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Scientific reports 12, 19173 (2022). doi:10.1038/s41598-022-23666-z, Published by Macmillan Publishers Limited, part of Springer Nature, [London]

Friedreich's ataxia (FRDA) is a rare autosomal-recessive slowly progressive neurodegenerative disorder. As common clinical measures for this devastating disease lack sensitivity, we explored whether (a) the quantitative motor assessments of the Q-Motor battery can enhance clinical characterisation of FRDA; (b) clinical measures can predict Q-Motor outcomes and (c) Q-Motor is sensitive to longitudinal change. At baseline 29 patients and 23 controls and in a 1-year follow-up 14 patients and 6 controls were included. The Q-Motor included lift (manumotography), finger tapping (digitomotography) and pronate/supinate (dysdiadochomotography) tasks. To model responses, a search of generalised linear models was conducted, selecting best fitting models, using demographic and clinical data as predictors. Predictors from selected models were used in linear mixed models to investigate longitudinal changes. Patients with FRDA performed worse than controls on most measures. Modelling of the pronate/supinate task was dominated by SCAFI (SCA functional index) subtasks, while tapping task and lift task models suggested a complex relationship with clinical measures. Longitudinal modelling implied minor changes from baseline to follow-up, while clinical scales mainly showed no change in this sample. Overall Q-Motor likely has favourable properties for assessing distinct motor aspects in severe FRDA as it can be administered in wheelchair-bound patients. Further longitudinal research is warranted to fully characterise its relation to routinely used measures and scales for FRDA.

Background: In rare disorders diagnosis may be delayed due to limited awareness and unspecific presenting symptoms. Herein, we address the issue of diagnostic delay in Friedreich's Ataxia (FRDA), a genetic disorder usually caused by homozygous GAA-repeat expansions. Methods: Six hundred eleven genetically confirmed FRDA patients were recruited within a multicentric natural history study conducted by the EFACTS (European FRDA Consortium for Translational Studies, ClinicalTrials.gov -Identifier NCT02069509). Age at first symptoms as well as age at first suspicion of FRDA by a physician were collected retrospectively at the baseline visit. Results: In 554 of cases (90.7%), disease presented with gait or coordination disturbances. In the others (n = 57, 9.3%), non-neurological features such as scoliosis or cardiomyopathy predated ataxia. Before the discovery of the causal mutation in 1996, median time to diagnosis was 4(IQR = 2-9) years and it improved significantly after the introduction of genetic testing (2(IQR = 1-5) years, p < 0.001). Still, after 1996, time to diagnosis was longer in patients with a) non-neurological presentation (mean 6.7, 95%CI [5.5,7.9] vs 4.5, [4.2,5] years in those with neurological presentation, p = 0.001) as well as in b) patients with late-onset (3(IQR = 1-7) vs 2(IQR = 1-5) years compared to typical onset < 25 years of age, p = 0.03). Age at onset significantly correlated with the length of the shorter GAA repeat (GAA1) in case of neurological onset (r = - 0,6; p < 0,0001), but not in patients with non-neurological presentation (r = - 0,1; p = 0,4). Across 54 siblings' pairs, differences in age at onset did not correlate with differences in GAA-repeat length (r = - 0,14, p = 0,3). Conclusions: In the genetic era, presentation with non-neurological features or in the adulthood still leads to a significant diagnostic delay in FRDA. Well-known correlations between GAA1 repeat length and disease milestones are not valid in case of atypical presentations or positive family history., SCOPUS: ar.j, info:eu-repo/semantics/published

OBJECTIVE: To provide a systematic evaluation of the broad clinical variability in Friedreich ataxia (FRDA), a multisystem disorder presenting mainly with afferent ataxia but also a complex phenotype of nonataxia symptoms. METHODS: From the large database of the European Friedreich's Ataxia Consortium for Translational Studies, 650 patients with genetically confirmed FRDA were included. Detailed data of medical history documentation, questionnaires, and reports on clinical features were analyzed to provide in-depth description of the clinical profile and frequency rates of phenotypical features with a focus on differences between typical-onset and late-onset FRDA. Logistic regression modeling was used to identify predictors for the presence of the most common clinical features. RESULTS: The most frequent clinical features beyond afferent ataxia were abnormal eye movements (90.5%), scoliosis (73.5%), deformities of the feet (58.8%), urinary dysfunction (42.8%), cardiomyopathy and cardiac hypertrophy (40.3%), followed by decreased visual acuity (36.8%); less frequent features were, among others, depression (14.1%) and diabetes (7.1%). Most of these features were more common in the typical-onset group compared to the late-onset group. Logistic regression models for the presence of these symptoms demonstrated the predictive value of GAA repeat length on the shorter allele and age at onset, but also severity of ataxia signs, sex, and presence of neonatal problems. CONCLUSIONS: This joint European effort demonstrates the multisystem nature of this neurodegenerative disease encompassing most the central nervous, neuromuscular, cardiologic, and sensory systems. A distinct and deeper knowledge of this rare and chronic disease is highly relevant for clinical practice and designs of clinical trials., SCOPUS: ar.j, info:eu-repo/semantics/published

Summary 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.

Myopathies and mitochondrial diseases pose a major challenge in diagnosis due to the multitude of different entities and - in the case of mitochondriopathies - the possible involvement of multiple organs. Furthermore, there is broad clinical variability within particular diseases; patients with hereditary myopathy, for example, can show great phenotypic variability despite identical genetic defects. In addition to environmental factors, gender-specific influences, and the degree of heteroplasmy in mitochondrial diseases, the existence of disease-modifying genes has long been assumed as an explanation. In recent years, risk genes, which can influence the course of disease, have been identified for some myopathies and mitochondrial diseases. The precise role of these disease-modifying genes in the pathogenesis of the diseases is largely unexplained and requires further research.

Background In Friedreich's ataxia (FA) the genetically decreased expression of the mitochondrial protein frataxin leads to disturbance of the mitochondrial iron metabolism. Within the cerebellum the dentate nuclei (DN) are primarily affected. Histopathological studies show atrophy and accumulation of mitochondrial iron in DN. Dentate iron content has been suggested as a biomarker to measure the effects of siderophores/antioxidant treatment of FA. We assessed the iron content and the volume of DN in FA patients and controls based on ultra-high-field MRI (7 Tesla) images. Methods Fourteen FA patients (mean age 38.1 yrs) and 14 age- and gender-matched controls participated. Multi-echo gradient echo and susceptibility weighted imaging (SWI) sequences were acquired on a 7 T whole-body scanner. For comparison SWI images were acquired on a 1.5 T MR scanner. Volumes of the DN and cerebellum were assessed at 7 and 1.5 T, respectively. Parametric maps of T2 and T2* sequences were created and proton transverse relaxation rates were estimated as a measure of iron content. Results In FA, the DN and the cerebellum were significantly smaller compared to controls. However, proton transverse relaxation rates of the DN were not significantly different between both groups. Conclusions Applying in vivo MRI methods we could demonstrate significant atrophy of the DN in the presence of normal iron content. The findings suggest that relaxation rates are not reliable biomarkers in clinical trials evaluating the potential effect of FA therapy. © 2014 The Authors. Published by Elsevier Inc. OA gold

Summary Background Friedreich Ataxia (FRDA) is the most common hereditary ataxia, with dysarthria as one of its key clinical signs. Objective To describe the voice profile of individuals with FRDA to inform outcome marker development and goals of speech therapy. Methods Thirty-six individuals with FRDA and 30 age-matched controls provided sustained vowel and connected speech samples. Speech and voice samples were analyzed acoustically using the Analysis of Dysphonia in Speech and Voice program and perceptually using the Consensus Auditory-Perceptual Evaluation of Voice form. Correlations between dysphonia and overall dysarthria severity, demographic, clinical, and genetic information were explored. Results Individuals with FRDA presented with mild dysphonia characterized by hoarseness (combined roughness and breathiness), increased strain, and altered pitch variability (increased in vowel productions; slightly decreased on reading samples). Acoustically, individuals with FRDA had significantly higher scores on the Cepstral Spectral Index of Dysphonia during vowel production. A combination of perceptual and acoustic measures of dysphonia used in this study was quite effective in categorizing the FRDA versus control participants, with >80% overall accuracy. Conclusions Although dysphonia severity in FRDA did not correlate significantly with overall disease severity, speaking rate and syllabic duration significantly correlated with age at disease onset and disease duration, and also have an effect on listener perception of dysphonia. The relationship between dysphonia and dysarthria in FRDA suggests that reducing overall dysphonia severity via therapeutic techniques that improve phonatory stability and increase speaking rate is a viable target for speech therapy.

Summary Background The European Friedreich's Ataxia Consortium for Translational Studies (EFACTS) is a prospective international registry investigating the natural history of Friedreich's 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 Friedreich's 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 Friedreich's 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 Friedreich's ataxia. Funding European Commission.

Background Mitochondrial dysfunction due to respiratory chain impairment is a key feature in pathogenesis of Friedreich ataxia. Friedreich ataxia affects the nervous system, heart and pancreas. Methods We assessed hepatic mitochondrial function by 13C-methionine-breath-test in 16 Friedreich ataxia patients and matched healthy controls. Results Patients exhaled significantly smaller amounts of 13CO2 over 90 minutes. Maximal exhaled percentage dose of 13CO2 recovery was reduced compared to controls. Conclusions 13C-methionine-breath-test indicates subclinical hepatic mitochondrial dysfunction in Friedreich ataxia but did not correlate with GAA repeat lengths, disease duration or disease severity.