Patient-Reported Outcome Measure of Ataxia Correlates with Canonical Clinical Assessments in Chinese Spinocerebellar Ataxias

Spinocerebellar ataxia (SCA) patients' reports of their own experiences are essential to the outcome evaluation in clinical trials. To better understand the health condition and well-being of ataxia population, Patient-Reported Outcome Measure of Ataxia (PROM-Ataxia) was developed. The aim of our study was to culturally adapt the PROM-Ataxia into Chinese version and assess its correlation with canonical clinical assessments. We translated the PROM-Ataxia into Chinese following the ISPOR TCA Task Force guidelines and evaluated its correlation with measures of motor ataxia, non-ataxia signs, quality of life, and mental health in 92 Chinese SCA participants. Nearly all the participants found this questionnaire complete and intelligible but some items were found repetitive or ambiguous. The total score of PROM-Ataxia from stage 0 to stage 3 was 23.24 ± 18.53, 79.11 ± 40.45, 144.30 ± 41.30, and 176.20 ± 31.74, respectively (p < 0.0001). It was strongly correlated with the Scale for the Assessment and Rating of Ataxia (SARA) (r = 0.832, p < 0.0001). Physical and activities domain of PROM-Ataxia were correlated with measures of motor ataxia, quality of life, and psychological health while mental health domain was correlated with all the clinical assessments including inventory of non-ataxia signs and cognitive assessment. We translated the PROM-Ataxia into Chinese for the first time, which allows transnational comparability in future studies. Our study validated the responsiveness of PROM-Ataxia to established clinical measures in Chinese SCA patients and implied its potential to evaluate the therapeutic effect and optimize the sensitivity of changes in clinical outcome assessments.

Clinical stage and plasma neurofilament concentration in adults with Friedreich ataxia

Objectives

Friedreich Ataxia (FRDA) is the most common recessive ataxia disorder. Yet, little is known of the prevalence in Sweden. In the future, there may be effective disease-modifying therapies, and use of clinical rating scales as well as possible biomarkers in serum or cerebrospinal fluid may be of importance. We evaluated the axonal protein neurofilament light in plasma (p-NfL) as a possible biomarker for disease severity in FRDA.

Materials & methods

We searched for all possible genetically confirmed FRDA cases in the Västra Götaland Region (VGR) of Sweden, and investigated each patient clinically and obtained blood sample for analysis of p-NfL.

Results

We found eight patients corresponding to 1/170.000 adults in the VGR, and 5 of these participated in the study. Three out of the five FRDA patients displayed a small or moderate increase in the p-NfL value, compared to the age-adjusted cut-offs for p-NfL established in the Clinical Neurochemistry Laboratory at our hospital. The two others were the oldest and most severely affected, displayed normal values according the cut-off values. The cohort is too small to make any statistically significant correlation between the five p-NfL values with regard to disease severity.

Conclusions

FRDA is less prevalent in our region of Sweden than could be assumed. In concordance with previous studies from other authors, we find that p-NfL may be increased in patients with FRDA, but less so in older more clinically affected patients. Thus, we conclude that on an individual basis, p-NFL is of uncertain clinical value as a suitable biomarker.

The C-Terminal Cross-linked Telopeptide of Type I Collagen (CTX-I) as a Potential Cardiomyopathy Biomarker in Friedreich Ataxia Patients

Friedreich's ataxia (FRDA) is the most common inherited recessive ataxia. Cardiomyopathy (CM) with myocardial hypertrophy is the predominant cause of death. The presence of CM is variable and the risk factors for cardiac involvement are not entirely clear. Markers of collagen degradation, such as C-terminal cross-linked telopeptide of type I collagen (CTX-I), seem to be associated with unfavorable cardiovascular outcomes. The aim of our study was to measure serum CTX-I as a marker of cardiac fibrosis in FRDA patients. We measured serum CTX value in twenty-five FRDA patients (mean age, 31.3 ± 14.7 years) and nineteen healthy controls (mean age, 34.0 ± 13.5 years). Patients underwent echocardiography and SARA scale evaluation. CTX values were significantly higher in the patients than in the control group (31.82 ± 2.27 vs 16.44 ± 1.6 μg/L; p = 0.006). CTX-I was inversely correlated with age (R =  - 0,535; n = 44; p < 0.001). The regression model identified disease duration and TT3 levels to be independent predictors of CTX-I (model R2 = 0.938; intercept - 64.0, p = 0.071; disease duration coefficient =  - 2.34, p = 0.005; TT3 coefficient = 127.17, p = 0.011). CTX-I, a biomarkers of collagen turnover, is elevated in FRDA and should provide complementary information to identify patients with high cardiological risk even if longitudinal studies are needed to define the role of this serologic marker of collagen metabolism in the natural history of cardiomyopathy in FRDA patients.

Apparent Opportunities and Hidden Pitfalls: The Conflicting Results of Restoring NRF2-Regulated Redox Metabolism in Friedreich's Ataxia Pre-Clinical Models and Clinical Trials

Friedreich's ataxia (FRDA) is an autosomal, recessive, inherited neurodegenerative disease caused by the loss of activity of the mitochondrial protein frataxin (FXN), which primarily affects dorsal root ganglia, cerebellum, and spinal cord neurons. The genetic defect consists of the trinucleotide GAA expansion in the first intron of FXN gene, which impedes its transcription. The resulting FXN deficiency perturbs iron homeostasis and metabolism, determining mitochondrial dysfunctions and leading to reduced ATP production, increased reactive oxygen species (ROS) formation, and lipid peroxidation. These alterations are exacerbated by the defective functionality of the nuclear factor erythroid 2-related factor 2 (NRF2), a transcription factor acting as a key mediator of the cellular redox signalling and antioxidant response. Because oxidative stress represents a major pathophysiological contributor to FRDA onset and progression, a great effort has been dedicated to the attempt to restore the NRF2 signalling axis. Despite this, the beneficial effects of antioxidant therapies in clinical trials only partly reflect the promising results obtained in preclinical studies conducted in cell cultures and animal models. For these reasons, in this critical review, we overview the outcomes obtained with the administration of various antioxidant compounds and critically analyse the aspects that may have contributed to the conflicting results of preclinical and clinical studies.

A wearable motion capture suit and machine learning predict disease progression in Friedreich's ataxia

Friedreich's ataxia (FA) is caused by a variant of the Frataxin (FXN) gene, leading to its downregulation and progressively impaired cardiac and neurological function. Current gold-standard clinical scales use simplistic behavioral assessments, which require 18- to 24-month-long trials to determine if therapies are beneficial. Here we captured full-body movement kinematics from patients with wearable sensors, enabling us to define digital behavioral features based on the data from nine FA patients (six females and three males) and nine age- and sex-matched controls, who performed the 8-m walk (8-MW) test and 9-hole peg test (9 HPT). We used machine learning to combine these features to longitudinally predict the clinical scores of the FA patients, and compared these with two standard clinical assessments, Spinocerebellar Ataxia Functional Index (SCAFI) and Scale for the Assessment and Rating of Ataxia (SARA). The digital behavioral features enabled longitudinal predictions of personal SARA and SCAFI scores 9 months into the future and were 1.7 and 4 times more precise than longitudinal predictions using only SARA and SCAFI scores, respectively. Unlike the two clinical scales, the digital behavioral features accurately predicted FXN gene expression levels for each FA patient in a cross-sectional manner. Our work demonstrates how data-derived wearable biomarkers can track personal disease trajectories and indicates the potential of such biomarkers for substantially reducing the duration or size of clinical trials testing disease-modifying therapies and for enabling behavioral transcriptomics.

Robot Assisted Gait Training in a Patient with Ataxia

Background: Ataxia is a neurological sign characterized by motor coordination during gait/voluntary limb movements impairment. Ataxic gait leads to disability and worsening of quality of life; physiotherapy intervention is recommended to improve motor function. Recent studies showed benefits due to repetitive robotized assisted gait training using a static exoskeleton in patients affected by acquired ataxias. The aim of the study was to perform a preliminary evaluation of the short-term effects of overground UAN.GO^®-assisted gait training in an adult patient with ataxia but with no clear genetic pattern. Methods: This case report study was conducted on a single male adult patient, who presented ataxic spastic gait, posterior chain tightness, pes cavus, and unstable standing position. The patient underwent two preliminary sessions to take part in the study. Treatment protocol planned 10 sessions and each one lasted 80 min, 60 of which were spent in gait training using the mobile overground exoskeleton UAN.GO^®. At T1 (start of the study) and T10 (final evaluation) assessments using the Scale for the Assessment and Rating of Ataxia, Berg Balance Scale, 6-Minute Walking Test, and Likert Scale were administered. Space-time parameters of gait cycle were also evaluated: left and right step length, stance and swing percentages. Results: improvements on the Scale for the Assessment and Rating of Ataxia, Berg Balance Scale, and in the distance travelled at 6-Minute Walking Test emerged. The patient gave a positive opinion towards the treatment, showed by Likert Scale results. Kinematic gait analysis showed more physiological step length, stance and swing percentages, joint angles. The patient completed the training program with an excellent compliance. Discussion: Since these encouraging outcomes were obtained, it is possible to consider robot-assisted gait training performed with UAN.GO^® as a therapeutic option to improve motor and functional performance in patients with ataxic gait.

Objective Assessment of Progression and Disease Characterization of Friedreich Ataxia via an Instrumented Drinking Cup: Preliminary Results

The monitoring of disease progression in certain neurodegenerative conditions can significantly be quantified with the help of objective assessments. The severity assessment of diseases like Friedreich ataxia (FRDA) are usually based on different subjective measures. The ability of a participant with FRDA to perform standard neurological tests is the most common way of assessing disease progression. In this feasibility study, an Ataxia Instrumented Measurement-Cup (AIM-C) is proposed to quantify the disease progression of 10 participants (mean age 39 years, onset of disease 16.3 years) in longitudinal timepoints. The device consists of a sensing system with the provision of extracting both kinetic and kinematic information while engaging in an activity closely associated with activities of daily living (ADL). A common functional task of simulated drinking was used to capture features that possesses disease progression information as well as certain other features which intrinsically correlate with commonly used clinical scales such as the modified Friedreich Ataxia Rating Scale (mFARS), the Functional Staging of Ataxia score and the ADL scale. Frequency and time-frequency domain features allowed the longitudinal assessment of participants with FRDA. Furthermore, both kinetic and kinematic measures captured clinically relevant features and correlated 85% with clinical assessments.

Detection of ataxia in low disability MS patients by hybrid convolutional neural networks based on images of plantar pressure distribution

BACKGROUND

This study aimed to detect ataxia in patients with multiple sclerosis (PwMS) with a deep learning-based approach based on images showing plantar pressure distribution of the patients. The secondary aim of the study was to investigate an alternative and objective method in the early diagnosis of ataxia in these patients.

METHODS

A total of 105 images showing plantar pressure distribution of 43 ataxic PwMS and 62 healthy individuals were analyzed. The images were resized for the models including VGG16, VGG19, ResNet, DenseNet, MobileNet, NasNetMobile, and NasNetLarge. Feature vectors were extracted from the resized images and then classified using Support Vector Machines (SVM), K-Nearest Neighbors (K-NN), and Artificial Neural Network (ANN). A 10-fold cross-validation was applied to increase the validity of the classifiers.

RESULTS

The VGG19-SVM hybrid model showed the highest accuracy, sensitivity, and specificity values (89.23%, 89.65%, and 88.88%, respectively).

CONCLUSION

The proposed method provided an automatic decision support system for detecting ataxia based on images showing plantar pressure distribution in patients with PwMS. The performance of the proposed method indicated that this method can be applied in clinical practice to establish a rapid diagnosis of ataxia that is asymptomatic or difficult to detect clinically and that it can be recommended as a useful aid for the physician in clinical practice.

Giant axonal neuropathy: cross sectional analysis of a large natural history cohort

Giant axonal neuropathy (GAN) is an ultra-rare autosomal recessive, progressive neurodegenerative disease with early childhood onset that presents as a prominent sensorimotor neuropathy and commonly progresses to affect both the peripheral nervous system and central nervous system. The disease is caused by biallelic mutations in the GAN gene located on 16q23.2, leading to loss of functional gigaxonin, a substrate specific ubiquitin ligase adapter protein necessary for the regulation of intermediate filament turnover. Here, we report on cross-sectional data from the first study visit of a prospectively collected natural history study of 45 individuals, age range 3-21 years with genetically confirmed giant axonal neuropathy to describe and cross-correlate baseline clinical and functional cohort characteristics. We review causative variants distributed throughout the GAN gene in this cohort and identify a recurrent founder mutation in individuals with giant axonal neuropathy of Mexican descent as well as cases of recurrent uniparental isodisomy. Through cross correlation analysis of measures of strength, motor function, and electrophysiologic markers of disease severity, we identified the Motor Function Measure 32 (MFM-32) to have the strongest correlation across measures and age in individuals with giant axonal neuropathy. We analysed the Motor Function Measure 32 scores as they correspond to age and ambulatory status. Importantly, we identified and characterized a sub cohort of individuals with a milder form of giant axonal neuropathy and with a presentation similar to Charcot-Marie-Tooth disease. Such a clinical presentation is distinct from the classic presentation of giant axonal neuropathy, and we demonstrate how the two groups diverge in performance on the Motor Function Measure 32 and other functional motor scales. We further present data on the first systematic clinical analysis of autonomic impairment in giant axonal neuropathy as performed on a subset of the natural history cohort. Our cohort of individuals with genetically confirmed giant axonal neuropathy is the largest reported to date and highlights the clinical heterogeneity and the unique phenotypic and functional characteristics of giant axonal neuropathy in relation to disease state. The present work is designed to serve as a foundation for a prospective natural history study and functions in concert with the ongoing gene therapy trial for children with giant axonal neuropathy.

Quantitative Assessment of Friedreich Ataxia via Self-Drinking Activity

Effective monitoring of the progression of neurodegenerative conditions can be significantly improved by objective assessments. Clinical assessments of conditions such as Friedreich's Ataxia (FA), currently rely on subjective measures commonly practiced in clinics as well as the ability of the affected individual to perform conventional tests of the neurological examination. In this study, we propose an ataxia measuring device, in the form of a pressure canister capable of sensing certain kinetic and kinematic parameters of interest to quantify the impairment levels of participants particularly when engaged in an activity that is closely associated with daily living. In particular, the functional task of simulated drinking was utilised to capture characteristic features of disability manifestation in terms of diagnosis (separation of individuals with FA and controls) and severity assessment of individuals diagnosed with the debilitating condition of FA. Time and frequency domain analysis of these biomarkers enabled the classification of individuals with FA and control subjects to reach an accuracy of 98% and a correlation level reaching 96% with the clinical scores.

Spinocerebellar ataxia clinical trials: opportunities and challenges

The spinocerebellar ataxias (SCAs) are a group of dominantly inherited diseases that share the defining feature of progressive cerebellar ataxia. The disease process, however, is not confined to the cerebellum; other areas of the brain, in particular, the brainstem, are also affected, resulting in a high burden of morbidity and mortality. Currently, there are no disease‐modifying treatments for the SCAs, but preclinical research has led to the development of therapeutic agents ripe for testing in patients. Unfortunately, due to the rarity of these diseases and their slow and variable progression, there are substantial hurdles to overcome in conducting clinical trials. While the epidemiological features of the SCAs are immutable, the feasibility of conducting clinical trials is being addressed through a combination of strategies. These include improvements in clinical outcome measures, the identification of imaging and fluid biomarkers, and innovations in clinical trial design. In this review, we highlight current challenges in initiating clinical trials for the SCAs and also discuss pathways for researchers and clinicians to mitigate these challenges and harness opportunities for clinical trial development.

Reverse Phase Protein Array Reveals Correlation of Retinoic Acid Metabolism With Cardiomyopathy in Friedreich's Ataxia

Identifying biomarkers is important for assessment of disease progression, prediction of symptom development, and determination of treatment effectiveness. While unbiased analyses of differential gene expression using next-generation sequencing methods are now routinely conducted, proteomics studies are more challenging because of traditional methods predominantly being low throughput and offering a limited dynamic range for simultaneous detection of hundreds of proteins that drastically differ in their intracellular abundance. We utilized a sensitive and high-throughput proteomic technique, reverse phase protein array (RPPA), to attain protein expression profiles of primary fibroblasts obtained from patients with Friedreich's ataxia (FRDA) and unaffected controls (CTRLs). The RPPA was designed to detect 217 proteins or phosphorylated proteins by individual antibody, and the specificity of each antibody was validated prior to the experiment. Among 62 fibroblast samples (44 FRDA and 18 CTRLs) analyzed, 30 proteins/phosphoproteins were significantly changed in FRDA fibroblasts compared with CTRL cells (p < 0.05), mostly representing signaling molecules and metabolic enzymes. As expected, frataxin was significantly downregulated in FRDA samples, thus serving as an internal CTRL for assay integrity. Extensive bioinformatics analyses were conducted to correlate differentially expressed proteins with critical disease parameters (e.g., selected symptoms, age of onset, guanine-adenine-adenine sizes, frataxin levels, and Functional Assessment Rating Scale scores). Members of the integrin family of proteins specifically associated with hearing loss in FRDA. Also, RPPA data, combined with results of transcriptome profiling, uncovered defects in the retinoic acid metabolism pathway in FRDA samples. Moreover, expression of aldehyde dehydrogenase family 1 member A3 differed significantly between cardiomyopathy-positive and cardiomyopathy-negative FRDA cohorts, demonstrating that metabolites such as retinol, retinal, or retinoic acid could become potential predictive biomarkers of cardiac presentation in FRDA.

Gauging Gait Disorders with a Method Inspired by Motor Control Theories: A Pilot Study in Friedreich's Ataxia

To date, it has been challenging for clinicians and researchers alike to use the multiple outcome measures available to create a meaningful clinical picture and perform effective longitudinal follow-up. It has been found that instrumented gait analysis can provide information associated with a patient’s performance and help to remedy the shortcomings of the currently available outcome measures. The goal of this methodological article is to set the background and justify a new outcome measure inspired by the motor control theories to analyze gait using spatiotemporal parameters. The method is applied in a population of individuals living with Friedreich’s ataxia (FRDA), a neurodegenerative disease. The sample population consisted of 19 subjects, 11 to 65 years of age with FRDA, who either ambulated independently, with a cane, or with a rollator. Three scores based on the distance from healthy normative data were used: Organization Score, Variability Score, and an overall measurement, the Global Ambulation Score. The scores were then compared to the Scale for Assessment and Rating of Ataxia (SARA) Gait Score (SARA-GS), a clinical scale currently being used for gait analysis in FRDA. Organization Scores demonstrated a longitudinal deterioration in the gait characteristics from independent ambulators to those who ambulated with a rollator. Variability Scores mostly reflected dynamic instability, which became greater as the requirement of an ambulation aid or the switch from a cane to a rollator was imminent. The global value given by the Global Ambulation Score, which takes into consideration both the Organization Score, the Variability Score, and the level of assistive device, demonstrated a logarithmic relationship with the SARA-GS. Overall, these results highlight that both components introduced should be analyzed concurrently and suggest that the Global Ambulation Score may be a valuable outcome measure for longitudinal disease progression.

Safety and feasibility of upper limb cardiopulmonary exercise test in Friedreich ataxia

Aims

To explore the feasibility of upper limbs cardiopulmonary exercise test (CPET) in Friedreich ataxia (FRDA) patients and to compare the results with sex, age, and body mass index (BMI) matched cohort of healthy controls (HC).

Methods and results

Cardiopulmonary exercise test was performed using an upper limbs cycle ergometer on fasting subjects. Peak oxygen uptake (peak VO2) was recorded as the mean value of VO2 during a 20 s period at the maximal effort of the test at an appropriate respiratory exchange rate. The ventilatory anaerobic threshold (AT) was detected by the use of the V-slope method. We performed echocardiography with an ultrasound system equipped with a 2.5 MHz multifrequency transducer for complete M-mode, two-dimensional, Doppler, and Tissue Doppler Imaging analyses. We studied 55 FRDA and 54 healthy matched controls (HC). Peak VO2 showed a significant 31% reduction in FRDA patients compared to HC (15.2 ± 5.7 vs. 22.0 ± 6.1 mL/kg/min; P &lt; 0.001). Peak workload was reduced by 41% in FRDA (42.9 ± 12.5 vs. 73.1 ± 21.2 W; P &lt; 0.001). In FRDA patients, peak VO2 is inversely correlated with the Scale for Assessment and Rating of Ataxia score, disease duration, and 9HPT performance, and directly correlated with activities of daily living. The AT occurred at 48% of peak workload time in FRDA patients and at 85% in HC (P &lt; 0.001).

Conclusions

Upper limb CPET is useful in the assessment of exercise tolerance and a possible tool to determine the functional severity of the mitochondrial oxidative defect in patients with FRDA. The cardiopulmonary exercise test is an ideal functional endpoint for Phases II and III trials through a simple, non-invasive, and safe exercise test.

Emerging therapies in Friedreich's Ataxia

INTRODUCTION

Friedreich's ataxia (FRDA) is a progressive, neurodegenerative disease that results in gait and limb ataxia, diabetes, cardiac hypertrophy, and scoliosis. At the cellular level, FRDA results in the deficiency of frataxin, a mitochondrial protein that plays a vital role in iron homeostasis and amelioration of oxidative stress. No cure currently exists for FRDA, but exciting therapeutic developments which target different parts of the pathological cascade are on the horizon.

AREAS COVERED

Areas covered include past and emerging therapies for FRDA, including antioxidants and mitochondrial-related agents, nuclear factor erythroid-derived 2-related factor 2 (Nrf2) activators, deuterated polyunsaturated fatty acids, iron chelators, histone deacetylase (HDAC) inhibitors, trans-activator of transcription (TAT)-frataxin, interferon gamma (IFNγ), erythropoietin, resveratrol, gene therapy, and anti-sense oligonucleotides (ASOs), among others.

EXPERT OPINION

While drug discovery has been challenging, new and exciting prospective treatments for FRDA are currently on the horizon, including pharmaceutical agents and gene therapy. Agents that enhance mitochondrial function, such as Nrf2 activators, dPUFAs and catalytic antioxidants, as well as novel methods of frataxin augmentation and genetic modulation will hopefully provide treatment for this devastating disease.

Quantitative Assessment of Friedreich Ataxia through the self-drinking activity

The progression of neurodegenerative conditions can be effectively monitored and improved by using objective assessments. The conditions such as Friedreich Ataxia (FA) are clinically assessed by means of subjective measures commonly practised in clinics. Here, we propose a device capable of measuring ataxia, in the form of a `cup' capable of sensing certain kinematic parameters of interest while engaging in an activity that is closely related to daily living. In this study, the functional task of 'drinking' was utilised to diagnose participants with FA and capture features in terms of diagnosis (separation) and correlation with the clinical scales. Frequency domain analysis was incorporated enabling the classification of control subjects and FA patients to an accuracy of 88% with a correlation of 90% with the clinical scores.

Assessment of Ataxia Rating Scales and Cerebellar Functional Tests: Critique and Recommendations

BACKGROUND

We assessed the clinimetric properties of ataxia rating scales and functional tests, and made recommendations regarding their use.

METHODS

A systematic literature search was conducted to identify the instruments used to rate ataxia symptoms. The identified rating scales and functional ability tests were reviewed and ranked by the panel as "recommended," "suggested," or "listed" for the assessment of patients with discrete cerebellar disorders, using previously established criteria.

RESULTS

We reviewed 14 instruments (9 rating scales and 5 functional tests). "Recommended" rating scales for the assessment of symptoms severity were: for Friedreich's ataxia, the Friedreich's Ataxia Rating Scale, the International Cooperative Ataxia Rating Scale (ICARS), and the Scale for the Assessment and Rating of Ataxia (SARA); for spinocerebellar ataxias, ICARS and SARA; for ataxia telangiectasia: ICARS and SARA; for brain tumors, SARA; for congenital disorder of glycosylation-phosphomannomutase-2 deficiency, ICARS; for cerebellar symptoms in multiple sclerosis, ICARS; for cerebellar symptoms in multiple system atrophy: Unified Multiple System Atrophy Rating Scale and ICARS; and for fragile X-associated tremor ataxia syndrome, ICARS. "Recommended" functional tests were: for Friedreich's ataxia, Ataxia Functional Composite Score and Composite Cerebellar Functional Severity Score; and for spinocerebellar ataxias, Ataxia Functional Composite Score, Composite Cerebellar Functional Severity Score, and SCA Functional Index.

CONCLUSIONS

We identified some "recommended" scales and functional tests for the assessment of patients with major hereditary ataxias and other cerebellar disorders. The main limitations of these instruments include the limited assessment of patients in the more severe end of the spectrum and children. Further research in these populations is warranted. © 2020 International Parkinson and Movement Disorder Society.

Vestibular impact of Friedreich ataxia in early onset patients

Background

Friedreich ataxia (FRDA) is the most frequent form of inherited ataxias. Vestibular and auditory assessments are not commonly part of the check up for these patients despite hearing and balance complaints. Screening of vestibular and auditory function was performed in a large group of young patients with genetically confirmed FRDA.

Methods

Our study included 43 patients (7–24 years of age). A complete vestibular assessment was performed including the canals function evaluation at 3 head velocities (bithermal caloric test, earth vertical axis rotation (EVAR) and head impulse test (HIT)) and otolith function evaluation (cervical vestibular evoked myogenic potentials). Information regarding the hearing evaluation of the patients were also retrieved including impedance tympanometry, distortion product otoacoustic emissions (DPOAEs), air and bone conduction audiometry and auditory brainstem response (ABR).

Results

Vestibular responses were impaired for canal responses (only at high and middle head velocities) and vestibulospinal otolithic responses. Abnormal neural conduction in the central auditory pathways was frequently observed. Oculomotor abnormalities were frequent, mostly hypermetric saccades and gaze instability. Inhibition of the vestibulo-ocular reflex by fixation was normal.

Conclusions

We show that Friedreich ataxia, even at onset, frequently associate saccadic intrusions, abnormal ABRs and decreased vestibulo-ocular and vestibulospinal responses progressing over time. These sensory impairments combined with ataxia further impair patient’s autonomy. These vestibular, auditory and visual impairments could be used as markers of the severity and progression of the disease. Adding vestibular and auditory testing to Friedreich patient’s evaluation may help physicians improve patient’s management.

Temporal but not spatial dysmetria relates to disease severity in FA

Friedreich's ataxia (FA) is an inherited disease that causes degeneration of the nervous system. Features of FA include proprioceptive and cerebellar deficits leading to impaired muscle coordination and, consequently, dysmetria in force and time of movement. The aim of this study is to characterize dysmetria and its association to disease severity. Also, we examine the neural mechanisms of dysmetria by quantifying the EMG burst area, duration, and time-to-peak of the agonist muscle. Twenty-seven individuals with FA and 13 healthy controls (HCs) performed the modified Functional Ataxia Rating Scale and goal-directed movements with the ankle. Dysmetria was quantified as position and time error during dorsiflexion. FA individuals exhibited greater time but not position error than HCs. Moreover, time error correlated with disease severity and was related to increased agonist EMG burst. Temporal dysmetria is associated to disease severity, likely due to altered activation of the agonist muscle.NEW & NOTEWORTHY For the first time, we quantified spatial and temporal dysmetria and its relation to disease severity in Friedreich's ataxia (FA). We found that FA individuals exhibit temporal but not spatial dysmetria relative to healthy controls. Temporal dysmetria correlated to disease severity in FA and was predicted from an altered activation of the agonist muscle. Therefore, these results provide novel evidence that FA exhibit temporal but not spatial dysmetria, which is different from previous findings on SCA6.

Quantitative Proteomic and Network Analysis of Differentially Expressed Proteins in PBMC of Friedreich's Ataxia (FRDA) Patients

Friedreich’s ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by an expanded (GAA) trinucleotide repeat in the FXN gene. The extended repeats expansion results in reduced transcription and, thereby, decreased expression of the mitochondrial protein, frataxin. Given the ongoing drug trials, identification of reliable and easily accessible biomarkers for monitoring disease progression and therapeutic intervention is a foremost requirement. In this study, comparative proteomic profiling of PBMC proteins from FRDA patients and age- and gender-matched healthy controls was done using 2D-Differential in-Gel Electrophoresis (2D-DIGE). Protein–protein interaction (PPI) was analyzed using BioGRID and STRING pathway analysis tools. Using biological variance analysis (BVA) and LC/MS, we found eight differentially expressed proteins with fold change ≥1.5; p ≤ 0.05. Based on their cellular function, the identified proteins showed a strong pathological role in neuroinflammation, cardiomyopathy, compromised glucose metabolism, and iron transport, which are the major clinical manifestations of FRDA. Protein–protein network analysis of differentially expressed proteins with frataxin further supports their involvement in the pathophysiology of FRDA. Considering their crucial role in the cardiac and neurological complications, respectively, the two down-regulated proteins, actin α cardiac muscle 1 (ACTC1) and pyruvate dehydrogenase E1 component subunit β (PDHE1), are suggested as potential prognostic markers for FRDA.

Peripheral blood gene expression reveals an inflammatory transcriptomic signature in Friedreich's ataxia patients

Transcriptional changes in Friedreich's ataxia (FRDA), a rare and debilitating recessive Mendelian neurodegenerative disorder, have been studied in affected but inaccessible tissues-such as dorsal root ganglia, sensory neurons and cerebellum-in animal models or small patient series. However, transcriptional changes induced by FRDA in peripheral blood, a readily accessible tissue, have not been characterized in a large sample. We used differential expression, association with disability stage, network analysis and enrichment analysis to characterize the peripheral blood transcriptome and identify genes that were differentially expressed in FRDA patients (n = 418) compared with both heterozygous expansion carriers (n = 228) and controls (n = 93 739 individuals in total), or were associated with disease progression, resulting in a disease signature for FRDA. We identified a transcriptional signature strongly enriched for an inflammatory innate immune response. Future studies should seek to further characterize the role of peripheral inflammation in FRDA pathology and determine its relevance to overall disease progression.

Corneal confocal microscopy: Neurologic disease biomarker in Friedreich ataxia

OBJECTIVE

Friedreich ataxia (FRDA), an autosomal recessive neurodegenerative disease caused by mutations in the gene encoding for the mitochondrial protein frataxin, is characterized by ataxia and gait instability, immobility, and eventual death. We evaluated corneal confocal microscopy (CCM) quantification of corneal nerve morphology as a novel, noninvasive, in vivo quantitative imaging biomarker for the severity of neurological manifestations in FRDA.

METHODS

Corneal nerve fiber density, branch density, and fiber length were quantified in individuals with FRDA (n = 23) and healthy age-matched controls (n = 14). All individuals underwent genetic testing and a detailed neurological assessment with the Scale for the Assessment and Rating of Ataxia (SARA) and Friedreich's Ataxia Rating Scale (FARS). A subset of individuals with FRDA who were ambulatory underwent quantitative gait assessment.

RESULTS

CCM demonstrated a significant reduction in nerve fiber density and length in FRDA compared to healthy controls. Importantly, CCM parameters correlated with genotype, SARA and FARS neurological scales, and linear regression modeling of CCM nerve parameter-generated equations that predict the neurologic severity of FRDA.

INTERPRETATION

Together, the data suggest that CCM quantification of corneal nerve morphology is a rapid, sensitive imaging biomarker for quantifying the severity of neurologic disease in individuals with FRDA. Ann Neurol 2018;84:893-904.

Quantification of Axial Abnormality Due to Cerebellar Ataxia with Inertial Measurements

Cerebellar Ataxia (CA) leads to deficiencies in muscle movement and lack of coordination that is often manifested as gait and balance disabilities. Conventional CA clinical assessments are subjective, cumbersome and provide less insight into the functional capabilities of patients. This cross-sectional study investigates the use of wearable inertial sensors strategically positioned on the front-chest and upper-back locations during the Romberg and Trunk tests for objective assessment of human postural balance due to CA. The primary aim of this paper is to quantify the performance of postural stability of 34 patients diagnosed with CA and 22 healthy subjects as controls. Several forms of entropy descriptions were considered to uncover characteristics of movements intrinsic to CA. Indeed, correlation with clinical observation is vital in ascertaining the validity of the inertial measurements in addition to capturing unique features of movements not typically observed by the practicing clinician. Both of these aspects form an integral part of the underlying objective assessment scheme. Uncertainty in the velocity contained a significant level of information with respect to truncal instability and, based on an extensive clustering and discrimination analysis, fuzzy entropy was identified as an effective measure in characterising the underlying disability. Front-chest measurements demonstrated a strong correlation with clinical assessments while the upper-back measurements performed better in classifying the two cohorts, inferring that the standard clinical assessments are relatively influenced by the frontal observations. The Romberg test was confirmed to be an effective test of neurological diagnosis as well as a potential candidate for objective assessment resulting in a significant correlation with the clinical assessments. In contrast, the Trunk test is observed to be relatively less informative.

Autonomic function testing in Friedreich's ataxia

Background

Friedreich ataxia (FRDA) is an inherited movement disorder which manifests with progressive gait instability, sensory loss and cardiomyopathy. Peripheral neuropathy is an established feature of FRDA. At neuropathological examination, a depletion of large, myelinated axons is evident, but also unmyelinated fibers are affected which may result in a variety of sensory and autonomic signs and symptoms. Impaired temperature perception, vasomotor disturbances of lower extremities and a high prevalence of urinary symptoms have been documented in FRDA, but data from autonomic function testing in genetically confirmed cases are lacking.

Methods

Genetically confirmed FRDAs were recruited in an outpatient setting. In a screening visit, general and neurological examination, laboratory testing, ECG and echocardiography were performed. Autonomic functions were evaluated by means of systematic questionnaires (SCOPA-Aut, OHQ), skin sympathetic reflex and cardiovascular autonomic function testing (CAFT). For the latter, a comparison with matched healthy controls was performed.

Results

20 patients were recruited and 13 underwent CAFT. Symptoms referred to multiple autonomic domains, particularly bladder function, thermoregulation and sweating were reported. SCOPA-Aut scores were significantly predicted by disease severity. At CAFT, FRDAs did not differ from controls except for increased heart rate at rest and during orthostatic challenge. Two patients had non-neurogenic orthostatic hypotension (14%). Skin sympathetic responses were pathologic in 3 out of 10 patients (of whom 2 aged > 50).

Conclusions

FRDA patients may experience several autonomic symptoms and overall their burden correlates with disease severity. Nonetheless, clinical testing shows no major involvement of sudomotor and cardiovascular autonomic function.

A systematic review of the gait characteristics associated with Cerebellar Ataxia

BACKGROUND

Cerebellar Ataxias are a group of gait disorders resulting from dysfunction of the cerebellum, commonly characterised by slowly progressing incoordination that manifests as problems with balance and walking leading to considerable disability. There is increasing acceptance of gait analysis techniques to quantify subtle gait characteristics that are unmeasurable by current clinical methods This systematic review aims to identify the gait characteristics able to differentiate between Cerebellar Ataxia and healthy controls.

METHODS

Following systematic search and critical appraisal of the literature, gait data relating to preferred paced walking in Cerebellar Ataxia was extracted from 21 studies. A random-effect model meta-analysis was performed for 14 spatiotemporal parameters. Quality assessment was completed to detect risk of bias.

RESULTS

There is strong evidence that compared with healthy controls, Cerebellar Ataxia patients walk with a reduced walking speed and cadence, reduced step length, stride length, and swing phase, increased walking base width, stride time, step time, stance phase and double limb support phase with increased variability of step length, stride length, and stride time.

CONCLUSION

The consensus description provided here, clarifies the gait pattern associated with ataxic gait disturbance in a large cohort of participants. High quality research and reporting is needed to explore specific genetic diagnoses and identify biomarkers for disease progression in order to develop well-evidenced clinical guidelines and interventions for Cerebellar Ataxia.

Friedreich's ataxia: clinical features, pathogenesis and management

INTRODUCTION

Friedreich's ataxia is the most common inherited ataxia.

SOURCES OF DATA

Literature search using PubMed with keywords Friedreich's ataxia together with published papers known to the authors.

AREAS OF AGREEMENT

The last decade has seen important advances in our understanding of the pathogenesis of disease. In particular, the genetic and epigenetic mechanisms underlying the disease now offer promising novel therapeutic targets.

AREAS OF CONTROVERSY

The search for effective disease-modifying agents continues. It remains to be determined whether the most effective approach to treatment lies with increasing frataxin protein levels or addressing the metabolic consequences of the disease, for example with antioxidants.

AREAS TIMELY FOR DEVELOPING RESEARCH

Management of Freidreich's ataxia is currently focussed on symptomatic management, delivered by the multidisciplinary team. Phase II clinical trials in agents that address the abberrant silencing of the frataxin gene need to be translated into large placebo-controlled Phase III trials to help establish their therapeutic potential.

Longitudinal gait and balance decline in Friedreich's Ataxia: A pilot study

INTRODUCTION

Friedreich's Ataxia (FA) is a devastating, progressive, neurodegenerative disease. Objective measures that detect changes in neurological function in FA patients are needed to facilitate therapeutic clinical trials. The purpose of this pilot study was to analyze longitudinal changes in gait and balance in subjects with FA using the GAITRite Walkway System^® and Biodex Balance System™, respectively, and to test the ability of these measures to detect change over time compared to the Friedreich's Ataxia Rating Scale (FARS).

METHODS

This was a 24-month longitudinal study comparing ambulatory FA subjects with age- and gender-matched, healthy controls. Eight FA subjects and 8 controls were tested at regular intervals using the GAITRite and Biodex Balance systems and the FARS.

RESULTS

In the FA group, comfortable and fast gait velocity declined 8.0% and 13.9% after 12 months and 24.1% and 30.3% after 24 months, respectively. Postural stability indices increased in FA subjects an average of 41% from baseline to 24 months, representing a decline in balance. Subjects with FA also demonstrated a 17.7% increase in FARS neurological exam scores over 24 months. There were no changes in gait or balance variables in controls. In the FA group, multiple gait and balance measures correlated significantly with FARS neurological exam scores.

CONCLUSIONS

The GAITRite and Biodex Balance systems provided objective and clinically relevant measures of functional decline in subjects with FA that correlated significantly with performance measures in the FARS. Gait velocity may be an important objective measure to identify disease progression in adults with FA.

Friedreich Ataxia: current status and future prospects

Friedreich ataxia (FA) represents the most frequent type of inherited ataxia. Most patients carry homozygous GAA expansions in the first intron of the frataxin gene on chromosome 9. Due to epigenetic alterations, frataxin expression is significantly reduced. Frataxin is a mitochondrial protein. Its deficiency leads to mitochondrial iron overload, defective energy supply and generation of reactive oxygen species. This review gives an overview over clinical and genetic aspects of FA and discusses current concepts of frataxin biogenesis and function as well as new therapeutic strategies.

Mitochondrial capacity, muscle endurance, and low energy in friedreich ataxia

INTRODUCTION

In this study we noninvasively evaluated skeletal muscle mitochondrial capacity, muscle-specific endurance, and energy/fatigue feelings in persons with Friedreich ataxia (FRDA) and able-bodied controls (AB).

METHODS

Forearm mitochondrial capacity was measured in FRDA (n = 16) and AB (n = 10) study participants using the rate of recovery of oxygen consumption after electrical stimulation with near-infrared spectroscopy. Mechanomyography (MMG) assessed muscle endurance after electrical stimulation for 3 minutes at 2 Hz, 4 Hz, and 6 Hz. Validated scales assessed disease severity and energy/fatigue feelings.

RESULTS

Groups did not differ in mitochondrial capacity (FRDA and AB: 1.8 ± 0.3 L/min). The difference in muscle endurance at 6 Hz was lower by 19.2% in the FRDA group (group effect: P < 0.001). Feelings of physical energy were 34% lower in FRDA group. In FDRA muscle, endurance was positively related to mitochondrial capacity (r = 0.59, P = 0.03), and disease severity was negatively related to mitochondrial capacity (r = -0.55, P = 0.04) and muscle endurance (r = -0.60, P = 0.01).

CONCLUSION

Non-invasive measures of skeletal muscle mitochondrial capacity and muscle-specific endurance are useful in monitoring FRDA. Muscle Nerve 56: 773-779, 2017.

Neurobehavioral deficits in the KIKO mouse model of Friedreich's ataxia

Friedreich's Ataxia (FA) is a pediatric neurodegenerative disease whose clinical presentation includes ataxia, muscle weakness, and peripheral sensory neuropathy. The KIKO mouse is an animal model of FA with frataxin deficiency first described in 2002, but neurobehavioral deficits have never been described in this model. The identification of robust neurobehavioral deficits in KIKO mice could support the testing of drugs for FA, which currently has no approved therapy. We tested 13 neurobehavioral tasks to identify a robust KIKO phenotype: Open Field, Grip Strength Test(s), Cylinder, Skilled Forelimb Grasp Task(s), Treadmill Endurance, Locotronic Motor Coordination, Inverted Screen, Treadscan, and Von Frey. Of these, Inverted Screen, Treadscan and Von Frey produced significant neurobehavioral deficits at >8 months of age, and relate to the clinically relevant endpoints of muscle strength and endurance, gait ataxia, and peripheral insensitivity. Thus we identify robust phenotypic measures related to Friedreich's ataxia clinical endpoints which could be used to test effectiveness of potential drug therapy.

Emerging therapies in Friedreich's ataxia

Friedreich's ataxia (FRDA) is an inherited, progressive neurodegenerative disease that typically affects teenagers and young adults. Therapeutic strategies and disease insight have expanded rapidly over recent years, leading to hope for the FRDA population. There is currently no US FDA-approved treatment for FRDA, but advances in research of its pathogenesis have led to clinical trials of potential treatments. This article reviews emerging therapies and discusses future perspectives, including the need for more precise measures for detecting changes in neurologic symptoms as well as a disease-modifying agent.

Functional and Gait Assessment in Children and Adolescents Affected by Friedreich's Ataxia: A One-Year Longitudinal Study

Friedreich's ataxia is the most common autosomal recessive form of neurodegenerative ataxia. We present a longitudinal study on the gait pattern of children and adolescents affected by Friedreich's ataxia using Gait Analysis and the Scale for the Assessment and Rating of Ataxia (SARA). We assessed the spectrum of changes over 12 months of the gait characteristics and the relationship between clinical and instrumental evaluations. We enrolled 11 genetically confirmed patients affected by Friedreich's ataxia in this study together with 13 normally developing age-matched subjects. Eight patients completed a 12-month follow-up under the same protocol. By comparing the gait parameters of Friedreich's ataxia with the control group, we found significant differences for some relevant indexes. In particular, the increased knee and ankle extension in stance revealed a peculiar biomechanical pattern, which correlated reliably with SARA Total, Gait and Sitting scores. The knee pattern showed its consistency also at the follow-up: Knee extension increased from 6.8±3.5° to -0.5±3.7° and was significantly correlated with the SARA total score. This feature anticipated the loss of the locomotor function in two patients. In conclusion, our findings demonstrate that the selective and segmental analysis of kinetic/kinematic features of ataxic gait, in particular the behavior of the knee, provides sensitive measures to detect specific longitudinal and functional alterations, more than the SARA scale, which however has proved to be a reliable and practical assessment tool. Functional outcomes measures integrated by instrumental evaluation increase their sensitivity, reliability and suitability for the follow-up of the disease progression and for the application in clinical trials and in rehabilitative programs.

Long-term treatment with thiamine as possible medical therapy for Friedreich ataxia

Thiamine (vitamin B1) is a cofactor of fundamental enzymes of cell energetic metabolism; its deficiency causes disorders affecting both the peripheral and central nervous system. Previous studies reported low thiamine levels in cerebrospinal fluid and pyruvate dehydrogenase dysfunction in Friedreich ataxia (FRDA). We investigated the effect of long-term treatment with thiamine in FRDA, evaluating changes in neurological symptoms, echocardiographic parameters, and plasma FXN mRNA levels. Thirty-four consecutive FRDA patients have been continuously treated with intramuscular thiamine 100 mg twice a week and have been assessed with the Scale for the Assessment and Rating of Ataxia (SARA) at baseline, after 1 month, and then every 3 months during treatment. Thiamine administration ranged from 80 to 930 days and was effective in improving total SARA scores from 26.6 ± 7.7 to 21.5 ± 6.2 (p < 0.02). Moreover, deep tendon reflexes reappeared in 57 % of patients with areflexia at baseline, and swallowing improved in 63 % of dysphagic patients. Clinical improvement was stable in all patients, who did not show worsening even after 2 years of treatment. In a subgroup of 13 patients who performed echocardiogram before and during treatment, interventricular septum thickness reduced significantly (p < 0.02). Frataxin mRNA blood levels were modestly increased in one-half of treated patients. We suppose that a focal thiamine deficiency may contribute to a selective neuronal damage in the areas involved in FRDA. Further studies are mandatory to evaluate thiamine role on FXN regulation, to exclude placebo effect, to verify our clinical results, and to confirm restorative and neuroprotective action of thiamine in FRDA.

Standardized Assessment of Hereditary Ataxia Patients in Clinical Studies

BACKGROUND

Hereditary ataxias are a heterogeneous group of degenerative diseases of the cerebellum, brainstem, and spinal cord. They may present with isolated ataxia or with additional symptoms going beyond cerebellar deficits. There are an increasing number of clinical studies with the goal to define the natural history of these disorders, develop biomarkers, and investigate therapeutic interventions. Especially, early and preclinical disease stages are currently of particular interest.

METHODS AND RESULTS

Evidence-based, we review standards for sampling and storage of biomaterials, clinical and neuropsychological assessment, as well as neurophysiology and neuroimaging and recommendations for standardized assessment of ataxia patients in multicenter studies.

CONCLUSIONS

DNA, RNA, serum, and, if possible, cerebrospinal fluid samples should be processed following established standards. Clinical assessment in ataxia studies must include use of a validated clinical ataxia scale. There are several validated clinical ataxia scales available. There are no instruments that were specifically designed for assessing neuropsychological and psychiatric symptoms in ataxia disorders. We provide a list of tests that may prove valuable. Quantitative performance tests have the potential to supplement clinical scales. They provide additional objective and quantitative information. Posturography and quantitative movement analysis-despite valid approaches-require standardization before implemented in multicenter studies. Standardization of neurophysiological tools, as required for multicenter interventional trials, is still lacking. Future multicenter neuroimaging studies in ataxias should implement quality assurance measures as defined by the ADNI or other consortia. MRI protocols should allow morphometric analyses.

Clinical Outcome Assessments: Conceptual Foundation-Report of the ISPOR Clinical Outcomes Assessment - Emerging Good Practices for Outcomes Research Task Force

An outcome assessment, the patient assessment used in an endpoint, is the measuring instrument that provides a rating or score (categorical or continuous) that is intended to represent some aspect of the patient's health status. Outcome assessments are used to define efficacy endpoints when developing a therapy for a disease or condition. Most efficacy endpoints are based on specified clinical assessments of patients. When clinical assessments are used as clinical trial outcomes, they are called clinical outcome assessments (COAs). COAs include any assessment that may be influenced by human choices, judgment, or motivation. COAs must be well-defined and possess adequate measurement properties to demonstrate (directly or indirectly) the benefits of a treatment. In contrast, a biomarker assessment is one that is subject to little, if any, patient motivational or rater judgmental influence. This is the first of two reports by the ISPOR Clinical Outcomes Assessment - Emerging Good Practices for Outcomes Research Task Force. This report provides foundational definitions important for an understanding of COA measurement principles. The foundation provided in this report includes what it means to demonstrate a beneficial effect, how assessments of patients relate to the objective of showing a treatment's benefit, and how these assessments are used in clinical trial endpoints. In addition, this report describes intrinsic attributes of patient assessments and clinical trial factors that can affect the properties of the measurements. These factors should be considered when developing or refining assessments. These considerations will aid investigators designing trials in their choice of using an existing assessment or developing a new outcome assessment. Although the focus of this report is on the development of a new COA to define endpoints in a clinical trial, these principles may be applied more generally. A critical element in appraising or developing a COA is to describe the treatment's intended benefit as an effect on a clearly identified aspect of how a patient feels or functions. This aspect must have importance to the patient and be part of the patient's typical life. This meaningful health aspect can be measured directly or measured indirectly when it is impractical to evaluate it directly or when it is difficult to measure. For indirect measurement, a concept of interest (COI) can be identified. The COI must be related to how a patient feels or functions. Procedures are then developed to measure the COI. The relationship of these measurements with how a patient feels or functions in the intended setting and manner of use of the COA (the context of use) could then be defined. A COA has identifiable attributes or characteristics that affect the measurement properties of the COA when used in endpoints. One of these features is whether judgment can influence the measurement, and if so, whose judgment. This attribute defines four categories of COAs: patient reported outcomes, clinician reported outcomes, observer reported outcomes, and performance outcomes. A full description as well as explanation of other important COA features is included in this report. The information in this report should aid in the development, refinement, and standardization of COAs, and, ultimately, improve their measurement properties.

Milestones in Friedreich ataxia: more than a century and still learning

Friedreich ataxia (FRDA) is the most common autosomal recessive ataxia worldwide. This review highlights the main clinical features, pathophysiological mechanisms, and therapeutic approaches for FRDA patients. The disease is characterized by a combination of neurological involvement (ataxia and neuropathy), cardiomyopathy, skeletal abnormalities, and glucose metabolism disturbances. FRDA is caused by expanded guanine-adenine-adenine (GAA) triplet repeats in the first intron of the frataxin gene (FXN), resulting in reduction of messenger RNA and protein levels of frataxin in different tissues. The molecular and metabolic disturbances, including iron accumulation, lead to pathological changes characterized by spinal cord and dorsal root ganglia atrophy, dentate nucleus atrophy without global cerebellar volume reduction, and hypertrophic cardiomyopathy. DNA analysis is the hallmark for the diagnosis of FRDA. There is no specific treatment to stop the disease progression in FRDA patients. However, a number of drugs are under investigation. Therapeutic approaches intend to improve mitochondrial functioning and to increase FXN expression.

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

BACKGROUND

Friedreich's 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 Friedreich's ataxia database registry.

METHODS

Within the European Friedreich's Ataxia Consortium for Translational Studies (EFACTS) framework, we assessed a cohort of patients with genetically confirmed Friedreich's 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 Friedreich's Ataxia Rating Scale and EQ-5D. The Friedreich's 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 Friedreich's 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 Friedreich's ataxia, for which SARA might be the most suitable measure to monitor disease progression.

FUNDING

European Commission.

Sensitivity of spatiotemporal gait parameters in measuring disease severity in Friedreich ataxia

Friedreich ataxia (FRDA) is an autosomal recessive disease with gait ataxia being the main source of morbidity. Mobility progressively declines, from initial symptom onset at approximately 10-15 years of age to being unable to ambulate 10-15 years later. Here, we sought to investigate the relationship between spatiotemporal gait parameters and clinical markers of disease severity. Thirteen people with FRDA walked along an 8.3-m GAITRite® mat six times each at their preferred fast and slow speeds. Relationships between spatiotemporal gait parameters and a range of clinical and disease characteristics were examined. Significant correlations were found between spatiotemporal gait characteristics at each of the walking speeds and Friedreich Ataxia Rating Scale (FARS) score and disease duration. During the fast-walking condition, gait speed and cadence decreased with an increase in disease duration and the FARS score. GAA1 repeat expansion negatively correlated with double-support percentage of the gait cycle in all speed conditions demonstrating a relationship between the genetic mutation and compensatory strategies for impaired dynamic balance. In all speed conditions, there were correlations between a range of spatiotemporal gait characteristics and the timed 25-ft walk test, a well-established measure of gait mobility. These findings suggest that spatiotemporal gait parameters are a sensitive measure of gait decline in individuals with FRDA and should be considered for inclusion in intervention studies whilst participants are still ambulant.

Epigenetic therapy for Friedreich ataxia

OBJECTIVE

To investigate whether a histone deacetylase inhibitor (HDACi) would be effective in an in vitro model for the neurodegenerative disease Friedreich ataxia (FRDA) and to evaluate safety and surrogate markers of efficacy in a phase I clinical trial in patients.

METHODS

We used a human FRDA neuronal cell model, derived from patient induced pluripotent stem cells, to determine the efficacy of a 2-aminobenzamide HDACi (109) as a modulator of FXN gene expression and chromatin histone modifications. FRDA patients were dosed in 4 cohorts, ranging from 30mg/day to 240mg/day of the formulated drug product of HDACi 109, RG2833. Patients were monitored for adverse effects as well as for increases in FXN mRNA, frataxin protein, and chromatin modification in blood cells.

RESULTS

In the neuronal cell model, HDACi 109/RG2833 increases FXN mRNA levels and frataxin protein, with concomitant changes in the epigenetic state of the gene. Chromatin signatures indicate that histone H3 lysine 9 is a key residue for gene silencing through methylation and reactivation through acetylation, mediated by the HDACi. Drug treatment in FRDA patients demonstrated increased FXN mRNA and H3 lysine 9 acetylation in peripheral blood mononuclear cells. No safety issues were encountered.

INTERPRETATION

Drug exposure inducing epigenetic changes in neurons in vitro is comparable to the exposure required in patients to see epigenetic changes in circulating lymphoid cells and increases in gene expression. These findings provide a proof of concept for the development of an epigenetic therapy for this fatal neurological disease.

[Anaesthesia for correction of scoliosis in pediatric patient with Friedreich's ataxia]

Friedreich ataxia (FA) is an inherited autosomal recessive disease characterized by a neurological degenerative process of the cerebellum, spinal cord, and peripheral nerves. FA is associated with ataxia, dysarthria, motor and sensory impairment, scoliosis, cardiomyopathy, and diabetes. There is a significant risk of perioperative major complications during the anesthetic management of these patients. We present the case of a fourteen-year-old patient with FA, who had a posterior spinal fusion and instrumentation underwent to total intravenous anesthesia.