Rani K. Singh

De novo mutations in epileptic encephalopathies

Epileptic encephalopathies are a devastating group of severe childhood epilepsy disorders for which the cause is often unknown. Here we report a screen for de novo mutations in patients with two classical epileptic encephalopathies: infantile spasms (n = 149) and Lennox–Gastaut syndrome (n = 115). We sequenced the exomes of 264 probands, and their parents, and confirmed 329 de novo mutations. A likelihood analysis showed a significant excess of de novo mutations in the ∼4,000 genes that are the most intolerant to functional genetic variation in the human population (P = 2.9 × 10−3). Among these are GABRB3, with de novo mutations in four patients, and ALG13, with the same de novo mutation in two patients; both genes show clear statistical evidence of association with epileptic encephalopathy. Given the relevant site-specific mutation rates, the probabilities of these outcomes occurring by chance are P = 4.1 × 10−10 and P = 7.8 × 10−12, respectively. Other genes with de novo mutations in this cohort include CACNA1A, CHD2, FLNA, GABRA1, GRIN1, GRIN2B, HNRNPU, IQSEC2, MTOR and NEDD4L. Finally, we show that the de novo mutations observed are enriched in specific gene sets including genes regulated by the fragile X protein (P < 10−8), as has been reported previously for autism spectrum disorders.

Ultra-rare genetic variation in common epilepsies: a case-control sequencing study

BACKGROUND Despite progress in understanding the genetics of rare epilepsies, the more common epilepsies have proven less amenable to traditional gene-discovery analyses. We aimed to assess the contribution of ultra-rare genetic variation to common epilepsies. METHODS We did a case-control sequencing study with exome sequence data from unrelated individuals clinically evaluated for one of the two most common epilepsy syndromes: familial genetic generalised epilepsy, or familial or sporadic non-acquired focal epilepsy. Individuals of any age were recruited between Nov 26, 2007, and Aug 2, 2013, through the multicentre Epilepsy Phenome/Genome Project and Epi4K collaborations, and samples were sequenced at the Institute for Genomic Medicine (New York, USA) between Feb 6, 2013, and Aug 18, 2015. To identify epilepsy risk signals, we tested all protein-coding genes for an excess of ultra-rare genetic variation among the cases, compared with control samples with no known epilepsy or epilepsy comorbidity sequenced through unrelated studies. FINDINGS We separately compared the sequence data from 640 individuals with familial genetic generalised epilepsy and 525 individuals with familial non-acquired focal epilepsy to the same group of 3877 controls, and found significantly higher rates of ultra-rare deleterious variation in genes established as causative for dominant epilepsy disorders (familial genetic generalised epilepsy: odd ratio [OR] 2·3, 95% CI 1·7-3·2, p=9·1 × 10-8; familial non-acquired focal epilepsy 3·6, 2·7-4·9, p=1·1 × 10-17). Comparison of an additional cohort of 662 individuals with sporadic non-acquired focal epilepsy to controls did not identify study-wide significant signals. For the individuals with familial non-acquired focal epilepsy, we found that five known epilepsy genes ranked as the top five genes enriched for ultra-rare deleterious variation. After accounting for the control carrier rate, we estimate that these five genes contribute to the risk of epilepsy in approximately 8% of individuals with familial non-acquired focal epilepsy. Our analyses showed that no individual gene was significantly associated with familial genetic generalised epilepsy; however, known epilepsy genes had lower p values relative to the rest of the protein-coding genes (p=5·8 × 10-8) that were lower than expected from a random sampling of genes. INTERPRETATION We identified excess ultra-rare variation in known epilepsy genes, which establishes a clear connection between the genetics of common and rare, severe epilepsies, and shows that the variants responsible for epilepsy risk are exceptionally rare in the general population. Our results suggest that the emerging paradigm of targeting of treatments to the genetic cause in rare devastating epilepsies might also extend to a proportion of common epilepsies. These findings might allow clinicians to broadly explain the cause of these syndromes to patients, and lay the foundation for possible precision treatments in the future. FUNDING National Institute of Neurological Disorders and Stroke (NINDS), and Epilepsy Research UK.

Seizures in acute childhood stroke.

OBJECTIVES To describe the risk of seizures in children with acute stroke and identify factors predicting their later risk of epilepsy. STUDY DESIGN Data for patients >3.5 years of age at a tertiary care childrens hospital with acute stroke were collected and reviewed. RESULTS Seventy-seven patients were identified (mean age, 8.4 years); 21% had clinical seizures. An additional 10% of patients had a clinical seizure during the acute hospitalization. Status epilepticus was common in infants and patients with cortical strokes. Non-convulsive status epilepticus was captured only in patients with prolonged electroencephalograms and always within 24 hours of monitoring. Six months after their stroke, 24% of our patients had epilepsy, all of whom experienced seizures at initial presentation with stroke. CONCLUSION In our series of pediatric patients with stroke, most of the clinical seizures occurred within the first 24 hours of presentation and did not vary in stroke subtype. Status epilepticus was common, especially in infants. Epilepsy had a high likelihood of developing in the next 6 months in children with seizures in the first 24 hours of stroke onset. Prolonged electroencephalogram monitoring was useful in detecting non-convulsive status epilepticus, but not in predicting the risk of epilepsy at 6 months.

Copy number variant analysis from exome data in 349 patients with epileptic encephalopathy

Infantile spasms (IS) and Lennox–Gastaut syndrome (LGS) are epileptic encephalopathies characterized by early onset, intractable seizures, and poor developmental outcomes. De novo sequence mutations and copy number variants (CNVs) are causative in a subset of cases. We used exome sequence data in 349 trios with IS or LGS to identify putative de novo CNVs. We confirm 18 de novo CNVs in 17 patients (4.8%), 10 of which are likely pathogenic, giving a firm genetic diagnosis for 2.9% of patients. Confirmation of exome‐predicted CNVs by array‐based methods is still required due to false‐positive rates of prediction algorithms. Our exome‐based results are consistent with recent array‐based studies in similar cohorts and highlight novel candidate genes for IS and LGS. Ann Neurol 2015;78:323–328

Advanced treatments for childhood epilepsy: beyond antiseizure medications.

A substantial minority of children with epilepsy have continued seizures despite adequate trials of standard antiseizure medications. To maximize seizure control and thereby optimize their neurodevelopmental outcomes, alternate nonmedication therapies should be considered for these patients. Dietary therapies, including the ketogenic diet and its variations, have been available for years. With a recent resurgence in popularity and expansion of indications, these treatments can lead to freedom from seizures or a significantly reduced seizure burden for a large number of patients. For carefully selected individuals, resective epilepsy surgery may offer the best hope for a cure. For others, palliation may be achieved through additional surgical approaches, such as corpus callosotomy and multiple subpial transections, or through neurostimulation techniques, such as the vagus nerve stimulator. In this review, we present these nonmedication approaches to treatment-resistant childhood epilepsy, with attention to patient selection and the potential risks and benefits.

Teaching Video NeuroImage: Near complete ophthalmoplegia in GQ1b antibody-positive Miller Fisher: Video and MRI correlation

An 8-year-old boy developed near complete ophthalmoplegia (video and figure 1), sparing the pupils, with mild gait ataxia, and areflexia. Miller Fisher syndrome was diagnosed after high titers of anti-GQ1b IgG, which are highly disease specific,1 …

The Utility of Infarct Volume Measurement in Pediatric Ischemic Stroke

This study aims to determine if stroke volume as measured on diffusion-weighted imaging is associated with neurologic outcome in children with acute arterial ischemic stroke. A cohort of patients presenting to a tertiary care childrens hospital with acute ischemic stroke were studied. The relationship between stroke volume, clinical characteristics, and neurologic outcome utilizing the Glasgow Outcome Scale were analyzed. In children with poor outcome, the median volume of infarction on diffusion-weighted imaging was larger when compared with children who had a good outcome. Children with stroke volume >10% of total brain volume were more likely than patients with stroke volume <5% total brain volume to have a poor outcome. Seizures were associated with a 10.5-fold increase in the risk of a poor outcome. Stroke volume, in conjunction with clinical characteristics, can assist practitioners in identifying a subset of patients with acute ischemic stroke who might benefit from aggressive medical and/or surgical management.

Subdural Hemorrhages Associated With Antithrombotic Therapy in Infants With Cerebral Atrophy

Low-molecular-weight heparins, such as enoxaparin, are often used to treat thrombosis in infants. We present 4 infants with diffuse brain injury who developed cerebral venous sinus thrombosis or deep vein thrombosis and were treated with enoxaparin. These infants subsequently developed subdural hemorrhages, and enoxaparin was stopped. In 3 cases, the subdural hemorrhages were found on routine surveillance brain MRI, and in 1 case imaging was urgently obtained because of focal seizures. Two patients needed urgent neurosurgical intervention, and all subdural hemorrhages improved or resolved on follow-up imaging. Each infant developed severe neurologic deficits, probably from the coexisting diffuse brain injury rather than from the subdural hemorrhages themselves. The risk of intracranial hemorrhage from enoxaparin may be accentuated in patients with diffuse brain injury, and careful consideration should be given before treatment in this population.

A 4-year-old boy with ascending weakness and a new 'skin tag'.

4-year-old boy from Singapore, while on vacation in the United States (fi rst to Georgia and then Washington, D.C.), was evaluated for a subacute progressive ascending weakness. Five days before, he had noted the onset of vague paresthesias and muscular pains beginning in the distal left leg and later in the distal right leg. There was a gradual progression of diffi culties with walking during the next 5 days.

Vitamin D and bone health among people with epilepsy

Both adults and children with epilepsy are at high risk for poor bone health, with associated osteopenia and fractures. Epilepsy has consistently been associated with low vitamin D levels, a key indicator of bone health. Many anticonvulsant medications, such as phenytoin and carbamazepine, induce hepatic CYP450 enzymes, resulting in accelerated vitamin D metabolism. This might be the mechanism by which some epilepsy treatments decrease vitamin D levels. However, even medications which result in less-potent CYP450 induction (e.g. oxcarbazepine), or inhibit hepatic enzymes (e.g. valproate), have been associated with abnormal vitamin D levels and poor bone health. Data are lacking for many of the newer anticonvulsant medications. Although vitamin D is only one among many risk factors for abnormal bone mineral density, it is a modifiable risk factor for people with epilepsy. We suggest guidelines for screening and treatment of vitamin D insufficiency for people with epilepsy.