Genome sequencing identifies rare tandem repeat expansions and copy number variants in Lennox-Gastaut syndrome.

Epilepsies are a group of common neurological disorders with a substantial genetic basis. Despite this, the molecular diagnosis of epilepsies remains challenging due to its heterogeneity. Studies utilizing whole-genome sequencing may provide additional insights into genetic causes of epilepsies of unknown aetiology. Whole-genome sequencing was used to evaluate a cohort of adults with unexplained developmental and epileptic encephalopathies (n = 30), for whom prior genetic tests, including whole-exome sequencing in some cases, were negative or inconclusive. Rare single nucleotide variants, insertions/deletions, copy number variants and tandem repeat expansions were analysed. Seven pathogenic or likely pathogenic single nucleotide variants, and two pathogenic deleterious copy number variants were identified in nine patients (32.1% of the cohort). One of the copy number variants, identified in a patient with Lennox-Gastaut syndrome, was too small to be detected by chromosomal microarray techniques. We also identified two tandem repeat expansions with clinical implications in two other patients with Lennox-Gastaut syndrome: a CGG repeat expansion in the 5'untranslated region of DIP2B, and a CTG expansion in ATXN8OS (previously implicated in spinocerebellar ataxia type 8). Three patients had KCNA2 pathogenic variants. One of them died of sudden unexpected death in epilepsy. The other two patients had, in addition to a KCNA2 variant, a second de novo variant impacting potential epilepsy-relevant genes (KCNIP4 and UBR5). Overall, whole-genome sequencing provided a genetic explanation in 32.1% of the total cohort. This is also the first report of coding and non-coding tandem repeat expansions identified in patients with Lennox-Gastaut syndrome. This study demonstrates that using whole-genome sequencing, the examination of multiple types of rare genetic variation, including those found in the non-coding region of the genome, can help resolve unexplained epilepsies.

Starting stiripentol in adults with Dravet syndrome? Watch for ammonia and carnitine.

OBJECTIVE: Dravet syndrome (DS) is a rare cause of severe and pharmacoresistant epileptic encephalopathy. Stiripentol (STP) has a significant therapeutic benefit in the pediatric DS population. However, STP effects on adult patients have not been well studied. In our adult STP-naive DS patient population, STP initiation was associated with encephalopathy, despite decreases in valproate and clobazam dosage. Here we explored the cause and treatment of encephalopathic manifestations associated with STP in adults. METHODS: Twenty-eight patients with a confirmed clinical and genetic diagnosis of DS who attended the Adult Epilepsy Genetics Clinic were identified retrospectively. Patients who declined or discontinued STP after fewer than 3 months of use, patients who were deceased before starting STP or seizure-free when the genetic diagnosis was confirmed, and those who started STP before leaving the pediatric system (<18 years) were excluded. Levels of ammonia, carnitine, and other anti-epileptic drugs (AEDs) were observed for patients receiving STP. Patients with high ammonia levels who received carnitine supplementation were reevaluated. They were also offered an increased dosage of stiripentol if treatment with carnitine improved the encephalopathy. RESULTS: We observed hyperammonemic encephalopathy in 77% of patients treated with STP. In seven of nine patients, we observed a rate of improvement in ammonia levels of 35% (95% confidence interval [CI] 21%-49%) at a mean carnitine dose of 991 ± 286 mg/d (range 660-1320 mg/d). Five patients whose ammonia levels normalized were also offered an increase in STP dose and they were able to tolerate higher doses with improvement in side effects. Despite such adjustments, the mean maximum stiripentol dose reached was 14.89 ± 8.72 mg/kg/d, which is lower than what is typically recommended in children (50 mg/kg/d). SIGNIFICANCE: We report hyperammonemia in adult STP-naive patients who were on valproate and clobazam, despite dose reduction of the latter drugs. We also report that treatment with carnitine improved hyperammonemia, allowing the continuation of STP.

Seizures and early onset dementia: D2HGA1 inborn error of metabolism in adults.

D-2-hydroxyglutaric aciduria type 1 (D2HGA1) is a rare inherited metabolic disorder usually manifesting in infancy/early childhood with seizures and significant central nervous system involvement. We report two siblings with D2HGA1 presenting with mild intellectual disability, and the onset of seizures in adulthood. One of them was misdiagnosed as tuberous sclerosis due to her presentation and the presence of subependymal nodules on brain imaging. Both further developed early onset dementia. This report expands the phenotype of D2HGA1 to include late-onset seizures and early onset dementia in adults.

The liver X receptor agonist GW3965 improves recovery from mild repetitive traumatic brain injury in mice partly through apolipoprotein E.

Traumatic brain injury (TBI) increases Alzheimer's disease (AD) risk and leads to the deposition of neurofibrillary tangles and amyloid deposits similar to those found in AD. Agonists of Liver X receptors (LXRs), which regulate the expression of many genes involved in lipid homeostasis and inflammation, improve cognition and reduce neuropathology in AD mice. One pathway by which LXR agonists exert their beneficial effects is through ATP-binding cassette transporter A1 (ABCA1)-mediated lipid transport onto apolipoprotein E (apoE). To test the therapeutic utility of this pathway for TBI, we subjected male wild-type (WT) and apoE-/- mice to mild repetitive traumatic brain injury (mrTBI) followed by treatment with vehicle or the LXR agonist GW3965 at 15 mg/kg/day. GW3965 treatment restored impaired novel object recognition memory in WT but not apoE-/- mice. GW3965 did not significantly enhance the spontaneous recovery of motor deficits observed in all groups. Total soluble Aß(40) and Aß(42) levels were significantly elevated in WT and apoE-/- mice after injury, a response that was suppressed by GW3965 in both genotypes. WT mice showed mild but significant axonal damage at 2 d post-mrTBI, which was suppressed by GW3965. In contrast, apoE-/- mice showed severe axonal damage from 2 to 14 d after mrTBI that was unresponsive to GW3965. Because our mrTBI model does not produce significant inflammation, the beneficial effects of GW3965 we observed are unlikely to be related to reduced inflammation. Rather, our results suggest that both apoE-dependent and apoE-independent pathways contribute to the ability of GW3965 to promote recovery from mrTBI.

Hypoglycemia-occipital syndrome: a specific neurologic syndrome following neonatal hypoglycemia?

This study attempted to elaborate the existence of a specific neurologic pattern observed in children who experienced neonatal hypoglycemia. Twenty-seven patients with seizure and history of neonatal hypoglycemia were compared with 28 children suffering from idiopathic occipital epilepsy. In both groups the most common type of seizure activities included eye movements and impaired consciousness responding well to treatment; however, ictal vomiting was more common in controls. Subjects were in epileptic and nonepileptic groups. Ninety percent of cases showed abnormal signal of the posterior head region on magnetic resonance imaging (MRI). A large number showed posterior abnormalities on electroencephalography (EEG). Visual loss with abnormal visual evoked potential was the most frequent visual finding. Fifty-five percent showed mild psychomotor retardation. This study demonstrates that neonatal hypoglycemia can induce a syndrome with a specific clinical spectrum consisting of epilepsy, visual disturbances, and psychomotor retardation. Hypoglycemia-occipital syndrome is an entity without statistically significant semiologic differences from the idiopathic type.