ABSTRACT
PURPOSE: Plant-derived highly purified cannabidiol (CBD) reduced the frequency of seizures associated with Lennox-Gastaut syndrome (LGS) and Dravet syndrome (DS) and improved the overall condition of patients in placebo-controlled phase 3 clinical trials. Anecdotal reports also suggest a positive effect on nonseizure outcomes. In this study, we aimed to identify, through a caregiver survey which nonseizure outcomes were most likely to change in these patients. METHODS: The BEhavior, COgnition, and More with Epidiolex® (BECOME) was a 20-minute, cross-sectional, online survey that was developed with extensive input from caregivers, healthcare professionals, and epilepsy researchers, and was based on questions from validated measures and previously published caregiver reports. US-based caregivers (from Jazz Pharmaceuticals patient/caregiver database) of people with LGS or DS who were treated with CBD (Epidiolex®, 100 mg/mL oral solution) for ≥3 months were asked to compare the past month to the period before CBD initiation and rate their impression of changes using symmetrical Likert scales. RESULTS: A total of 498 caregivers (97% parents) of patients with LGS (80%) or DS (20%) completed the survey. Mean (range) age of patients was 16 (1-73) years, and 52% were male. Patients were taking a median CBD dose of 14 mg/kg/d and median 4 concomitant antiseizure medications. A large proportion of respondents reported improvements in ≥1 survey question for all nonseizure-related domains: alertness, cognition, and executive function (85%); emotional functioning (82%); language and communication (79% in nonverbal patients and 74% in verbal); activities of daily living (51%); sleep (51%); and physical functioning (46%). Respondents reported improvements in seizure-related domains, including overall seizure frequency (85%), overall seizure severity (76%), seizure-free days per week for ≥1 seizure type (67%), and seizure freedom during the past month (16%). The majority of respondents who reported reduction in seizure frequency also reported improvements in nonseizure outcomes domains (51-80%). However, improvements in nonseizure outcomes (18-56%) were also reported in patients who either had no change or worsening of seizure frequency. CONCLUSIONS: This survey characterized and quantified caregiver impression of changes in the seizure and nonseizure outcomes in patients taking add-on CBD treatment. Overall, 93% of caregivers reported planning to continue CBD treatment, primarily because of reduced seizure burden but also because of improvements in nonseizure-related outcomes. Despite the limitations that are associated with a retrospective survey-based study design, these results support further evaluation of the effect of CBD treatment on nonseizure outcomes among patients with LGS or DS.
Subject(s)
Cannabidiol , Epilepsies, Myoclonic , Lennox Gastaut Syndrome , Humans , Adolescent , Young Adult , Adult , Middle Aged , Aged , Cannabidiol/therapeutic use , Cannabidiol/adverse effects , Lennox Gastaut Syndrome/drug therapy , Lennox Gastaut Syndrome/complications , Caregivers , Activities of Daily Living , Cross-Sectional Studies , Retrospective Studies , Anticonvulsants/adverse effects , Epilepsies, Myoclonic/drug therapy , Epilepsies, Myoclonic/complications , Seizures/drug therapy , Surveys and Questionnaires , Patient Reported Outcome MeasuresABSTRACT
OBJECTIVES: Lennox-Gastaut Syndrome (LGS) and other drug-resistant epilepsy (DRE) can impact behavior, communication, and quality of life (QoL). In collaboration with community engagement efforts with the Lennox-Gastaut Syndrome Foundation (LGSF), we aimed to gain an initial snapshot of patient and family perspectives and experiences with evaluation of behavior, communication, and QoL. METHODS: A cross-sectional survey was conducted to collect self-reported information from caregivers of children with LGS and other DRE regarding their perspectives and experiences with healthcare providers' evaluation of behavior, communication, and QoL. The survey tool was developed by the study investigators in partnership with the LGS Foundation and had diffused to caregivers online by epilepsy advocacy groups including the Pediatric Epilepsy Surgery Alliance (PESA). Responses were analyzed. Descriptive statistics were calculated. The survey asked for caregiver perspectives and assessed which instruments the caregivers had previously been given for measuring these domains. RESULTS: Responses from 245 caregivers were included, with 132 (54%) caregivers of an individual with LGS and 113 (46%) caregivers of an individual with non-LGS related DRE. Respondents reported that 66% of their loved ones had undergone epilepsy-related surgery. Over 90% agreed that measuring behavior, communication, and QoL was important, but fewer than half felt that their healthcare providers evaluated these domains well. LGS caregivers largely shared non-LGS caregivers' perspectives; however, they reported more frequently that communication was not evaluated enough. Barriers to measuring these domains included a lack of good surveys (developmentally appropriate and specific to the type of epilepsy) or not receiving any survey instruments for these domains during clinic appointments. Caregivers play a crucial role for individuals with DRE, and their input is essential in identifying challenges and needs. Caregivers believe that measuring behavior, communication, and quality of life is important, and most of them feel that their loved ones are not adequately evaluated during their healthcare encounters. There is a need for appropriately scaled survey instruments to measure areas of importance for patients and caregivers, as well as incorporation of these outcomes in the healthcare discussion.
Subject(s)
Drug Resistant Epilepsy , Epilepsy , Lennox Gastaut Syndrome , Humans , Child , Quality of Life , Cross-Sectional Studies , Epilepsy/therapy , Drug Resistant Epilepsy/therapy , Surveys and Questionnaires , CommunicationABSTRACT
Lennox-Gastaut syndrome (LGS) is a severe, chronic, complex form of early childhood-onset epilepsy characterized by multiple seizure types, generalized slow (≤2.5 Hz) spike-and-wave activity and other electroencephalography abnormalities, and cognitive impairment. A key treatment goal is early seizure control, and several anti-seizure medications (ASMs) are available. Due to the low success rate in achieving seizure control with monotherapy and an absence of efficacy data supporting any particular combination of ASMs for treating LGS, a rational approach to selection of appropriate polytherapy should be applied to maximize benefit to patients. Such "rational polytherapy" involves consideration of factors including safety (including boxed warnings), potential drug-drug interactions, and complementary mechanisms of action. Based on the authors' clinical experience, rufinamide offers a well-considered first adjunctive therapy for LGS, particularly in combination with clobazam and other newer agents for LGS, and may be particularly useful for reducing the frequency of tonic-atonic seizures associated with LGS.
Subject(s)
Lennox Gastaut Syndrome , Humans , Child, Preschool , Lennox Gastaut Syndrome/drug therapy , Expert Testimony , Triazoles/therapeutic use , Clobazam/therapeutic use , Anticonvulsants/therapeutic useSubject(s)
Neurosciences , Humans , Grounded Theory , Neurosciences/ethics , Brain , Research Personnel , HeadABSTRACT
Seizure clusters (also referred to as acute repetitive seizures) consist of several seizures interspersed with brief interictal periods. Seizure clusters can break down γ-aminobutyric acidergic (GABAergic) inhibition of dentate granule cells, leading to hyperactivation. Functional changes to GABAA receptors, which play a vital neuroinhibitory role, can include altered GABAA receptor subunit trafficking and cellular localization, intracellular chloride accumulation, and dysregulation of proteins critical to chloride homeostasis. A reduction in neuroinhibition and potentiation of excitatory neurotransmission in CA1 pyramidal neurons represent pathological mechanisms that underlie seizure clusters. Benzodiazepines are well-established treatments for seizure clusters; however, there remain barriers to appropriate care. At the clinical level, there is variability in seizure cluster definitions, such as the number and/or type of seizures associated with a cluster as well as the interictal duration between seizures. This can lead to delays in diagnosis and timely treatment. There are gaps in understanding between clinicians, their patients, and caregivers regarding acute treatment for seizure clusters, such as the use of rescue medications and emergency services. This lack of consensus to define seizure clusters in addition to a lack of education for appropriate treatment can affect quality of life for patients and place a greater burden on patient families and caregivers. For patients with seizure clusters, the sense of unpredictability can lead to continuous traumatic stress, during which patients and families live with a heightened level of anxiety. Clinicians can affect patient quality of life and clinical outcomes through improved seizure cluster education and treatment, such as the development and implementation of a personalized seizure action plan as well as prescriptions for suitable rescue medications indicated for seizure clusters and instructions for their proper use. In all, the combination of targeted therapy along with patient education and support can improve quality of life.
Subject(s)
Epilepsy, Generalized , Quality of Life , Chlorides/therapeutic use , Humans , Receptors, GABA-A/physiology , Seizures , gamma-Aminobutyric Acid/physiologyABSTRACT
PURPOSE OF REVIEW: Disease-related treatment action plans for acute exacerbations providing information that may be helpful for self-management for patients and caregivers are commonly used for chronic conditions such as asthma and diabetes. However, among patients with epilepsy, a review of the literature suggested that the majority did not have an action plan in place for acute seizure treatment. RECENT FINDINGS: Currently, there is a lack of unified guidance on seizure action plans (SAPs) in the literature. In the authors' opinion, available formats have limitations for practical use and may not be easily customizable to individual patients, and they are not often designed to provide simple-to-follow steps for rapid immediate steps to determine and initiate appropriate treatment of seizure emergencies. Our group reviewed current examples of SAPs and provided guidance on the development of acute seizure action plans (ASAPs) designed to facilitate rapid, appropriate acute care in the community and to be as useful as possible for a wide range of care partners, including those with limited experience. SUMMARY: This paper provides agreed upon expert opinion recommendations and considerations for goals, development process, types of content, and format for an ASAP.
Subject(s)
Epilepsy , Seizures , Caregivers , Emergencies , Humans , Seizures/therapyABSTRACT
OBJECTIVE: Caring for children with developmental and epileptic encephalopathies (DEEs) places substantial demands on the entire family unit, including siblings. The Sibling Voices Survey assesses parental and sibling responses to questions designed to assess how children adapt to growing up with siblings with DEE. METHODS: Participants responded to 1 of 4 online, age- and role-specific surveys (9-12, 13-17, and ≥18-year-old [adult] siblings; parents responded with perceptions of their unaffected child's/children's feelings). Survey questions used visual analog scales, categorical responses, and free-form responses. RESULTS: Survey submissions (nâ¯=â¯248) included 128 parents and 120 siblings (9- to 12-year-olds, nâ¯=â¯24; 13- to 17-year-olds, nâ¯=â¯17; adults, nâ¯=â¯79). All groups identified home life as the most substantially affected area of their lives (71%-84%), compared with interactions at school (21%-32%) or with friends (28%-42%). The most difficult aspect across all sibling groups was "feeling worried/scared when their sibling has seizures" (58%-70%). Feeling "overly responsible" for the sibling was reported by most adult siblings (63%), 41% of 13- to 17-year-old siblings, and 34% of parents. Siblings reported more symptoms of depressed mood (e.g., "down/unhappy," 47%-62%) than their parents perceived them feeling (25%). Most sibling groups (29%-49%) reported more symptoms of anxious mood (e.g., "nightmares/bad dreams") than parents perceived (15%). Identification of potential helpful coping mechanisms varied by age group. Most respondents (68%-76%) reported positive aspects, including greater maturity and compassion. SIGNIFICANCE: The Sibling Voices Survey provided important insights into how DEE impacts siblings psychologically and socially. This study highlights the need for increased awareness among parents and healthcare providers to monitor siblings for potential signs of depressed or anxious mood, to provide proper support, and to decrease potential for negative long-term consequences.
Subject(s)
Brain Diseases , Mental Disorders , Adaptation, Psychological , Adolescent , Adult , Child , Humans , Parents , SiblingsABSTRACT
RATIONALE: Developmental epilepsies and encephalopathies (DEEs) are characterized by many severe developmental impairments, which are not well-described. A functional framework could facilitate understanding of their nature and severity and guide the selection instruments to measure improvements in therapeutic trials. METHODS: An online survey administered through several parent-organized foundations utilized accepted functional classifications and questionnaires derived from common instruments to determine levels of mobility, fine motor, communication, and feeding functions. Statistical analyses focused on overall levels of function and across-group comparisons adjusted for age. RESULTS: From 6/2018 to 2/2020, 252 parents provided information for one or more functional domains. Median age was 7.2â¯years (interquartile range (IQR): 3.9 to 11.8), and 128 (51%) were females. DEE groups were Dravet syndrome (Nâ¯=â¯72), KCNQ2-DEE (Nâ¯=â¯80), KCNB1-DEE, (Nâ¯=â¯33), Lennox-Gastaut syndrome (LGS; Nâ¯=â¯26), electrographic status epilepticus in sleep (ESES; Nâ¯=â¯15), and others (Nâ¯=â¯26). Overall, functional hand grasp was absent in 48 (20%). Of children ≥2â¯years old, 60/214 (28%) could not walk independently, 85 (40%) were dependent on someone else for feeding, and 153 (73%) did not effectively communicate with unfamiliar people. Impairments entailing absence or near absence of independent function (profound impairment) were observed in 0, 1, 2, 3, and 4 domains for 58 (25%), 78 (34%), 40 (17%), 33 (14%), and 22 (10%) children, respectively. After adjustment for age, impairment levels varied substantially across DEE group for mobility (pâ¯<â¯0.0001), feeding (pâ¯<â¯0.0001), communication (pâ¯<â¯0.0001), hand grasp (pâ¯<â¯0.0001), and number of profoundly impaired domains (pâ¯<â¯0.0001). Three or four profoundly affected domains were reported in 44% of KCNQ2-DEE participants, followed by LGS (29%), KCNB1-DEE (27%), ESES (7%), and Dravet syndrome (6%). CONCLUSIONS: Many children with DEEs experience severe functional impairments, and few children have typical function. As precision therapies will emphasize nonseizures consequences of DEEs, understanding the nature of abilities and impairments will be critical to selecting appropriate outcome measures in therapeutic trials.
Subject(s)
Developmental Disabilities/genetics , Epilepsies, Myoclonic/genetics , KCNQ2 Potassium Channel/genetics , Lennox Gastaut Syndrome/genetics , Shab Potassium Channels/genetics , Status Epilepticus/genetics , Adolescent , Child , Child, Preschool , Cross-Sectional Studies , Developmental Disabilities/diagnosis , Developmental Disabilities/physiopathology , Electroencephalography/methods , Epilepsies, Myoclonic/diagnosis , Epilepsies, Myoclonic/physiopathology , Female , Humans , Infant , Lennox Gastaut Syndrome/diagnosis , Lennox Gastaut Syndrome/physiopathology , Male , Sleep/physiology , Status Epilepticus/diagnosis , Status Epilepticus/physiopathology , Surveys and QuestionnairesABSTRACT
OBJECTIVES: Seizure burden is typically measured by seizure frequency yet it entails more than seizure counts, especially for people with severe epilepsies and their caregivers. We aimed to characterize the multi-faceted nature of seizure burden in young people and their parents who are living with severe early-life epilepsies. METHODS: A one-day workshop and a series of teleconferences were held with parents of children with severe, refractory epilepsy of early-life origin and providers for children with epilepsy. The workshop sessions were structured as focus groups and aimed to identify components of seizure burden and their impact from the perspective of parents and providers. Data were gathered, organized, and refined during the workshop using an iterative 4-step process that drew upon grounded theory. RESULTS: Three primary components of seizure burden were identified: frequency, severity, and unpredictability, which was as important if not more important at times than frequency and severity. Caregivers noted that the impacts of seizures were experienced as acute-immediate consequences, longer-term consequences, and as chronic effects that develop and evolve over time. The severity of the child's neurological and medical status as well as where in the disease journey a family was represented additional contextual factors that influenced the experience of seizure burden. SIGNIFICANCE: Patient-reported and patient-centered outcomes are increasingly incorporated into the evaluation of treatment effectiveness. Without understanding how the disease creates burden for the patient (or family), it is difficult to know how to assess the impact of treatment. Our preliminary findings indicate seizure burden is a complex construct and unpredictability can be as important as frequency and severity.
ABSTRACT
ADP-ribosylation, the addition of poly-ADP ribose (PAR) onto proteins, is a response signal to cellular challenges, such as excitotoxicity or oxidative stress. This process is catalyzed by a group of enzymes referred to as poly(ADP-ribose) polymerases (PARPs). Because the accumulation of proteins with this modification results in cell death, its negative regulation restores cellular homeostasis: a process mediated by poly-ADP ribose glycohydrolases (PARGs) and ADP-ribosylhydrolase proteins (ARHs). Using linkage analysis and exome or genome sequencing, we identified recessive inactivating mutations in ADPRHL2 in six families. Affected individuals exhibited a pediatric-onset neurodegenerative disorder with progressive brain atrophy, developmental regression, and seizures in association with periods of stress, such as infections. Loss of the Drosophila paralog Parg showed lethality in response to oxidative challenge that was rescued by human ADPRHL2, suggesting functional conservation. Pharmacological inhibition of PARP also rescued the phenotype, suggesting the possibility of postnatal treatment for this genetic condition.
ABSTRACT
The randomized controlled trial is the unequivocal gold standard for demonstrating clinical efficacy and safety of investigational therapies. Recently there have been concerns raised about prolonged exposure to placebo and ineffective therapy during the course of an add-on regulatory trial for new antiepileptic drug approval (typically â¼6 months in duration), due to the potential risks of continued uncontrolled epilepsy for that period. The first meeting of the Research Roundtable in Epilepsy on May 19-20, 2016, focused on "Reducing placebo exposure in epilepsy clinical trials," with a goal of considering new designs for epilepsy regulatory trials that may be added to the overall development plan to make it, as a whole, safer for participants while still providing rigorous evidence of effect. This topic was motivated in part by data from a meta-analysis showing a 3- to 5-fold increased rate of sudden unexpected death in epilepsy in participants randomized to placebo or ineffective doses of new antiepileptic drugs. The meeting agenda included rationale and discussion of different trial designs, including active-control add-on trials, placebo add-on to background therapy with adjustment, time to event designs, adaptive designs, platform trials with pooled placebo control, a pharmacokinetic/pharmacodynamic approach to reducing placebo exposure, and shorter trials when drug tolerance has been ruled out. The merits and limitations of each design were discussed and are reviewed here.
Subject(s)
Anticonvulsants/therapeutic use , Epilepsy/psychology , Epilepsy/therapy , Placebo Effect , Research Design , Female , Humans , Male , Randomized Controlled Trials as Topic , Research Design/standardsABSTRACT
Dendritic spines represent the major site of neuronal activity in the brain; they serve as the receiving point for neurotransmitters and undergo rapid activity-dependent morphological changes that correlate with learning and memory. Using a combination of homozygosity mapping and next-generation sequencing in two consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability, we identified truncating mutations in formin 2 (FMN2), encoding a protein that belongs to the formin family of actin cytoskeleton nucleation factors and is highly expressed in the maturing brain. We found that FMN2 localizes to punctae along dendrites and that germline inactivation of mouse Fmn2 resulted in animals with decreased spine density; such mice were previously demonstrated to have a conditioned fear-learning defect. Furthermore, patient neural cells derived from induced pluripotent stem cells showed correlated decreased synaptic density. Thus, FMN2 mutations link intellectual disability either directly or indirectly to the regulation of actin-mediated synaptic spine density.
Subject(s)
Chromosome Disorders/genetics , Intellectual Disability/genetics , Microfilament Proteins/genetics , Nuclear Proteins/genetics , Sequence Deletion , Adolescent , Adult , Base Sequence , Chromosome Disorders/physiopathology , Cohort Studies , Consanguinity , Egypt , Exome/genetics , Female , Formins , Genes, Recessive , Genetic Linkage , High-Throughput Nucleotide Sequencing , Homozygote , Humans , Intellectual Disability/physiopathology , Male , Microfilament Proteins/metabolism , Molecular Sequence Data , Nuclear Proteins/metabolism , Pakistan , Pedigree , Sequence Analysis, DNAABSTRACT
Proteins of the major histocompatibility complex class I (MHCI) negatively regulate synapse density in the developing vertebrate brain (Glynn et al., 2011; Elmer et al., 2013; Lee et al., 2014), but the underlying mechanisms remain largely unknown. Here we identify a novel MHCI signaling pathway that involves the inhibition of a known synapse-promoting factor, the insulin receptor. Dominant-negative insulin receptor constructs decrease synapse density in the developing Xenopus visual system (Chiu et al., 2008), and insulin receptor activation increases dendritic spine density in mouse hippocampal neurons in vitro (Lee et al., 2011). We find that genetically reducing cell surface MHCI levels increases synapse density selectively in regions of the hippocampus where insulin receptors are expressed, and occludes the neuronal insulin response by de-repressing insulin receptor signaling. Pharmacologically inhibiting insulin receptor signaling in MHCI-deficient animals rescues synapse density, identifying insulin receptor signaling as a critical mediator of the tonic inhibitory effects of endogenous MHCI on synapse number. Insulin receptors co-immunoprecipitate MHCI from hippocampal lysates, and MHCI unmasks a cytoplasmic epitope of the insulin receptor that mediates downstream signaling. These results identify an important role for an MHCI-insulin receptor signaling pathway in circuit patterning in the developing brain, and suggest that changes in MHCI expression could unexpectedly regulate neuronal insulin sensitivity in the aging and diseased brain.
Subject(s)
Hippocampus/metabolism , Histocompatibility Antigens Class I/metabolism , Neurogenesis/physiology , Receptor, Insulin/metabolism , Synapses/metabolism , Animals , Blotting, Western , Hippocampus/growth & development , Immunohistochemistry , Immunoprecipitation , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Microscopy, Electron, Transmission , Neurons/metabolism , Neurons/ultrastructure , Organ Culture Techniques , Signal Transduction , Synapses/ultrastructureABSTRACT
This report represents a summary of the discussions led by the antiseizure treatment working group of the International League Against Epilepsy (ILAE)/American Epilepsy Society (AES) Working Groups joint meeting in London (London Meeting). We review here what is currently known about the pharmacologic characteristics of current models of refractory seizures, both for adult and pediatric epilepsy. In addition, we address how the National Institute of Neurological Disorders and Stroke (NINDS)-funded Anticonvulsant Screening Program (ASP) is evolving to incorporate appropriate animal models in the search for molecules that might be sufficiently novel to warrant further pharmacologic development. We also briefly address what we believe is necessary, going forward, to achieve the goal of stopping seizures in all patients, with a call to arms for funding agencies, the pharmaceutical industry, and basic researchers.
Subject(s)
Anticonvulsants/therapeutic use , Disease Models, Animal , Drug Discovery , Drug Evaluation , Drugs, Investigational/therapeutic use , Adult , Animals , Child , Drug Industry , Humans , Research Support as Topic , Translational Research, BiomedicalABSTRACT
Wolcott-Rallison syndrome (WRS) and the recently delineated microcephaly with simplified gyration, epilepsy, and permanent neonatal diabetes syndrome (MEDS) are clinically overlapping autosomal recessive disorders characterized by early onset diabetes, skeletal defects, and growth retardation. While liver and renal symptoms are more severe in WRS, neurodevelopmental characteristics are more pronounced in MEDS patients, in which microcephaly and uncontrolled epilepsy are uniformly present. Mutations in the EIF2AK3 gene were described in patients with WRS and defects in this gene lead to increased susceptibility to apoptotic cell death. Mutations in IER3IP1 have been reported in patients with MEDS and similarly, loss of activity results in apoptosis of neurons and pancreatic beta cells in patients. Here we report on a homozygous mutation of the IER3IP1 gene in four patients from two unrelated consanguineous Egyptian families presenting with MEDS who display burst suppression patterns on EEG. All patients presented with mildly elevated liver enzymes, microalbuminuria, and skeletal changes such as scoliosis and osteopenia, leading to repeated bone fractures. We expand the phenotypic spectrum of MEDS caused by IER3IP1 gene mutations and propose that WRS and MEDS are overlapping clinical syndromes, displaying significant gene-dependent clinical variability.
Subject(s)
Carrier Proteins/genetics , Diabetes Mellitus, Type 1/genetics , Homozygote , Membrane Proteins/genetics , Mutation , Osteochondrodysplasias/genetics , Base Sequence , Bone and Bones/pathology , Brain/pathology , Child, Preschool , Consanguinity , Diabetes Mellitus, Type 1/diagnosis , Epiphyses/abnormalities , Facies , Female , Humans , Infant , Magnetic Resonance Imaging , Male , Osteochondrodysplasias/diagnosis , PedigreeABSTRACT
De novo somatic mutations in focal areas are well documented in diseases such as neoplasia but are rarely reported in malformation of the developing brain. Hemimegalencephaly (HME) is characterized by overgrowth of either one of the two cerebral hemispheres. The molecular etiology of HME remains a mystery. The intractable epilepsy that is associated with HME can be relieved by the surgical treatment hemispherectomy, allowing sampling of diseased tissue. Exome sequencing and mass spectrometry analysis in paired brain-blood samples from individuals with HME (n = 20 cases) identified de novo somatic mutations in 30% of affected individuals in the PIK3CA, AKT3 and MTOR genes. A recurrent PIK3CA c.1633G>A mutation was found in four separate cases. Identified mutations were present in 8-40% of sequenced alleles in various brain regions and were associated with increased neuronal S6 protein phosphorylation in the brains of affected individuals, indicating aberrant activation of mammalian target of rapamycin (mTOR) signaling. Thus HME is probably a genetically mosaic disease caused by gain of function in phosphatidylinositol 3-kinase (PI3K)-AKT3-mTOR signaling.
Subject(s)
Malformations of Cortical Development/genetics , Mutation, Missense , Phosphatidylinositol 3-Kinases/genetics , Proto-Oncogene Proteins c-akt/genetics , TOR Serine-Threonine Kinases/genetics , Child, Preschool , Class I Phosphatidylinositol 3-Kinases , DNA Mutational Analysis , Exome , Female , Humans , Infant , Magnetic Resonance Imaging , Male , Malformations of Cortical Development/metabolism , Malformations of Cortical Development/pathology , Mosaicism , Signal Transduction/geneticsABSTRACT
The translation of "next-generation" sequencing directly to the clinic is still being assessed but has the potential for genetic diseases to reduce costs, advance accuracy, and point to unsuspected yet treatable conditions. To study its capability in the clinic, we performed whole-exome sequencing in 118 probands with a diagnosis of a pediatric-onset neurodevelopmental disease in which most known causes had been excluded. Twenty-two genes not previously identified as disease-causing were identified in this study (19% of cohort), further establishing exome sequencing as a useful tool for gene discovery. New genes identified included EXOC8 in Joubert syndrome and GFM2 in a patient with microcephaly, simplified gyral pattern, and insulin-dependent diabetes. Exome sequencing uncovered 10 probands (8% of cohort) with mutations in genes known to cause a disease different from the initial diagnosis. Upon further medical evaluation, these mutations were found to account for each proband's disease, leading to a change in diagnosis, some of which led to changes in patient management. Our data provide proof of principle that genomic strategies are useful in clarifying diagnosis in a proportion of patients with neurodevelopmental disorders.
Subject(s)
Exome/genetics , Female , Humans , Male , Mutation , Pedigree , Sequence Analysis, DNA , Vesicular Transport Proteins/geneticsABSTRACT
One of the fundamental goals in human genetics is to link gene function to phenotype, yet the function of the majority of the genes in the human body is still poorly understood. This is especially true for the developing human brain. The study of human phenotypes that result from inherited, mutated alleles is the most direct evidence for the requirement of a gene in human physiology. Thus, the study of Mendelian central nervous system (CNS) diseases can be an extremely powerful approach to elucidate such phenotypic/genotypic links and to increase our understanding of the key components required for development of the human brain. In this review, we highlight examples of how the study of inherited neurodevelopmental disorders contributes to our knowledge of both the "normal" and diseased human brain, as well as elaborate on the future of this type of research. Mendelian disease research has been, and will continue to be, key to understanding the molecular mechanisms that underlie human brain function, and will ultimately form a basis for the design of intelligent, mechanism-specific treatments for nervous system disorders.