Jennifer Müller vom Hagen

A Pan-European Study of the C9orf72 Repeat Associated with FTLD: Geographic Prevalence, Genomic Instability, and Intermediate Repeats

We assessed the geographical distribution of C9orf72 G4C2 expansions in a pan‐European frontotemporal lobar degeneration (FTLD) cohort (n = 1,205), ascertained by the European Early‐Onset Dementia (EOD) consortium. Next, we performed a meta‐analysis of our data and that of other European studies, together 2,668 patients from 15 Western European countries. The frequency of the C9orf72 expansions in Western Europe was 9.98% in overall FTLD, with 18.52% in familial, and 6.26% in sporadic FTLD patients. Outliers were Finland and Sweden with overall frequencies of respectively 29.33% and 20.73%, but also Spain with 25.49%. In contrast, prevalence in Germany was limited to 4.82%. In addition, we studied the role of intermediate repeats (7–24 repeat units), which are strongly correlated with the risk haplotype, on disease and C9orf72 expression. In vitro reporter gene expression studies demonstrated significantly decreased transcriptional activity of C9orf72 with increasing number of normal repeat units, indicating that intermediate repeats might act as predisposing alleles and in favor of the loss‐of‐function disease mechanism. Further, we observed a significantly increased frequency of short indels in the GC‐rich low complexity sequence adjacent to the G4C2 repeat in C9orf72 expansion carriers (P < 0.001) with the most common indel creating one long contiguous imperfect G4C2 repeat, which is likely more prone to replication slippage and pathological expansion.

Biological and clinical characteristics of the European Friedreich's Ataxia Consortium for Translational Studies (EFACTS) cohort: a cross-sectional analysis of baseline data.

BACKGROUND Friedreichs ataxia is a rare autosomal recessive neurodegenerative disorder. Here we report cross-sectional baseline data to establish the biological and clinical characteristics for a prospective, international, European Friedreichs ataxia database registry. METHODS Within the European Friedreichs Ataxia Consortium for Translational Studies (EFACTS) framework, we assessed a cohort of patients with genetically confirmed Friedreichs ataxia. The primary outcome measure was the Scale for the Assessment and Rating of Ataxia (SARA) and secondary outcome measures were the Inventory of Non-Ataxia Signs (INAS), the performance-based coordination test Spinocerebellar Ataxia Functional Index (SCAFI), the neurocognitive phonemic verbal fluency test, and two quality-of-life measures: the activities of daily living (ADL) part of the Friedreichs Ataxia Rating Scale and EQ-5D. The Friedreichs ataxia cohort was subdivided into three groups: early disease onset (≤14 years), intermediate onset (15-24 years), and late onset (≥25 years), which were compared for clinical characteristics and outcome measures. We used linear regression analysis to estimate the annual decline of clinical outcome measures based on disease duration. This study is registered with ClinicalTrials.gov, number NCT02069509. FINDINGS We enrolled 592 patients with genetically confirmed Friedreichs ataxia between Sept 15, 2010, and April 30, 2013, at 11 sites in seven European countries. Age of disease onset was inversely correlated with the number of GAA repeats in the frataxin (FXN) gene: every 100 GAA repeats on the smaller repeat allele was associated with a 2·3 year (SE 0·2) earlier onset. Regression analyses showed significant estimated annual worsening of SARA (regression coefficient 0·86 points [SE 0·05], INAS (0·14 points [0·01]), SCAFI Z scores (-0·09 [0·01]), verbal fluency (-0·34 words [0·07]), and ADL (0·64 points [0·04]) during the first 25 years of disease; the regression slope for health-related quality-of-life state from EQ-5D was not significant (-0·33 points [0·18]). For SARA, the predicted annual rate of worsening was significantly higher in early-onset patients (n=354; 1·04 points [0·13]) and intermediate-onset patients (n=137; 1·17 points [0·22]) than in late-onset patients (n=100; 0·56 points [0·10]). INTERPRETATION The results of this cross-sectional baseline analysis of the EFACTS cohort suggest that earlier disease onset is associated with larger numbers of GAA repeats and more rapid disease progression. The differential estimated progression of ataxia symptoms related to age of onset have implications for the design of clinical trials in Friedreichs ataxia, for which SARA might be the most suitable measure to monitor disease progression. FUNDING European Commission.

Screening in ALS and FTD patients reveals 3 novel UBQLN2 mutations outside the PXX domain and a pure FTD phenotype.

Mutations in UBQLN2 have recently been shown to cause dominant X-linked amyotrophic lateral sclerosis (ALS) and ALS plus frontotemporal dementia (FTD). Information on their frequency in different populations is still rare, and a pure FTD phenotype has not yet been reported. Moreover, the mutational spectrum of known UBQLN2 mutations is still limited to its PXX repeat region. Based on a screening of 206 ALS and FTD patients, we here report 3 novel UBQLN2 mutations, accounting for 1.2% (2/161) ALS and 2.2% (1/45) FTD patients, including a patient with pure FTD. All mutations were located in highly conserved domains outside the PXX repeat region and not observed in 1450 ethnically matched control X-chromosomes. All affected patients presented with apparently sporadic disease. UBQLN2 mutations are rare in Central European ALS and FTD patients, but contribute significantly to patients with seemingly sporadic disease. UBQLN2 is able to cause any disease on the ALS-FTD continuum, including pure FTD. Because the pathogenic mechanism of UBQLN2 mutations is not limited to its PXX region, UBQLN2 screening in neurodegenerative patients should not be limited to this region.

Chorein-sensitive polymerization of cortical actin and suicidal cell death in chorea-acanthocytosis

Chorea‐acanthocytosis is an inevitably lethal genetic disease characterized by a progressive hyperkinetic movement disorder and cognitive and behavioral abnormalities as well as acanthocytosis. The disease is caused by loss‐of‐function mutations of the gene encoding vacuolar protein sorting‐associated protein 13A (VPS13A) or chorein, a protein with unknown function expressed in various cell types. How chorein deficiency leads to the pathophysiology of chorea‐acanthocytosis remains enigmatic. Here we show decreased phosphoinositide‐3‐kinase (PI3K)‐p85‐subunit phosphorylation, ras‐related C3 botunlinum toxin substrate 1 (Rac1) activity, and p21 protein‐activated kinase 1 (PAK1) phosphorylation as well as depolymerized cortical actin in erythrocytes from patients with chorea‐acanthocytosis and in K562‐erythrocytic cells following chorein silencing. Pharmacological inhibition of PI3K, Rac1, or PAK1 similarly triggered actin depolymerization. Moreover, in K562 cells, both chorein silencing and PAK1 inhibition with IPA‐3 decreased phosphorylation of Bad, a Bcl2‐associated protein, promoting apoptosis by forming mitochondrial pores, followed by mitochondrial depolarization, DNA fragmentation, and phosphatidylserine exposure at the cell surface, all hallmarks of apoptosis. Our observations reveal chorein as a novel powerful regulator of cytoskeletal architecture and cell survival, thus explaining erythrocyte misshape and possibly neurodegeneration in chorea‐acanthocytosis.—Föller, M., Hermann, A., Gu, S., Alesutan, I., Qadri, S. M., Borst, O., Schmidt, E.‐M., Schiele, F., Müller vom Hagen, J., Saft, C., Schöls, L., Lerche, H., Stournaras, C., Storch, A., Lang, F. Chorein‐sensitive polymerization of cortical actin and suicidal cell death in chorea‐acanthocytosis. FASEB J. 26, 1526–1534 (2012). www.fasebj.org

Safety and tolerability of carbamylated erythropoietin in Friedreich's ataxia

Erythropoietin (EPO) derivatives have been found to increase frataxin levels in Friedreichs ataxia (FRDA) in vitro. This multicenter, double‐blind, placebo‐controlled, phase II clinical trial aimed to evaluate the safety and tolerability of Lu AA24493 (carbamylated EPO; CEPO).

Progression characteristics of the European Friedreich’s Ataxia Consortium for Translational Studies (EFACTS): a 2 year cohort study

BACKGROUND The European Friedreichs Ataxia Consortium for Translational Studies (EFACTS) is a prospective international registry investigating the natural history of Friedreichs ataxia. We used data from EFACTS to assess disease progression and the predictive value of disease-related factors on progression, and estimated sample sizes for interventional randomised clinical trials. METHODS We enrolled patients with genetically confirmed Friedreichs ataxia from 11 European study sites in Austria, Belgium, France, Germany, Italy, Spain, and the UK. Patients were seen at three visits-baseline, 1 year, and 2 years. Our primary endpoint was the Scale for the Assessment and Rating of Ataxia (SARA). Secondary outcomes were the Inventory of Non-Ataxia Signs (INAS), the Spinocerebellar Ataxia Functional Index (SCAFI), phonemic verbal fluency (PVF), and the quality of life measures activities of daily living (ADL) and EQ-5D-3L index. We estimated the yearly progression for each outcome with linear mixed-effect modelling. This study is registered with ClinicalTrials.gov, number NCT02069509, and follow-up assessments and recruitment of new patients are ongoing. FINDINGS Between Sept 15, 2010, and Nov 21, 2013, we enrolled 605 patients with Friedreichs ataxia. 546 patients (90%) contributed data with at least one follow-up visit. The progression rate on SARA was 0·77 points per year (SE 0·06) in the overall cohort. Deterioration in SARA was associated with younger age of onset (-0·02 points per year [0·01] per year of age) and lower SARA baseline scores (-0·07 points per year [0·01] per baseline point). Patients with more than 353 GAA repeats on the shorter allele of the FXN locus had a higher SARA progression rate (0·09 points per year [0·02] per additional 100 repeats) than did patients with fewer than 353 repeats. Annual worsening was 0·10 points per year (0·03) for INAS, -0·04 points per year (0·01) for SCAFI, 0·93 points per year (0·06) for ADL, and -0·02 points per year (0·004) for EQ-5D-3L. PVF performance improved by 0·99 words per year (0·14). To detect a 50% reduction in SARA progression at 80% power, 548 patients would be needed in a 1 year clinical trial and 184 would be needed for a 2 year trial. INTERPRETATION Our results show that SARA is a suitable clinical rating scale to detect deterioration of ataxia symptoms over time; ADL is an appropriate measure to monitor changes in daily self-care activities; and younger age at disease onset is a major predictor for faster disease progression. The results of the EFACTS longitudinal analysis provide suitable outcome measures and sample size calculations for the design of upcoming clinical trials of Friedreichs ataxia. FUNDING European Commission.

Niemann-Pick type C is frequent in adult ataxia with cognitive decline and vertical gaze palsy.

Niemann-Pick type C (NPC) disease is a rare, usually fatal neurodegenerative lysosomal storage disorder. It is inherited in an autosomal-recessive fashion and caused by mutation of either NPC1 (95%) or NPC2 gene.1 Age at onset is broadly variable, ranging from neonatal fatal neurovisceral manifestations to a primarily neurodegenerative disease in adulthood that may be recognized as late as 70 years of age.1 Due to its diverse clinical manifestation, correct diagnosis is challenging, frequencies might be underestimated, and diagnosis may be delayed, in particular in patients with adult-onset disease. This is particularly momentous because a potential therapy for deceleration of disease progression is now available.2

X-linked Charcot-Marie-Tooth disease, Arts syndrome, and prelingual non-syndromic deafness form a disease continuum: evidence from a family with a novel PRPS1 mutation.

BackgroundX-linked Charcot-Marie-Tooth disease type 5 (CMTX5), Arts syndrome, and non-syndromic sensorineural deafness (DFN2) are allelic syndromes, caused by reduced activity of phosphoribosylpyrophosphate synthetase 1 (PRS-I) due to loss-of-function mutations in PRPS1. As only few families have been described, knowledge about the relation between these syndromes, the phenotypic spectrum in patients and female carriers, and the relation to underlying PRS-I activity is limited.MethodsWe investigated a family with a novel PRPS1 mutation (c.830A > C, p.Gln277Pro) by extensive phenotyping, MRI, and genetic and enzymatic tests.ResultsThe male index subject presented with an overlap of CMTX5 and Arts syndrome features, whereas his sister presented with prelingual DFN2. Both showed mild parietal and cerebellar atrophy on MRI. Enzymatically, PRS-I activity was undetectable in the index subject, reduced in his less affected sister, and normal in his unaffected mother.ConclusionsOur findings demonstrate that CMTX5, Arts syndrome and DFN2 are phenotypic clusters on an intrafamilial continuum, including overlapping phenotypes even within individuals. The respective phenotypic presentation seems to be determined by the exact PRPS1 mutation and the residual enzyme activity, the latter being largely influenced by the degree of skewed X-inactivation. Finally, our findings show that brain atrophy might be more common in PRPS1-disorders than previously thought.

Friedreich and dominant ataxias: quantitative differences in cerebellar dysfunction measurements

Background Sensitive outcome measures for clinical trials on cerebellar ataxias are lacking. Most cerebellar ataxias progress very slowly and quantitative measurements are required to evaluate cerebellar dysfunction. Methods We evaluated two scales for rating cerebellar ataxias: the Composite Cerebellar Functional Severity (CCFS) Scale and Scale for the Assessment and Rating of Ataxia (SARA), in patients with spinocerebellar ataxia (SCA) and controls. We evaluated these scales for different diseases and investigated the factors governing the scores obtained. All patients were recruited prospectively. Results There were 383 patients with Friedreich’s ataxia (FRDA), 205 patients with SCA and 168 controls. In FRDA, 31% of the variance of cerebellar signs with the CCFS and 41% of that with SARA were explained by disease duration, age at onset and the shorter abnormal repeat in the FXN gene. Increases in CCFS and SARA scores per year were lower for FRDA than for SCA (CCFS index: 0.123±0.123 per year vs 0.163±0.179, P<0.001; SARA index: 1.5±1.2 vs 1.7±1.7, P<0.001), indicating slower cerebellar dysfunction indexes for FRDA than for SCA. Patients with SCA2 had higher CCFS scores than patients with SCA1 and SCA3, but similar SARA scores. Conclusions Cerebellar dysfunction, as measured with the CCFS and SARA scales, was more severe in FRDA than in patients with SCA, but with lower progression indexes, within the limits of these types of indexes. Ceiling effects may occur at late stages, for both scales. The CCFS scale is rater-independent and could be used in a multicentre context, as it is simple, rapid and fully automated. Trial registration number ClinicalTrials.gov: NCT02069509.

A Cognitive Brain-Computer Interface for Patients with Amyotrophic Lateral Sclerosis

Brain-computer interfaces (BCIs) are often based on the control of sensorimotor processes, yet sensorimotor processes are impaired in patients suffering from amyotrophic lateral sclerosis (ALS). We devised a new paradigm that targets higher-level cognitive processes to transmit information from the user to the BCI. We instructed five ALS patients and twelve healthy subjects to either activate self-referential memories or to focus on a process without mnemonic content while recording a high-density electroencephalogram (EEG). Both tasks are designed to modulate activity in the default mode network (DMN) without involving sensorimotor pathways. We find that the two tasks can be distinguished after only one experimental session from the average of the combined bandpower modulations in the theta- (4-7Hz) and alpha-range (8-13Hz), with an average accuracy of 62.5% and 60.8% for healthy subjects and ALS patients, respectively. The spatial weights of the decoding algorithm show a preference for the parietal area, consistent with modulation of neural activity in primary nodes of the DMN.