Neurology Genetics

Background and Objectives: Vascular contributions to cognitive impairment and dementia (VCID) represent the second leading cause of dementia and a common comorbidity for reduced functional capacity in many individuals, but clinical management and clinical trial readiness are severely hindered by extreme phenotypic and mechanistic heterogeneity. This study establishes the baseline clinical, functional, and multimodal biomarker characteristics of the first United States (US) cohort of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), serving as a single-cause, monogenic small vessel disease model for sporadic VCID. Methods: Cross-sectional analysis of baseline data collected from October 2022 through January 2025 from a longitudinal cohort at 12 US enrollment sites. Adults from families with a documented NOTCH3 variant were recruited through clinical referrals, medical record review, advocacy organizations, and community outreach. Exclusion criteria included other conditions that prevented interpretation of findings and modified Rankin Scale (mRS) scores greater than 3. Central genetic characterization assigned persons with a pathogenic or likely pathogenic NOTCH3 variant to low-, medium-, or high-risk tiers based on epidermal growth factor-like repeat domains. Standardized assessments included clinical histories, exams, objective cognitive and physical assessments, self-reported, companion-reported, and clinician-rated measures, MRI, genetics, and proteomics acquired under harmonized protocols. Group comparisons used Fishers exact and Kruskal-Wallis tests. Multivariable regression used adjustment for age, sex, race, and education. Results: Of 560 participants completing baseline visits, 46 had variants of unknown significance, and 55 had pending genetic analyses. The analytic cohort included 343 persons with a CADASIL-causing NOTCH3 variant and 116 non-carrier family controls. Median age was 47.9 years (IQR 38.7-59.1), median education was 16 years (IQR 14-17), 62.5% were female, and 91.4% were White. Carriers were classified in CADASIL risk tiers: low (7.0%), medium (18.4%), or high (74.6%). Compared with controls, adjusted odds of classification into a more impaired CDR category were higher in all tiers (OR 2.55-5.08, 95% CI 1.22-11.34). Discussion: The US CADASIL Consortium has established a large, genetics-confirmed cohort spanning presymptomatic to moderate disease stages, providing a robust, harmonized platform to define early biomarker signatures and endpoints for targeted VCID therapies.

Familial recurrence of amyotrophic lateral sclerosis (ALS) or frontotemporal dementia (FTD) is the clinical cornerstone for assuming Mendelian, monogenic inheritance which informs genetic testing, counselling and gene-discovery strategies in standard practice. Polygenic inheritance can lead to familial clustering of ALS, while pathogenic variants with reduced penetrance may present sporadically in small, modern-day pedigrees. As both rare genetic variants and polygenic disease contribute to the occurrence of ALS, the accuracy of a positive family history to predict the underlying genetic architecture remains unknown. Using growing knowledge of the genetic architecture of ALS, we designed the APECS simulator: a large-scale pedigree simulator using historical demographic parameters, unifying frameworks for monogenic and polygenic disease models. We simulated 1,000,000 three-generation pedigrees and modelled ALS, FTD, and other dementias under both inheritance models. For index patients with ALS, we examined the performance of proposed familial ALS (fALS) definitions to predict the underlying genetic architecture. Simulation results were benchmarked against real-world population estimates, over a wide range of demographic and genetic parameters. We assessed the phenocopy rate for monogenic index patients, defined as relatives with polygenic ALS or a pathogenic allele from a different ancestor. Finally, we illustrated the value of distant relatedness among apparently sporadic, but monogenic ALS patients. Simulations generated 55.3 million individuals, yielding 5,431 ALS-affected index patients (16.4% monogenic). The proposed criterion for 'definite fALS' (2 or more relatives with ALS among relatives within two degrees) had a 31.1% sensitivity, while falsely classifying 10.0% of 'fALS' as monogenic. The sensitivity of 'definite fALS' was improved to 43.3% when also considering relatives with FTD. Considering any type of dementia raised the false positive rate to 35.9%. In total, 5.3% of monogenic index patients had a phenocopy with ALS in relatives up to the third degree. Of seemingly sporadic monogenic index patients, 83.1% had distant relatives with ALS/FTD up to the fifth degree. A family history provides limited accuracy for inferring genetic architecture in ALS. Considering unspecified dementias in the family history reduces this accuracy, while adding definite FTD improves accuracy. Relying on traditional fALS criteria risks both missing cases for genetic testing and treatments, and falsely alarming families with polygenic ALS. Given the limited value of a family history and risk of phenocopies, routine genetic testing regardless of family history and systematic approaches for detecting distant relatedness will help to find known and novel genetic causes in ALS.

Background: Hereditary spastic paraplegia (HSP) comprises a heterogeneous group of neurodegenerative disorders characterized by progressive lower-extremity weakness and spasticity, with or without additional neurological symptoms. Objectives: To characterize the molecular genetic spectrum, inheritance patterns, molecular finding rate, and clinical characteristics of HSP within a multicenter Canadian cohort. Methods: We investigated 671 patients from 423 families who met clinical criteria for HSP identified through the Canadian HSP (CanHSP) registry from 7 medical centers across Canada. Patients were evaluated using known HSP and HSP mimic gene panels, whereas unsolved and more recent patients underwent whole-exome sequencing (WES). 435 individuals underwent gene-panel testing and 485 underwent WES. Copy-number variants (CNVs) were assessed using ExomeDepth, and candidate CNVs using multiplex ligation-dependent probe amplification (MLPA). Results: Molecular findings were identified in 426 of 671 individuals (63.5%): 351 (52.3%) had HSP-associated findings, 70 (10.4%) HSP-mimicking disorders, and five (0.7%) other molecular findings; 245 (36.5%) remained unresolved. Candidate variants were found in 80 relevant genes, 36 of which were HSP-associated genes. The most frequently implicated genes were SPAST (22.5%), SPG7 (5.7%), ATL1 (5.2%), SPG11 (3.6%), and SPG8 (3.3%). Phenotypically, SPAST, ATL1, and SPG8 w[zg1.1]ere predominantly associated with pure HSP, whereas SPG7 and SPG11 more often showed complicated phenotypes, with prominent cerebellar involvement in SPG7 and cognitive and developmental features in SPG11. Conclusion: Patients in CanHSP present with genetic and phenotypic heterogeneity. Reanalysis and complementary approaches, including whole-genome, RNA, and long-read sequencing, may increase diagnostic yield.

Several polyglutamine-encoding repeat expansions cause spinocerebellar ataxias (SCAs) and other movement disorders. SCAs are genetically heterogeneous with a substantial diagnostic gap. We used genome sequencing data from 266 individuals of European and Asian ancestry and screened genome-wide for repeat expansions using STRling, a dedicated repeat expansion caller. The cohort comprised patients with movement disorders, predominantly dystonia and ataxia, as well as unaffected participants. Further, we screened another 436 individuals with ataxia and 427 ethnically matched controls through fragment analysis of the most promising candidate locus in EP400. We applied targeted long-read sequencing to expansion carriers and one control individual to resolve the sequence structure of the repeat locus. Finally, we used microsatellite markers in chromosome 12q24.32-33 to test for a common founder. A genome-wide outlier analysis in STRling revealed a polyglutamine-encoding repeat expansion (GRCh38 chr12:132,062,525-132,062,590) in the E1A binding protein p400 (EP400) gene in two patients with ataxia. Through screening of additional ataxia patients, we identified in total 18 patients from 14 families with heterozygous repeat expansions in EP400. All expansion carriers were from Serbia. The repeat number in affected individuals ranged from 37 to 55, whereas the longest control allele had 32 repeats. We demonstrated that non-expanded alleles carried a CAA interruption within the 5-prime CAG tract; this interruption was lost in expanded alleles. Expansion carriers have pure SCA with onset mainly in their 40s and 50s. There is an inverse correlation between the number of repeats and age at onset. The EP400-encoded protein plays an essential role in chromatin remodeling, epigenetic regulation and DNA repair. Pathogenic sequence variants in EP400 have previously been implicated in a neurodevelopmental disorder. Our study identifies repeat expansions in EP400 as a novel and frequent cause of ataxia in Serbian patients. This finding further increases the diagnostic yield of ataxia testing and warrants investigation in ataxia patients worldwide. We add EP400 to the growing list of ataxia-associated repeat loci, which warrants inclusion in diagnostic ataxia panels.

Background and objectives: Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is the most common monogenic cerebral small vessel disease. Though neuropsychiatric symptoms (NPS) of CADASIL profoundly impact function and quality of life, these symptoms remain understudied. This analysis characterizes the prevalence, severity, and profile of NPS among individuals with CADASIL-causing NOTCH3 variants and non-carrier biological family controls in the United States CADASIL Consortium (USCC). Methods: This cross-sectional analysis used multimodal baseline data from 12 enrollment sites across the country. Statistical analyses used nonparametric tests and regression models to compare clinical and neuropsychiatric outcomes across CADASIL risk tiers and controls, adjusting for age, sex, race, and education where appropriate. The primary outcome measure was the Neuropsychiatric Inventory Questionnaire (NPI-Q), an informant-reported measure which assesses 12 categories of NPS. NPI-Q item severity and distress were evaluated for individuals with confirmed cysteine-altering NOTCH3 variants and compared with controls. Results: Four hundred fifty-nine USCC participants were included in the analytic cohort: 343 cases [256 high-risk (HR); 63 medium-risk (MR); 24 low-risk (LR)]; and 116 controls. Among participants with available NPI-Q data, at least one neuropsychiatric symptom was reported by 72.6% (n = 228/314) of cases compared with 53.2% (n = 58/109) of controls. Reported symptoms were more common among CADASIL cases than controls, occurring in 75.0%, 71.2%, and 72.7% of participants in the LR, MR, and HR groups, respectively, compared with 53.2% of controls. Compared with controls, participants in the MR group and HR group had higher NPI-Q severity scores. HR participants also had higher NPI-Q distress scores than controls. Discussion: Our findings support the notion that NPS are an important clinical manifestation of CADASIL. Beyond previously reported symptoms, additional neuropsychiatric manifestations were identified. Given the higher burden and variability in the neuropsychiatric presentation of CADASIL, the relationships among neuropsychiatric, neurological, and patient-reported outcomes merit further investigation. The NPS profile may enhance the evaluation of the safety and efficacy of different treatments to target these symptoms for CADASIL patients. Trial Registration Information: The study is registered at ClinicalTrials.gov (NCT05677880, 12/12/2022).

Amyotrophic lateral sclerosis (ALS) shows well-established sex differences in incidence, age at onset and progression, but their biological basis is unclear. We hypothesised that the DNA methylation changes associated with ALS differ between the sexes, which would point to sex-specific disease processes. To test this, we performed a blood-based epigenome-wide association meta-analysis of ALS cases and controls from Project MinE, an international ALS genomics consortium, and an independent Australian cohort, comprising 8,946 individuals after quality control (5,129 males and 3,817 females; 8,942 with complete covariates in the primary models). We analysed 781,648 autosomal CpGs using complementary sex-stratified case-control models and an ALS-by-sex interaction model that directly tested whether ALS-associated methylation effects differed by sex. Sex-stratified analyses identified no genome-wide significant differences between male and female ALS effects. In contrast, interaction testing identified seven robust sex-dependent ALS-associated differentially methylated positions (P < 9 x 10-8), mapping to KCNQ1, ADPRH, HLA-F, GHRLOS, IRF5, RAD51B and one intergenic region. The strongest signal was at KCNQ1 (P = 3.1 x 10-9). Six of the seven remained genome-wide significant in a four-stratum sensitivity analysis, and none was detected in previous conventional ALS or population sex-associated methylation analyses. Together, these findings suggest a distinct sex-conditional component of the ALS blood methylome, implicating immune, metabolic and ion-channel loci and providing new candidates for investigating biological heterogeneity between males and females with ALS.

Objectives: Genotype-phenotype studies in rare epilepsies typically relate a pathogenic DNA sequence change to clinical outcome, without considering the broader molecular context of a given variant. Here we ask whether clinical heterogeneity in SCN8A-related disorders (SCN8A-RD) is patterned along molecular dimensions that go beyond the specific genetic alteration, to include position in the linear channel topology, proximity to post-translational modification (PTM) and structural sites, and predicted effects on mRNA splicing. Using the International SCN8A Registry, we map these features against seizure, developmental, and treatment-response phenotypes to identify the regions and molecular feature classes with which clinical variability is associated. Methods: We identify "hot-spots" across the coding sequence for seizure types and severity of developmental disability (DD). We then test for enrichment of clinical features near sites related to PTM and protein structure, identify variants that may alter mRNA splicing, and evaluate the interaction between these features and clinical subgroups. Results: We expand on previous work identifying regions of coding DNA sequence that are pathogenic or benign "hot-spots". We show regional enrichment of numerous seizure types and severities of DD. Enrichment analysis of PTM and protein structural sites shows distinct enrichment profiles for developmental, seizure, and medication-response features. Finally, we identify 14 variants that are likely to alter RNA splicing. Significance: We provide a higher-resolution map of pathogenic variation across SCN8A and show that seizure types, developmental severity, and medication response are regionally organized along the coding sequence. Proximity to structural and glycosylation sites distinguishes phenotypic subgroups is associated with differential drug response, including a glycosylation-gabapentin relationship, and 14 missense variants are flagged as likely splice-altering, nominating targets for splice-directed therapy and providing candidates for experimental validation of dual pathogenic mechanisms.

Background Parkinson's disease (PD), the most common neurodegenerative movement disorder, is commonly thought of as an aging and sporadic disease; however, 5-14% of individuals experience disease onset before the age of 50 years (early-onset PD; EOPD) and about 20% have a positive family history. In the case of both EOPD and people with a family history of PD, evidence suggests higher rates of a disease-causing genetic contribution. Objectives Our goal was to perform a variant screening of seven PD-related genes and 21 genes associated with related parkinsonian disorders to identify pathogenic/likely pathogenic variants and variants of uncertain significance within EOPD and family-history-positive individuals within the Latin American Research Consortium on the Genetics of PD (LARGE-PD). Methods We performed short-read whole-genome sequencing on a subset of 263 individuals with EOPD and/or a familial history of PD who had no known pathogenic PD variant in genotyping data. Results Of the analyzed individuals, a monogenic burden in primary and secondary PD genes due to pathogenic or likely pathogenic variants for PD was observed in 4.7%, an additional 5.5% had pathogenic or likely pathogenic variants for Gaucher's disease, and 2.7% had known risk variants in GBA1. Conclusions By expanding the reported spectrum of disease-associated variants in a Latin American population, we identified previously unreported or underrepresented variants that would likely be missed by array-based or targeted screening approaches and contribute to the characterization of EOPD and familial PD in Latin America.

Background: To determine the crude and age-adjusted point prevalence of motor neuron disease (MND) and its phenotypes (classical amyotrophic lateral sclerosis [ALS], primary lateral sclerosis [PLS] and progressive muscular atrophy [PMA]) using a comprehensive multi-source case ascertainment strategy. Methods: Cross-sectional population-based study with a prevalence date of 1 January 2025. Cases were identified through five complementary regional data sources and confirmed by clinical review against the revised El Escorial and Gold Coast criteria. Cases were classified by phenotype as ALS, PLS or PMA. The reference population was the population aged 15 years or older in Valencian Community (n=4,433,999). Crude prevalence was calculated per 100,000 with 95% Poisson confidence intervals; age-adjusted rates were obtained by direct standardisation to the 2013 European Standard Population. Results: A total of 374 confirmed MND cases were identified. The overall crude prevalence of MND was 8.43 per 100,000 (95% CI: 7.60-9.29) and the age-adjusted prevalence was 7.85 per 100,000 (95% CI: 7.05-8.65). By phenotype, ALS accounted for 325 cases (86.9%; crude prevalence 7.33 per 100,000), PLS for 26 (7.0%; 0.59 per 100,000) and PMA for 23 (6.1%; 0.52 per 100,000). Prevalence was consistent across provinces. Mean age was 65.9 years, the male-to-female ratio was 1.37:1, and 83.4% were receiving riluzole. Conclusions: This is the first comprehensive, multi-source population-based estimate of MND prevalence and its subtypes in the Valencian Community. The estimate is higher than the previous single-unit figure and consistent with recent European data, underscoring the value of multi-source ascertainment.

Friedreich ataxia (FRDA) is an inherited multisystem disorder caused by a GAA repeat expansion in the FXN gene and consequent frataxin deficiency, causing progressive neurodegeneration and heart disease. Clinical studies have documented autonomic dysfunction in FRDA, including elevated resting heart rate, raised plasma catecholamines and a high burden of urinary, bowel and sexual symptoms. Consistent with this, autopsy studies show degeneration of the cardiac conduction system and its associated ganglia in FRDA. Whether these features are intrinsic to FRDA autonomic neurons has been untestable without a human cellular model. Here, a human model of FRDA autonomic neurons was established by differentiating induced pluripotent stem cells (iPSCs) from individuals with FRDA and from their CRISPR/Cas9-corrected isogenic controls. FRDA autonomic neurons expressed canonical autonomic lineage markers and retained reduced FXN mRNA and frataxin protein levels. Electrophysiological analysis revealed pronounced hyperexcitability, with an approximately five-fold increase in spike number, shortened interspike intervals, and longer bursts. FRDA autonomic neurons also exhibited increased cell death, elevated mitochondrial reactive oxygen species, and a shift from networked to tubular mitochondrial morphology. Bulk RNA sequencing of all three isogenic pairs revealed loss of extracellular matrix programs and activation of stress response pathways. The top differentially expressed gene was MEG3, a maternally imprinted long noncoding RNA, which was consistently upregulated across all three isogenic pairs. MEG3 sits within the imprinted 14q32 DLK1-DIO3 locus, whose maternally expressed noncoding transcripts were co-ordinately de-repressed in FRDA autonomic neurons. Competitive gene-set testing of 43 imprinted genes across 20 domains showed this to be specific to 14q32: no other imprinted domain was co-ordinately altered. Together, these findings establish hyperexcitability of autonomic neurons as a cell autonomous consequence of frataxin deficiency, accompanied by mitochondrial dysfunction. This provides a cellular basis for the increased sympathetic tone observed in clinical studies.

Recent evidence suggests that TMEM106B expression is reduced in the brains of patients with Parkinson's disease (PD). However, an association between rare genetic variants in TMEM106B and PD risk has not been previously established. In this work, we investigated the association between rare TMEM106B variants and PD risk. We leveraged whole-genome sequencing data from 22,010 cases and 40,550 controls across diverse ancestries from the Global Parkinson's Genetics Program (GP2), the Accelerating Medicines Partnership in Parkinson's Disease (AMP-PD), and the UK Biobank (UKBB). A total of 4,581 unique rare variants were identified across all groups. No pathogenic or likely pathogenic variants according to ClinVar were observed in any cohort. We found no evidence that rare coding variants in TMEM106B were associated with PD risk, either individually or through cumulative burden. These findings suggest that rare variation in TMEM106B does not play a major role in PD susceptibility across the populations studied.

Background: CADASIL caused by cysteine-altering NOTCH3 variants, the most frequent hereditary cerebral small vessel disease worldwide, is characterized by marked phenotypic variability. Mutation location within the EGFr domains of the NOTCH3 receptor has emerged as a key determinant of this variability. We investigated phenotypic variability and potential modifiers of CADASIL expression by comparing individuals harbouring the same pathogenic NOTCH3 variant across distinct recruitment settings in three European countries. Methods: We compared clinical features, MRI markers, and cardiovascular risk factors among individuals harbouring the p.Arg1231Cys NOTCH3 mutation across three distinct recruitment settings: a multigenerational founder population from Cilento, Italy (CILCAD), a population-based cohort from the UK Biobank (UKB), and a clinically referred cohort from a national referral centre in Lariboisiere Hospital, Paris, France (LRB). In addition, CILCAD carriers were compared with NON-Carriers from the same population. The NOTCH3 locus was finally analysed to define the shared haplotype in CILCAD and explore potential genetic contributions to phenotypic variability. Findings: By comparing populations from three European countries, this study showed marked context-dependent phenotypic variability associated with the sole pathogenic p.Arg1231Cys NOTCH3 variant. In CILCAD, a multigenerational founder population, the haplotype carrying the NOTCH3 mutation also predisposes to decreased LDL levels, resulting in an unusually low LDL cholesterol profile in this sample. Strikingly, these very low LDL levels were associated with a higher likelihood of stroke. Interpretation: In European carriers of NOTCH3 p.Arg1231Cys, factors beyond mutation location, including genetic background, may substantially shape disease expression, while exceptionally low LDL levels could paradoxically be associated with greater disease severity.

Objectives Alzheimer's disease (AD) progresses from a cognitively unimpaired stage through mild cognitive impairment (MCI) to dementia. Because language impairment often emerges before dementia, it is a candidate marker of disease stage. Yet the standard batteries of large AD research cohorts rely on a narrow set of tests that mainly evaluate the lexical-semantic domain (i.e., picture naming and verbal fluency), leaving other language domains, such as semantic memory, phonology, morphosyntax, and single-word reading, rarely assessed. We evaluated the diagnostic utility of standard and specialized language tests for distinguishing amyloid-positive MCI and dementia of the Alzheimer's type (DAT) from healthy controls (HC) and from each other. Methods We included 286 participants from the National Alzheimer's Coordinating Center (125 HC, 53 MCI, 108 DAT) assessed with three standard tests from UDSv3 (semantic fluency, letter fluency, and Multilingual Naming Test [MINT]) and nine specialized tests from the FTLD Module (regular and irregular word reading, semantic word-picture matching, semantic associates, Northwestern Anagram Test - Short Form [NAT-S], Northwestern Naming Battery noun and verb naming, sentence repetition, and sentence reading). For each test, the area under the receiver operating characteristic curve (AUC) was computed for DAT vs. HC, MCI vs. HC, and DAT vs. MCI, and AUCs were compared between tests with DeLong's test. Results Eight of 12 measures reached acceptable discrimination (AUC [&ge;] .700) for DAT vs. HC, five for MCI vs. HC, but only semantic fluency and NAT-S for DAT vs. MCI. Semantic fluency showed the highest discrimination in each contrast, though it did not significantly outperform the NAT-S for MCI vs. HC or DAT vs. MCI. MINT, letter fluency, and irregular word reading reached clinically meaningful accuracy in distinguishing MCI and DAT from HC, but not DAT from MCI. The remaining specialized tests reached it only for DAT vs. HC, or not at all. In a post hoc regression, adjusting for cognitive flexibility and working memory attenuated group differences; the DAT difference was no longer significant, whereas the MCI difference remained significant. Discussion Semantic fluency was the strongest single language marker across the AD continuum. Among specialized tests, NAT-S was the most informative, challenging the view that syntax is spared in early AD. Its performance was partly explained by executive function, mainly in DAT, whereas a residual morphosyntactic component remained in MCI, and several specialized tests were limited by ceiling effects. Clinically, the NAT-S may complement semantic fluency for staging, and specialized tests may help characterize heterogeneous language profiles in MCI and DAT.

Background and Objectives Huntington's disease is a rare neurodegenerative disease in which optimizing clinical trial design is essential. Although baseline characteristics are known to predict disease progression, the statistical efficiency gains achievable by formally integrating prognostic predictions into trial analyses have not been systematically quantified. We aimed to benchmark prognostic modeling approaches, quantify the trial efficiency gains from prognostic covariate adjustment, and deliver a ready-to-deploy framework for immediate implementation. Methods: We developed a two-step modeling pipeline using longitudinal Enroll-HD natural history data (NCT01574053) to train nine machine learning algorithms to predict disease progression across five UHDRS endpoints. For this, we used 16 predictive baseline covariates representing stage of disease (baseline score levels), disease specific (CAP, CAG length), demographics and co-medication use that could be quantified in one clinical visit. For Total Function Capacity (TFC), frequently used as a primary endpoint in clinical trials, we also devised a minimal prognostic model based on 6 covariates. Model performance was tested using the placebo arm of the GENERATION HD1 phase 3 trial (NCT03761849). Results: Models were trained on 16,398 Enroll-HD participants and tested on 260 participants from the GENERATION HD1 placebo arm. Models that take into account nonlinear relationships between the covariates showed no performance advantage over linear-based models on the test set. For TFC, a minimal six-covariate linear prognostic model performed on par with the full 16-feature model. Adjusting for the prognostic score increased the signal-to-noise ratio across different trial visits by 8-18%, raising statistical power from 80% to up to 90% at a fixed sample size, or, equivalently, reducing required sample size by 15-28% compared to unadjusted analyses (no covariate adjustment). Compared to routinely used covariate adjustments (including baseline score, age, CAG repeat length, and CAP score), adjusting for a prognostic score consistently delivered meaningful additional efficiency gains. Discussion: Prognostic covariate adjustment using a simple six-covariate linear score derived from a single baseline visit yields meaningful gains in statistical power for HD clinical trials, while remaining fully embedded within standard, regulator-accepted analysis frameworks. This approach offers a practical and immediately deployable tool to improve trial design.

Importance: Blood biomarkers for Alzheimer disease(AD), Parkinson disease(PD), and amyotrophic lateral sclerosis(ALS) are typically developed as disease-specific single-analyte tests. Whether one shared plasma panel can support disease-selective classification remains unclear. Objective: To test whether the Olink Target 48 Neurodegeneration plasma panel, analyzed with disease-specific Elastic Net models, can discriminate AD, PD, and ALS in a heterogeneous neurological cohort. Design, Setting, and Participants: Single-center diagnostic cohort study at Keio University Hospital, Tokyo, Japan. After quality control and one consent withdrawal, 302 participants were analyzed(healthy controls n = 62; AD continuum n = 93; PD n = 39; ALS n = 27; other neurological disorders n = 81) and allocated by diagnosis-stratified sampling into a discovery training set(n = 211) and a locked hold-out test set(n = 91). Exposures: Plasma normalized protein expression from 42 assays retained after protein quality control. Plasma DOPA decarboxylase was excluded a priori from all classifiers because blood levels primarily reflect dopaminergic treatment exposure. Main Outcomes and Measures: Hold-out receiver operating characteristic area under the curve(AUC). Sensitivity and specificity at a training-set Youden threshold locked for Test. Results: Hold-out AUCs were 0.974(95% CI, 0.942-0.995) for AD, 0.926(0.820-1.000) for PD, and 0.995(0.980-1.000) for ALS. At locked Youden cutoffs, sensitivity was 0.929 (95% CI, 0.765-0.991) and specificity was 0.921 (95% CI, 0.824-0.974) for AD, 0.833 (95% CI, 0.516-0.979) and 0.975 (95% CI, 0.912-0.997) for PD, and 1.000 (95% CI, 0.631-1.000) and 0.940 (95% CI, 0.865-0.980) for ALS. Conclusions and Relevance: A single plasma neurodegeneration panel supported disease-selective classification of AD, PD, and ALS in internal validation. Multicenter external validation is needed before clinical application.

Background and Objectives Transient ischemic attack (TIA) diagnosis is challenging because it relies mainly on clinical assessment and exclusion of common differential. Functional MRI (fMRI) may provide a diagnostic biomarker by detecting transient brain dysfunction not visible on conventional imaging. This pilot study aimed to characterize acute motor-task BOLD activation in patients with suspected DWI-negative TIA and compare functional patterns between confirmed TIA and alternative diagnoses. Secondary objectives were to assess longitudinal changes in activation and connectivity at 3 months. Methods In this prospective single-center study, adults presenting within 24 h of transient anterior-circulation neurological symptoms underwent conventional MRI and additional motor-task fMRI. Patients with acute DWI lesions were excluded. Final diagnosis was established after 3-month follow-up. Whole-brain analyses, individualized motor cortex region-of-interest (ROI) analyses, and generalized psychophysiological interaction (gPPI) connectivity analyses were performed during the acute phase and at 3 months. Results Eight patients were enrolled; six had complete longitudinal imaging data and were included in the final analyses. Final diagnoses were TIA (n=2), migraine aura (n=2), functional neurological disorder (n=1), and hypoglycemia (n=1). Whole-brain and ROI analyses showed reduced bilateral motor-related BOLD responses during the acute phase in both TIA patients and in the patient with hypoglycemia. In contrast, patients with migraine and functional neurological disorder exhibited less marked longitudinal changes. In TIA patients, motor cortex activation increased at 3 months, tending to normalize toward values observed in non-TIA participants. Connectivity analyses revealed heterogeneous patterns, but the 2 TIA patients demonstrated increased longitudinal connectivity between the motor cortex contralateral to symptoms and other sensorimotor regions, including supplementary motor, premotor, parietal, and postcentral cortices. Discussion These preliminary findings suggest that TIA may be associated with transient bilateral reductions in motor-network activity. Functional abnormalities appeared to improve over time, supporting the hypothesis of reversible network dysfunction. Although limited by the very small sample size, this study provides the first longitudinal assessment of emergency task-based fMRI in rigorously defined TIA and supports further investigation of acute functional MRI as a potential biomarker of transient cerebral dysfunction.

The brain differences of dyslexia are well described and its genetic risk is now measurable; the brain systems that connect the two are unknown. That link decides which measures complement one another in early identification and which systems intervention research should examine. Here we compared large-scale polygenic score maps of brain structure in dyslexia with normative maps of brain neurotransmitter systems. The structural signature of genetic liability aligned with the cortical distribution of neurotransmitter systems. The strongest and most consistent alignment appeared for the histamine H3 receptor, the vesicular acetylcholine transporter (VAChT) and the N-methyl-D-aspartate (NMDA) glutamate receptor. The alignment was most pronounced in cingulate, medial and superior frontal cortex and the paracentral lobule. The H3 alignment held after adjustment for cortical position and for metabolic and cognitive reference maps. Once the component common to all nineteen maps and position were removed together, no individual system remained significant, while the shared component itself aligned with liability. The signature therefore follows the topography these systems share. In 169 children, per-person alignment with the H3 map related to reading skill with the opposite sign to liability. To our knowledge, this is the first study to relate the structural signature of genetic liability for dyslexia to normative maps of neurotransmitter receptor and transporter density. It places that signature within the shared geography of the systems that set attention, arousal and synaptic plasticity during learning, and gives the genetics of dyslexia a testable biological axis.

The Vanishing White Matter (VWM) Registry is a single-center database containing longitudinal survey data from >470 untreated patients with DNA- and MRI-confirmed VWM. VWM is a rare genetic disorder of the brain's white matter with an estimated live birth incidence of 1 per 100,000 and prevalence of 1.3 per 1,000,000 people in the Netherlands. The Registry represents a remarkably extensive collection of systematically gathered information on this disease, enabling crucial research into the natural history of VWM and providing a valuable resource for control arms in clinical trials. Data, initially collected on paper from 2004, have been maintained electronically since 2018, and include validated scales alongside a disease-specific customized questionnaire covering clinical, functional, and psychosocial domains. Survey packages, available in eight languages, are sent one to four times a year, depending on patient age. Built-in validity checks and review by pediatric and adult neurologists ensure data quality. The dataset is continuously updated with questionnaires expanding its scope, and structured for analysis and reuse in research on VWM.

CACNA1A-related disorders arise from altered function of the P/Q-type calcium channel Cav2.1 and encompass a broad spectrum of neurological phenotypes, including developmental and epileptic encephalopathy, familial hemiplegic migraine type 1 and episodic ataxia type 2. Although loss-of-function and gain-of-function mechanisms have both been implicated, interpretation of rare CACNA1A missense variants remains challenging because clinical presentation is heterogeneous and many variants identified through diagnostic sequencing remain classified as variants of uncertain significance. To generate clinically interpretable functional evidence, we developed a calibrated high-throughput automated patch-clamp assay to assess the CACNA1A variants. Twenty-six curated benign/likely benign and 30 curated pathogenic/likely pathogenic missense variants were expressed in Flp-In HEK293 cells with CACNB4 and CACNA2D1. We quantified current density, {Lambda}V0.5 activation,{Lambda}V0.5 inactivation and recovery from inactivation (T0.5 RFI), and used benign controls to define parameter-specific normal ranges with {+/-}3 Z-score thresholds. This multi-parameter framework classified all benign controls as functionally normal and 29 of 30 pathogenic controls as abnormal, yielding 100% specificity and 96.7% sensitivity. Current density identified 19 pathogenic controls with loss of function, while gating and recovery from inactivation identified additional abnormal variants with preserved or partially preserved current density. The assay generated likelihood ratios of 0.033 for normal function and 25.13 for abnormal function, supporting BS3 and PS3 functional evidence, respectively. Application to 23 CACNA1A variants identified in Australian patients showed abnormal function in all four variants already classified as pathogenic or likely pathogenic. Among 19 variants of uncertain significance, 11 were functionally abnormal and nine were reclassified as likely pathogenic after integration of PS3 evidence with other ACMG/AMP criteria. These data show that CACNA1A missense variants can produce loss-of-function, gain-of-function or mixed effects, and that multi-parameter functional assessment is required for accurate interpretation. This calibrated automated patch-clamp framework provides clinically interpretable evidence for refining CACNA1A variant classification in diagnostic practice.

C9orf72 encodes a protein that is important for both typical neurodevelopment and homeostatic processes across the lifespan. Pathogenic C9orf72 repeat expansions constitute the most common genetic cause of frontotemporal lobar degeneration (FTLD). Collectively, preclinical models and clinical neuroimaging studies have observed smaller thalamic volumes in C9orf72-associated FTLD, including in asymptomatic young adult C9orf72 repeat expansion carriers across 18 to 30 years old, supportive of potential neurodevelopmental origins. However, it is unknown whether asymptomatic young adult C9orf72 expansion carriers demonstrate volume differences in specific thalamic nuclei, as reported in older asymptomatic carriers and symptomatic patients; if so, normative transcriptomic patterns could reveal relevant neurodevelopmental and/or FTLD-related neurodegenerative processes. This study investigated volumetric MRI differences of the thalamic nuclei in asymptomatic young adult C9orf72 expansion carriers compared to non-carriers, and examined spatial associations with normative thalamic transcriptomics from 8 weeks post-conception through middle age. Young adult C9orf72 expansion carriers (n=72) and non-carriers (n=48) were enrolled in the Frontotemporal Dementia Prevention Initiative across Europe, Canada, and the USA (ages: 18-30 years; sex: 57% female). Spatial associations between young adult thalamic nuclei volumes and normative transcriptomics from the Allen Human Brain Atlas were examined using complementary data-driven and hypothesis-driven approaches. Spatial expression patterns of transcripts of interest were characterized across prenatal and postnatal neurodevelopment using BrainSpan data. Smaller volumes of the pulvinar, mediodorsal, and lateral nuclei were observed in young adult C9orf72 expansion carriers compared to non-carriers. These nuclei showed higher normative expression of transcripts involved concurrently in neurodevelopmental and C9orf72-associated FTLD neurodegenerative processes (including lysosomal, autophagic, and small GTPase functions), and lower normative expression of CALB1, a marker of prenatal human thalamic development. Normative expression of CALB2 (another human thalamic development marker) yielded positive correlations with C9orf72 across prenatal development to adulthood. These findings identify candidate transcripts that may provide insight into the molecular architecture leading to smaller thalamic nuclei volumes in C9orf72-associated FTLD.