Ann M. E. Bye

Targeted resequencing in epileptic encephalopathies identifies de novo mutations in CHD2 and SYNGAP1

Epileptic encephalopathies are a devastating group of epilepsies with poor prognosis, of which the majority are of unknown etiology. We perform targeted massively parallel resequencing of 19 known and 46 candidate genes for epileptic encephalopathy in 500 affected individuals (cases) to identify new genes involved and to investigate the phenotypic spectrum associated with mutations in known genes. Overall, we identified pathogenic mutations in 10% of our cohort. Six of the 46 candidate genes had 1 or more pathogenic variants, collectively accounting for 3% of our cohort. We show that de novo CHD2 and SYNGAP1 mutations are new causes of epileptic encephalopathies, accounting for 1.2% and 1% of cases, respectively. We also expand the phenotypic spectra explained by SCN1A, SCN2A and SCN8A mutations. To our knowledge, this is the largest cohort of cases with epileptic encephalopathies to undergo targeted resequencing. Implementation of this rapid and efficient method will change diagnosis and understanding of the molecular etiologies of these disorders.

De novo mutations in ATP1A3 cause alternating hemiplegia of childhood

Alternating hemiplegia of childhood (AHC) is a rare, severe neurodevelopmental syndrome characterized by recurrent hemiplegic episodes and distinct neurological manifestations. AHC is usually a sporadic disorder and has unknown etiology. We used exome sequencing of seven patients with AHC and their unaffected parents to identify de novo nonsynonymous mutations in ATP1A3 in all seven individuals. In a subsequent sequence analysis of ATP1A3 in 98 other patients with AHC, we found that ATP1A3 mutations were likely to be responsible for at least 74% of the cases; we also identified one inherited mutation in a case of familial AHC. Notably, most AHC cases are caused by one of seven recurrent ATP1A3 mutations, one of which was observed in 36 patients. Unlike ATP1A3 mutations that cause rapid-onset dystonia-parkinsonism, AHC-causing mutations in this gene caused consistent reductions in ATPase activity without affecting the level of protein expression. This work identifies de novo ATP1A3 mutations as the primary cause of AHC and offers insight into disease pathophysiology by expanding the spectrum of phenotypes associated with mutations in ATP1A3.

Infection-Triggered Familial or Recurrent Cases of Acute Necrotizing Encephalopathy Caused by Mutations in a Component of the Nuclear Pore, RANBP2

Acute necrotizing encephalopathy (ANE) is a rapidly progressive encephalopathy that can occur in otherwise healthy children after common viral infections such as influenza and parainfluenza. Most ANE is sporadic and nonrecurrent (isolated ANE). However, we identified a 7 Mb interval containing a susceptibility locus (ANE1) in a family segregating recurrent ANE as an incompletely penetrant, autosomal-dominant trait. We now report that all affected individuals and obligate carriers in this family are heterozygous for a missense mutation (c.1880C-->T, p.Thr585Met) in the gene encoding the nuclear pore protein Ran Binding Protein 2 (RANBP2). To determine whether this mutation is the susceptibility allele, we screened controls and other patients with ANE who are unrelated to the index family. Patients from 9 of 15 additional kindreds with familial or recurrent ANE had the identical mutation. It arose de novo in two families and independently in several other families. Two other patients with familial ANE had different RANBP2 missense mutations that altered conserved residues. None of the three RANBP2 missense mutations were found in 19 patients with isolated ANE or in unaffected controls. We conclude that missense mutations in RANBP2 are susceptibility alleles for familial and recurrent cases of ANE.

Validation of a New Quality of Life Measure for Children with Epilepsy

Summary: Purpose: There is no adequate measure of health‐related quality of life (HRQOL) specifically for children with epilepsy. The aim of this study was to develop an epilepsy‐specific HRQOL questionnaire for children, covering five domains: physical function, emotional well‐being, cognitive function, social function, and behavior. Second, we aimed to demonstrate the instruments reliability and validity, and its sensitivity to differences in epilepsy severity.

Memory function in childhood epilepsy syndromes

Objective:  Children with epilepsy are at risk of specific cognitive deficits. We aimed to compare and characterize the memory function of children with childhood absence epilepsy (CAE), frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE).

The health-related quality of life of children with refractory epilepsy: a comparison of those with and without intellectual disability.

Summary:  Purpose: To determine whether refractory epilepsy affects the health‐related quality of life (HRQOL) of children with or without intellectual disability (ID), and if the presence of ID independently compromises HRQOL in children with refractory epilepsy.

The Neuropsychological and Language Profile of Children with Benign Rolandic Epilepsy

Summary:  Purpose: Benign rolandic epilepsy (BRE) has an excellent prognosis for seizures, but recent research has raised concerns using cognition as an outcome measure. Methodologic problems related to recruitment bias and assessment processes are evident in previous studies. With well‐defined criteria for inclusion and comprehensive assessment, the aim of this study was to define the cognitive profile of children with BRE and to assess the effect of interictal EEG activity.

Intelligence in childhood epilepsy syndromes

UNLABELLED Intellectual deficits play a significant role in the psychosocial comorbidity of children with epilepsy. Early educational intervention is critical. OBJECTIVE This study aims to determine the intellectual ability of children with common childhood epilepsy syndromes-generalised idiopathic epilepsy (GIE), generalised symptomatic epilepsy (GSE), temporal lobe epilepsy (TLE), frontal lobe epilepsy (FLE), central epilepsy (CE) and non-localised partial epilepsy (PE). METHODS A prospective consecutive series of 169 children were recruited. Epilepsy syndrome was identified by clinical data, seizure semiology, interictal and ictal EEG in each child, using International League Against Epilepsy criteria. Each child had neuropsychology assessment using age-normed and validated instruments. After adjusting for important epilepsy variables, 95% confidence intervals were generated for mean full-scale intelligence quotient (FSIQ) using ANCOVA. RESULTS Significant differences between epilepsy syndrome groups were found for age of onset (P<0.001), duration of active epilepsy (P=0.027), seizure frequency (P=0.037) and polytherapy (P=0.024). Analysing FSIQ, children with GIE, CE and TLE performed best, and did not differ statistically. Children with GSE had a statistically lower FSIQ than other syndrome groups except PE. FLE functioned significantly better than GSE, but did not differ statistically from other groups. CONCLUSIONS In childhood epilepsy, delineation of the syndrome has important implications when considering intellectual potential. This information is invaluable in planning educational interventions and supporting the family.

Validation of the Quality of Life in Childhood Epilepsy Questionnaire in American epilepsy patients

The aim of this study was to adapt the Australian Quality of Life in Childhood Epilepsy Questionnaire (QOLCE) and determine its psychometric properties in a North American population. Participants were North American families with children diagnosed with epilepsy. Parents were asked to complete the American QOLCE (USQOLCE) and the Child Health Questionnaire (CHQ). Seventy-one families completed the USQOLCE. The internal consistency reliability of the subscales was good. USQOLCE subscales correlated highly with theoretically similar subscales contained in the CHQ. Theoretically dissimilar subscales on the two instruments did not correlate as well. USQOLCE correlated significantly with a parental rating of seizure severity and an independent measure of degree of postoperative seizure control. This study demonstrated that the USQOLCE is suitable for a North American population with evidence of its reliability and validity including its sensitivity to seizure burden.

Cerebral and Cerebellar Volume Reduction in Children with Intractable Epilepsy

Summary: Purpose: Adult epilepsy studies have demonstrated cerebral and cerebellar volume reduction beyond the epileptogenic zone, correlating this with an inferior surgical outcome. We determined whether brain volumes were reduced in childhood epilepsy and the significance of this.