SLC6A1 variant pathogenicity, molecular function and phenotype: a genetic and clinical analysis.

Genetic variants in the SLC6A1 gene can cause a broad phenotypic disease spectrum by altering the protein function. Thus, systematically curated clinically relevant genotype-phenotype associations are needed to understand the disease mechanism and improve therapeutic decision-making. We aggregated genetic and clinical data from 172 individuals with likely pathogenic/pathogenic (lp/p) SLC6A1 variants and functional data for 184 variants (14.1% lp/p). Clinical and functional data were available for a subset of 126 individuals. We explored the potential associations of variant positions on the GAT1 3D structure with variant pathogenicity, altered molecular function and phenotype severity using bioinformatic approaches. The GAT1 transmembrane domains 1, 6 and extracellular loop 4 (EL4) were enriched for patient over population variants. Across functionally tested missense variants (n = 156), the spatial proximity from the ligand was associated with loss-of-function in the GAT1 transporter activity. For variants with complete loss of in vitro GABA uptake, we found a 4.6-fold enrichment in patients having severe disease versus non-severe disease (P = 2.9 × 10-3, 95% confidence interval: 1.5-15.3). In summary, we delineated associations between the 3D structure and variant pathogenicity, variant function and phenotype in SLC6A1-related disorders. This knowledge supports biology-informed variant interpretation and research on GAT1 function. All our data can be interactively explored in the SLC6A1 portal (https://slc6a1-portal.broadinstitute.org/).

The genomic landscape across 474 surgically accessible epileptogenic human brain lesions.

Understanding the exact molecular mechanisms involved in the aetiology of epileptogenic pathologies with or without tumour activity is essential for improving treatment of drug-resistant focal epilepsy. Here, we characterize the landscape of somatic genetic variants in resected brain specimens from 474 individuals with drug-resistant focal epilepsy using deep whole-exome sequencing (>350×) and whole-genome genotyping. Across the exome, we observe a greater number of somatic single-nucleotide variants in low-grade epilepsy-associated tumours (7.92 ± 5.65 single-nucleotide variants) than in brain tissue from malformations of cortical development (6.11 ± 4 single-nucleotide variants) or hippocampal sclerosis (5.1 ± 3.04 single-nucleotide variants). Tumour tissues also had the largest number of likely pathogenic variant carrying cells. low-grade epilepsy-associated tumours had the highest proportion of samples with one or more somatic copy-number variants (24.7%), followed by malformations of cortical development (5.4%) and hippocampal sclerosis (4.1%). Recurring somatic whole chromosome duplications affecting Chromosome 7 (16.8%), chromosome 5 (10.9%), and chromosome 20 (9.9%) were observed among low-grade epilepsy-associated tumours. For germline variant-associated malformations of cortical development genes such as TSC2, DEPDC5 and PTEN, germline single-nucleotide variants were frequently identified within large loss of heterozygosity regions, supporting the recently proposed 'second hit' disease mechanism in these genes. We detect somatic variants in 12 established lesional epilepsy genes and demonstrate exome-wide statistical support for three of these in the aetiology of low-grade epilepsy-associated tumours (e.g. BRAF) and malformations of cortical development (e.g. SLC35A2 and MTOR). We also identify novel significant associations for PTPN11 with low-grade epilepsy-associated tumours and NRAS Q61 mutated protein with a complex malformation of cortical development characterized by polymicrogyria and nodular heterotopia. The variants identified in NRAS are known from cancer studies to lead to hyperactivation of NRAS, which can be targeted pharmacologically. We identify large recurrent 1q21-q44 duplication including AKT3 in association with focal cortical dysplasia type 2a with hyaline astrocytic inclusions, another rare and possibly under-recognized brain lesion. The clinical-genetic analyses showed that the numbers of somatic single-nucleotide variant across the exome and the fraction of affected cells were positively correlated with the age at seizure onset and surgery in individuals with low-grade epilepsy-associated tumours. In summary, our comprehensive genetic screen sheds light on the genome-scale landscape of genetic variants in epileptic brain lesions, informs the design of gene panels for clinical diagnostic screening and guides future directions for clinical implementation of epilepsy surgery genetics.

Predictive models for starting antiseizure medication withdrawal following epilepsy surgery in adults.

More than half of adults with epilepsy undergoing resective epilepsy surgery achieve long-term seizure freedom and might consider withdrawing antiseizure medications. We aimed to identify predictors of seizure recurrence after starting postoperative antiseizure medication withdrawal and develop and validate predictive models. We performed an international multicentre observational cohort study in nine tertiary epilepsy referral centres. We included 850 adults who started antiseizure medication withdrawal following resective epilepsy surgery and were free of seizures other than focal non-motor aware seizures before starting antiseizure medication withdrawal. We developed a model predicting recurrent seizures, other than focal non-motor aware seizures, using Cox proportional hazards regression in a derivation cohort (n = 231). Independent predictors of seizure recurrence, other than focal non-motor aware seizures, following the start of antiseizure medication withdrawal were focal non-motor aware seizures after surgery and before withdrawal [adjusted hazard ratio (aHR) 5.5, 95% confidence interval (CI) 2.7-11.1], history of focal to bilateral tonic-clonic seizures before surgery (aHR 1.6, 95% CI 0.9-2.8), time from surgery to the start of antiseizure medication withdrawal (aHR 0.9, 95% CI 0.8-0.9) and number of antiseizure medications at time of surgery (aHR 1.2, 95% CI 0.9-1.6). Model discrimination showed a concordance statistic of 0.67 (95% CI 0.63-0.71) in the external validation cohorts (n = 500). A secondary model predicting recurrence of any seizures (including focal non-motor aware seizures) was developed and validated in a subgroup that did not have focal non-motor aware seizures before withdrawal (n = 639), showing a concordance statistic of 0.68 (95% CI 0.64-0.72). Calibration plots indicated high agreement of predicted and observed outcomes for both models. We show that simple algorithms, available as graphical nomograms and online tools (predictepilepsy.github.io), can provide probabilities of seizure outcomes after starting postoperative antiseizure medication withdrawal. These multicentre-validated models may assist clinicians when discussing antiseizure medication withdrawal after surgery with their patients.

Novel de novo TREX1 mutation in a patient with retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations mimicking demyelinating disease.

Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a rare fatal autosomal dominant vasculopathy associated with mutations in the TREX1 gene. Only one de novo case has been reported in the literature. We report the long-term clinical, radiological, and pathological presentation of a patient with a de novo and novel mutation in this gene. Description of the clinical, genetic, imaging and pathologic characteristics is important to better characterize RVCL-S and prevent unnecessary interventions. RVCL-S should be considered in patients with tumefactive brain lesions unresponsive to immunotherapy.

Early age of onset predicts severity of visual impairment in patients with neuromyelitis optica spectrum disorder.

BACKGROUND: Severe residual visual loss (SRVL) is frequent in neuromyelitis optica spectrum disorders (NMOSD). Identifying higher-risk patients at onset is important to prevent disability accumulation. OBJECTIVE: To determine predictors of SRVL in a large NMOSD cohort. METHODS: Patient characteristics at last visual acuity (VA) evaluation were retrospectively collected. VA was scored 0: better than 20/40, 1: 20/40-20/99, 2: 20/100-20/200, and 3: worse than 20/200. SRVL was defined as a combined score (VA worst + best eye) ⩾ 4. Descriptive statistics were used to compare groups and logistic regression to evaluate predictors of VA. RESULTS: 106 patients (mean age at disease onset (AO): 35.8 ± 16.5 years) were included. Patients with SRVL had earlier AO (mean: 26.7 vs 38.0 years) compared to non-SRVL group (p = 0.005). Patients with AO < 21 years were more likely to have SRVL, be blind, present with binocular optic neuritis, have recurrent optic neuritis, and receive oral therapy first-line than those with AO ⩾ 21. After adjusting for race, sex, and disease duration, the odds of SRVL were 4.68 times higher in patients < 21 at disease onset (95% CI: 1.53-14.34, p = 0.007). CONCLUSION: Early AO predicts SRVL in NMOSD, independent of disease duration. High-efficacy therapies should be considered for first-line treatment in this group.

Cerebrovascular complications and vasculopathy in patients with herpes simplex virus central nervous system infection.

OBJECTIVE: Herpes simplex viruses (HSV) are neurotropic and known to cause central nervous system (CNS) infections. We aimed to describe the clinical and imaging features of cerebrovascular complications in patients with HSV CNS infections. METHODS: We reviewed records of patients with HSV infections by querying acyclovir use in a clinical registry of parenteral anti-infective therapy at a tertiary medical center from January 2010 until September 2018. One patient who met the inclusion criteria is subsequently added. Diagnostic criteria for HSV CNS infection were intrathecal presence of viral DNA with clinical signs of CNS involvement. RESULTS: Of 36 patients who met the criteria for HSV CNS infections, cerebrovascular complications occurred in 6 patients (17%). Two patients with HSV-1 encephalitis had cerebrovascular complications (1 ischemic stroke, 1 intraparenchymal hemorrhage). Four patients had HSV-2 infection without encephalitis had cerebrovascular complications (3 ischemic strokes, 1 cerebral vein thrombosis). All 3 patients with ischemic strokes without encephalitis had pattern of vasculitis on vessel imaging on MRI with segmental narrowing and vessel wall irregularities of large intracranial arteries with circumferential wall enhancement. CONCLUSION: Cerebrovascular complications of HSV can occur with encephalitis or as isolated events with vasculitis.

Outcomes of Chronic Phase Chronic Myeloid Leukemia after Treatment with Multiple Tyrosine Kinase Inhibitors.

We sought to evaluate the outcomes of chronic phase (CP) chronic myeloid leukemia (CML) in an era where five tyrosine kinase inhibitors (TKIs) are commercially available for the treatment of CML. Records of patients diagnosed with CP CML, treated with TKIs and referred to our center were reviewed. Between January 2005 and April 2016, 206 patients were followed for a median of 48.8 (1.4-190.1) months. A total of 76 (37%) patients received one TKI, 73 (35%) received two TKIs and 57 (28%) were exposed to >3 TKIs (3 TKIs, n = 33; 4 TKIs, n = 17; 5 TKIs, n = 7). Nineteen (9.2%) patients progressed to advanced phases of CML (accelerated phase, n = 6; myeloid blastic phase, n = 4; lymphoid blastic phase, n = 9). One third (n = 69) achieved complete molecular response (CMR) at first-line treatment. An additional 55 patients achieved CMR after second-line treatment. Twenty-five patients (12.1%) attempted TKI discontinuation and 14 (6.8%) stopped TKIs for a median of 6.3 months (range 1-53.4). The 10-year progression-free survival and overall survival (OS) rates were 81% and 87%, respectively. OS after 10-years, based on TKI exposure, was 100% (1 TKI), 82% (2 TKIs), 87% (3 TKIs), 75% (4 TKIs) and 55% (5 TKIs). The best OS was observed in patients tolerating and responding to first line TKI, but multiple TKIs led patients to gain treatment-free remission.

Clinical course of infectious intracranial aneurysm undergoing antibiotic treatment.

INTRODUCTION: Infectious intracranial aneurysm (IIA, or mycotic aneurysm) is a cerebrovascular complication of infective endocarditis. We aimed to describe the clinical course of IIAs during antibiotic treatment. METHODS: We reviewed medical records of persons with infective endocarditis who underwent cerebral angiography at a single tertiary referral center from 2011 to 2016. Aneurysms were followed with subsequent angiography for unfavorable outcome (growth, rupture, no change, or new IIA formation) or favorable outcome (regression or resolution) until endovascular therapy, aneurysm resolution, or end of observation. RESULTS: Of 618 patients included, 40 (6.5%) had 43 IIAs. Eighteen (42%) aneurysms underwent initial endovascular treatment. Twenty-five unruptured aneurysms were followed for a median 18 antibiotic days after IIA discovery (interquartile range [IQR] 4-32). Eleven (44%) aneurysms had unfavorable outcome (1 rupture, 2 new IIA formation, 6 enlargement, and 2 no change) at median 21 days (IQR 5-32). Favorable angiographic outcome was seen in 7 (28%) patients (6 resolution, 1 regression) at median 36 days (IQR 24-41). Seven aneurysms had no angiographic reevaluations but showed no evidence of rupture during clinical follow-up for median 4 days (IQR 3-12) until hospital discharge. Saccular morphology was associated with unfavorable aneurysmal outcome (p = 0.013). Longer duration of antibiotic exposure prior to IIA discovery was associated with favorable aneurysmal outcome (p = 0.046). CONCLUSION: IIAs represent a dynamic disease. Only a quarter of IIAs resolve with antibiotics alone. Saccular aneurysmal morphology might predict unfavorable aneurysmal outcome. IIA found after longer antibiotic therapy has higher likelihood of resolution or regression on antibiotic treatment.

Magnetic Resonance Imaging Susceptibility-Weighted Imaging Lesion and Contrast Enhancement May Represent Infectious Intracranial Aneurysm in Infective Endocarditis.

BACKGROUND: Infectious intracranial aneurysm (IIA) can complicate infective endocarditis (IE). We aimed to describe the magnetic resonance imaging (MRI) characteristics of IIA. METHODS: We reviewed IIAs among 116 consecutive patients with active IE by conducting a neurological evaluation at a single tertiary referral center from January 2015 to July 2016. MRIs and digital cerebral angiograms (DSA) were reviewed to identify MRI characteristics of IIAs. MRI susceptibility weighted imaging (SWI) was performed to collect data on cerebral microbleeds (CMBs) and sulcal SWI lesions. RESULTS: Out of 116 persons, 74 (63.8%) underwent DSA. IIAs were identified in 13 (17.6% of DSA, 11.2% of entire cohort) and 10 patients with aneurysms underwent MRI with SWI sequence. Nine (90%) out of 10 persons with IIAs had CMB >5 mm or sulcal lesions in SWI (9 in sulci, 6 in parenchyma, and 5 in both). Five out of 8 persons who underwent MRI brain with contrast had enhancement within the SWI lesions. In a multivariate logistic regression analysis, both sulcal SWI lesions (p < 0.001, OR 69, 95% CI 7.8-610) and contrast enhancement (p = 0.007, OR 16.5, 95% CI 2.3-121) were found to be significant predictors of the presence of IIAs. CONCLUSIONS: In the individuals with IE who underwent DSA and MRI, we found that neuroimaging characteristics, such as sulcal SWI lesion with or without contrast enhancement, are associated with the presence of IIA.

Phase 1 dose-finding study of rebastinib (DCC-2036) in patients with relapsed chronic myeloid leukemia and acute myeloid leukemia.

A vailable tyrosine kinase inhibitors for chronic myeloid leukemia bind in an adenosine 5'-triphosphate-binding pocket and are affected by evolving mutations that confer resistance. Rebastinib was identified as a switch control inhibitor of BCR-ABL1 and FLT3 and may be active against resistant mutations. A Phase 1, first-in-human, single-agent study investigated rebastinib in relapsed or refractory chronic or acute myeloid leukemia. The primary objectives were to investigate the safety of rebastinib and establish the maximum tolerated dose and recommended Phase 2 dose. Fifty-seven patients received treatment with rebastinib. Sixteen patients were treated using powder-in-capsule preparations at doses from 57 mg to 1200 mg daily, and 41 received tablet preparations at doses of 100 mg to 400 mg daily. Dose-limiting toxicities were dysarthria, muscle weakness, and peripheral neuropathy. The maximum tolerated dose was 150 mg tablets administered twice daily. Rebastinib was rapidly absorbed. Bioavailability was 3- to 4-fold greater with formulated tablets compared to unformulated capsules. Eight complete hematologic responses were achieved in 40 evaluable chronic myeloid leukemia patients, 4 of which had a T315I mutation. None of the 5 patients with acute myeloid leukemia responded. Pharmacodynamic analysis showed inhibition of phosphorylation of substrates of BCR-ABL1 or FLT3 by rebastinib. Although clinical activity was observed, clinical benefit was insufficient to justify continued development in chronic or acute myeloid leukemia. Pharmacodynamic analyses suggest that other kinases inhibited by rebastinib, such as TIE2, may be more relevant targets for the clinical development of rebastinib (clinicaltrials.gov Identifier:00827138).

The Use of the Pipeline Embolization Device in the Management of Recurrent Previously Coiled Cerebral Aneurysms.

BACKGROUND: The biggest downside of cerebral aneurysm coiling is the high rates of recurrence and retreatments. With the increasing number of aneurysm recurrences after failed coiling procedures, the best retreatment strategy remains unknown. OBJECTIVE: To assess the efficacy and safety of the Pipeline Embolization Device (PED) in the treatment of recurrent previously coiled aneurysms. METHODS: Thirty-three patients who underwent treatment with the PED of a recurrent previously coiled aneurysm were retrospectively identified. Efficacy was assessed in terms of angiographic occlusion at the latest cerebral angiogram, recurrence and retreatment rates after PED placement, and clinical outcome at the latest follow-up. Safety was assessed by looking at the complications, morbidity, and mortality after PED treatment. RESULTS: The mean patient age was 53 years. The mean percent recurrence from coiling to PED placement was 34%. The mean time from coiling to PED placement was 40 months. PED treatment resulted in complete aneurysm occlusion in 76.7% of patients and near-complete aneurysm occlusion (≥90%) in 10%, for a total rate of complete and near-complete aneurysm occlusion of 86.7%. All patients, including those with incomplete aneurysm occlusion, had a significant reduction in aneurysm size. Two aneurysms required another retreatment after PED placement (6.2%). Ninety-seven percent of patients had a good clinical outcome. Complications were observed in 1 patient (3%), who suffered an intracerebral hemorrhage. There were no mortalities. CONCLUSION: The use of the PED in the management of recurrent, previously coiled aneurysms is safe and effective in achieving aneurysm occlusion.