectrum associated with LAMSHF and consolidates evidence that SOX5 haploinsufficiency leads to variable degrees of intellectual disability, language delay, and other clinical features.