Immunotherapy for GRIN2A and GRIN2D-related epileptic encephalopathy

Continuous Spike-Waves during Slow Sleep Today: An Update

In the context of childhood epilepsy, the concept of continuous spike-waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau-Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies.

An Extraordinary EEG Phenomenon Misdiagnosed as Nonconvulsive Status Epilepticus: Frequent Subclinical Periodic Discharges Terminated by Sudden Auditory Stimuli

Triggering or modulation of seizures and rhythmic EEG patterns by external stimuli are well-known with the most common clinical appearance of stimulus induced periodic discharges (SI- PDs) patterns which are elicited by physical or auditory stimulation. However, stimulus terminated periodic discharges (ST-PDs), in other words, the periodic discharges stopped by external stimuli is an extremely rare electroencephalographic (EEG) finding. We report a 20-year-old woman with a marked psychomotor developmental delay of unknown cause, with frequent EEG patterns of long-lasting (10-60 s) bilateral paroxysmal high-voltage slow waves with occasional spikes, misdiagnosed as non-convulsive status epilepticus. However, no apparent clinical change was noted by the technician, physician, and her mother during these subclinical ictal EEG recordings. Interestingly, however, these epileptic discharges were abruptly interrupted by sudden verbal stimuli on the EEG, repeatedly. Whole exome sequencing and genotyping were performed to investigate possible genetic etiology that revealed two sequence variants, a frameshift variant of CACNA1H NM_021098.3:c.1701del;p.Asp568ThrfsTer15 and a missense variant of GRIN2D NM_000836.4:c.1783A>T;p.Thr595Ser as well as a copy number variant part deletion of ATP6V1A gene arr [hg19]3q13.31(113,499,698_113,543,081)x1 as possible pathogenic candidates. The subclinical periodic discharges terminated by verbal stimuli, is a very rare manifestation and needs particular attention. External modulation of ictal-appearing EEG patterns is important to identify stimulus terminated EEG patterns.

GRIN2A-related epilepsy and speech disorders: A comprehensive overview with a focus on the role of precision therapeutics

Language dysfunction is a common and serious comorbidity of epilepsy, especially in individuals with epilepsy aphasia spectrum syndromes. Childhood epilepsy with centrotemporal spikes is on the mild end of the spectrum, while epileptic encephalopathy with continuous spike-and-wave during sleep syndrome is on the severe end. Traditional antiseizure medicines and immunotherapy are currently used to treat severely affected patients, but the results are usually disappointing. The discovery that GRIN2A is the primary monogenic etiology of these diseases has opened the door to precision treatments. The GRIN2A gene encodes GluN2A protein, which constitutes a subunit of the NMDA receptor (NMDAR). The GRIN2A pathogenic variants cause gain or loss of function of NMDAR; the former can be treated with uncompetitive NMDAR antagonists, such as memantine, while the latter with NMDAR co-agonist serine. Hyper-precision therapies with various other effective agents are likely to be developed shortly to target the diverse functional effects of different variants. Precision treatments for GRIN2A-related disorders will benefit those who suffer from the condition and pave the way for new therapeutic approaches to a variety of other NMDAR-linked neurodegenerative and psychiatric diseases (schizophrenia, Parkinson's disease, Alzheimer's disease, and so on). Furthermore, more research into GRIN2A-related disorders will help us better understand the neuroinflammatory and neuroimmunological basis of epilepsy, as well as the pathological and physiological network activation mechanisms that cause sleep activation of central-temporal spikes and language impairment.

Epilepsy and Cognitive Impairment in Childhood and Adolescence: A Mini-Review

Managing epilepsy in people with an intellectual disability remains a therapeutic challenge and must take into account additional issues such as diagnostic difficulties and frequent drug resistance. Advances in genomic technologies improved our understanding of epilepsy and raised the possibility to develop patients-tailored treatments acting on the key molecular mechanisms involved in the development of the disease. In addition to conventional antiseizure medications (ASMs), ketogenic diet, hormone therapy and epilepsy surgery play an important role, especially in cases of drugresistance. This review aims to provide a comprehensive overview of the mainfactors influencing cognition in children and adolescents with epilepsy and the main therapeutic options available for the epilepsies associated with intellectual disability.

A Systematic Review and Meta-Analysis of Immunoglobulin G Abnormalities and the Therapeutic Use of Intravenous Immunoglobulins (IVIG) in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder affecting approximately 2% of children in the United States. Growing evidence suggests that immune dysregulation is associated with ASD. One immunomodulatory treatment that has been studied in ASD is intravenous immunoglobulins (IVIG). This systematic review and meta-analysis examined the studies which assessed immunoglobulin G (IgG) concentrations and the therapeutic use of IVIG for individuals with ASD. Twelve studies that examined IgG levels suggested abnormalities in total IgG and IgG 4 subclass concentrations, with concentrations in these IgGs related to aberrant behavior and social impairments, respectively. Meta-analysis supported possible subsets of children with ASD with low total IgG and elevated IgG 4 subclass but also found significant variability among studies. A total of 27 publications reported treating individuals with ASD using IVIG, including four prospective, controlled studies (one was a double-blind, placebo-controlled study); six prospective, uncontrolled studies; 2 retrospective, controlled studies; and 15 retrospective, uncontrolled studies. In some studies, clinical improvements were observed in communication, irritability, hyperactivity, cognition, attention, social interaction, eye contact, echolalia, speech, response to commands, drowsiness, decreased activity and in some cases, the complete resolution of ASD symptoms. Several studies reported some loss of these improvements when IVIG was stopped. Meta-analysis combining the aberrant behavior checklist outcome from two studies demonstrated that IVIG treatment was significantly associated with improvements in total aberrant behavior and irritability (with large effect sizes), and hyperactivity and social withdrawal (with medium effect sizes). Several studies reported improvements in pro-inflammatory cytokines (including TNF-alpha). Six studies reported improvements in seizures with IVIG (including patients with refractory seizures), with one study reporting a worsening of seizures when IVIG was stopped. Other studies demonstrated improvements in recurrent infections, appetite, weight gain, neuropathy, dysautonomia, and gastrointestinal symptoms. Adverse events were generally limited but included headaches, vomiting, worsening behaviors, anxiety, fever, nausea, fatigue, and rash. Many studies were limited by the lack of standardized objective outcome measures. IVIG is a promising and potentially effective treatment for symptoms in individuals with ASD; further research is needed to provide solid evidence of efficacy and determine the subset of children with ASD who may best respond to this treatment as well as to investigate biomarkers which might help identify responsive candidates.

GRIN2A Variant in A 3-Year-Old-An Expanding Spectrum?

Glutamate, the major excitatory neurotransmitter, plays a ubiquitous role in most aspects of normal brain functioning. Its indispensable position is paradoxically doubled by a high excitotoxic potential following disruption of its dynamic equilibrium. Several lines of evidence have suggested the involvement of the glutamatergic N-methyl-D-aspartate receptor (NMDAR) in learning, memory formation, and human cognition. Furthermore, NMDARs play a pivotal role in various neuropsychiatric disorders, recently being identified as an important locus for disease-associated genomic variation. The GRIN2A gene encodes the NMDAR’s GluN2A subunit. Genetic alterations of GRIN2A result in phenotypic pleiotropy, predisposing to a broad range of epilepsy syndromes, with an elusive and unpredictable evolution and response to treatment. The archetypal GRIN2A-related phenotype comprises the idiopathic focal epilepsies (IFEs), with a higher incidence of GRIN2A mutants among entities at the more severe end of the spectrum. We report the case of a patient heterozygous for GRIN2A, c.1081C>T, presenting with febrile convulsions and later superimposed atonic seizures, expressive language delay, and macrocephaly. As the number of reported GRIN2A variants is continuously increasing, the phenotypic boundaries gradually grow faint. Therefore, it is fundamental to maintain an acute critical awareness of the possible genetic etiology of different epilepsy syndromes. So far, therapeutic strategies rely on empirical observations relating genotypes to specific drugs, but the overall success of treatment remains unpredictable. Deciphering the functional consequences of individual GRIN2A variants could lead to the development of precision therapeutic approaches for patients carrying NMDAR mutations.

Treatable inherited metabolic disorders causing intellectual disability: 2021 review and digital app

BACKGROUND

The Treatable ID App was created in 2012 as digital tool to improve early recognition and intervention for treatable inherited metabolic disorders (IMDs) presenting with global developmental delay and intellectual disability (collectively 'treatable IDs'). Our aim is to update the 2012 review on treatable IDs and App to capture the advances made in the identification of new IMDs along with increased pathophysiological insights catalyzing therapeutic development and implementation.

METHODS

Two independent reviewers queried PubMed, OMIM and Orphanet databases to reassess all previously included disorders and therapies and to identify all reports on Treatable IDs published between 2012 and 2021. These were included if listed in the International Classification of IMDs (ICIMD) and presenting with ID as a major feature, and if published evidence for a therapeutic intervention improving ID primary and/or secondary outcomes is available. Data on clinical symptoms, diagnostic testing, treatment strategies, effects on outcomes, and evidence levels were extracted and evaluated by the reviewers and external experts. The generated knowledge was translated into a diagnostic algorithm and updated version of the App with novel features.

RESULTS

Our review identified 116 treatable IDs (139 genes), of which 44 newly identified, belonging to 17 ICIMD categories. The most frequent therapeutic interventions were nutritional, pharmacological and vitamin and trace element supplementation. Evidence level varied from 1 to 3 (trials, cohort studies, case-control studies) for 19% and 4-5 (case-report, expert opinion) for 81% of treatments. Reported effects included improvement of clinical deterioration in 62%, neurological manifestations in 47% and development in 37%.

CONCLUSION

The number of treatable IDs identified by our literature review increased by more than one-third in eight years. Although there has been much attention to gene-based and enzyme replacement therapy, the majority of effective treatments are nutritional, which are relatively affordable, widely available and (often) surprisingly effective. We present a diagnostic algorithm (adjustable to local resources and expertise) and the updated App to facilitate a swift and accurate workup, prioritizing treatable IDs. Our digital tool is freely available as Native and Web App (www.treatable-id.org) with several novel features. Our Treatable ID endeavor contributes to the Treatabolome and International Rare Diseases Research Consortium goals, enabling clinicians to deliver rapid evidence-based interventions to our rare disease patients.