First case of adult onset neuronal intranuclear inclusion disease with both typical radiological signs and NOTCH2NLC repeat expansions in a Caucasian individual.

BACKGROUND AND PURPOSE: Adult onset neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disorder with a heterogeneous clinical presentation that can mimic stroke and various forms of dementia. To date, it has been described almost exclusively in Asian individuals. METHODS: This case presentation includes magnetic resonance imaging (MRI) of the neurocranium, histology by skin biopsy, and long-read genome sequencing. RESULTS: A 75-year-old Caucasian female presented with paroxysmal encephalopathy twice within a 14-month period. Brain MRI revealed high-intensity signals at the cerebral corticomedullary junction (diffusion-weighted imaging) and the paravermal area (fluid-attenuated inversion recovery), a typical distribution observed in adult onset NIID. The diagnosis was corroborated by skin biopsy, which demonstrated eosinophilic intranuclear inclusion bodies, and confirmed by long-read genome sequencing, showing an expansion of the GGC repeat in exon 1 of NOTCH2NLC. CONCLUSIONS: Our case proves adult onset NOTCH2NLC-GGC-positive NIID with typical findings on MRI and histology in a Caucasian patient and underscores the need to consider this diagnosis in non-Asian individuals.

Real-Life Turning Movements Capture Subtle Longitudinal and Preataxic Changes in Cerebellar Ataxia.

BACKGROUND: Clinical and regulatory acceptance of upcoming molecular treatments in degenerative ataxias might greatly benefit from ecologically valid endpoints that capture change in ataxia severity in patients' real life. OBJECTIVES: This longitudinal study aimed to unravel quantitative motor biomarkers in degenerative ataxias in real-life turning movements that are sensitive for changes both longitudinally and at the preataxic stage. METHODS: Combined cross-sectional (n = 30) and longitudinal (n = 14, 1-year interval) observational study in degenerative cerebellar disease (including eight preataxic mutation carriers) compared to 23 healthy controls. Turning movements were assessed by three body-worn inertial sensors in three conditions: (1) instructed laboratory assessment, (2) supervised free walking, and (3) unsupervised real-life movements. RESULTS: Measures that quantified dynamic balance during turning-lateral velocity change (LVC) and outward acceleration-but not general turning measures such as speed, allowed differentiating ataxic against healthy subjects in real life (effect size δ = 0.68), with LVC also differentiating preataxic against healthy subjects (δ = 0.53). LVC was highly correlated with clinical ataxia severity (scale for the assessment and rating of ataxia [SARA] score, effect size ρ = 0.79) and patient reported balance confidence (activity-specific balance confidence scale [ABC] score, ρ = 0.66). Moreover, LVC in real life-but not general turning measures or the SARA score-allowed detecting significant longitudinal change in 1-year follow-up with high effect size (rprb  = 0.66). CONCLUSIONS: Measures of turning allow capturing specific changes of dynamic balance in degenerative ataxia in real life, with high sensitivity to longitudinal differences in ataxia severity and to the preataxic stage. They thus present promising ecologically valid motor biomarkers, even in the highly treatment-relevant early stages of degenerative cerebellar disease. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Individual changes in preclinical spinocerebellar ataxia identified via increased motor complexity.

BACKGROUND: Movement changes in autosomal-dominant spinocerebellar ataxias are suggested to occur many years before clinical manifestation. Detecting and quantifying these changes in the preclinical phase offers a window for future treatment interventions and allows the clinician to decipher the earliest dysfunctions starting the evolution of spinocerebellar ataxia. We hypothesized that quantitative movement analysis of complex stance and gait tasks allows to (i) reveal movement changes already at early stages of the preclinical phase when clinical ataxia signs are still absent and to (ii) quantify motor progression in this phase. METHODS: A total of 46 participants (14 preclinical spinocerebellar ataxia mutation carriers [spinocerebellar ataxias 1,2,3,6], 9 spinocerebellar ataxia patients at an early stage; 23 healthy controls) were assessed by quantitative movement analyses of increasingly complex stance and walking tasks in a cross-sectional design. RESULTS: Body sway in stance and spatiotemporal variability in tandem walking differentiated between preclinical mutation carriers and healthy controls (P < .01). Complex movement conditions allowed one to discriminate even those mutation carriers without any clinical signs in posture and gait (SARAposture&gait = 0; P < .04). Multivariate regression analysis categorized preclinical mutation carriers on a single-subject level with 100% accuracy within a range of 10 years to the estimated onset. Movement features in stance and gait correlated significantly with genetically estimated time to onset, indicating a gradual increase of motor changes with increasing proximity to disease manifestation. CONCLUSION: Our results provide evidence for subclinical motor changes in spinocerebellar ataxia, which allow to discriminate patients without clinical signs even on a single-subject basis and may help capture disease progression in the preclinical phase. © 2016 International Parkinson and Movement Disorder Society.

HBOC multi-gene panel testing: comparison of two sequencing centers.

Multi-gene panels are used to identify genetic causes of hereditary breast and ovarian cancer (HBOC) in large patient cohorts. This study compares the diagnostic workflow in two centers and gives valuable insights into different next-generation sequencing (NGS) strategies. Moreover, we present data from 620 patients sequenced at both centers. Both sequencing centers are part of the German consortium for hereditary breast and ovarian cancer (GC-HBOC). All 620 patients included in this study were selected following standard BRCA1/2 testing guidelines. A set of 10 sequenced genes was analyzed per patient. Twelve samples were exchanged and sequenced at both centers. NGS results were highly concordant in 12 exchanged samples (205/206 variants = 99.51 %). One non-pathogenic variant was missed at center B due to a sequencing gap (no technical coverage). The custom enrichment at center B was optimized during this study; for example, the average number of missing bases was reduced by a factor of four (vers. 1: 1939.41, vers. 4: 506.01 bp). There were no sequencing gaps at center A, but four CCDS exons were not included in the enrichment. Pathogenic mutations were found in 12.10 % (75/620) of all patients: 4.84 % (30/620) in BRCA1, 4.35 % in BRCA2 (27/620), 0.97 % in CHEK2 (6/620), 0.65 % in ATM (4/620), 0.48 % in CDH1 (3/620), 0.32 % in PALB2 (2/620), 0.32 % in NBN (2/620), and 0.16 % in TP53 (1/620). NGS diagnostics for HBOC-related genes is robust, cost effective, and the method of choice for genetic testing in large cohorts. Adding 8 genes to standard BRCA1- and BRCA2-testing increased the mutation detection rate by one-third.

A progressive dopaminergic phenotype associated with neurotoxic conversion of α-synuclein in BAC-transgenic rats.

Conversion of soluble α-synuclein into insoluble and fibrillar inclusions is a hallmark of Parkinson's disease and other synucleinopathies. Accumulating evidence points towards a relationship between its generation at nerve terminals and structural synaptic pathology. Little is known about the pathogenic impact of α-synuclein conversion and deposition at nigrostriatal dopaminergic synapses in transgenic mice, mainly owing to expression limitations of the α-synuclein construct. Here, we explore whether both the rat as a model and expression of the bacterial artificial chromosome construct consisting of human full-length wild-type α-synuclein could exert dopaminergic neuropathological effects. We found that the human promoter induced a pan-neuronal expression, matching the rodent α-synuclein expression pattern, however, with prominent C-terminally truncated fragments. Ageing promoted conversion of both full-length and C-terminally truncated α-synuclein species into insolube and proteinase K-resistant fibres, with strongest accumulation in the striatum, resembling biochemical changes seen in human Parkinson's disease. Transgenic rats develop early changes in novelty-seeking, avoidance and smell before the progressive motor deficit. Importantly, the observed pathological changes were associated with severe loss of the dopaminergic integrity, thus resembling more closely the human pathology.

Transcript-Specific Loss-of-Function Variants in VPS16 Are Enriched in Patients With Dystonia.

BACKGROUND AND OBJECTIVES: Our objective was to improve rare variant interpretation using statistical measures as well as publicly accessible annotation of expression levels and tissue specificity of different splice isoforms. We describe rare VPS16 variants observed in patients with dystonia and patients without dystonia, elaborate on our interpretation of VPS16 variants affecting different transcripts, and provide detailed clinical description of the movement disorder caused by VPS16 variants. METHODS: In-house exome and genome data sets (n = 11,539) were screened for rare heterozygous missense and putative loss-of-function (pLoF) variants in VPS16. Using pext (proportion expressed across transcripts) values from the Genome Aggregation Database (gnomAD), we differentiated variants affecting weakly and highly expressed exons/transcripts and applied statistical measures to systematically identify disease-associated genetic variation among patients with dystonia (n = 280). RESULTS: Six different heterozygous pLoFs in VPS16 transcripts were identified in 13 individuals. Three of these pLoFs occurred in 9 individuals with different phenotypes, and 3 pLoFs were identified in 4 unrelated individuals with early-onset dystonia. Although pLoFs were enriched in the dystonia cohort (n = 280; p = 2.04 × 10-4; 4/280 cases vs 9/11,259 controls; Fisher exact test), it was not exome-wide significant. According to the pext values in gnomAD, all 3 pLoFs observed in the patients with dystonia were located in the highly expressed canonical transcript ENST00000380445.3, whereas 2 of 3 pLoFs detected in 8 individuals without dystonia were located in the first exon of the noncanonical transcript ENST00000380443.3 that is weakly expressed across all tissues. Taking these biological implications into account, pLoFs involving the canonical transcript were exome-wide significantly enriched in patients with dystonia (p = 1.67 × 10-6; 4/280 cases vs 1/11,259 controls; Fisher exact test). All VPS16 patients showed mild progressive dystonia with writer's cramp as the presenting symptom between age 7 and 34 years (mean 20 years) that often progressed to generalized dystonia and was even accompanied by hyperkinetic movements and myoclonus in 1 patient. DISCUSSION: Our data provide strong evidence for VPS16 pLoFs to be implicated in dystonia and knowledge on exon resolution expression levels as well as statistical measures proved to be useful for variant interpretation.

Conversion of individuals at risk for spinocerebellar ataxia types 1, 2, 3, and 6 to manifest ataxia (RISCA): a longitudinal cohort study.

BACKGROUND: Spinocerebellar ataxias (SCAs) are autosomal dominant neurodegenerative diseases. Our aim was to study the conversion to manifest ataxia among apparently healthy carriers of mutations associated with the most common SCAs (SCA1, SCA2, SCA3, and SCA6), and the sensitivity of clinical and functional measures to detect change in these individuals. METHODS: In this prospective, longitudinal, observational cohort study, based at 14 referral centres in seven European countries, we enrolled children or siblings of patients with SCA1, SCA2, SCA3, or SCA6. Eligible individuals were those without ataxia, defined by a score on the Scale for the Assessment and Rating of Ataxia (SARA) of less than 3; participants had to be aged 18-50 years for children or siblings of patients with SCA1, SCA2, or SCA3, and 35-70 years for children or siblings of patients with SCA6. Study visits took place at recruitment and after 2, 4, and 6 years (plus or minus 3 months). We did genetic testing to identify mutation carriers, with results concealed to the participant and clinical investigator. We assessed patients with clinical scales, questionnaires of patient-reported outcome measures, a rating of the examiner's confidence of presence of ataxia, and performance-based coordination tests. Conversion to ataxia was defined by an SARA score of 3 or higher. We analysed the association of factors at baseline with conversion to ataxia and the evolution of outcome parameters on temporal scales (time from inclusion and time to predicted age at ataxia onset) in the context of mutation status and conversion status. This study is registered with ClinicalTrials.gov, NCT01037777. FINDINGS: Between Sept 13, 2008, and Oct 28, 2015, 302 participants were enrolled. We analysed data for 252 participants with at least one follow-up visit. 83 (33%) participants were from families affected by SCA1, 99 (39%) by SCA2, 46 (18%) by SCA3, and 24 (10%) by SCA6. In participants who carried SCA mutations, 26 (52%) of 50 SCA1 carriers, 22 (59%) of 37 SCA2 carriers, 11 (42%) of 26 SCA3 carriers, and two (13%) of 15 SCA6 carriers converted to ataxia. One (3%) of 33 SCA1 non-carriers and one (2%) of 62 SCA2 non-carriers converted to ataxia. Owing to the small number of people who met our criteria for ataxia, subsequent analyses could not be done in carriers of the SCA6 mutation. Baseline factors associated with conversion were age (hazard ratio 1·13 [95% CI 1·03-1·24]; p=0·011), CAG repeat length (1·25 [1·11-1·41]; p=0·0002), and ataxia confidence rating (1·72 [1·23-2·41]; p=0·0015) for SCA1; age (1·08 [1·02-1·14]; p=0·0077) and CAG repeat length (1·65 [1·27-2·13]; p=0·0001) for SCA2; and age (1·27 [1·09-1·50]; p=0·0031), confidence rating (2·60 [1·23-5·47]; p=0·012), and double vision (14·83 [2·15-102·44]; p=0·0063) for SCA3. From the time of inclusion, the SARA scores of SCA1, SCA2, and SCA3 mutation carriers increased, whereas they remained stable in non-carriers. On a timescale defined by the predicted time of ataxia onset, SARA progression in SCA1, SCA2, and SCA3 mutation carriers was non-linear, with marginal progression before ataxia and increasing progression after ataxia onset. INTERPRETATION: Our study provides quantitative data on the conversion of non-ataxic SCA1, SCA2, and SCA3 mutation carriers to manifest ataxia. Our data could prove useful for the design of preventive trials aimed at delaying the onset of ataxia by aiding sample size calculations and stratification of study participants. FUNDING: European Research Area Network for Research Programmes on Rare Diseases, Polish Ministry of Science and Higher Education, Italian Ministry of Health, European Community's Seventh Framework Programme.

De novo ITPR1 variants are a recurrent cause of early-onset ataxia, acting via loss of channel function.

We explored the clinico-genetic basis of spinocerebellar ataxia 29 (SCA29) by determining the frequency, phenotype, and functional impact of ITPR1 missense variants associated with early-onset ataxia (EOA). Three hundred thirty one patients from a European EOA target cohort (n = 120), US-American EOA validation cohort (n = 72), and early-onset epileptic encephalopathy (EOEE) control cohort (n = 139) were screened for de novo ITPR1 variants. The target cohort was also screened for inherited ITPR1 variants. The variants' functional impact was determined by IP3-induced Ca2+ release in HEK293 cells. 3/120 patients (2.5%) from the target cohort and 4/72 patients (5.5%) from the validation cohort, but none from the EOEE control cohort, carried de novo ITPR1 variants. However, most ITPR1 variants (7/10 = 70%) in the target cohort were inherited from a healthy parent, with 3/6 patients carrying disease-causing variants in other genes. This suggests limited or no phenotypic impact of many ITPR1 missense variants, even if ultra-rare and well-conserved. While common bioinformatics tools did not discriminate de novo from other ITPR1 variants, functional characterization demonstrated reduced IP3-induced Ca2+ release for all de novo variants, including the recurrent c.805C>T (p.(R269W)) variant. In sum, these findings show that de novo ITPR1 missense variants are a recurrent cause of EOA (SCA29) across independent cohorts, acting via loss of IP3 channel function. Inherited ITPR1 variants are also enriched in EOA, but often without strong impact, albeit rare and well-conserved. Functional studies allow identifying ITPR1 variants with large impact, likely disease-causing. Such functional confirmation is warranted for inherited ITPR1 variants before making a SCA29 diagnosis.

Clinical and genetic characteristics of sporadic adult-onset degenerative ataxia.

OBJECTIVE: To define the clinical phenotype and natural history of sporadic adult-onset degenerative ataxia and to identify putative disease-causing mutations. METHODS: The primary measure of disease severity was the Scale for the Assessment and Rating of Ataxia (SARA). DNA samples were screened for mutations using a high-coverage ataxia-specific gene panel in combination with next-generation sequencing. RESULTS: The analysis was performed on 249 participants. Among them, 83 met diagnostic criteria of clinically probable multiple system atrophy cerebellar type (MSA-C) at baseline and another 12 during follow-up. Positive MSA-C criteria (4.94 ± 0.74, p < 0.0001) and disease duration (0.22 ± 0.06 per additional year, p = 0.0007) were associated with a higher SARA score. Forty-eight participants who did not fulfill MSA-C criteria and had a disease duration of >10 years were designated sporadic adult-onset ataxia of unknown etiology/non-MSA (SAOA/non-MSA). Compared with MSA-C, SAOA/non-MSA patients had lower SARA scores (13.6 ± 6.0 vs 16.0 ± 5.8, p = 0.0200) and a slower annual SARA increase (1.1 ± 2.3 vs 3.3 ± 3.2, p = 0.0013). In 11 of 194 tested participants (6%), a definitive or probable genetic diagnosis was made. CONCLUSIONS: Our study provides quantitative data on the clinical phenotype and progression of sporadic ataxia with adult onset. Screening for causative mutations with a gene panel approach yielded a genetic diagnosis in 6% of the cohort. CLINICALTRIALSGOV REGISTRATION: NCT02701036.

NPC1 is enriched in unexplained early onset ataxia: a targeted high-throughput screening.

Niemann-Pick disease type C (NP-C) is a rare autosomal-recessive neurodegenerative disease featuring pleiotropic neurological, psychiatric and visceral manifestations. Since many of the adult manifestations can be non-specific or missed, NP-C often goes undetected in adult-onset patients. Here we hypothesized that targeted high-throughput sequencing allows identifying NP-C patients among subjects with unexplained early-onset ataxia (EOA) and, moreover, that this population is enriched for NPC1 mutations. From 204 consecutive EOA patients, all 108 subjects with an established diagnosis were removed (including 4 NPC1 patients), yielding a target cohort of 96 subjects with unexplained EOA, but without primary suspicion of NP-C. This cohort was investigated for NPC1/NPC2 mutations using a high-coverage HaloPlex gene panel including 122 ataxia genes. Among 96 samples, we identified 4 known NPC1 mutations, 3 novel NPC1 missense variants of uncertain significance (VUS) and 1 novel NPC2 missense VUS. The total mutant allele frequency (8/192 = 4.17 %) was significantly enriched compared with control population data (1.57 %; p = 0.011). Two NPC1-positive patients were identified (both with non-specific incipient clinical features), giving a NPC1 patient frequency of 2/96 = 2.1 % in unexplained EOA and of 6/204 = 2.9 % in the total EOA series. NPC1 mutations are substantially enriched in unexplained EOA, demonstrating EOA as a risk-group for NP-C disease. Targeted high-throughput sequencing allows to identify also those NP-C patients with non-specific conditions where the diagnosis has initially been missed. This method does not require having considered NP-C during differential diagnosis, but allows identification of NP-C as part of the default analysis.