A novel de novo HCN2 loss-of-function variant causing developmental and epileptic encephalopathy treated with a ketogenic diet.

Missense variants of hyperpolarization-activated, cyclic nucleotide-gated (HCN) ion channels cause variable phenotypes, ranging from mild generalized epilepsy to developmental and epileptic encephalopathy (DEE). Although variants of HCN1 are an established cause of DEE, those of HCN2 have been reported in generalized epilepsies. Here we describe the first case of DEE caused by the novel de novo heterozygous missense variant c.1379G>A (p.G460D) of HCN2. Functional characterization in transfected HEK293 cells and neonatal rat cortical neurons revealed that HCN2 p.G460D currents were strongly reduced compared to wild-type, consistent with a dominant negative loss-of-function effect. Immunofluorescence staining showed that mutant channels are retained within the cell and do not reach the membrane. Moreover, mutant HCN2 also affect HCN1 channels, by reducing the Ih current expressed by the HCN1-HCN2 heteromers. Due to the persistence of frequent seizures despite pharmacological polytherapy, the patient was treated with a ketogenic diet, with a significant and long-lasting reduction of episodes. In vitro experiments conducted in a ketogenic environment demonstrated that the clinical improvement observed with this dietary regimen was not mediated by a direct action on HCN2 activity. These results expand the clinical spectrum related to HCN2 channelopathies, further broadening our understanding of the pathogenesis of DEE.

Paradigm shift in the treatment of tuberous sclerosis: Effectiveness of everolimus.

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterised by abnormal cell proliferation and differentiation that affects multiple organs and can lead to the growth of hamartomas. Tuberous sclerosis complex is caused by the disinhibition of the protein mTOR (mammalian target of rapamycin). In the past, various therapeutic approaches, even if only symptomatic, have been attempted to improve the clinical effects of this disease. While all of these therapeutic strategies are useful and are still used and indicated, they are symptomatic therapies based on the individual symptoms of the disease and therefore not fully effective in modifying long-term outcomes. A new therapeutic approach is the introduction of allosteric inhibitors of mTORC1, which allow restoration of metabolic homeostasis in mutant cells, potentially eliminating most of the clinical manifestations associated with Tuberous sclerosis complex. Everolimus, a mammalian target of the rapamycin inhibitor, is able to reduce hamartomas, correcting the specific molecular defect that causes Tuberous sclerosis complex. In this review, we report the findings from the literature on the use of everolimus as an effective and safe drug in the treatment of TSC manifestations affecting various organs, from the central nervous system to the heart.

Case report: Early-onset parkinsonism among the neurological features in children with PHACTR1 variants.

PACHTR1 is expressed in cardiovascular and neurological tissues. In the brain, it has a role in pre- and post-natal maturation. Previously reported PHACTR1-mutated patients showed early-onset epilepsy and intellectual disability. We describe two unreported cases with de novo pathogenic variants in PHACTR1 and their clinical pictures, compared with those of cases already reported in the literature. In line with previous reports, the two patients presented early-onset developmental and epileptic encephalopathy. In addition, one patient developed a speech disorder and a progressive movement disorder characterized by hypertonus, hypo-bradykinesia, hypomimia, ataxic gait, and retropulsion. She was treated with levodopa without any clinical improvement. Pathogenic variants in PHACTR1 may result in a cardiological or neurological phenotype. Severe developmental delay, intellectual disability, and early-onset developmental and epileptic encephalopathy are the main features of PHACTR1-mutated patients with neurological involvement. Movement and speech disorders have never previously been described and could be new features of the neurological phenotype.

Long-term follow-up of nutritional status in children with GLUT1 Deficiency Syndrome treated with classic ketogenic diet: a 5-year prospective study.

Introduction: The classic ketogenic diet (cKD) is an isocaloric, high fat, low-carbohydrate diet that induces the production of ketone bodies. High consumption of dietary fatty acids, particularly long-chain saturated fatty acids, could impair nutritional status and increase cardiovascular risk. The purpose of this study was to evaluate the long-term effects of a 5-year cKD on body composition, resting energy expenditure, and biochemical parameters in children affected by Glucose Transporter 1 Deficiency Syndrome (GLUT1DS). Methods: This was a prospective, multicenter, 5-year longitudinal study of children with GLUT1DS treated with a cKD. The primary outcome was to assess the change in nutritional status compared with pre-intervention, considering anthropometric measurements, body composition, resting energy expenditure, and biochemical parameters such as glucose and lipid profiles, liver enzymes, uric acid, creatinine, and ketonemia. Assessments were conducted at pre-intervention and every 12 months of cKD interventions. Results: Ketone bodies increased significantly in children and adolescents, and remained stable at 5 years, depending on the diet. No significant differences were reported in anthropometric and body composition standards, as well as in resting energy expenditure and biochemical parameters. Bone mineral density increased significantly over time according to increasing age. Body fat percentage significantly and gradually decreased in line with the increase in body weight and the consequent growth in lean mass. As expected, we observed a negative trend in respiratory quotient, while fasting insulin and insulin resistance were found to decrease significantly after cKD initiation. Conclusion: Long-term adherence to cKD showed a good safety profile on anthropometric measurements, body composition, resting energy expenditure, and biochemical parameters, and we found no evidence of potential adverse effects on the nutritional status of children and adolescents.

FDXR-associated disease: a challenging differential diagnosis with inflammatory peripheral neuropathy.

BACKGROUND AND AIMS: Mutations in FDXR gene, involved in mitochondrial pathway, cause a rare recessive neurological disorder with variable severity of phenotypes. The most common presentation includes optic and/or auditory neuropathy, variably associated to developmental delay or regression, global hypotonia, pyramidal, cerebellar signs, and seizures. The review of clinical findings in previously described cases from literature reveals also a significant incidence of sensorimotor peripheral polyneuropathy (22.72%) and ataxia (43.18%). To date, 44 patients with FDXR mutations have been reported. We describe here on two new patients, siblings, who presented with a quite different phenotype compared to previously described patients. METHODS: Clinical, neurophysiological, and genetic features of two siblings and a systematic literature review focused on the clinical spectrum of the disease are described. RESULTS: Both patients presented with an acute-sub-acute onset of peripheral neuropathy and only in later stages of the disease developed the typical features of FDXR-associated disease. INTERPRETATION: The peculiar clinical presentation at onset and the evolution of the disease in our patients and in some cases revised from the literature shed lights on a new possible phenotype of FDXR-associated disease: a peripheral neuropathy which can mimic an acute inflammatory disease.

GLUT1-DS Italian registry: past, present, and future: a useful tool for rare disorders.

BACKGROUND: GLUT1 deficiency syndrome is a rare, genetically determined neurological disorder for which Ketogenic Dietary Treatment represents the gold standard and lifelong treatment. Patient registries are powerful tools providing insights and real-world data on rare diseases. OBJECTIVE: To describe the implementation of a national web-based registry for GLUT1-DS. METHODS: This is a retrospective and prospective, multicenter, observational registry developed in collaboration with the Italian GLUT1-DS association and based on an innovative, flexible and configurable cloud computing technology platform, structured according to the most rigorous requirements for the management of patient's sensitive data. The Glut1 Registry collects baseline and follow-up data on the patient's demographics, history, symptoms, genotype, clinical, and instrumental evaluations and therapies. RESULTS: Five Centers in Italy joined the registry, and two more Centers are currently joining. In the first two years of running, data from 67 patients (40 females and 27 males) have been collected. Age at symptom onset was within the first year of life in most (40, 60%) patients. The diagnosis was formulated in infancy in almost half of the cases (34, 51%). Symptoms at onset were mainly paroxysmal (mostly epileptic seizure and paroxysmal ocular movement disorder) or mixed paroxysmal and fixed symptoms (mostly psychomotor delay). Most patients (53, 79%) are currently under Ketogenic dietary treatments. CONCLUSIONS: We describe the principles behind the design, development, and deployment of the web-based nationwide GLUT1-DS registry. It represents a stepping stone towards a more comprehensive understanding of the disease from onset to adulthood. It also represents a virtuous model from a technical, legal, and organizational point of view, thus representing a possible paradigmatic example for other rare disease registry implementation.

Molecular Genetics of GLUT1DS Italian Pediatric Cohort: 10 Novel Disease-Related Variants and Structural Analysis.

GLUT1 deficiency syndrome (GLUT1DS1; OMIM #606777) is a rare genetic metabolic disease, characterized by infantile-onset epileptic encephalopathy, global developmental delay, progressive microcephaly, and movement disorders (e.g., spasticity and dystonia). It is caused by heterozygous mutations in the SLC2A1 gene, which encodes the GLUT1 protein, a glucose transporter across the blood-brain barrier (BBB). Most commonly, these variants arise de novo resulting in sporadic cases, although several familial cases with AD inheritance pattern have been described. Twenty-seven Italian pediatric patients, clinically suspect of GLUT1DS from both sporadic and familial cases, have been enrolled. We detected by trios sequencing analysis 25 different variants causing GLUT1DS. Of these, 40% of the identified variants (10 out of 25) had never been reported before, including missense, frameshift, and splice site variants. Their structural mapping on the X-ray structure of GLUT1 strongly suggested the potential pathogenic effects of these novel disease-related mutations, broadening the genotypic spectrum heterogeneity found in the SLC2A1 gene. Moreover, 24% is located in a vulnerable region of the GLUT1 protein that involves transmembrane 4 and 5 helices encoded by exon 4, confirming a mutational hotspot in the SLC2A1 gene. Lastly, we investigated possible correlations between mutation type and clinical and biochemical data observed in our GLUT1DS cohort, revealing that splice site and frameshift variants are related to a more severe phenotype and low CSF parameters.

Glut1 deficiency syndrome throughout life: clinical phenotypes, intelligence, life achievements and quality of life in familial cases.

BACKGROUND: Glut1 deficiency syndrome (Glut1-DS) is a rare metabolic encephalopathy. Familial forms are poorly investigated, and no previous studies have explored aspects of Glut1-DS over the course of life: clinical pictures, intelligence, life achievements, and quality of life in adulthood. Clinical, biochemical and genetic data in a cohort of familial Glut1-DS cases were collected from medical records. Intelligence was assessed using Raven's Standard Progressive Matrices and Raven's Colored Progressive Matrices in adults and children, respectively. An ad hoc interview focusing on life achievements and the World Health Organization Quality of Life Questionnaire were administered to adult subjects. RESULTS: The clinical picture in adults was characterized by paroxysmal exercise-induced dyskinesia (PED) (80%), fatigue (60%), low intelligence (60%), epilepsy (50%), and migraine (50%). However, 20% of the adults had higher-than-average intelligence. Quality of Life (QoL) seemed unrelated to the presence of PED or fatigue in adulthood. An association of potential clinical relevance, albeit not statistically significant, was found between intelligence and QoL. The phenotype of familial Glut1-DS in children was characterized by epilepsy (83.3%), intellectual disability (50%), and PED (33%). CONCLUSION: The phenotype of familial Glut1-DS shows age-related differences: epilepsy predominates in childhood; PED and fatigue, followed by epilepsy and migraine, characterize the condition in adulthood. Some adults with familial Glut1-DS may lead regular and fulfilling lives, enjoying the same QoL as unaffected individuals. The disorder tends to worsen from generation to generation, with new and more severe symptoms arising within the same family. Epigenetic studies might be useful to assess the phenotypic variability in Glut1-DS.

EEG at onset and MRI predict long-term clinical outcome in Aicardi syndrome.

OBJECTIVE: Descriptions of electroencephalographic (EEG) patterns in Aicardi syndrome (AIC) have to date referred to small cohorts of up to six cases and indicated severe derangement of electrical activity in all cases. The present study was conducted to describe the long-term EEG evolution in a larger AIC cohort, followed for up to 23 years, and identify possible early predictors of the clinical and EEG outcomes. METHODS: In a retrospective study, two experienced clinical neurophysiologists systematically reviewed all EEG traces recorded in 12 AIC cases throughout their follow-up, from epilepsy onset to the present. Clinical outcome was assessed with standardized clinical outcome scales. RESULTS: Analysis of the data revealed two distinct AIC phenotypes. In addition to the "classical severe phenotype" already described in the literature, we identified a new "mild phenotype". The two phenotypes show completely different EEG features at onset of epilepsy and during its evolution, which correspond to different clinical outcomes. CONCLUSIONS: Data from our long-term EEG and clinical-neuroradiological study allowed us to describe two different phenotypes of AIC, with different imaging severity and, in particular, different EEG at onset, which tend to remain constant over time. SIGNIFICANCE: Together, these findings might help to predict long-term clinical outcomes.

Acute encephalitis in pediatric multisystem inflammatory syndrome associated with COVID-19.

OBJECTIVE: To characterize neurological involvement in multisystem inflammatory syndrome in children (MIS-C) related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: Retrospective analysis of the clinical, electroencephalographic, CSF and neuroradiological parameters recorded in seven children (3 males, aged 3-10 years) affected by MIS-C with acute neurological involvement. RESULTS: All cases presented acute encephalopathy with drowsiness, irritability, mood deflection and diffuse EEG slowing with periodic posterior complexes. Focal neurological signs, normal brain MRI and CSF, were present in four patients; these patients received intravenous methylprednisolone at 30 mg/kg/day for 3 days. In all cases, the clinical picture rapidly improved in the first three days, and all neurological symptoms and EEG abnormalities disappeared within 10 and 30 days respectively. The severity and duration of the EEG abnormalities was proportional to the extent of the neurological involvement. CONCLUSIONS: Patients with MIS-C may present acute encephalitis characterized by rapid-onset encephalopathy and EEG abnormalities (slow wave activity and/or epileptic abnormalities), in some cases associated with focal neurological signs that disappear with immunomodulatory therapy. The detection through neurological evaluation of sentinel neurological signs and distinctive EEG patterns documentable at disease onset will allow timely diagnosis and treatment of these cases.

Tuberous sclerosis complex (TSC), lymphangioleiomyomatosis, and COVID-19: The experience of a TSC clinic in Italy.

Individuals with comorbidities are at higher risk of coronavirus disease 2019 (COVID-19) and worse outcome, but little information has been available about patients with genetic diseases and COVID-19. This study aims at evaluating the presence and outcome of COVID-19 in a cohort of Italian patients with tuberous sclerosis complex (TSC) and/or lymphangioleiomyomatosis (LAM), and at reviewing the possible effects of mTOR inhibitors on SARS-CoV-2 infection. We included 102 unselected individuals with a diagnosis of TSC and/or LAM assessed between January 1, 2020 and April 24, 2020 (29% children, 71% adults). Twenty-six patients were on mTOR inhibitors. Demographic data, TSC manifestations, presence, and outcomes in individuals with confirmed or suspected SARS-CoV-2 infection were evaluated. Health status and outcomes of all patients on mTOR inhibitors were assessed. One patient with severe TSC had polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection, was admitted to ICU, and died. Nine additional patients either met the definition of suspect case or presented with at least two of the most common symptoms of SARS-CoV-2 infection. All recovered fully. None of the patients treated with mTOR inhibitors for their underlying comorbidities was diagnosed with COVID-19, and those who showed suspicious respiratory symptoms recovered fully. This cohort study provides preliminary information on COVID-19 in people with TSC in Italy and suggests feasibility to systematically evaluate the role of mTOR inhibitors in SARS-CoV-2 infection.