Expression and processing of mature human frataxin after gene therapy in mice.

Friedreich's ataxia is a degenerative and progressive multisystem disorder caused by mutations in the highly conserved frataxin (FXN) gene that results in FXN protein deficiency and mitochondrial dysfunction. While gene therapy approaches are promising, consistent induction of therapeutic FXN protein expression that is sub-toxic has proven challenging, and numerous therapeutic approaches are being tested in animal models. FXN (hFXN in humans, mFXN in mice) is proteolytically modified in mitochondria to produce mature FXN. However, unlike endogenous hFXN, endogenous mFXN is further processed into N-terminally truncated, extra-mitochondrial mFXN forms of unknown function. This study assessed mature exogenous hFXN expression levels in the heart and liver of C57Bl/6 mice 7-10 months after intravenous administration of a recombinant adeno-associated virus encoding hFXN (AAVrh.10hFXN) and examined the potential for hFXN truncation in mice. AAVrh.10hFXN induced dose-dependent expression of hFXN in the heart and liver. Interestingly, hFXN was processed into truncated forms, but found at lower levels than mature hFXN. However, the truncations were at different positions than mFXN. AAVrh.10hFXN induced mature hFXN expression in mouse heart and liver at levels that approximated endogenous mFXN levels. These results suggest that AAVrh.10hFXN can likely induce expression of therapeutic levels of mature hFXN in mice.

Emerging therapies for childhood-onset movement disorders.

PURPOSE OF REVIEW: We highlight novel and emerging therapies in the treatment of childhood-onset movement disorders. We structured this review by therapeutic entity (small molecule drugs, RNA-targeted therapeutics, gene replacement therapy, and neuromodulation), recognizing that there are two main approaches to treatment: symptomatic (based on phenomenology) and molecular mechanism-based therapy or 'precision medicine' (which is disease-modifying). RECENT FINDINGS: We highlight reports of new small molecule drugs for Tourette syndrome, Friedreich's ataxia and Rett syndrome. We also discuss developments in gene therapy for aromatic l-amino acid decarboxylase deficiency and hereditary spastic paraplegia, as well as current work exploring optimization of deep brain stimulation and lesioning with focused ultrasound. SUMMARY: Childhood-onset movement disorders have traditionally been treated symptomatically based on phenomenology, but focus has recently shifted toward targeted molecular mechanism-based therapeutics. The development of precision therapies is driven by increasing capabilities for genetic testing and a better delineation of the underlying disease mechanisms. We highlight novel and exciting approaches to the treatment of genetic childhood-onset movement disorders while also discussing general challenges in therapy development for rare diseases. We provide a framework for molecular mechanism-based treatment approaches, a summary of specific treatments for various movement disorders, and a clinical trial readiness framework.

Management of Friedreich Ataxia-Associated Cardiomyopathy in Pregnancy: A Review of the Literature.

A major manifestation of Friedreich ataxia (FRDA) is cardiomyopathy, caused by mitochondrial proliferation in myocytes. Because the lifespan for patients with FRDA improves with better treatment modalities, more patients are becoming pregnant, meaning that more medical providers must know how to care for this population. This report provides a review of the literature on multidisciplinary management of pregnant patients with FRDA and cardiomyopathy from preconception through lactation. A cardio-obstetrics team, including cardiology, anesthesiology, and obstetrics, should be involved for this entire period. All patients should be counseled on pregnancy risk using elements of existing stratification systems, and contraception should be discussed, highlighting the safety of intrauterine devices. Electrocardiogram should be obtained at baseline and each trimester, looking for atrial arrhythmias and ST-segment changes, as should transthoracic echocardiogram, with a focus on left ventricular ejection fraction-which is typically normal in FRDA cardiomyopathy-and relative wall thickness and global longitudinal strain-which tend to decrease as cardiomyopathy progresses. Brain natriuretic peptide is also a helpful marker to detect adverse events. If heart failure develops, it should be treated like any other etiology of heart failure during pregnancy. Atrial arrhythmias should be treated with ß blockers or electrical cardioversion and anticoagulation, as necessary. Most patients with FRDA can deliver vaginally, and neuraxial analgesia is recommended during labor because of the risks associated with general anesthesia. Breastfeeding is encouraged, even for those taking cardiac medications.

Quantification of human mature frataxin protein expression in nonhuman primate hearts after gene therapy.

Deficiency in human mature frataxin (hFXN-M) protein is responsible for the devastating neurodegenerative and cardiodegenerative disease of Friedreich's ataxia (FRDA). It results primarily through epigenetic silencing of the FXN gene by GAA triplet repeats on intron 1 of both alleles. GAA repeat lengths are most commonly between 600 and 1200 but can reach 1700. A subset of approximately 3% of FRDA patients have GAA repeats on one allele and a mutation on the other. FRDA patients die most commonly in their 30s from heart disease. Therefore, increasing expression of heart hFXN-M using gene therapy offers a way to prevent early mortality in FRDA. We used rhesus macaque monkeys to test the pharmacology of an adeno-associated virus (AAV)hu68.CB7.hFXN therapy. The advantage of using non-human primates for hFXN-M gene therapy studies is that hFXN-M and monkey FXN-M (mFXN-M) are 98.5% identical, which limits potential immunologic side-effects. However, this presented a formidable bioanalytical challenge in quantification of proteins with almost identical sequences. This could be overcome by the development of a species-specific quantitative mass spectrometry-based method, which has revealed for the first time, robust transgene-specific human protein expression in monkey heart tissue. The dose response is non-linear resulting in a ten-fold increase in monkey heart hFXN-M protein expression with only a three-fold increase in dose of the vector.

Patient-derived iPSC models of Friedreich ataxia: a new frontier for understanding disease mechanisms and therapeutic application.

Friedreich ataxia (FRDA) is a rare genetic multisystem disorder caused by a pathological GAA trinucleotide repeat expansion in the FXN gene. The numerous drawbacks of historical cellular and rodent models of FRDA have caused difficulty in performing effective mechanistic and translational studies to investigate the disease. The recent discovery and subsequent development of induced pluripotent stem cell (iPSC) technology provides an exciting platform to enable enhanced disease modelling for studies of rare genetic diseases. Utilising iPSCs, researchers have created phenotypically relevant and previously inaccessible cellular models of FRDA. These models enable studies of the molecular mechanisms underlying GAA-induced pathology, as well as providing an exciting tool for the screening and testing of novel disease-modifying therapies. This review explores how the use of iPSCs to study FRDA has developed over the past decade, as well as discussing the enormous therapeutic potentials of iPSC-derived models, their current limitations and their future direction within the field of FRDA research.

Friedreich's ataxia: new insights.

Friedreich ataxia (FRDA) is an inherited disease that is typically caused by GAA repeat expansion within the first intron of the FXN gene coding for frataxin. This results in the frataxin deficiency that affects mostly muscle, nervous, and cardiovascular systems with progressive worsening of the symptoms over the years. This review summarizes recent progress that was achieved in understanding of molecular mechanism of the disease over the last few years and latest treatment strategies focused on overcoming the frataxin deficiency.

Finding an Appropriate Mouse Model to Study the Impact of a Treatment for Friedreich Ataxia on the Behavioral Phenotype.

Friedreich ataxia (FRDA) is a progressive neurodegenerative disease caused by a GAA repeat in the intron 1 of the frataxin gene (FXN) leading to a lower expression of the frataxin protein. The YG8sR mice are Knock-Out (KO) for their murine frataxin gene but contain a human frataxin transgene derived from an FRDA patient with 300 GAA repeats. These mice are used as a FRDA model but even with a low frataxin concentration, their phenotype is mild. We aimed to find an optimized mouse model with a phenotype comparable to the human patients to study the impact of therapy on the phenotype. We compared two mouse models: the YG8sR injected with an AAV. PHP.B coding for a shRNA targeting the human frataxin gene and the YG8-800, a new mouse model with a human transgene containing 800 GAA repeats. Both mouse models were compared to Y47R mice containing nine GAA repeats that were considered healthy mice. Behavior tests (parallel rod floor apparatus, hanging test, inverted T beam, and notched beam test) were carried out from 2 to 11 months and significant differences were noticed for both YG8sR mice injected with an anti-FXN shRNA and the YG8-800 mice compared to healthy mice. In conclusion, YG8sR mice have a slight phenotype, and injecting them with an AAV-PHP.B expressing an shRNA targeting frataxin does increase their phenotype. The YG8-800 mice have a phenotype comparable to the human ataxic phenotype.

How Great a Risk Do You Take? A Qualitative Study Exploring Attitudes of Individuals with Friedreich Ataxia Toward Gene Therapy.

Scientists and pharmaceutical companies are working toward delivering gene therapy (GT) for Friedreich ataxia (FRDA). Understanding the views of people with lived experience of FRDA and their parents toward GT is essential to inform trial design and identify potential barriers to participation in clinical trials. The goals of this study were to identify the attitudes toward GT held by individuals with FRDA and parents of individuals with FRDA, and to explore how these may impact future trials for this condition. Audiorecorded, semistructured, qualitative interviews with 19 Australians explored experiences of FRDA, knowledge about clinical trials, views on GT, including risks and benefits, and potential barriers to participation in trials. Participants included thirteen individuals living with FRDA aged between 15-43 years, and six parents of children with FRDA aged 4-12 years of age. Thematic analysis of the interviews identified six main themes. Findings from this study indicate there is strong desire for information regarding GT in FRDA, however the current level of uncertainty around GT makes decision making challenging. The desire to maintain functional status and avoid additional risk of deterioration from an investigational treatment was apparent. Importantly, neurological targets were identified as preferred for GT trials. Further research is required to identify if attitudes and perceptions differ according to geographical location and disease stage.

Anodal Cerebellar Transcranial Direct Current Stimulation Reduces Motor and Cognitive Symptoms in Friedreich's Ataxia: A Randomized, Sham-Controlled Trial.

BACKGROUND: Friedreich Ataxia is the most common recessive ataxia with only one therapeutic drug approved solely in the United States. OBJECTIVE: The aim of this work was to investigate whether anodal cerebellar transcranial direct current stimulation (ctDCS) reduces ataxic and cognitive symptoms in individuals with Friedreich's ataxia (FRDA) and to assess the effects of ctDCS on the activity of the secondary somatosensory (SII) cortex. METHODS: We performed a single-blind, randomized, sham-controlled, crossover trial with anodal ctDCS (5 days/week for 1 week, 20 min/day, density current: 0.057 mA/cm2 ) in 24 patients with FRDA. Each patient underwent a clinical evaluation (Scale for the Assessment and Rating of Ataxia, composite cerebellar functional severity score, cerebellar cognitive affective syndrome scale) before and after anodal and sham ctDCS. Activity of the SII cortex contralateral to a tactile oddball stimulation of the right index finger was evaluated with brain functional magnetic resonance imaging at baseline and after anodal/sham ctDCS. RESULTS: Anodal ctDCS led to a significant improvement in the Scale for the Assessment and Rating of Ataxia (-6.5%) and in the cerebellar cognitive affective syndrome scale (+11%) compared with sham ctDCS. It also led to a significant reduction in functional magnetic resonance imaging signal at the SII cortex contralateral to tactile stimulation (-26%) compared with sham ctDCS. CONCLUSIONS: One week of treatment with anodal ctDCS reduces motor and cognitive symptoms in individuals with FRDA, likely by restoring the neocortical inhibition normally exerted by cerebellar structures. This study provides class I evidence that ctDCS stimulation is effective and safe in FRDA. © 2023 International Parkinson and Movement Disorder Society.

Identification of Safe and Effective Intravenous Dose of AAVrh.10hFXN to Treat the Cardiac Manifestations of Friedreich's Ataxia.

Friedreich's ataxia (FA) is a life-threatening autosomal recessive disorder characterized by neurological and cardiac dysfunction. Arrhythmias and heart failure are the main cause of premature death. From prior studies in murine models of FA, adeno-associated virus encoding the normal human frataxin gene (AAVrh.10hFXN) effectively treated the cardiac manifestations of the disease. However, the therapeutic dose window is limited by high level of human frataxin (hFXN) gene expression associated with toxicity. As a therapeutic goal, since FA heterozygotes have no clinical manifestations of FA, we estimated the level of frataxin (FXN) necessary to convert the heart of a homozygote to that of a heterozygote. In noncardiac cells, FA heterozygotes have 30-80% of normal FXN levels (17.7-47.2 ng/mg, average 32.5 ng/mg) and FA homozygotes 2-30% normal levels (1.2-17.7 ng/mg, average 9.4 ng/mg). Therefore, an AAV vector would need to augment endogenous in an FA homozygote by >8.3 ng/mg. To determine the required dose of AAVrh.10hFXN, we administered 1.8 × 1011, 5.7 × 1011, or 1.8 × 1012 gc/kg of AAVrh.10hFXN intravenously (IV) to muscle creatine kinase (mck)-Cre conditional knockout Fxn mice, a cardiac and skeletal FXN knockout model. The minimally effective dose was 5.7 × 1011 gc/kg, resulting in cardiac hFXN levels of 6.1 ± 4.2 ng/mg and a mild (p < 0.01 compared with phosphate-buffered saline controls) improvement in mortality. A dose of 1.8 × 1012 gc/kg resulted in cardiac hFXN levels of 33.7 ± 6.4 ng/mg, a significant improvement in ejection fraction and fractional shortening (p < 0.05, both comparisons) and a 21.5% improvement in mortality (p < 0.001). To determine if the significantly effective dose of 1.8 × 1012 gc/kg could achieve human FA heterozygote levels in a large animal, this dose was administered IV to nonhuman primates. After 12 weeks, the vector-expressed FXN in the heart was 17.8 ± 4.9 ng/mg, comparable to the target human levels. These data identify both minimally and significantly effective therapeutic doses that are clinically relevant for the treatment of the cardiac manifestations of FA.

[Gene Therapy for Ataxias]. / Gentherapie für Ataxien.

Ataxias are progressive diseases that are usually the result of cerebellar degeneration. Ataxias are divided into genetic, sporadic degenerative and acquired (secondary) forms. While there are established therapies for acquired (secondary) ataxias, genetic and sporadic degenerative ataxias are currently not medically treatable. For these ataxias, the development of somatic gene therapies is a promising avenue. The goals of gene therapies for genetic ataxias are to inactivate deleterious genes by gene silencing or to replace or correct a non-functional gene. Another option, which may also be considered for sporadic degenerative ataxias, are therapies that involve transferring new or modified genes. Gene therapies are being actively developed for the more common ataxias, such as Friedreich's ataxia, certain spinocerebellar ataxias, and multiple system atrphy, and initial phase I trials are underway.

Removal of the GAA repeat in the heart of a Friedreich's ataxia mouse model using CjCas9.

Most Friedreich ataxia (FRDA) cases are caused by the elongation of the GAA repeat (GAAr) sequence in the first intron of the FXN gene, leading to a decrease of the frataxin protein expression. Deletion of this GAAr with CRISPR/Cas9 technology leads to an increase in frataxin expression in vitro. We are therefore aiming to develop FRDA treatment based on the deletion of GAAr with CRISPR/Cas9 technology using a single AAV expressing a small Cas9 (CjCas9) and two single guide RNAs (sgRNAs) targeting the FXN gene. This AAV was intraperitoneally administrated to YG8sR (250-300 GAAr) and to YG8-800 (800 GAAr) mice. DNA and RNA were extracted from different organs a month later. PCR amplification of part of intron 1 of the FXN gene detected some GAAr deletion in some cells in heart and liver of both mouse models, but the editing rate was not sufficient to cause an increase in frataxin mRNA in the heart. However, the correlation observed between the editing rate and the distribution of AAV suggests a possible therapy based on the removal of the GAAr with a better delivery tool of the CRISPR/Cas9 system.

The inherited cerebellar ataxias: an update.

This narrative review aims at providing an update on the management of inherited cerebellar ataxias (ICAs), describing main clinical entities, genetic analysis strategies and recent therapeutic developments. Initial approach facing a patient with cerebellar ataxia requires family medical history, physical examination, exclusions of acquired causes and genetic analysis, including Next-Generation Sequencing (NGS). To guide diagnosis, several algorithms and a new genetic nomenclature for recessive cerebellar ataxias have been proposed. The challenge of NGS analysis is the identification of causative variant, trio analysis being usually the most appropriate option. Public genomic databases as well as pathogenicity prediction software facilitate the interpretation of NGS results. We also report on key clinical points for the diagnosis of the main ICAs, including Friedreich ataxia, CANVAS, polyglutamine spinocerebellar ataxias, Fragile X-associated tremor/ataxia syndrome. Rarer forms should not be neglected because of diagnostic biomarkers availability, disease-modifying treatments, or associated susceptibility to malignancy. Diagnostic difficulties arise from allelic and phenotypic heterogeneity as well as from the possibility for one gene to be associated with both dominant and recessive inheritance. To complicate the phenotype, cerebellar cognitive affective syndrome can be associated with some subtypes of cerebellar ataxia. Lastly, we describe new therapeutic leads: antisense oligonucleotides approach in polyglutamine SCAs and viral gene therapy in Friedreich ataxia. This review provides support for diagnosis, genetic counseling and therapeutic management of ICAs in clinical practice.

Clinical management guidelines for Friedreich ataxia: best practice in rare diseases.

BACKGROUND: Individuals with Friedreich ataxia (FRDA) can find it difficult to access specialized clinical care. To facilitate best practice in delivering healthcare for FRDA, clinical management guidelines (CMGs) were developed in 2014. However, the lack of high-certainty evidence and the inadequacy of accepted metrics to measure health status continues to present challenges in FRDA and other rare diseases. To overcome these challenges, the Grading of Recommendations Assessment and Evaluation (GRADE) framework for rare diseases developed by the RARE-Bestpractices Working Group was adopted to update the clinical guidelines for FRDA. This approach incorporates additional strategies to the GRADE framework to support the strength of recommendations, such as review of literature in similar conditions, the systematic collection of expert opinion and patient perceptions, and use of natural history data. METHODS: A panel representing international clinical experts, stakeholders and consumer groups provided oversight to guideline development within the GRADE framework. Invited expert authors generated the Patient, Intervention, Comparison, Outcome (PICO) questions to guide the literature search (2014 to June 2020). Evidence profiles in tandem with feedback from individuals living with FRDA, natural history registry data and expert clinical observations contributed to the final recommendations. Authors also developed best practice statements for clinical care points that were considered self-evident or were not amenable to the GRADE process. RESULTS: Seventy clinical experts contributed to fifteen topic-specific chapters with clinical recommendations and/or best practice statements. New topics since 2014 include emergency medicine, digital and assistive technologies and a stand-alone section on mental health. Evidence was evaluated according to GRADE criteria and 130 new recommendations and 95 best practice statements were generated. DISCUSSION AND CONCLUSION: Evidence-based CMGs are required to ensure the best clinical care for people with FRDA. Adopting the GRADE rare-disease framework enabled the development of higher quality CMGs for FRDA and allows individual topics to be updated as new evidence emerges. While the primary goal of these guidelines is better outcomes for people living with FRDA, the process of developing the guidelines may also help inform the development of clinical guidelines in other rare diseases.

A systematic review of disease prevalence, health-related quality of life, and economic outcomes associated with Friedreich's Ataxia.

INTRODUCTION: Friedreich ataxia (FA) is a rare, inherited neuromuscular disease characterized by an early onset and progressive limb and gait ataxia. Currently, there are no approved treatments for FA. It is important to understand the burden of FA, including its extent and the most salient elements. The objective of this study is therefore to systematically review the literature regarding the aspects of prevalence, health-related quality of life (HRQoL), and economic outcomes that are associated with FA, and to subsequently identify relevant knowledge gaps. METHODS: Three systematic literature reviews were conducted to assess publications regarding FA prevalence, HRQoL, and economic outcomes. Search strategies were implemented in MEDLINE (Ovid) and EMBASE databases; study selection and quality assessment were conducted using current best practices. For each review, study characteristics and findings were summarized. RESULTS: A total of 36 studies were included. Review of prevalence studies (n = 22) indicated variation in the number of cases by region, and many regions were not represented at all. Regarding HRQoL (n = 12 studies), physical domains were consistently impacted, although findings regarding other domains and overall HRQoL were less clear. Cost studies (n = 2) encompassed 4 regions and revealed that costs related to the provision of care, including non-medical direct costs and indirect costs, accounted for the majority of FA-related costs. DISCUSSION: Findings from this systematic review revealed several knowledge gaps that would preclude the conduct of a robust assessment of the benefits and outcomes associated with a disease-modifying FA therapy. Additional understanding regarding patient and caregiver HRQoL and costs is required.

Friedreich ataxia: clinical features and new developments.

Friedreich's ataxia (FRDA), a neurodegenerative disease characterized by ataxia and other neurological features, affects 1 in 50,000-100,000 individuals in the USA. However, FRDA also includes cardiac, orthopedic and endocrine dysfunction, giving rise to many secondary disease characteristics. The multifaceted approach for clinical care has necessitated the development of disease-specific clinical care guidelines. New developments in FRDA include the advancement of clinical drug trials targeting the NRF2 pathway and frataxin restoration. Additionally, a novel understanding of gene silencing in FRDA, reflecting a variegated silencing pattern, will have applications to current and future therapeutic interventions. Finally, new perspectives on the neuroanatomy of FRDA and its developmental features will refine the time course and anatomical targeting of novel approaches.

Friedreich's ataxia (FRDA), mainly referred to as a disorder of balance, is characterized by loss of coordination (ataxia) in the arms and legs and other neurological features, affecting about 1 in 50,000 people in the USA. FRDA also includes serious heart disease, aggressive scoliosis, diabetes and many other disease characteristics. Due to various clinical care needs, disease-specific clinical care guidelines have been created. New developments in FRDA include the advancement of clinical drug trials targeting cell signaling pathways and restoration of the deficient protein found in individuals with FRDA. Additionally, a new understanding of the role of the various genetic factors that contribute to the development of FRDA could affect current and future therapies. Finally, new perspectives on the early developmental features of FRDA will help refine the time course and accelerate new treatments.

Source of medical information and behavioral seeking patterns in patients affected with Friedreich's ataxia and their caregivers: a survey study.

BACKGROUND: Friedreich's ataxia (FRDA) is an untreatable disease that negatively impacts patients' and caregivers' quality of life. OBJECTIVES: The aims were to improve the quality of the information for FRDA patients and caregivers and suggest a possible tool to spread this information. MATERIAL AND METHODS: Thirty-four FRDA patients and 45 caregivers were interviewed separately using a structured self-administered survey about their information-seeking behavior, their level of expectation and satisfaction for the information received, and the need for further information. RESULTS AND CONCLUSION: For patients and caregivers, the main source of information was the FRDA specialist and the media. The most searched items were "general information"; patients and particularly caregivers desired to get more information on existing and experimental therapies. Adequate information supply is part of good medical care; therefore, a deeper insight of clinicians in information-seeking behavior of FRDA patients and caregivers would provide tailored information and improve therapeutic alliance.

The Cost of Living with Inherited Ataxia in Ireland.

Inherited ataxias are a heterogenous group of neurodegenerative disorders characterised by progressive impairment of balance and coordination, typically leading to permanent and progressive disability. Diagnosis and management of these disorders incurs a range of direct and indirect financial costs. The aim of this study was to collect individual ataxia-related healthcare resources in a large cohort of individuals with different subtypes of inherited ataxia and calculate the associated cost of illness in the Republic of Ireland. One hundred twenty-nine respondents completed a cross-sectional study on healthcare resource utilisation for progressive ataxia in Ireland. Costs were calculated using a prevalence-based approach and bottom-up methodology. The COI for inherited ataxia in 2016 was €59,993 per person per year. Results were similar between participants with Friedreich's ataxia (FRDA, n = 56), non-FRDA (n = 18) and those with undetermined ataxia (n = 55). Indirect costs, based on productivity losses by participants or caregivers, accounted for 52% of the cost of illness. Inherited ataxia is associated with significant health and social care costs. Further funding for inherited ataxia to ease the financial burden on patients, caregivers and healthcare system and improve standards of care compliance is warranted.

Targeting 3' and 5' untranslated regions with antisense oligonucleotides to stabilize frataxin mRNA and increase protein expression.

Friedreich's ataxia (FRDA) is a severe multisystem disease caused by transcriptional repression induced by expanded GAA repeats located in intron 1 of the Frataxin (FXN) gene encoding frataxin. FRDA results from decreased levels of frataxin; thus, stabilization of the FXN mRNA already present in patient cells represents an attractive and unexplored therapeutic avenue. In this work, we pursued a novel approach based on oligonucleotide-mediated targeting of FXN mRNA ends to extend its half-life and availability as a template for translation. We demonstrated that oligonucleotides designed to bind to FXN 5' or 3' noncoding regions can increase FXN mRNA and protein levels. Simultaneous delivery of oligonucleotides targeting both ends increases efficacy of the treatment. The approach was confirmed in several FRDA fibroblast and induced pluripotent stem cell-derived neuronal progenitor lines. RNA sequencing and single-cell expression analyses confirmed oligonucleotide-mediated FXN mRNA upregulation. Mechanistically, a significant elongation of the FXN mRNA half-life without any changes in chromatin status at the FXN gene was observed upon treatment with end-targeting oligonucleotides, indicating that transcript stabilization is responsible for frataxin upregulation. These results identify a novel approach toward upregulation of steady-state mRNA levels via oligonucleotide-mediated end targeting that may be of significance to any condition resulting from transcription downregulation.