Disruption of cellular iron homeostasis by IREB2 missense variants causes severe neurodevelopmental delay, dystonia and seizures.

Altered brain iron homeostasis can contribute to neurodegeneration by interfering with the delivery of the iron needed to support key cellular processes, including mitochondrial respiration, synthesis of myelin and essential neurotransmitters. Intracellular iron homeostasis in mammals is maintained by two homologous ubiquitously expressed iron-responsive element-binding proteins (IRP1 and IRP2). Using exome sequencing, two patients with severe neurodegenerative disease and bi-allelic mutations in the gene IREB2 were first identified and clinically characterized in 2019. Here, we report the case of a 7-year-old male patient with compound heterozygous missense variants in IREB2, whose neurological features resembled those of the two previously reported IRP2-deficient patients, including a profound global neurodevelopmental delay and dystonia. Biochemical characterization of a lymphoblast cell line derived from the patient revealed functional iron deficiency, altered post-transcriptional regulation of iron metabolism genes and mitochondrial dysfunction. The iron metabolism abnormalities of the patient cell line were reversed by lentiviral-mediated restoration of IREB2 expression. These results, in addition to confirming the essential role of IRP2 in the regulation of iron metabolism in humans, expand the scope of the known IRP2-related neurodegenerative disorders and underscore that IREB2 pathological variants may impact the iron-responsive element-binding activity of IRP2 with varying degrees of severity. The three severely affected patients identified so far all suffered from complete loss of function of IRP2, raising the possibility that individuals with significant but incomplete loss of IRP2 function may develop less severe forms of the disease, analogous to other human conditions that present with a wide range of phenotypic manifestations.

Persistence of suppression-bursts in a patient with Ohtahara syndrome.

Early infantile epileptic encephalopathy, or Ohtahara syndrome, is characterized by tonic spasms and a suppression-burst pattern on the electroencephalography (EEG). The EEG demonstrates a suppression-burst pattern during waking and sleeping states that often evolves into hypsarrhythmia and followed later by a diffuse slow spike-wave pattern. In other patients, the EEG evolves into focal spike discharges or multiple independent spike foci. We report a 5-year-old girl with Ohtahara syndrome that persistently demonstrated tonic spasms and suppression-burst on multiple EEGs. Over her lifetime, neither hypsarrhythmia nor diffuse slow spike-wave pattern were seen. This suggests that in Ohtahara syndrome, a suppression-burst pattern can persist over a long period of time.

Focal Seizures in Patients With SCN1A Mutations.

The SCN1A gene has been implicated in the etiology of various forms of epilepsy. New research has linked this gene to specific types of epilepsy, all of which present in infancy or early childhood. This study examines the time course and pathology of pediatric patients who have a mutation in the SCN1A gene in order to open a discussion regarding the key trends of this form of epilepsy as well as important clinical considerations in management for patients who present with symptoms relating to the SCN1A mutations. We retrospectively examined 20 patients who presented to the clinic with focal seizures, as well as were positive for an SCN1A genetic mutation. Despite the small sample size, we were able to find important trends in the time course of the disorder as well as important areas of clinical practice that must be taken into consideration for these patients.

The semiology of benign focal epilepsy with affective symptoms.

Benign focal epilepsy with affective symptoms (BFEAS) is a rare childhood epilepsy syndrome essentially characterized by "epileptic attacks with affective symptoms of a terrifying type". Since the original description, approximately 50 cases have been reported. To our knowledge, however, none of the studies included video-EEG data. Herein, we detail the electroclinical features of a neurodevelopmentally normal 9-year-old boy with epilepsy since the age of 2 years. His seizure semiology essentially consisted of nocturnal focal seizures featuring abrupt fear and autonomic phenomena (such as excessive sweating, repeated swallowing, and coughing), associated with impaired consciousness. These seizures were often secondary generalized, and he had multiple episodes of convulsive status epilepticus. He has been seizure-free for the past year and a half on dual antiepileptic therapy with sulthiamine and valproate. His intellectual and social abilities are excellent (IQ of 116), although he does have difficulties particularly in language learning, and was recently diagnosed with phonological dyslexia with dysorthography. By presenting our patient's history and video-EEG, we intend to further detail the semiology of seizures with affective symptomatology. [Published with video sequence on www.epilepticdisorders.com].

Research conference summary from the 2014 International Task Force on ATP1A3-Related Disorders.

OBJECTIVE: ATP1A3-related neurologic disorders encompass a broad range of phenotypes that extend well beyond initial phenotypic criteria associated with alternating hemiplegia of childhood (AHC) and rapid-onset dystonia parkinsonism. METHODS: In 2014, the Alternating Hemiplegia of Childhood Foundation hosted a multidisciplinary workshop intended to address fundamental challenges surrounding the diagnosis and management of individuals with ATP1A3-related disorders. RESULTS: Workshop attendees were charged with the following: (1) to achieve consensus on expanded diagnostic criteria to facilitate the identification of additional patients, intended to supplement existing syndrome-specific diagnostic paradigms; (2) to standardize definitions for the broad range of paroxysmal manifestations associated with AHC to disseminate to families; (3) to create clinical recommendations for common recurrent issues facing families and medical care providers; (4) to review data related to the death of individuals in the Alternating Hemiplegia of Childhood Foundation database to guide future efforts in identifying at-risk subjects and potential preventative measures; and (5) to identify critical gaps where we most need to focus national and international research efforts. CONCLUSIONS: This report summarizes recommendations of the workshop committee, highlighting the key phenotypic features to facilitate the diagnosis of possible ATP1A3 mutations, providing recommendations for genetic testing, and outlining initial acute management for common recurrent clinical conditions, including epilepsy.

Vagus nerve stimulation for intractable seizures in children.

Forty-three children less than 12 years of age having intractable seizures were treated with vagus nerve stimulation. Five children were monitored for <12 months, 16 children for 12 to 17 months, and 22 children for > or =18 months with overall median seizure reduction of 55%. Thirty-seven percent had at least 90% reduction. Vagus nerve stimulation was effective in children with generalized, mixed, and partial medically refractory seizures.

Alternating Hemiplegia of Childhood: Retrospective Genetic Study and Genotype-Phenotype Correlations in 187 Subjects from the US AHCF Registry.

Mutations in ATP1A3 cause Alternating Hemiplegia of Childhood (AHC) by disrupting function of the neuronal Na+/K+ ATPase. Published studies to date indicate 2 recurrent mutations, D801N and E815K, and a more severe phenotype in the E815K cohort. We performed mutation analysis and retrospective genotype-phenotype correlations in all eligible patients with AHC enrolled in the US AHC Foundation registry from 1997-2012. Clinical data were abstracted from standardized caregivers' questionnaires and medical records and confirmed by expert clinicians. We identified ATP1A3 mutations by Sanger and whole genome sequencing, and compared phenotypes within and between 4 groups of subjects, those with D801N, E815K, other ATP1A3 or no ATP1A3 mutations. We identified heterozygous ATP1A3 mutations in 154 of 187 (82%) AHC patients. Of 34 unique mutations, 31 (91%) are missense, and 16 (47%) had not been previously reported. Concordant with prior studies, more than 2/3 of all mutations are clusteredin exons 17 and 18. Of 143 simplex occurrences, 58 had D801N (40%), 38 had E815K(26%) and 11 had G947R (8%) mutations [corrected].Patients with an E815K mutation demonstrate an earlier age of onset, more severe motor impairment and a higher prevalence of status epilepticus. This study further expands the number and spectrum of ATP1A3 mutations associated with AHC and confirms a more deleterious effect of the E815K mutation on selected neurologic outcomes. However, the complexity of the disorder and the extensive phenotypic variability among subgroups merits caution and emphasizes the need for further studies.

Intravenous immunoglobulin as adjunctive therapy for juvenile spasms.

Intravenous immunoglobulin has been reported to be an effective treatment for infantile spasms. Juvenile spasms are electrically and clinically similar to infantile spasms but occur in a later age group. We retrospectively reviewed the charts of five children (aged 4.5-11.5 years) at our institution. Their primary seizure type was juvenile spasms and they were treated with a single inpatient course of intravenous immunoglobulin (400 mg/kg/day intravenously for 5 consecutive days) on an adjunctive basis. Seizure frequency was determined from parental reports. By 3 months after treatment, improvement (a 50-92% reduction in seizure frequency) was noted in four patients; sustained benefit was seen in three patients for up to 12 months. One patient showed no response at 3 and 6 months and had an increase in seizure frequency at 1 year. We conclude that single-course intravenous immunoglobulin can be effective as adjunctive therapy for juvenile spasms and that benefit can persist for many months. However, larger controlled, prospective clinical trials are needed to validate this unconventional treatment modality for specific seizure types such as juvenile spasms.