Calculators, Algorithms, Drug Interaction CheckersTools
Back To Search Results

Friedreich Ataxia

Author: Carla T. Williams Editor: Ankush Maheshwary Updated: 3/22/2026 10:09:29 AM

Introduction

Friedreich ataxia (FRDA) represents the most common inherited form of ataxia, accounting for approximately 50% of all ataxia cases.[1][2][3][4][5][6] Currently, the prevalence in the United States ranges from 1 in 30,000 to 50,000 individuals, with higher rates in Europe.[1][6][7][8] First described in 1863 by the German clinician Nikolaus Friedreich, Friedreich ataxia is an inherited autosomal recessive neurodegenerative disease.[9] Friedreich ataxia presents with a combination of symptoms, including gait abnormalities, muscle weakness, neuropathy, and speech disturbances.[10][11][12][13][14][15][16][17] The symptoms typically begin in childhood, and the progression often leads to significant disability, necessitating mobility aids such as wheelchairs, and includes vision and hearing impairments.[17][18]

The etiology of Friedreich ataxia (FRDA) is predominantly linked to an intronic GAA (guanine-adenine-adenine) triplet repeat expansion within the frataxin (FXN) gene on chromosome 9.[2][3][4][19]. The FXN gene encodes a protein vital for mitochondrial adenosine triphosphate (ATP) synthesis and iron homeostasis.[2][20][21] Pathogenic expansions of trinucleotide repeats lead to gene silencing and reduced FXN expression.[3][4][22][23] The resultant FXN deficiency causes mitochondrial iron overload and increased oxidative stress, leading to cellular damage and apoptosis.[23][24][25] Highly energy-dependent cells, such as neurons, cardiomyocytes, and pancreatic β-cells, are particularly susceptible to these effects.[13][23][26][27][28] The coexistence of neurological impairments and extraneural manifestations, such as diabetes mellitus, scoliosis, and hypertrophic cardiomyopathy, underscores the need for interdisciplinary clinical management.[28][29]

Etiology

Register For Free And Read The Full Article
Get the answers you need instantly with the StatPearls Clinical Decision Support tool. StatPearls spent the last decade developing the largest and most updated Point-of Care resource ever developed. Earn CME/CE by searching and reading articles.
  • Dropdown arrow Search engine and full access to all medical articles
  • Dropdown arrow 10 free questions in your specialty
  • Dropdown arrow Free CME/CE Activities
  • Dropdown arrow Free daily question in your email
  • Dropdown arrow Save favorite articles to your dashboard
  • Dropdown arrow Emails offering discounts

Learn more about a Subscription to StatPearls Point-of-Care

Etiology

Friedreich ataxia results from loss-of-function mutations in the frataxin (FXN) gene, located in the centromeric region of chromosome 9q (9q13 to 21.1).[2][3][4][13][14][26][30][31][32] The FXN gene encodes frataxin, a mitochondrial protein vital for maintaining iron homeostasis, facilitating the biogenesis of iron-sulfur clusters, and supporting ATP synthesis via oxidative phosphorylation.[2][3][4][11][23][26] Nearly all patients with Friedreich ataxia exhibit a profound decrease in frataxin messenger RNA levels—often by 70% to 95% relative to healthy individuals—leading to insufficient frataxin protein production and disruption of crucial mitochondrial functions.[23][33][34][35] Although frataxin is ubiquitously expressed, frataxin concentration is notably higher in tissues with high energy demands, including the nervous system, myocardium, and pancreatic β-cells.

The predominant mutation involves an expansion of GAA (guanine-adenine-adenine) trinucleotide repeats in the first intron of both FXN alleles, leading to epigenetic silencing and significantly reduced frataxin expression.[3][4][13][31][32][36][37] Normal alleles contain 7 to 34 repeats, whereas affected alleles can harbor between 66 and 1700 repeats.[38][39] Larger GAA repeat expansions, especially on the smaller allele, correlate with earlier disease onset, more rapid progression of muscular weakness, increased incidence of cardiomyopathy, and the presence of upper extremity areflexia.[4][31][39][40][41] Repeats in the range of 34 to 100, particularly when interrupted by non-GAA sequences, are rarely pathogenic and are considered premutations with the potential to expand beyond 300 repeats in a single generation.[38] 

The vast majority of FRDA cases are homozygous for GAA expansions, accounting for approximately 98% of patients.[2][5][13][32][34] The remaining 2% are compound heterozygotes, carrying a GAA expansion on one allele and a different mutation—such as missense, nonsense, intronic, or exonic alterations—on the other.[5][13][34][41][42][43] Missense mutations tend to produce milder phenotypes, whereas other variants can lead to more severe clinical manifestations. Notably, amino-terminal point mutations are associated with less severe presentations compared to carboxy-terminal mutations, with a total of 17 distinct point mutations documented.[44]

Common heterozygous mutations include the I154M variant, prevalent in southern Italian populations; the ATG>ATT initiation codon mutation; and the G130V variant, which is associated with slower disease progression, hyperreflexia, and milder dysarthria. Familial cases of genetic heterogeneity have been reported, though genetic heterogeneity within families is rare.[6][45][46][47] Patients with compound heterozygosity may display atypical features, such as later onset beyond age 25, preserved or exaggerated reflexes, and isolated spastic paraparesis without ataxia.[5][44] While most patients present with the typical FRDA phenotype, approximately 25% exhibit atypical features, including later age of onset and preserved tendon reflexes.[48]

Epidemiology

Friedreich ataxia represents the most prevalent hereditary ataxia, accounting for approximately 50% of all ataxia cases and roughly 75% in patients under 25 years of age.[1][2][3][4][5][6][12] In the United States, its prevalence ranges from 1 in 30,000 to 50,000 individuals, with a higher incidence observed among populations of western European descent.[1][5][7][8] Globally, FRDA affects approximately 1 in 40,000 individuals and is particularly prevalent in Europe, the Middle East, South Asia, and North Africa.[1][7][8][49][50]

FRDA exhibits a higher prevalence among individuals of European descent compared to other racial and ethnic groups, likely due to its origin from a common European ancestor.[6] The carrier frequency is approximately 1 in 75.[6] As an autosomal recessive disorder, FRDA affects men and women equally. Onset typically occurs in childhood or early adolescence, most commonly between ages 8 and 15; however, symptoms can initially appear as early as 18 months or as late as 75 years of age. The phenotypic variability observed is often correlated with the length of the GAA (guanine-adenine-adenine) trinucleotide repeat expansion.[4][31][40][41] Consequently, the multisystemic characteristics of FRDA contribute to an average age at death of approximately 38 years, despite substantial advancements in managing the primary cause of death, hypertrophic cardiomyopathy.[13][26][27][29]

Pathophysiology

Frataxin plays a pivotal role in essential mitochondrial processes, including the maintenance of iron homeostasis via iron chaperoning, detoxification, and storage regulation, as well as the biogenesis of iron-sulfur clusters required for ATP synthesis via oxidative phosphorylation.[2][3][10][11][23][26][51][52] In FRDA, a mutation in the FXN gene leads to gene silencing, reducing frataxin protein production.[3][10][11] Frataxin deficiency hampers the activation of antioxidant defenses, such as aconitase, permitting unrestrained oxidative damage.[1][2][3][10][23][26][52][53] Iron accumulates within the mitochondria, generating free radicals that induce cellular damage and disrupt ATP synthesis, ultimately leading to cell death.[13][23][26]

Cells most vulnerable to this damage are predominantly neurons and cardiomyocytes, which produce the highest levels of frataxin.[23][26] A characteristic dying back phenomenon involves progressive axonal loss of myelinated peripheral neurons and secondary gliosis in the spinal cord and roots in patients with FRDA.[9][13] Demyelination affects the posterior columns, corticospinal tracts, and ventral or dorsal spinocerebellar tracts due to loss of large myelinated fibers. The degeneration results in fibrosis replacing lost neurons, thinning of the spinal cord, and a reduction in its thoracic anteroposterior and transverse diameters. The dorsal spinal ganglia are also impacted.[54] 

Eventually, neurons in regions such as the lumbosacral area and the Clarke column are lost and replaced by capsular cells.[9] Notably, corticospinal tracts are relatively spared up to the cervicomedullary junction. Degeneration of the posterior column correlates with impaired proprioception and sensory ataxia; loss of sensory ganglia leads to diminished tendon reflexes. Kyphoscoliosis arises from spinal muscular imbalance.

Additional affected regions include the dentate nucleus, which exhibits mild to moderate neuronal loss, and the middle and superior cerebellar peduncles, which demonstrate atrophy. There is a patchy loss of Purkinje cells within the superior vermis of the cerebellum, along with neuronal loss in the inferior olivary, pontine, and medullary nuclei, as well as in the optic tracts.[13] Cerebellar ataxia results from the loss of the lateral and ventral spinocerebellar tracts, Clarke column, dentate nucleus, superior vermis, and dentatorubral pathways.[9] Cranial nerves VII, X, and XII are frequently affected, leading to facial weakness, dysarthria, and dysphagia.[9]

Another significant group of cells with high frataxin expression comprises cardiomyocytes.[22][26][30][55] In cardiac tissue, muscle fibers are replaced by macrophages and fibroblasts, leading to inflammation and interstitial fibrosis.[13] Affected cardiomyocytes display hyperchromatic nuclei, vacuolation, and granular cytoplasm with frequent lipofuscin deposits, culminating in hypertrophic cardiomyopathy.[27]

Histopathology

Numerous histopathological findings in FRDA have been consistently documented since the original description in 1863. Findings include the following:

  • The loss of myelinated fibers in the dorsal columns and corticospinal tracts of the spinal cord
  • Compact fibrillary gliosis without inflammatory infiltrates within these tracts
  • Degeneration and subsequent death of fibers of the dorsal columns and corticospinal tracts
  • Shrinkage of the dorsal columns and corticospinal tracts, accompanied by capsular cell proliferation
  • Absence of large myelinated fibers in the posterior nerve roots
  • Decrease in myelinated axons in peripheral nerves
  • Neuronal destruction with atrophy of the dorsal root ganglion
  • Hypoplasia of the dorsal root ganglion
  • Degeneration and loss of cells of the Clarke column in the thoracic spinal cord
  • Progressive atrophy of large neurons of the dentate nucleus
  • Patchy loss of Purkinje cells in the superior vermis of the cerebellum
  • Neuronal loss in the inferior olivary, pontine, and medullary nuclei
  • Neuronal loss in the optic tracts
  • Lack of Betz cells in the motor cortex [56][57][58][59][60][61]

History and Physical

Ataxia

Symmetric gait ataxia is typically the presenting symptom in a young patient.[1][9][16] The onset of ataxia is insidious, generally beginning with difficulty in standing and running.[16] Ataxia manifests in a child or adolescent who has exhibited normal physical development. Some patients may experience hemiataxia; however, hemiataxia will eventually become generalized.[16] A febrile illness may precipitate gait ataxia.[62] 

Patients exhibit a wide-based gait with continuous shifting to maintain balance. Attempts to rectify imbalances often result in erratic or uncontrolled movements. Individuals may present with a steppage gait, characterized by an uneven, irregular impact of the soles of the feet against the ground, attributable to sensory deficits. As the condition advances, ataxia extends to affect the trunk and upper limbs. Titubation, observed during sitting and standing, may also involve the trunk. As ataxia progresses to include the arms, patients may develop action and intention tremors, along with choreiform movements. Additionally, facial and buccal tremors may be present. Progressive disability may necessitate the use of ambulatory aids such as a walker, then a wheelchair, and may ultimately result in the patient being bedridden.

Other Symptoms

Constitutional symptoms include easy fatigability, weakness, and daytime somnolence. Dysarthria results from cerebellar involvement and is characterized by slurred, slow speech that may eventually become unintelligible. Dysphagia occurs as the muscles responsible for swallowing weaken. When combined with incoordination of speech and swallowing, dysphagia can lead to choking episodes. Vision loss is attributable to the degeneration of optic tract fibers.[17] Additional reported symptoms include deafness, vertigo, urinary urgency, and incontinence. Neuropsychological assessments demonstrate impairments in executive functioning and temporoparietal function, most likely due to disruption of cerebrocerebellar circuits. A family history of FRDA is also considered a critical factor in the diagnostic process.

Musculoskeletal Examination

  • Progressive limb and gait ataxia that develops typically in adolescence
  • Truncal ataxia
  • Motor weakness
  • Loss of muscle tone
  • Muscular atrophy
  • Foot deformities such as high plantar arch, foot inversion, and hammertoes
  • Pes cavus
  • Kyphoscoliosis

Neurological Examination

  • Hyporeflexia or areflexia
  • Extensor plantar responses
  • Flexor spasms
  • Sensory neuropathy
  • Loss of 2-point discrimination
  • Loss of proprioception and vibration
  • Loss of pain and temperature sensation
  • Dysarthria
  • Dysmetria
  • Loss of visual acuity
  • Horizontal nystagmus, particularly with lateral gaze
  • Abnormal extraocular movements such as square-wave jerks, saccadic pursuit, and poor fixation
  • Abnormal visual evoked potentials with reduced amplitude and delayed latency
  • Impaired vestibulo-ocular reflexes

Psychological Examination

  • Mild executive dysfunction
  • Emotional lability [63]

Cardiovascular Examination

  • Peripheral cyanosis
  • Cardiomegaly
  • Tachycardia
  • Atrial fibrillation
  • Systolic ejection murmurs and additional heart sounds

Evaluation

The diagnosis of FRDA includes a thorough history and physical examination. The history should include a comprehensive family history with a pedigree, and any balance or cardiovascular issues at a young age should be noted. Further evaluation should be conducted to rule out alternative diagnoses and assess for abnormalities that can cause fatal complications:

Laboratory Investigations

  • Nutritional and metabolic panels: Glycated hemoglobin level, vitamin E, vitamin B12, serum folate, methylmalonic acid level, ceruloplasmin, heavy metals
  • Infectious disease panel: Venereal disease research laboratory test
  • Autoimmune and paraneoplastic antibody panel

Once FRDA is suspected, the subsequent tests should be performed.

Imaging Studies

Magnetic resonance imaging (MRI) is the preferred modality for assessing the extent of atrophic changes in FRDA. Patients suspected of having FRDA should undergo an MRI of the brain and spinal cord, which will reveal atrophy of the cervical and thoracic spinal cord as well as the cerebellum.

Nerve Conduction Studies and Electromyography

Nerve conduction studies are notable for absent or reduced amplitude sensory nerve action potentials.

Genetic Testing

Genetic testing is the cornerstone of evaluating patients with FRDA. A trinucleotide repeat expansion assay is available, and FRDA is the only disease with pathological GAA repeats.[13] Prenatal testing is available via direct mutation testing.[13]

Evaluation for Common Comorbid Complications:

  • An electrocardiogram can show tachycardia or atrial fibrillation.[64]
  • An echocardiogram typically shows symmetric concentric ventricular hypertrophy.[31] Some patients have shown asymmetric septal hypertrophy.[22][30][55][65]
  • Auditory evoked potential testing shows absent waves III and IV, while wave I is preserved.[18]
  • Vision testing shows abnormal visual evoked potentials, with absent or delayed latencies and reduced P100 wave amplitude.[17]

Treatment / Management

Despite being identified more than 150 years ago, there remains no cure for FRDA.[1][2][12][37] The treatment plan emphasizes the effective management of symptoms and complications associated with conditions such as diabetes mellitus and congestive heart failure.[1](B3)

Physical and Occupational Therapy

Physical therapy is the primary recommendation for delaying disease progression and preserving functional capacity.[66][67][68] The principal objective of physical therapy is to strengthen posture and promote muscular engagement. Typical physical therapy regimens include low-intensity strength-training exercises to enhance coordination, balance, strength, and stabilization. These exercises help patients maintain functional use of their extremities, improve ataxia, and manage scoliosis effectively.(A1)

Furthermore, Frenkel exercises and proprioceptive neuromuscular facilitation stretching are used to improve proprioception.[17] Stretching and muscle-relaxation exercises play a critical role in reducing muscle spasticity and preventing back and foot deformities. Breathing exercises are equally important, alongside techniques designed to reduce overall energy expenditure. Occupational therapy focuses on fostering independence by facilitating transfers and locomotion, implementing safe fall strategies, and using assistive devices for walking to ensure effective functioning in daily activities.

Devices

Orthopedic footwear, avoiding constrictive apparel, and using properly adjusted mobility aids such as rollator walkers, wheelchairs, and orthoses, have demonstrated benefits in ambulation, muscle spasticity, and the prevention of scoliosis and other deformities. Functional electrical stimulation and transcutaneous nerve stimulation may help alleviate gait disturbances and spasticity symptoms. Additionally, a standing frame can help reduce the duration of wheelchair dependence.

Medication

The medication treatment program is principally aimed at managing pain, addressing heart failure, and preventing infections, as there is no cure for FRDA.[30][62] However, the US Food and Drug Administration has recently approved omaveloxolone, a potent activator of nuclear factor erythroid 2-related factor 2 (Nrf2) and the first treatment for FRDA. A dose range of 80 to 160 mg/day has shown promising results in improving neurological function in these patients. Monitoring of liver function is required while receiving this drug.[69][70][71][72](B3)

Surgery

Surgical intervention may be indicated for the correction of kyphoscoliosis and foot deformities. Additionally, an automated implantable cardioverter-defibrillator may be necessary.[30] Heart transplant has been successfully conducted in patients with milder forms of FRDA who are also experiencing significant cardiomyopathy.[73](B3)

Differential Diagnosis

The differential diagnosis of FRDA includes:

  • Spinocerebellar ataxia types 1, 2, or 3, or pure cerebellar ataxia is an autosomal dominant disease characterized by early-onset ataxia, ophthalmoplegia, hearing loss, sensory axonal neuropathy, epilepsy, oculomotor apraxia, choreoathetosis, facial and extremity dystonias, sensorimotor polyneuropathy, cerebellar atrophy, and cognitive impairment. Neuroimaging distinguishes spinocerebellar ataxia from FRDA by demonstrating characteristic cerebellar atrophy.[22][74]
  • Dentatorubro-pallidoluysian atrophy is characterized by myoclonus, epilepsy, choreoathetosis, behavioral changes, intellectual disability, and ataxia. Behavioral, psychiatric, and intellectual symptoms distinguish dentatorubro-pallidoluysian atrophy from FRDA.[74][75]
  • Demyelinating peripheral neuropathy or chronic inflammatory demyelinating polyneuropathy is an autoimmune disorder characterized by symmetric proximal and distal muscle weakness and sensorimotor peripheral neuropathy. Lumbar puncture findings consistent with inflammation distinguish chronic inflammatory demyelinating polyneuropathy from FRDA.[76][77][78]
  • Roussy-Levy variant of Charcot-Marie-Tooth disease is an autosomal dominant disease characterized by areflexia and ataxia. Demyelination, rather than axonal neuropathy, and an autosomal dominant inheritance pattern distinguish the Roussy-Levy variant of Charcot-Marie-Tooth disease from FRDA.[79][80]
  • Cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss syndrome is a disorder caused by a single E818K mutation in the ATPase Na+/K+ transporting subunit α 3 (ATP1A3) gene on chromosome 19q13.[81] Genetic testing distinguishes cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss syndrome from FRDA. 
  • Episodic ataxia is distinguished from FRDA by history.[82][83][84]
  • Autosomal recessive spastic ataxia of Charlevoix-Saguenay is an autosomal recessive disease caused by a mutation in the sacsin molecular chaperone gene (SACS), which encodes the protein sacsin, and is characterized by a triad of early spasticity, cerebellar ataxia, and sensorimotor peripheral neuropathy. Magnetic resonance imaging of the brain distinguishes autosomal recessive spastic ataxia of Charlevoix-Saguenay from Friedreich ataxia by demonstrating involvement of the pons.[85][86]
  • Abetalipoproteinemia (Bassen-Kornzweig disease) is an autosomal recessive disease caused by a mutation in the microsomal triglyceride transfer protein gene, characterized by impaired fat absorption, low cholesterol and triglyceride levels, absent serum β lipoprotein, retinal degeneration, peripheral neuropathy, and ataxia. Abnormal lipid levels and neurologic improvement with fat-soluble vitamin supplementation distinguish abetalipoproteinemia from FRDA.[87]
  • Drug-induced ataxia is distinguished from FRDA by history and resolution of symptoms with removal of the offending agent.[88]
  • Ataxia with vitamin E deficiency is an autosomal recessive disease caused by a mutation in the α-tocopherol transfer protein gene, characterized by slowly progressive gait ataxia, neuropathy, and retinitis pigmentosa. Low vitamin E levels and neurologic improvement with vitamin E supplementation distinguish ataxia with vitamin E deficiency from FRDA.[89]
  • Ataxia-telangiectasia is an autosomal recessive disease caused by a mutation in the ataxia-telangiectasia mutated (ATM) gene, characterized by progressive cerebellar ataxia, abnormal eye movements, other neurologic abnormalities, immune deficiency, and oculocutaneous telangiectasias. Complications include pulmonary disease, increased risk of malignant neoplasm, radiation sensitivity, and diabetes mellitus. Elevated α-fetoprotein distinguishes ataxia-telangiectasia from FRDA.[90]
  • Refsum disease is an autosomal recessive disease caused by a mutation in the phytanoyl-CoA 2-hydroxylase (PHYH) gene, characterized by elevated phytanic acid levels, retinitis pigmentosa, ichthyosis, sensorimotor polyneuropathy, cerebellar ataxia, and sensorineural hearing loss. Elevated phytanic acid levels and improvement with dietary restriction distinguish Refsum disease from FRDA.[91][92]

Pertinent Studies and Ongoing Trials

While there is currently no effective treatment available for FRDA, numerous therapeutic approaches are under investigation to increase frataxin levels. These strategies include protein and gene replacement therapies, antioxidant treatments, iron chelation agents, and inflammation modulators.[1][2][11][93][94][95][96][97][98][99]

Gene Therapy

Current research endeavors are focused on elucidating the mechanisms underlying gene silencing of the expanded frataxin (FXN) gene, with the objective of developing effective treatments for FRDA. While pharmacological agents related to iron chelation and antioxidants are being examined, gene therapy is regarded as the most promising strategy for modifying disease progression.[37][100][101] Furthermore, investigations are underway to assess the efficacy of histone deacetylase inhibitors.[10][11] Additionally, the modulation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), which has been shown to be diminished in cells affected by FRDA, is also being evaluated, as studies indicate that Nrf2 induction may mitigate oxidative damage associated with the condition.[10][70][102]

Omaveloxolone, a Nrf2 activator, improves mitochondrial function, restores redox balance, and reduces inflammation in models of FRDA.[69][70][71][72][103][104] In the Safety and Efficacy of Omaveloxonlone in Friedreich Ataxia  (MOXIe) trial, an international, double-blind randomized placebo-controlled, parallel-group, registrational, phase 2 trial at 11 institutions in the United States, Europe, and Australia, omaveloxolone significantly improved neurological function compared to placebo.[69][70][71][72][103] Omaveloxolone is the first FDA-approved medication for Friedreich ataxia.[69][71]

Iron Chelation

  • Deferiprone is an iron chelator used to reduce iron accumulation in mitochondria.[11][105] This drug is often used in conjunction with idebenone and vitamin B2.[11][105][106]

Antioxidants

  • Idebenone, a synthetic form of coenzyme Q10 and a free radical scavenger used in FRDA to combat free radical damage.[11][26][99][105][106] The effect of this medication on cardiomyopathy is also a major focus of research.[26][107]
  • Coenzyme Q10 [11][26][108]
  • Vitamin E [26][106][108]
  • Vitamin B1 (thiamine)[11]
  • Vitamin B2 (riboflavin)[106]
  • Epicatechin (flavonoid)[104]
  • Vitamin B3 (niacinamide or nicotinamide)[104]

Reduction-Oxidation Modulators

  • EPI-743 (vatiquinone) is a synthetic analog of coenzyme Q10 that targets and activates the enzyme nicotinamide adenine dinucleotide phosphate (NADPH) quinone oxidoreductase 1 and is used in the treatment of genetically defined, life-threatening mitochondrial diseases.[104]

Inflammatory Modulators and Hormones

  • Erythropoietin [104]
  • Interferon γ-1b [11]
  • Phosphodiesterase inhibitors [109]
  • Resveratrol [104]
  • Corticosteroids [11]

Staging

Four distinct scales are used to assess the severity and progression of FRDA:

  • International Cooperative Ataxia Rating Scale (ICARS)[110][111]
  • Friedreich Ataxia Rating Scale (FARS)[111][112][113][114][115][116]
  • Scale for the Assessment and Rating of Ataxia (SARA)[111][117][118]
  • Friedreich Ataxia Composite Test is derived from the Timed 25-Foot Walk Test, the 9-Hole Peg Test, and the Low-Contrast Letter Acuity Test (FACT-Z3)[104]

Other scales used include:

  • 1-Minute Walk Test (1MW)
  • Cooperative Ataxia Group Rating Scale (CAGRS)
  • Composite Cerebellar Functional Severity Score (CCFS)
  • Cerebellar Cognitive Affective Syndrome Scale (CCAS-S)
  • Clinical Global Impression of Change (CGI-C)
  • International Cooperative Ataxia Rating Scale
  • Inherited Ataxia Clinical Rating Scale (IACRS)
  • Timed 25-Foot Walk (T25FW)
  • 9-Hole Peg Test (9-HPT)
  • Low-Contrast Letter Acuity (LCLA)
  • Speech Intelligibility Test (SIT)
  • Spinocerebellar Ataxia Functional Index (SCAFI) 
  • Low-Contrast Sloan Letter Chart (LCSLC)[104]

Prognosis

The prognosis for FRDA is generally regarded as poor. A significant proportion of patients become wheelchair-bound by the age of 45, and the average duration of the disease is typically between 15 and 20 years. On average, patients with this condition have a life expectancy of approximately 36.5 years, with reported ages at death ranging from 12 to 87 years.[119] Cardiac dysfunction, specifically congestive heart failure or arrhythmia, remains the most frequent contributor to mortality, resulting in the death of two-thirds of those diagnosed with FRDA.[22][27][30][31][55][62]

Complications

Complications of FRDA include:

Cardiac

  • Myocarditis
  • Myocardial fibrosis
  • Cardiomegaly
  • Symmetric hypertrophy
  • Congestive heart failure caused by dilated or hypertrophic cardiomyopathy [27][30][55][62]
  • Tachycardia
  • Atrial fibrillation
  • Heart block

Musculoskeletal

  • Kyphoscoliosis can produce significant cardiopulmonary morbidity due to restricted respiratory function
  • Pes cavus

Endocrine

  • Diabetes mellitus [28]

Consultations

An interdisciplinary team is essential for managing the numerous and diverse manifestations of FRDA, requiring expertise from neurological, cardiac, and musculoskeletal specialists. Given the varied clinical presentations and progressive course of FRDA, an integrated treatment strategy is vital. This strategy should incorporate pharmacological interventions, physical therapy, and supportive care to alleviate symptoms and improve patients' quality of life. Members of this interdisciplinary team include the following professionals:

  • Neurologist
  • Cardiologist
  • Ophthalmologist
  • Otolaryngologist
  • Physiatrist
  • Physical therapist
  • Occupational therapist
  • Orthopedic surgeon
  • Speech and language therapist
  • Psychologist
  • Psychiatrist
  • Social worker

Deterrence and Patient Education

Friedreich ataxia is a genetic disorder that cannot be prevented due to its autosomal recessive inheritance pattern. The age of onset typically occurs during childhood or early adolescence, most frequently between the ages of 8 and 15. For families with one affected child, there's a 25% chance of having another child with FRDA, and this risk increases in cases of consanguineous unions. Before conception, genetic screening and counseling are crucial. Genetic screening and counseling help assess carrier status and evaluate the risk of future children inheriting FRDA. When 1 parent passes on a pathogenic variant, the child may become a carrier.

While there is currently no cure for FRDA, understanding the condition can help patients and families prepare for its challenges. Most individuals with FRDA will eventually need mobility aids, like wheelchairs, and may encounter additional issues such as vision and hearing impairments, diabetes mellitus, or scoliosis. Individuals with milder symptoms may have longer survival, with some living into their sixties. Hypertrophic cardiomyopathy is the leading cause of mortality in Friedreich ataxia, highlighting the importance of ongoing cardiologic monitoring throughout a patient’s life.[27][30][55][62]

Pearls and Other Issues

Pearls regarding FRDA include the following:

  • FRDA is the most common hereditary ataxia, accounting for roughly 50% of all ataxia cases.
  • The disease causes neurodegeneration that manifests as difficulty ambulating, muscle weakness, impaired speech, and loss of sensation and proprioception.
  • FRDA has an autosomal recessive inheritance pattern, and symptom onset is usually in childhood or early adolescence, most commonly in children and adolescents aged 8 to 15 years.
  • The global prevalence is 1 in 40,000 population.
  • In the United States, FRDA affects 1 in 50,000 individuals and is most common in people of western European descent.
  • Symptoms worsen over time, so most people affected by this disease end up requiring mobility aids such as wheelchairs, lose their vision and hearing, and develop other medical complications such as diabetes mellitus and scoliosis.
  • Patients with FRDA have an abnormal number of trinucleotide repeats in the frataxin gene on chromosome 9.
  • Frataxin is a mitochondrial protein essential for ATP production, regulating iron stores, and supporting oxidative phosphorylation.
  • Genetic testing is the cornerstone of evaluating patients with FRDA.
  • A repeat expansion of the trinucleotide GAA (guanine-adenine-adenine), typically in the gene's first intron, is the leading cause of this disease.
  • There is still no cure for FRDA. Treatment is centered on managing symptoms and complications such as diabetes mellitus and congestive heart failure.
  • Overall, the prognosis of FRDA is poor.
  • The mean duration of the disease is 15 to 20 years. Since the disease presents in childhood or adolescence, most patients live to be 25 to 30 years old.
  • Cardiac dysfunction with hypertrophic cardiomyopathy is the most frequent cause of death. Two-thirds of patients will die from congestive heart failure or arrhythmia.
  • Close monitoring by a cardiologist is vital throughout a patient's life.
  • Gene therapy is considered the best chance of altering the disease course.

Enhancing Healthcare Team Outcomes

While neurologists are consistently involved in the care of patients with FRDA, consultation with an interprofessional team of specialists, including cardiologists, orthopedic surgeons, speech pathologists, and physiatrists, is imperative. Patients often eventually lose the ability to ambulate and require prostheses, walking aids, wheelchairs, and physical therapy to sustain an active lifestyle. Physical and occupational therapies enhance patients' physical functioning and support their work and home environments. Physiatrists or movement specialists may administer pharmacological agents to mitigate spasticity.

Urologists provide assessment and treatment for bladder dysfunction. Patients may require both nonoperative and operative interventions by orthopedic surgeons for foot deformities and scoliosis. A speech pathologist plays a crucial role in patients with dysphagia and communication impairments; however, some patients may require gastrostomy feedings. Ongoing cardiologic monitoring is essential for managing arrhythmias and cardiac failure to reduce morbidity and mortality.[27][30][120] Psychological evaluation and counseling are critically important to support affected patients and their families.[63] Close monitoring of dietary intake is vital, and modifications can improve dysphagia management and diabetes mellitus complications. An endocrinologist's assessment may be required in complex cases.[28] The Friedreich's Ataxia Research Alliance is an organization dedicated to assisting patients and families through information, resources, and research.[FARA-Friedreich's Ataxia Research Alliance. 2026] 

References

[1]

Cook A, Giunti P. Friedreich's ataxia: clinical features, pathogenesis and management. British medical bulletin. 2017 Dec 1:124(1):19-30. doi: 10.1093/bmb/ldx034. Epub     [PubMed PMID: 29053830]

[2]

Delatycki MB, Bidichandani SI. Friedreich ataxia- pathogenesis and implications for therapies. Neurobiology of disease. 2019 Dec:132():104606. doi: 10.1016/j.nbd.2019.104606. Epub 2019 Sep 5     [PubMed PMID: 31494282]

[3]

Lodi R, Tonon C, Calabrese V, Schapira AH. Friedreich's ataxia: from disease mechanisms to therapeutic interventions. Antioxidants & redox signaling. 2006 Mar-Apr:8(3-4):438-43     [PubMed PMID: 16677089]

Level 3 (low-level) evidence

[4]

Alper G, Narayanan V. Friedreich's ataxia. Pediatric neurology. 2003 May:28(5):335-41     [PubMed PMID: 12878293]

[5]

Zhu D, Burke C, Leslie A, Nicholson GA. Friedreich's ataxia with chorea and myoclonus caused by a compound heterozygosity for a novel deletion and the trinucleotide GAA expansion. Movement disorders : official journal of the Movement Disorder Society. 2002 May:17(3):585-9     [PubMed PMID: 12112211]

Level 3 (low-level) evidence

[6]

Malaquias MJ, Oliveira J, Santos M, Brandão AF, Sardoeira A, Sequeiros J, Barros J, Damásio J. Pseudodominance in Friedreich Ataxia-Impact of High Prevalence of Carriers and Intrafamilial Clinical Variation. Movement disorders clinical practice. 2023 Apr:10(4):670-676. doi: 10.1002/mdc3.13694. Epub 2023 Feb 25     [PubMed PMID: 37070055]

[7]

Keita M, McIntyre K, Rodden LN, Schadt K, Lynch DR. Friedreich ataxia: clinical features and new developments. Neurodegenerative disease management. 2022 Oct:12(5):267-283. doi: 10.2217/nmt-2022-0011. Epub 2022 Jun 29     [PubMed PMID: 35766110]

[8]

Lynch DR, Schadt K, Kichula E, McCormack S, Lin KY. Friedreich Ataxia: Multidisciplinary Clinical Care. Journal of multidisciplinary healthcare. 2021:14():1645-1658. doi: 10.2147/JMDH.S292945. Epub 2021 Jun 28     [PubMed PMID: 34234452]

[9]

Apolloni S, Milani M, D'Ambrosi N. Neuroinflammation in Friedreich's Ataxia. International journal of molecular sciences. 2022 Jun 4:23(11):. doi: 10.3390/ijms23116297. Epub 2022 Jun 4     [PubMed PMID: 35682973]

[10]

Strawser CJ, Schadt KA, Lynch DR. Therapeutic approaches for the treatment of Friedreich's ataxia. Expert review of neurotherapeutics. 2014 Aug:14(8):949-57. doi: 10.1586/14737175.2014.939173. Epub 2014 Jul 18     [PubMed PMID: 25034024]

[11]

Strawser C, Schadt K, Hauser L, McCormick A, Wells M, Larkindale J, Lin H, Lynch DR. Pharmacological therapeutics in Friedreich ataxia: the present state. Expert review of neurotherapeutics. 2017 Sep:17(9):895-907. doi: 10.1080/14737175.2017.1356721. Epub 2017 Jul 26     [PubMed PMID: 28724340]

[12]

Aranca TV, Jones TM, Shaw JD, Staffetti JS, Ashizawa T, Kuo SH, Fogel BL, Wilmot GR, Perlman SL, Onyike CU, Ying SH, Zesiewicz TA. Emerging therapies in Friedreich's ataxia. Neurodegenerative disease management. 2016:6(1):49-65. doi: 10.2217/nmt.15.73. Epub     [PubMed PMID: 26782317]

[13]

Palau F. Friedreich's ataxia and frataxin: molecular genetics, evolution and pathogenesis (Review). International journal of molecular medicine. 2001 Jun:7(6):581-9     [PubMed PMID: 11351269]

Level 3 (low-level) evidence

[14]

Tanaka H. [Friedreich ataxia with GAA repeat expansion: molecular mechanism and clinical feature]. Nihon rinsho. Japanese journal of clinical medicine. 1999 Apr:57(4):960-6     [PubMed PMID: 10222797]

[15]

Vavla M, Arrigoni F, Toschi N, Peruzzo D, D'Angelo MG, Gandossini S, Russo A, Diella E, Tirelli S, Salati R, Rufini A, Condo I, Testi R, Martinuzzi A. Sensitivity of Neuroimaging Indicators in Monitoring the Effects of Interferon Gamma Treatment in Friedreich's Ataxia. Frontiers in neuroscience. 2020:14():872. doi: 10.3389/fnins.2020.00872. Epub 2020 Oct 9     [PubMed PMID: 33162876]

[16]

Indelicato E, Wanschitz J, Löscher W, Boesch S. Skeletal Muscle Involvement in Friedreich Ataxia. International journal of molecular sciences. 2024 Sep 13:25(18):. doi: 10.3390/ijms25189915. Epub 2024 Sep 13     [PubMed PMID: 39337401]

[17]

Rojas P, de Hoz R, Cadena M, Salobrar-García E, Fernández-Albarral JA, López-Cuenca I, Elvira-Hurtado L, Urcelay-Segura JL, Salazar JJ, Ramírez JM, Ramírez AI. Neuro-Ophthalmological Findings in Friedreich's Ataxia. Journal of personalized medicine. 2021 Jul 23:11(8):. doi: 10.3390/jpm11080708. Epub 2021 Jul 23     [PubMed PMID: 34442352]

[18]

Teive HA, Iliadou VM, Manto M. Friedreich's Ataxia and Auditory Processing Disorder. Cerebellum (London, England). 2021 Aug:20(4):495-496. doi: 10.1007/s12311-021-01238-7. Epub     [PubMed PMID: 33599953]

[19]

Paparella G, Stragà C, Vavla M, Pesenti N, Merotto V, Martorel GA, Zalunardo S, Armellin M, Comiotto J, Martinuzzi A. Effectiveness of rehabilitation intervention in persons with Friedreich ataxia. Frontiers in neurology. 2023:14():1270296. doi: 10.3389/fneur.2023.1270296. Epub 2023 Nov 2     [PubMed PMID: 38020600]

[20]

Hohenfeld C, Terstiege U, Dogan I, Giunti P, Parkinson MH, Mariotti C, Nanetti L, Fichera M, Durr A, Ewenczyk C, Boesch S, Nachbauer W, Klopstock T, Stendel C, Rodríguez de Rivera Garrido FJ, Schöls L, Hayer SN, Klockgether T, Giordano I, Didszun C, Rai M, Pandolfo M, Rauhut H, Schulz JB, Reetz K. Prediction of the disease course in Friedreich ataxia. Scientific reports. 2022 Nov 10:12(1):19173. doi: 10.1038/s41598-022-23666-z. Epub 2022 Nov 10     [PubMed PMID: 36357508]

[21]

Mishra RK, Nunes AS, Enriquez A, Profeta VR, Wells M, Lynch DR, Vaziri A. At-home wearable-based monitoring predicts clinical measures and biological biomarkers of disease severity in Friedreich's Ataxia. Communications medicine. 2024 Oct 29:4(1):217. doi: 10.1038/s43856-024-00653-1. Epub 2024 Oct 29     [PubMed PMID: 39468362]

[22]

Weidemann F, Scholz F, Florescu C, Liu D, Hu K, Herrmann S, Ertl G, Störk S. [Heart involvement in Friedreich's ataxia]. Herz. 2015 Mar:40 Suppl 1():85-90. doi: 10.1007/s00059-014-4097-y. Epub 2014 May 23     [PubMed PMID: 24848865]

[23]

Ercanbrack WS, Ramirez M, Dungan A, Gaul E, Ercanbrack SJ, Wingert RA. Frataxin deficiency and the pathology of Friedreich's Ataxia across tissues. Tissue barriers. 2025:13(4):2462357. doi: 10.1080/21688370.2025.2462357. Epub 2025 Feb 21     [PubMed PMID: 39981684]

[24]

Petrillo S, Santoro M, La Rosa P, Perna A, Gallo MG, Bertini ES, Silvestri G, Piemonte F. Nuclear Factor Erythroid 2-Related Factor 2 Activation Might Mitigate Clinical Symptoms in Friedreich's Ataxia: Clues of an "Out-Brain Origin" of the Disease From a Family Study. Frontiers in neuroscience. 2021:15():638810. doi: 10.3389/fnins.2021.638810. Epub 2021 Feb 23     [PubMed PMID: 33708070]

[25]

DoÄŸan-Aslan M, Büyükvural-Åžen S, NakipoÄŸlu-Yüzer GF, Özgirgin N. Demographic and clinical features and rehabilitation outcomes of patients with Friedreich ataxia: A retrospective study. Turkish journal of physical medicine and rehabilitation. 2018 Sep:64(3):230-238. doi: 10.5606/tftrd.2018.2213. Epub 2018 Feb 22     [PubMed PMID: 31453516]

Level 2 (mid-level) evidence

[26]

Lodi R, Rajagopalan B, Bradley JL, Taylor DJ, Crilley JG, Hart PE, Blamire AM, Manners D, Styles P, Schapira AH, Cooper JM. Mitochondrial dysfunction in Friedreich's ataxia: from pathogenesis to treatment perspectives. Free radical research. 2002 Apr:36(4):461-6     [PubMed PMID: 12069111]

Level 3 (low-level) evidence

[27]

Lees JG, Napierala M, Pébay A, Dottori M, Lim SY. Cellular pathophysiology of Friedreich's ataxia cardiomyopathy. International journal of cardiology. 2022 Jan 1:346():71-78. doi: 10.1016/j.ijcard.2021.11.033. Epub 2021 Nov 16     [PubMed PMID: 34798207]

[28]

Tamaroff J, DeDio A, Wade K, Wells M, Park C, Leavens K, Rummey C, Kelly A, Lynch DR, McCormack SE. Friedreich's Ataxia related Diabetes: Epidemiology and management practices. Diabetes research and clinical practice. 2022 Apr:186():109828. doi: 10.1016/j.diabres.2022.109828. Epub 2022 Mar 14     [PubMed PMID: 35301072]

[29]

Reetz K, Lischewski SA, Dogan I, Didszun C, Pishnamaz M, Konrad K, Marx-Schütt K, Farmer J, Lynch DR, Corben LA, Pandolfo M, Schulz JB, FACROSS study group. Friedreich's ataxia-a rare multisystem disease. The Lancet. Neurology. 2025 Jul:24(7):614-624. doi: 10.1016/S1474-4422(25)00175-9. Epub     [PubMed PMID: 40541211]

[30]

Lynch DR, Regner SR, Schadt KA, Friedman LS, Lin KY, St John Sutton MG. Management and therapy for cardiomyopathy in Friedreich's ataxia. Expert review of cardiovascular therapy. 2012 Jun:10(6):767-77. doi: 10.1586/erc.12.57. Epub     [PubMed PMID: 22894632]

Level 3 (low-level) evidence

[31]

Bit-Avragim N, Perrot A, Schöls L, Hardt C, Kreuz FR, Zühlke C, Bubel S, Laccone F, Vogel HP, Dietz R, Osterziel KJ. The GAA repeat expansion in intron 1 of the frataxin gene is related to the severity of cardiac manifestation in patients with Friedreich's ataxia. Journal of molecular medicine (Berlin, Germany). 2001:78(11):626-32     [PubMed PMID: 11269509]

Level 2 (mid-level) evidence

[32]

Campuzano V, Montermini L, Moltò MD, Pianese L, Cossée M, Cavalcanti F, Monros E, Rodius F, Duclos F, Monticelli A, Zara F, Cañizares J, Koutnikova H, Bidichandani SI, Gellera C, Brice A, Trouillas P, De Michele G, Filla A, De Frutos R, Palau F, Patel PI, Di Donato S, Mandel JL, Cocozza S, Koenig M, Pandolfo M. Friedreich's ataxia: autosomal recessive disease caused by an intronic GAA triplet repeat expansion. Science (New York, N.Y.). 1996 Mar 8:271(5254):1423-7     [PubMed PMID: 8596916]

[33]

Doni D, Cavion F, Bortolus M, Baschiera E, Muccioli S, Tombesi G, d'Ettorre F, Ottaviani D, Marchesan E, Leanza L, Greggio E, Ziviani E, Russo A, Bellin M, Sartori G, Carbonera D, Salviati L, Costantini P. Human frataxin, the Friedreich ataxia deficient protein, interacts with mitochondrial respiratory chain. Cell death & disease. 2023 Dec 8:14(12):805. doi: 10.1038/s41419-023-06320-y. Epub 2023 Dec 8     [PubMed PMID: 38062036]

[34]

Monfort B, Want K, Gervason S, D'Autréaux B. Recent Advances in the Elucidation of Frataxin Biochemical Function Open Novel Perspectives for the Treatment of Friedreich's Ataxia. Frontiers in neuroscience. 2022:16():838335. doi: 10.3389/fnins.2022.838335. Epub 2022 Mar 2     [PubMed PMID: 35310092]

Level 3 (low-level) evidence

[35]

Zhang S, Napierala M, Napierala JS. Therapeutic Prospects for Friedreich's Ataxia. Trends in pharmacological sciences. 2019 Apr:40(4):229-233. doi: 10.1016/j.tips.2019.02.001. Epub     [PubMed PMID: 30905359]

[36]

Rojsajjakul T, Selvan N, De B, Rosenberg JB, Kaminsky SM, Sondhi D, Janki P, Crystal RG, Mesaros C, Khanna R, Blair IA. Expression and processing of mature human frataxin after gene therapy in mice. Research square. 2023 Dec 28:():. pii: rs.3.rs-3788652. doi: 10.21203/rs.3.rs-3788652/v1. Epub 2023 Dec 28     [PubMed PMID: 38234818]

[37]

Hebert MD, Whittom AA. Gene-based approaches toward Friedreich ataxia therapeutics. Cellular and molecular life sciences : CMLS. 2007 Dec:64(23):3034-43     [PubMed PMID: 17828464]

Level 3 (low-level) evidence

[38]

Brown AF, Parkinson MH, Garcia-Moreno H, Mudanohwo E, Labrum R, Sweeney M, Giunti P. Friedreich's Ataxia Frequency in a Large Cohort of Genetically Undetermined Ataxia Patients. Frontiers in neurology. 2021:12():736253. doi: 10.3389/fneur.2021.736253. Epub 2021 Dec 9     [PubMed PMID: 34956042]

[39]

Krasilnikova MM, Humphries CL, Shinsky EM. Friedreich's ataxia: new insights. Emerging topics in life sciences. 2023 Dec 14:7(3):313-323. doi: 10.1042/ETLS20230017. Epub     [PubMed PMID: 37698160]

[40]

Cnop M, Igoillo-Esteve M, Rai M, Begu A, Serroukh Y, Depondt C, Musuaya AE, Marhfour I, Ladrière L, Moles Lopez X, Lefkaditis D, Moore F, Brion JP, Cooper JM, Schapira AH, Clark A, Koeppen AH, Marchetti P, Pandolfo M, Eizirik DL, Féry F. Central role and mechanisms of β-cell dysfunction and death in friedreich ataxia-associated diabetes. Annals of neurology. 2012 Dec:72(6):971-82. doi: 10.1002/ana.23698. Epub     [PubMed PMID: 23280845]

[41]

Rummey C, Perlman S, Subramony SH, Corti M, Farmer J, Lynch DR. Disease Progression in Children With Friedreich Ataxia: Functional Performance and Other Outcome Assessments in the FACHILD Study. Journal of child neurology. 2026 Mar:41(3):321-329. doi: 10.1177/08830738251353475. Epub 2025 Jul 24     [PubMed PMID: 40708339]

[42]

Zühlke CH, Dalski A, Habeck M, Straube K, Hedrich K, Hoeltzenbein M, Konstanzer A, Hellenbroich Y, Schwinger E. Extension of the mutation spectrum in Friedreich's ataxia: detection of an exon deletion and novel missense mutations. European journal of human genetics : EJHG. 2004 Nov:12(11):979-82     [PubMed PMID: 15340363]

[43]

Indelicato E, Fleszar Z, Pellerin D, Nachbauer W, Zuchner S, Traschütz A, Amprosi M, Schöls L, Haack TB, Brais B, Boesch S, Synofzik M. GAA-FGF14 Expansions and CACNA1A Variants: Phenotypic Overlap and Diagnostic Implications. Movement disorders : official journal of the Movement Disorder Society. 2025 Oct:40(10):2262-2268. doi: 10.1002/mds.30328. Epub 2025 Aug 19     [PubMed PMID: 40879304]

[44]

Cossée M, Dürr A, Schmitt M, Dahl N, Trouillas P, Allinson P, Kostrzewa M, Nivelon-Chevallier A, Gustavson KH, Kohlschütter A, Müller U, Mandel JL, Brice A, Koenig M, Cavalcanti F, Tammaro A, De Michele G, Filla A, Cocozza S, Labuda M, Montermini L, Poirier J, Pandolfo M. Friedreich's ataxia: point mutations and clinical presentation of compound heterozygotes. Annals of neurology. 1999 Feb:45(2):200-6     [PubMed PMID: 9989622]

[45]

Kellett MW, Fletcher NA, Wood N, Enevoldson TP. Trinucleotide (GAA)n repeat expansion in two families with Friedreich's ataxia with retained reflexes. Journal of neurology, neurosurgery, and psychiatry. 1997 Dec:63(6):780-3     [PubMed PMID: 9416816]

Level 3 (low-level) evidence

[46]

Lucotte G, Berriche S, David F, Bathelier C, Turpin JC. Trinucleotide GAA repeat expansions in seven French Friedreich ataxia families. Genetic counseling (Geneva, Switzerland). 1997:8(3):189-94     [PubMed PMID: 9327260]

[47]

Rao VK, DiDonato CJ, Larsen PD. Friedreich's Ataxia: Clinical Presentation of a Compound Heterozygote Child with a Rare Nonsense Mutation and Comparison with Previously Published Cases. Case reports in neurological medicine. 2018:2018():8587203. doi: 10.1155/2018/8587203. Epub 2018 Aug 9     [PubMed PMID: 30159187]

Level 3 (low-level) evidence

[48]

Chutake YK, Lam C, Costello WN, Anderson M, Bidichandani SI. Epigenetic promoter silencing in Friedreich ataxia is dependent on repeat length. Annals of neurology. 2014 Oct:76(4):522-8. doi: 10.1002/ana.24249. Epub 2014 Aug 30     [PubMed PMID: 25112975]

[49]

Yilmaz MB, Koç AF, Kasap H, Güzel AI, Sarica Y, Süleymanova D. GAA repeat polymorphism in Turkish Friedreich's ataxia patients. The International journal of neuroscience. 2006 May:116(5):565-74     [PubMed PMID: 16644517]

[50]

Houshmand M, Panahi MS, Nafisi S, Soltanzadeh A, Alkandari FM. Identification and sizing of GAA trinucleotide repeat expansion, investigation for D-loop variations and mitochondrial deletions in Iranian patients with Friedreich's ataxia. Mitochondrion. 2006 Apr:6(2):82-8     [PubMed PMID: 16581313]

Level 2 (mid-level) evidence

[51]

Martelli A, Puccio H. Dysregulation of cellular iron metabolism in Friedreich ataxia: from primary iron-sulfur cluster deficit to mitochondrial iron accumulation. Frontiers in pharmacology. 2014:5():130. doi: 10.3389/fphar.2014.00130. Epub 2014 Jun 3     [PubMed PMID: 24917819]

[52]

Rötig A, Sidi D, Munnich A, Rustin P. Molecular insights into Friedreich's ataxia and antioxidant-based therapies. Trends in molecular medicine. 2002 May:8(5):221-4     [PubMed PMID: 12067631]

Level 3 (low-level) evidence

[53]

Rötig A, de Lonlay P, Chretien D, Foury F, Koenig M, Sidi D, Munnich A, Rustin P. Aconitase and mitochondrial iron-sulphur protein deficiency in Friedreich ataxia. Nature genetics. 1997 Oct:17(2):215-7     [PubMed PMID: 9326946]

[54]

Koeppen AH, Becker AB, Qian J, Feustel PJ. Friedreich Ataxia: Hypoplasia of Spinal Cord and Dorsal Root Ganglia. Journal of neuropathology and experimental neurology. 2017 Feb 1:76(2):101-108. doi: 10.1093/jnen/nlw111. Epub     [PubMed PMID: 28082326]

Level 2 (mid-level) evidence

[55]

Bertoni PD, Canziani R, Cozzi G, Arancio F, Marforio S. [Cardiac involvement in Friedreich's heredo-ataxia]. Giornale italiano di cardiologia. 1986 Jan:16(1):22-9     [PubMed PMID: 2940141]

[56]

Morral JA, Davis AN, Qian J, Gelman BB, Koeppen AH. Pathology and pathogenesis of sensory neuropathy in Friedreich's ataxia. Acta neuropathologica. 2010 Jul:120(1):97-108. doi: 10.1007/s00401-010-0675-0. Epub 2010 Mar 26     [PubMed PMID: 20339857]

Level 2 (mid-level) evidence

[57]

Koeppen AH, Morral JA, Davis AN, Qian J, Petrocine SV, Knutson MD, Gibson WM, Cusack MJ, Li D. The dorsal root ganglion in Friedreich's ataxia. Acta neuropathologica. 2009 Dec:118(6):763-76. doi: 10.1007/s00401-009-0589-x. Epub 2009 Aug 30     [PubMed PMID: 19727777]

Level 2 (mid-level) evidence

[58]

Koeppen AH, Mazurkiewicz JE. Friedreich ataxia: neuropathology revised. Journal of neuropathology and experimental neurology. 2013 Feb:72(2):78-90. doi: 10.1097/NEN.0b013e31827e5762. Epub     [PubMed PMID: 23334592]

[59]

Koeppen AH. Nikolaus Friedreich and degenerative atrophy of the dorsal columns of the spinal cord. Journal of neurochemistry. 2013 Aug:126 Suppl 1(0 1):4-10. doi: 10.1111/jnc.12218. Epub     [PubMed PMID: 23859337]

[60]

Koeppen AH. Friedreich's ataxia: pathology, pathogenesis, and molecular genetics. Journal of the neurological sciences. 2011 Apr 15:303(1-2):1-12. doi: 10.1016/j.jns.2011.01.010. Epub     [PubMed PMID: 21315377]

Level 3 (low-level) evidence

[61]

Koeppen AH, Morral JA, McComb RD, Feustel PJ. The neuropathology of late-onset Friedreich's ataxia. Cerebellum (London, England). 2011 Mar:10(1):96-103. doi: 10.1007/s12311-010-0235-0. Epub     [PubMed PMID: 21128039]

Level 2 (mid-level) evidence

[62]

Hanley A, Corrigan R, Mohammad S, MacMahon B. Friedreich's ataxia cardiomyopathy: case based discussion and management issues. Irish medical journal. 2010 Apr:103(4):117-8     [PubMed PMID: 20486316]

Level 3 (low-level) evidence

[63]

Karamazovova S, Matuskova V, Ismail Z, Vyhnalek M. Neuropsychiatric symptoms in spinocerebellar ataxias and Friedreich ataxia. Neuroscience and biobehavioral reviews. 2023 Jul:150():105205. doi: 10.1016/j.neubiorev.2023.105205. Epub 2023 May 1     [PubMed PMID: 37137435]

[64]

Wood AH, Dubrey SW. Cardiomyopathy and the electrocardiogram in Friedreich's ataxia. British journal of hospital medicine (London, England : 2005). 2013 Apr:74(4):232-3     [PubMed PMID: 23571398]

Level 3 (low-level) evidence

[65]

Dutka DP, Donnelly JE, Nihoyannopoulos P, Oakley CM, Nunez DJ. Marked variation in the cardiomyopathy associated with Friedreich's ataxia. Heart (British Cardiac Society). 1999 Feb:81(2):141-7     [PubMed PMID: 9922348]

[66]

Milne SC, Corben LA, Roberts M, Murphy A, Tai G, Georgiou-Karistianis N, Yiu EM, Delatycki MB. Can rehabilitation improve the health and well-being in Friedreich's ataxia: a randomized controlled trial? Clinical rehabilitation. 2018 May:32(5):630-643. doi: 10.1177/0269215517736903. Epub 2017 Oct 26     [PubMed PMID: 29072092]

Level 1 (high-level) evidence

[67]

Bonnechère B, Jansen B, Haack I, Omelina L, Feipel V, Van Sint Jan S, Pandolfo M. Automated functional upper limb evaluation of patients with Friedreich ataxia using serious games rehabilitation exercises. Journal of neuroengineering and rehabilitation. 2018 Oct 4:15(1):87. doi: 10.1186/s12984-018-0430-7. Epub 2018 Oct 4     [PubMed PMID: 30286776]

[68]

Maring JR, Croarkin E. Presentation and progression of Friedreich ataxia and implications for physical therapist examination. Physical therapy. 2007 Dec:87(12):1687-96     [PubMed PMID: 17911272]

[69]

Pilotto F, Chellapandi DM, Puccio H. Omaveloxolone: a groundbreaking milestone as the first FDA-approved drug for Friedreich ataxia. Trends in molecular medicine. 2024 Feb:30(2):117-125. doi: 10.1016/j.molmed.2023.12.002. Epub 2024 Jan 24     [PubMed PMID: 38272714]

Level 3 (low-level) evidence

[70]

Lynch DR, Perlman S, Schadt K. Omaveloxolone for the treatment of Friedreich ataxia: clinical trial results and practical considerations. Expert review of neurotherapeutics. 2024 Mar:24(3):251-258. doi: 10.1080/14737175.2024.2310617. Epub 2024 Jan 30     [PubMed PMID: 38269532]

[71]

Portillo-Carrasquer M, Sanz-Alcázar A, Sánchez-López B, Delaspre F, Pazos-Gil M, Oliveira-Jorge L, Castells-Roca L, Tamarit J, Ros J, Cabiscol E. Targeting frataxin deficiency in DRG neurons and fibroblasts: omaveloxolone restores metabolic and iron balance to reduce ferroptosis. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie. 2026 Feb:195():119031. doi: 10.1016/j.biopha.2026.119031. Epub 2026 Jan 23     [PubMed PMID: 41579709]

[72]

Lynch DR, Chin MP, Boesch S, Delatycki MB, Giunti P, Goldsberry A, Hoyle JC, Mariotti C, Mathews KD, Nachbauer W, O'Grady M, Perlman S, Subramony SH, Wilmot G, Zesiewicz T, Meyer CJ. Efficacy of Omaveloxolone in Friedreich's Ataxia: Delayed-Start Analysis of the MOXIe Extension. Movement disorders : official journal of the Movement Disorder Society. 2023 Feb:38(2):313-320. doi: 10.1002/mds.29286. Epub 2022 Nov 29     [PubMed PMID: 36444905]

[73]

Sedlak TL, Chandavimol M, Straatman L. Cardiac transplantation: a temporary solution for Friedreich's ataxia-induced dilated cardiomyopathy. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2004 Nov:23(11):1304-6     [PubMed PMID: 15539131]

Level 3 (low-level) evidence

[74]

Musova Z, Sedlacek Z, Mazanec R, Klempir J, Roth J, Plevova P, Vyhnalek M, Kopeckova M, Apltova L, Krepelova A, Zumrova A. Spinocerebellar ataxias type 8, 12, and 17 and dentatorubro-pallidoluysian atrophy in Czech ataxic patients. Cerebellum (London, England). 2013 Apr:12(2):155-61. doi: 10.1007/s12311-012-0403-5. Epub     [PubMed PMID: 22872568]

[75]

Li H, Hu X, Fei L, Zhang P, Chen X, Ouyang M, Zhang W, Liu X. [Clinical and genetic characteristics of patients with dentatorubro-pallidoluysian atrophy]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics. 2016 Oct:33(5):610-4. doi: 10.3760/cma.j.issn.1003-9406.2016.05.006. Epub     [PubMed PMID: 27577205]

[76]

Lewis RA. Chronic inflammatory demyelinating polyneuropathy. Current opinion in neurology. 2017 Oct:30(5):508-512. doi: 10.1097/WCO.0000000000000481. Epub     [PubMed PMID: 28763304]

Level 3 (low-level) evidence

[77]

Kuwabara S, Misawa S. Chronic Inflammatory Demyelinating Polyneuropathy. Advances in experimental medicine and biology. 2019:1190():333-343. doi: 10.1007/978-981-32-9636-7_21. Epub     [PubMed PMID: 31760654]

Level 3 (low-level) evidence

[78]

Lehmann HC, Burke D, Kuwabara S. Chronic inflammatory demyelinating polyneuropathy: update on diagnosis, immunopathogenesis and treatment. Journal of neurology, neurosurgery, and psychiatry. 2019 Sep:90(9):981-987. doi: 10.1136/jnnp-2019-320314. Epub 2019 Apr 16     [PubMed PMID: 30992333]

[79]

Koehler PJ. Gabrielle Lévy and the Roussy-Lévy syndrome. Journal of the history of the neurosciences. 2018 Apr-Jun:27(2):117-144. doi: 10.1080/0964704X.2018.1423848. Epub 2018 Feb 22     [PubMed PMID: 29469679]

[80]

Bartosik-Psujek H, Stelmasiak Z. A case of the Roussy-Levy syndrome family. Annales Universitatis Mariae Curie-Sklodowska. Sectio D: Medicina. 2001:56():393-5     [PubMed PMID: 11977346]

Level 3 (low-level) evidence

[81]

Roenn CP, Li M, Schack VR, Forster IC, Holm R, Toustrup-Jensen MS, Andersen JP, Petrou S, Vilsen B. Functional consequences of the CAPOS mutation E818K of Na(+),K(+)-ATPase. The Journal of biological chemistry. 2019 Jan 4:294(1):269-280. doi: 10.1074/jbc.RA118.004591. Epub 2018 Nov 8     [PubMed PMID: 30409907]

[82]

Jen JC, Wan J. Episodic ataxias. Handbook of clinical neurology. 2018:155():205-215. doi: 10.1016/B978-0-444-64189-2.00013-5. Epub     [PubMed PMID: 29891059]

[83]

Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, Hasan SM, D'Adamo MC. Episodic Ataxia Type 1. GeneReviews(®). 1993:():     [PubMed PMID: 20301785]

[84]

Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, Spacey S. Episodic Ataxia Type 2 – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY. GeneReviews(®). 1993:():     [PubMed PMID: 20301674]

[85]

Synofzik M, Németh AH. Recessive ataxias. Handbook of clinical neurology. 2018:155():73-89. doi: 10.1016/B978-0-444-64189-2.00005-6. Epub     [PubMed PMID: 29891078]

[86]

Briand MM, Rodrigue X, Lessard I, Mathieu J, Brais B, Côté I, Gagnon C. Expanding the clinical description of autosomal recessive spastic ataxia of Charlevoix-Saguenay. Journal of the neurological sciences. 2019 May 15:400():39-41. doi: 10.1016/j.jns.2019.03.008. Epub 2019 Mar 12     [PubMed PMID: 30901567]

[87]

Hernandez-Diaz S, Soukup SF. The role of lipids in autophagy and its implication in neurodegeneration. Cell stress. 2020 May 19:4(7):167-186. doi: 10.15698/cst2020.07.225. Epub 2020 May 19     [PubMed PMID: 32656499]

[88]

van Gaalen J, Kerstens FG, Maas RP, Härmark L, van de Warrenburg BP. Drug-induced cerebellar ataxia: a systematic review. CNS drugs. 2014 Dec:28(12):1139-53. doi: 10.1007/s40263-014-0200-4. Epub     [PubMed PMID: 25391707]

Level 1 (high-level) evidence

[89]

Adam MP, Bick S, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, Schuelke M. Ataxia with Vitamin E Deficiency. GeneReviews(®). 1993:():     [PubMed PMID: 20301419]

[90]

Rothblum-Oviatt C, Wright J, Lefton-Greif MA, McGrath-Morrow SA, Crawford TO, Lederman HM. Ataxia telangiectasia: a review. Orphanet journal of rare diseases. 2016 Nov 25:11(1):159     [PubMed PMID: 27884168]

[91]

Hochner I, Blickle JF, Brogard JM. [Refsum disease]. La Revue de medecine interne. 1996:17(5):391-8     [PubMed PMID: 8763099]

[92]

Wanders RJ, Jansen GA, Skjeldal OH. Refsum disease, peroxisomes and phytanic acid oxidation: a review. Journal of neuropathology and experimental neurology. 2001 Nov:60(11):1021-31     [PubMed PMID: 11706932]

[93]

Pallardó FV, Pagano G, Rodríguez LR, Gonzalez-Cabo P, Lyakhovich A, Trifuoggi M. Friedreich Ataxia: current state-of-the-art, and future prospects for mitochondrial-focused therapies. Translational research : the journal of laboratory and clinical medicine. 2021 Mar:229():135-141. doi: 10.1016/j.trsl.2020.08.009. Epub 2020 Aug 22     [PubMed PMID: 32841735]

[94]

Clay A, Hearle P, Schadt K, Lynch DR. New developments in pharmacotherapy for Friedreich ataxia. Expert opinion on pharmacotherapy. 2019 Oct:20(15):1855-1867. doi: 10.1080/14656566.2019.1639671. Epub 2019 Jul 16     [PubMed PMID: 31311349]

Level 3 (low-level) evidence

[95]

Lynch DR, Hauser L, McCormick A, Wells M, Dong YN, McCormack S, Schadt K, Perlman S, Subramony SH, Mathews KD, Brocht A, Ball J, Perdok R, Grahn A, Vescio T, Sherman JW, Farmer JM. Randomized, double-blind, placebo-controlled study of interferon-γ 1b in Friedreich Ataxia. Annals of clinical and translational neurology. 2019 Mar:6(3):546-553. doi: 10.1002/acn3.731. Epub 2019 Feb 27     [PubMed PMID: 30911578]

Level 1 (high-level) evidence

[96]

Nuñez MT, Chana-Cuevas P. New Perspectives in Iron Chelation Therapy for the Treatment of Neurodegenerative Diseases. Pharmaceuticals (Basel, Switzerland). 2018 Oct 19:11(4):. doi: 10.3390/ph11040109. Epub 2018 Oct 19     [PubMed PMID: 30347635]

Level 3 (low-level) evidence

[97]

Zesiewicz T, Salemi JL, Perlman S, Sullivan KL, Shaw JD, Huang Y, Isaacs C, Gooch C, Lynch DR, Klein MB. Double-blind, randomized and controlled trial of EPI-743 in Friedreich's ataxia. Neurodegenerative disease management. 2018 Aug:8(4):233-242. doi: 10.2217/nmt-2018-0013. Epub 2018 Jul 27     [PubMed PMID: 30051753]

Level 1 (high-level) evidence

[98]

Zesiewicz T, Heerinckx F, De Jager R, Omidvar O, Kilpatrick M, Shaw J, Shchepinov MS. Randomized, clinical trial of RT001: Early signals of efficacy in Friedreich's ataxia. Movement disorders : official journal of the Movement Disorder Society. 2018 Jul:33(6):1000-1005. doi: 10.1002/mds.27353. Epub 2018 Apr 6     [PubMed PMID: 29624723]

Level 1 (high-level) evidence

[99]

Edzeamey FJ, Ramchunder Z, Pourzand C, Anjomani Virmouni S. Emerging antioxidant therapies in Friedreich's ataxia. Frontiers in pharmacology. 2024:15():1359618. doi: 10.3389/fphar.2024.1359618. Epub 2024 Feb 6     [PubMed PMID: 38379897]

[100]

Carletti B, Piemonte F. Friedreich's Ataxia: A Neuronal Point of View on the Oxidative Stress Hypothesis. Antioxidants (Basel, Switzerland). 2014 Sep 10:3(3):592-603. doi: 10.3390/antiox3030592. Epub 2014 Sep 10     [PubMed PMID: 26785073]

[101]

Polak U, Li Y, Butler JS, Napierala M. Alleviating GAA Repeat Induced Transcriptional Silencing of the Friedreich's Ataxia Gene During Somatic Cell Reprogramming. Stem cells and development. 2016 Dec 1:25(23):1788-1800     [PubMed PMID: 27615158]

[102]

Abeti R, Baccaro A, Esteras N, Giunti P. Novel Nrf2-Inducer Prevents Mitochondrial Defects and Oxidative Stress in Friedreich's Ataxia Models. Frontiers in cellular neuroscience. 2018:12():188. doi: 10.3389/fncel.2018.00188. Epub 2018 Jul 17     [PubMed PMID: 30065630]

[103]

Lynch DR, Goldsberry A, Rummey C, Farmer J, Boesch S, Delatycki MB, Giunti P, Hoyle JC, Mariotti C, Mathews KD, Nachbauer W, Perlman S, Subramony SH, Wilmot G, Zesiewicz T, Weissfeld L, Meyer C. Propensity matched comparison of omaveloxolone treatment to Friedreich ataxia natural history data. Annals of clinical and translational neurology. 2024 Jan:11(1):4-16. doi: 10.1002/acn3.51897. Epub 2023 Sep 10     [PubMed PMID: 37691319]

[104]

Gavriilaki M, Chatzikyriakou E, Moschou M, Arnaoutoglou M, Sakellari I, Kimiskidis VK. Therapeutic Biomarkers in Friedreich's Ataxia: a Systematic Review and Meta-analysis. Cerebellum (London, England). 2024 Jun:23(3):1184-1203. doi: 10.1007/s12311-023-01621-6. Epub 2023 Oct 27     [PubMed PMID: 37889470]

Level 1 (high-level) evidence

[105]

Soriano S, Llorens JV, Blanco-Sobero L, Gutiérrez L, Calap-Quintana P, Morales MP, Moltó MD, Martínez-Sebastián MJ. Deferiprone and idebenone rescue frataxin depletion phenotypes in a Drosophila model of Friedreich's ataxia. Gene. 2013 Jun 1:521(2):274-81. doi: 10.1016/j.gene.2013.02.049. Epub 2013 Mar 28     [PubMed PMID: 23542074]

Level 3 (low-level) evidence

[106]

Arpa J, Sanz-Gallego I, Rodríguez-de-Rivera FJ, Domínguez-Melcón FJ, Prefasi D, Oliva-Navarro J, Moreno-Yangüela M. Triple therapy with deferiprone, idebenone and riboflavin in Friedreich's ataxia - open-label trial. Acta neurologica Scandinavica. 2014 Jan:129(1):32-40. doi: 10.1111/ane.12141. Epub 2013 May 14     [PubMed PMID: 23668357]

Level 3 (low-level) evidence

[107]

Cooper JM, Schapira AH. Friedreich's Ataxia: disease mechanisms, antioxidant and Coenzyme Q10 therapy. BioFactors (Oxford, England). 2003:18(1-4):163-71     [PubMed PMID: 14695932]

[108]

Cooper JM, Schapira AH. Friedreich's ataxia: coenzyme Q10 and vitamin E therapy. Mitochondrion. 2007 Jun:7 Suppl():S127-35     [PubMed PMID: 17485244]

Level 3 (low-level) evidence

[109]

Mollá B, Muñoz-Lasso DC, Calap P, Fernandez-Vilata A, de la Iglesia-Vaya M, Pallardó FV, Moltó MD, Palau F, Gonzalez-Cabo P. Phosphodiesterase Inhibitors Revert Axonal Dystrophy in Friedreich's Ataxia Mouse Model. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 2019 Apr:16(2):432-449. doi: 10.1007/s13311-018-00706-z. Epub     [PubMed PMID: 30761510]

[110]

Trouillas P, Takayanagi T, Hallett M, Currier RD, Subramony SH, Wessel K, Bryer A, Diener HC, Massaquoi S, Gomez CM, Coutinho P, Ben Hamida M, Campanella G, Filla A, Schut L, Timann D, Honnorat J, Nighoghossian N, Manyam B. International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome. The Ataxia Neuropharmacology Committee of the World Federation of Neurology. Journal of the neurological sciences. 1997 Feb 12:145(2):205-11     [PubMed PMID: 9094050]

[111]

Jain P, Badgujar L, Spoorendonk J, Buesch K. Clinical evidence of interventions assessed in Friedreich ataxia: a systematic review. Therapeutic advances in rare disease. 2022 Jan-Dec:3():26330040221139872. doi: 10.1177/26330040221139872. Epub 2022 Nov 29     [PubMed PMID: 37180421]

Level 1 (high-level) evidence

[112]

Subramony SH, May W, Lynch D, Gomez C, Fischbeck K, Hallett M, Taylor P, Wilson R, Ashizawa T, Cooperative Ataxia Group. Measuring Friedreich ataxia: Interrater reliability of a neurologic rating scale. Neurology. 2005 Apr 12:64(7):1261-2     [PubMed PMID: 15824358]

[113]

Fahey MC, Corben L, Collins V, Churchyard AJ, Delatycki MB. How is disease progress in Friedreich's ataxia best measured? A study of four rating scales. Journal of neurology, neurosurgery, and psychiatry. 2007 Apr:78(4):411-3     [PubMed PMID: 17056635]

[114]

Rummey C, Farmer JM, Lynch DR. Domain Specific Placebo Response in the Modified Friedreich's Ataxia Rating Scale. Annals of clinical and translational neurology. 2026 Feb:13(2):393-398. doi: 10.1002/acn3.70239. Epub 2025 Nov 26     [PubMed PMID: 41293985]

[115]

Rummey C, Corben LA, Delatycki MB, Subramony SH, Bushara K, Gomez CM, Hoyle JC, Yoon G, Ravina B, Mathews KD, Wilmot G, Zesiewicz T, Perlman S, Farmer JM, Lynch DR. Psychometric properties of the Friedreich Ataxia Rating Scale. Neurology. Genetics. 2019 Dec:5(6):371. doi: 10.1212/NXG.0000000000000371. Epub 2019 Oct 29     [PubMed PMID: 32042904]

[116]

Rummey C, Zesiewicz TA, Perez-Lloret S, Farmer JM, Pandolfo M, Lynch DR. Test-retest reliability of the Friedreich's ataxia rating scale. Annals of clinical and translational neurology. 2020 Sep:7(9):1708-1712. doi: 10.1002/acn3.51118. Epub 2020 Aug 11     [PubMed PMID: 32779859]

[117]

Schwabova J, Maly T, Laczo J, Zumrova A, Komarek V, Musova Z, Zahalka F. Application of a Scale for the Assessment and Rating of Ataxia (SARA) in Friedreich's ataxia patients according to posturography is limited. Journal of the neurological sciences. 2014 Jun 15:341(1-2):64-7. doi: 10.1016/j.jns.2014.04.001. Epub 2014 Apr 12     [PubMed PMID: 24768059]

[118]

Porcu L, Fichera M, Nanetti L, Rulli E, Giunti P, Parkinson MH, Durr A, Ewenczyk C, Boesch S, Nachbauer W, Indelicato E, Klopstock T, Stendel C, Rodríguez de Rivera FJ, Schöls L, Fleszar Z, Giordano I, Didszun C, Castaldo A, Rai M, Klockgether T, Pandolfo M, Schulz JB, Reetz K, Mariotti C, EFACTS Study Group. Longitudinal changes of SARA scale in Friedreich ataxia: Strong influence of baseline score and age at onset. Annals of clinical and translational neurology. 2023 Nov:10(11):2000-2012. doi: 10.1002/acn3.51886. Epub 2023 Aug 28     [PubMed PMID: 37641437]

[119]

Tsou AY, Paulsen EK, Lagedrost SJ, Perlman SL, Mathews KD, Wilmot GR, Ravina B, Koeppen AH, Lynch DR. Mortality in Friedreich ataxia. Journal of the neurological sciences. 2011 Aug 15:307(1-2):46-9. doi: 10.1016/j.jns.2011.05.023. Epub 2011 Jun 8     [PubMed PMID: 21652007]

Level 2 (mid-level) evidence

[120]

Hawley RJ, Gottdiener JS. Five-year follow-up of Friedreich's ataxia cardiomyopathy. Archives of internal medicine. 1986 Mar:146(3):483-8     [PubMed PMID: 3954519]