Novel risk loci in LGI1-antibody encephalitis: genome-wide association study discovery and validation cohorts.

Encephalitis with antibodies to leucine-rich glioma-inactivated 1 (LGI1-Ab-E) is a common form of autoimmune encephalitis, presenting with seizures and neuropsychiatric changes, predominantly in older males. More than 90% of patients carry the human leucocyte antigen (HLA) class II allele, HLA-DRB1*07:01. However, this is also present in 25% of healthy controls. Therefore, we hypothesised the presence of additional genetic predispositions. In this genome-wide association study and meta-analysis, we studied a discovery cohort of 131 French LGI1-Ab-E and a validation cohort of 126 American, British and Irish LGI1-Ab-E patients, ancestry-matched to 2613 and 2538 European controls, respectively. Outside the known major HLA signal, we found two single nucleotide polymorphisms (SNPs) at genome-wide significance (p < 5 x 10-8), implicating PTPRD, a protein tyrosine phosphatase, and LINC00670, a non-protein coding RNA gene. Meta-analysis defined four additional non-HLA loci, including the protein coding COBL gene. Polygenic risk scores with and without HLA variants proposed a contribution of non-HLA loci. In silico network analyses suggested LGI1 and PTPRD mediated interactions via the established receptors of LGI1, ADAM22 and ADAM23. Our results identify new genetic loci in LGI1-Ab-E. These findings present opportunities for mechanistic studies and offer potential markers of susceptibility, prognostics and therapeutic responses.

Serum neuronal exosomes predict and differentiate Parkinson's disease from atypical parkinsonism.

OBJECTIVE: Parkinson's disease is characterised neuropathologically by α-synuclein aggregation. Currently, there is no blood test to predict the underlying pathology or distinguish Parkinson's from atypical parkinsonian syndromes. We assessed the clinical utility of serum neuronal exosomes as biomarkers across the spectrum of Parkinson's disease, multiple system atrophy and other proteinopathies. METHODS: We performed a cross-sectional study of 664 serum samples from the Oxford, Kiel and Brescia cohorts consisting of individuals with rapid eye movement sleep behavioural disorder, Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, frontotemporal dementia, progressive supranuclear palsy, corticobasal syndrome and controls. Longitudinal samples were analysed from Parkinson's and control individuals. We developed poly(carboxybetaine-methacrylate) coated beads to isolate L1 cell adhesion molecule (L1CAM)-positive extracellular vesicles with characteristics of exosomes and used mass spectrometry or multiplexed electrochemiluminescence to measure exosomal proteins. RESULTS: Mean neuron-derived exosomal α-synuclein was increased by twofold in prodromal and clinical Parkinson's disease when compared with multiple system atrophy, controls or other neurodegenerative diseases. With 314 subjects in the training group and 105 in the validation group, exosomal α-synuclein exhibited a consistent performance (AUC=0.86) in separating clinical Parkinson's disease from controls across populations. Exosomal clusterin was elevated in subjects with non-α-synuclein proteinopathies. Combined neuron-derived exosomal α-synuclein and clusterin measurement predicted Parkinson's disease from other proteinopathies with AUC=0.98 and from multiple system atrophy with AUC=0.94. Longitudinal sample analysis showed that exosomal α-synuclein remains stably elevated with Parkinson's disease progression. CONCLUSIONS: Increased α-synuclein egress in serum neuronal exosomes precedes the diagnosis of Parkinson's disease, persists with disease progression and in combination with clusterin predicts and differentiates Parkinson's disease from atypical parkinsonism.

Multiomics Analyses Identify Genes and Pathways Relevant to Essential Tremor.

INTRODUCTION: The genetic factors and molecular mechanisms predisposing to essential tremor (ET) remains largely unknown. OBJECTIVE: The objective of this study was to identify pathways and genes relevant to ET by integrating multiomics approaches. METHODS: Case-control RNA sequencing of 2 cerebellar regions was done for 64 samples. A phenome-wide association study (pheWAS) of the differentially expressed genes was conducted, and a genome-wide gene association study (GWGAS) was done to identify pathways overlapping with the transcriptomic data. Finally, a transcriptome-wide association study (TWAS) was done to identify novel risk genes for ET. RESULTS: We identified several novel dysregulated genes, including CACNA1A and SHF. Pathways including axon guidance, olfactory loss, and calcium channel activity were significantly enriched. The ET GWGAS data found calcium ion-regulated exocytosis of neurotransmitters to be significantly enriched. The TWAS also found calcium and olfactory pathways enriched. The pheWAS identified that the underexpressed differentially expressed gene, SHF, is associated with a blood pressure medication (P = 9.3E-08), which is used to reduce tremor in ET patients. Treatment of cerebellar DAOY cells with the ET drug propranolol identified increases in SHF when treated, suggesting it may rescue the underexpression. CONCLUSION: We found that calcium-related pathways were enriched across the GWGAS, TWAS, and transcriptome. SHF was shown to have significantly decreased expression, and the pheWAS showed it was associated with blood pressure medication. The treatment of cells with propranolol showed that the drug restored levels of SHF. Overall, our findings highlight the power of integrating multiple different approaches to prioritize ET pathways and genes. © 2020 International Parkinson and Movement Disorder Society.

Clusterin/Apolipoprotein J immunoreactivity is associated with white matter damage in cerebral small vessel diseases.

AIM: Brain clusterin is known to be associated with the amyloid-ß deposits in Alzheimer's disease (AD). We assessed the distribution of clusterin immunoreactivity in cerebrovascular disorders, particularly focusing on white matter changes in small vessel diseases. METHODS: Post-mortem brain tissues from the frontal or temporal lobes of a total of 70 subjects with various disorders including cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral amyloid angiopathy (CAA) and AD were examined using immunohistochemistry and immunofluorescence. We further used immunogold electron microscopy to study clusterin immunoreactivity in extracellular deposits in CADASIL. RESULTS: Immunostaining with clusterin antibodies revealed strong localization in arterioles and capillaries, besides cortical neurones. We found that clusterin immunostaining was significantly increased in the frontal white matter of CADASIL and pontine autosomal dominant microangiopathy and leukoencephalopathy subjects. In addition, clusterin immunostaining correlated with white matter pathology severity scores. Immunostaining in axons ranged from fine punctate deposits in single axons to larger confluent areas with numerous swollen axon bulbs, similar to that observed with known axon damage markers such as non-phosphorylated neurofilament H and the amyloid precursor protein. Immunofluorescence and immunogold electron microscopy experiments showed that whereas clusterin immunoreactivity was closely associated with vascular amyloid-ß in CAA, it was lacking within the granular osmiophilic material immunolabelled by NOTCH3 extracelluar domain aggregates found in CADASIL. CONCLUSIONS: Our results suggest a wider role for clusterin associated with white matter damage in addition to its ability to chaperone proteins for clearance via the perivascular drainage pathways in several disease states.

Neurofilament light (NfL) as biomarker in serum and CSF in status epilepticus.

OBJECTIVE: We explored the potential of neurofilament light chain (NfL) in serum and cerebrospinal fluid as a biomarker for neurodestruction in status epilepticus. METHODS: In a retrospective analysis, we measured NfL in serum and cerebrospinal fluid samples of patients with status epilepticus using a highly sensitive single-molecule array technique (Simoa). Status epilepticus was diagnosed according to ILAE criteria. Additionally, we employed an alternative classification with more emphasis on the course of status epilepticus. We used data from three large control groups to compare NfL in status epilepticus versus neurologically healthy controls. RESULTS: We included 28 patients (mean age: 69.4 years, SD: 15 years) with a median status duration of 44 h (IQR: 80 h). Twenty-one patients (75%) suffered from convulsive status epilepticus and seven (25%) from non-convulsive status epilepticus. Six patients died (21%). Cerebrospinal fluid and serum NfL concentrations showed a high correlation (r = 0.73, p < 0.001, Pearson). The main determinant of NfL concentration was the status duration. NfL concentrations did not differ between convulsive status epilepticus and convulsive status epilepticus classified according to the ILAE or to the alternative classification without and with adjusting for status duration and time between status onset and sampling. We found no association of NfL concentration with death, treatment refractoriness, or prognostic scores. CONCLUSION: The results suggest that neurodestruction in status epilepticus measured by NfL is mainly determined by status duration, not status type nor therapy refractoriness. Therefore, our results suggest that regarding neurodestruction convulsive and non-convulsive status epilepticus are both neurological emergencies of comparable urgency.

Polymorphisms and noncardioembolic stroke in three case-control studies.

BACKGROUND: Gene variants associated with disease could reveal novel mechanisms. We searched for single nucleotide polymorphisms (SNPs) associated with noncardioembolic stroke (nonCES). METHODS: We tested 24,926 SNPs in or near genes for association with nonCES in the Vienna Study (551 cases, 815 controls) and then evaluated the associated SNPs in the UCSF-CC Study (570 cases, 1,604 controls) first in pooled DNA samples and then in individual DNA samples. We then asked whether the risk alleles of the SNPs associated with increased risk in both studies were also associated with increased risk of nonCES in the German Study (728 cases, 1,041 controls). RESULTS: Six of the 46 SNPs that were associated with nonCES in both the Vienna and the UCSF-CC Studies were also associated with nonCES in the German Study: rs362277 in HTT (OR 1.39, 90% CI 1.12-1.71), rs2924914 near CSMD1 (OR 1.22, 90% CI 1.04-1.43), rs1264352 near DDR1 (OR 1.20, 90% CI 1.02-1.41), rs544115 in NEU3 (OR 1.63, 90% CI 1.02-2.62), rs12481805 in UMODL1 (OR 1.31, 90% CI 1.01-1.81), and rs2857595 near NCR3 (OR 1.15, 90% CI 1.00-1.32). Accounting for multiple testing of 46 SNPs, these 6 SNPs had a false discovery rate of 0.69. CONCLUSIONS: Some of the 6 SNPs may be associated with nonCES but most may be false positives. These 6 SNPs merit investigation in additional nonCES study populations.

Genetic variants in the C-reactive protein gene are associated with microangiopathic ischemic stroke.

BACKGROUND AND PURPOSE: C-reactive protein (CRP) is an independent risk factor for cardiovascular disease and ischemic stroke. CRP serum levels are influenced by genetic variation in the CRP gene. Studies investigating the relationship between ischemic stroke and polymorphisms in the CRP gene produced equivocal results. Here we investigate single-nucleotide polymorphisms (SNPs) in the CRP gene in a large German ischemic stroke sample. METHODS: In a case-control design, 1,669 patients with ischemic stroke due to large-artery atherosclerosis, cardioembolism or cerebral microangiopathy were genotyped for 4 haplotype tagging SNPs (rs3093075, rs1205, rs1130864 and rs1800947) in the CRP gene which have been shown to influence CRP serum concentrations. Geographically matched controls were drawn from 2 prospective population-based studies, the Dortmund Health Study and the Study of Health in Pomerania. The genetic association between the SNPs and stroke was assessed using SNP and haplotype approaches. Results were adjusted for covariates by logistic regression. RESULTS: All 4 CRP SNPs reside in one linkage disequilibrium block. None of the SNPs or SNP haplotypes were associated with ischemic stroke as a whole. Three SNPs (rs3093075, rs1130864 and rs1800947) showed a significant association with microangiopathic stroke. A common 4-SNP haplotype was protective while 2 rarer haplotypes conferred susceptibility to microangiopathic stroke. All associations remained significant after adjustment for sex, age, hypertension, diabetes mellitus and hypercholesterolemia and after correction for multiple testing using the 'false discovery rate' method. CONCLUSION: Genetic variation in the CRP gene is associated with microangiopathic but not macroangiopathic or cardioembolic stroke in a large German stroke sample.

Neurosonographical follow-up in patients with spontaneous cervical artery dissection.

OBJECTIVE: Neurovascular ultrasound (nUS) is widely used as a screening and monitoring tool in patients with spontaneous cervical artery dissection (sCAD). The aim of the study was to describe the sonographical course of the affected arteries in patients with a MRI-proven sCAD by repetitive nUS. METHODS: Thirty-seven consecutive patients aged<60 years with 1.5 T MRI-proven sCAD were prospectively investigated by nUS, and within 48 hours after admission before MRI. The patients were re-investigated after 6 months and again after a period>12 months. RESULTS: Forty-nine sCAD were detected in 37 patients; 24 lesions (49%) were located in the internal carotid arteries (ICA), and 25 (51%) in the vertebral arteries (VA). An arterial occlusion was found in 13 arteries (27%). The recanalization rate of occluded arteries was 62%. Regression of stenosis/occlusion within the first 6 months was found in 34 (69%) of the affected arteries, while between 6 and >12 months, the improvement rate was lower (19%). A complete recanalization without residual stenosis after 6 months was found in 39%. In only one artery, initial high grade ICA stenosis progressed to complete persistent occlusion (2%). DISCUSSION: The course of arterial stenosis or occlusion caused by sCAD is highly dynamic during the first 6 month after the event. The vast majority of arteries show regression of stenosis or recanalization of initial occlusion. Only a minority of patients experience a persistent deterioration of the vessel status.

Analysis of blood-based gene expression in idiopathic Parkinson disease.

OBJECTIVE: To examine whether gene expression analysis of a large-scale Parkinson disease (PD) patient cohort produces a robust blood-based PD gene signature compared to previous studies that have used relatively small cohorts (≤220 samples). METHODS: Whole-blood gene expression profiles were collected from a total of 523 individuals. After preprocessing, the data contained 486 gene profiles (n = 205 PD, n = 233 controls, n = 48 other neurodegenerative diseases) that were partitioned into training, validation, and independent test cohorts to identify and validate a gene signature. Batch-effect reduction and cross-validation were performed to ensure signature reliability. Finally, functional and pathway enrichment analyses were applied to the signature to identify PD-associated gene networks. RESULTS: A gene signature of 100 probes that mapped to 87 genes, corresponding to 64 upregulated and 23 downregulated genes differentiating between patients with idiopathic PD and controls, was identified with the training cohort and successfully replicated in both an independent validation cohort (area under the curve [AUC] = 0.79, p = 7.13E-6) and a subsequent independent test cohort (AUC = 0.74, p = 4.2E-4). Network analysis of the signature revealed gene enrichment in pathways, including metabolism, oxidation, and ubiquitination/proteasomal activity, and misregulation of mitochondria-localized genes, including downregulation of COX4I1, ATP5A1, and VDAC3. CONCLUSIONS: We present a large-scale study of PD gene expression profiling. This work identifies a reliable blood-based PD signature and highlights the importance of large-scale patient cohorts in developing potential PD biomarkers.

Quantitative vascular pathology and phenotyping familial and sporadic cerebral small vessel diseases.

We quantified vascular changes in the frontal lobe and basal ganglia of four inherited small vessel diseases (SVDs) including cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), pontine autosomal dominant microangiopathy and leukoencephalopathy (PADMAL), hereditary multi-infarct dementia of Swedish type (Swedish hMID), and hereditary endotheliopathy with retinopathy, nephropathy, and stroke (HERNS). Vascular pathology was most severe in CADASIL, and varied with marginally greater severity in the basal ganglia compared to the frontal lobe. The overall sclerotic index values in frontal lobe were in the order CADASIL ≥ HERNS > PADMAL > Swedish hMID > sporadic SVD, and in basal ganglia CADASIL > HERNS > Swedish hMID > PADMAL> sporadic SVD. The subcortical white matter was almost always more affected than any gray matter. We observed glucose transporter-1 (GLUT-1) protein immunoreactivities were most affected in the white matter indicating capillary degeneration whereas collagen IV (COL4) immunostaining was increased in PADMAL cases in all regions and tissue types. Overall, GLUT-1 : COL4 ratios were higher in the basal ganglia indicating modifications in capillary density compared to the frontal lobe. Our study shows that the extent of microvascular degeneration varies in these genetic disorders exhibiting common end-stage pathologies but is the most aggressive in CADASIL.