Friedreich's ataxia explained

Synonyms:Spinocerebellar ataxia, FRDA, FA
Friedreich's ataxia
Field:Neurology
Symptoms:Lack of coordination, balance issues, gait abnormality
Complications:Cardiomyopathy, scoliosis, diabetes
Onset:5–20 years
Duration:Long-term
Causes:Genetic
Diagnosis:Medical history and physical examination
Treatment:None
Prognosis:Shortened life expectancy
Frequency:1 in 50,000 (United States)

Friedreich's ataxia (FRDA or FA) is an autosomal-recessive genetic disease that causes difficulty walking, a loss of coordination in the arms and legs, and impaired speech that worsens over time. Symptoms generally start between 5 and 20 years of age. Many develop hypertrophic cardiomyopathy and require a mobility aid such as a cane, walker, or wheelchair in their teens. As the disease progresses, some affected people lose their sight and hearing. Other complications may include scoliosis and diabetes.

The condition is caused by mutations in the FXN gene on chromosome 9, which makes a protein called frataxin. In FRDA, cells produce less frataxin. Degeneration of nerve tissue in the spinal cord causes the ataxia; particularly affected are the sensory neurons essential for directing muscle movement of the arms and legs through connections with the cerebellum. The spinal cord becomes thinner, and nerve cells lose some myelin sheath.

In February 2023, the first approval of a treatment for FRDA, omaveloxolone, was granted by the US Food and Drug Administration (FDA). Approval in the European Union was granted in February 2024.

FRDA affects one in 50,000 people in the United States and is the most common inherited ataxia. Rates are highest in people of Western European descent. The condition is named after German physician Nikolaus Friedreich, who first described it in the 1860s.

Symptoms

Symptoms typically start between the ages of 5 and 15, but in late-onset FRDA, they may occur after age 25 years.[1] The symptoms are broad, but consistently involve gait and limb ataxia, dysarthria and loss of lower limb reflexes.[1]

Classical symptoms

There is some variability in symptom frequency, onset and progression. All individuals with FRDA develop neurological symptoms, including dysarthria and loss of lower limb reflexes, and more than 90% present with ataxia.[1] Cardiac issues are very common with early onset FRDA .[1] Most individuals develop heart problems such as enlargement of the heart, symmetrical hypertrophy, heart murmurs, atrial fibrillation, tachycardia, hypertrophic cardiomyopathy, and conduction defects. Scoliosis is present in about 60%. 7% of people with FRDA also have diabetes and having diabetes has an adverse impact on people with FA, especially those that show symptoms when young.[2] [3]

Other symptoms

People who have been living with FRDA for a long time may develop other complications. 36.8% experience decreased visual acuity, which may be progressive and could lead to functional blindness.[3] Hearing loss is present in about 10.9% of cases.[3] Some patients report bladder and bowel symptoms.[4] Advanced stages of disease are associated with supraventricular tachyarrhythmias, most commonly atrial fibrillation.[1]

Other later stage symptoms can include, cerebellar effects such as nystagmus, fast saccadic eye movements, dysmetria and loss of coordination (truncal ataxia, and stomping gait).[1] Symptoms can involve the dorsal column such as the loss of vibratory sensation and proprioceptive sensation.[1]

The progressive loss of coordination and muscle strength leads to the full-time use of a wheelchair. Most young people diagnosed with FRDA require mobility aids such as a cane, walker, or wheelchair by early 20s.The disease is progressive, with increasing staggering or stumbling gait and frequent falling. By the third decade, affected people lose the ability to stand or walk without assistance and require a wheelchair for mobility.[5]

Early-onset cases

Non-neurological symptoms such as scoliosis, pes cavus, cardiomyopathy and diabetes are more frequent amongst the early-onset cases.[1]

Genetics

FRDA is an autosomal-recessive disorder that affects a gene (FXN) on chromosome 9, which produces an important protein called frataxin.[6]

In 96% of cases, the mutant FXN gene has 90–1,300 GAA trinucleotide repeat expansions in intron 1 of both alleles.[7] This expansion causes epigenetic changes and formation of heterochromatin near the repeat.[6] The length of the shorter GAA repeat is correlated with the age of onset and disease severity.[8] The formation of heterochromatin results in reduced transcription of the gene and low levels of frataxin.[9] People with FDRA might have 5-35% of the frataxin protein compared to healthy individuals. Heterozygous carriers of the mutant FXN gene have 50% lower frataxin levels, but this decrease is not enough to cause symptoms.[10]

In about 4% of cases, the disease is caused by a (missense, nonsense, or intronic) point mutation, with an expansion in one allele and a point mutation in the other.[11] A missense point mutation can have milder symptoms.[11] Depending on the point mutation, cells can produce no frataxin, nonfunctional frataxin, or frataxin that is not properly localized to the mitochondria.[12] [13]

Pathophysiology

FRDA affects the nervous system, heart, pancreas, and other systems.[14] [15]

Degeneration of nerve tissue in the spinal cord causes ataxia.[14] The sensory neurons essential for directing muscle movement of the arms and legs through connections with the cerebellum are particularly affected.[14] The disease primarily affects the spinal cord and peripheral nerves.

The spinal cord becomes thinner and nerve cells lose some myelin sheath.[14] The diameter of the spinal cord is smaller than that of unaffected individuals mainly due to smaller dorsal root ganglia.[15] The motor neurons of the spinal cord are affected to a lesser extent than sensory neurons.[14] In peripheral nerves, a loss of large myelinated sensory fibers occurs.[14]

Structures in the brain are also affected by FRDA, notably the dentate nucleus of the cerebellum.[15] The heart often develops some fibrosis, and over time, develops left-ventricle hypertrophy and dilatation of the left ventricle.[15]

Frataxin

The exact role of frataxin remains unclear.[16] Frataxin assists iron-sulfur protein synthesis in the electron transport chain to generate adenosine triphosphate, the energy molecule necessary to carry out metabolic functions in cells. It also regulates iron transfer in the mitochondria by providing a proper amount of reactive oxygen species (ROS) to maintain normal processes.[17] One result of frataxin deficiency is mitochondrial iron overload, which damages many proteins due to effects on cellular metabolism.

Without frataxin, the energy in the mitochondria falls, and excess iron creates extra ROS, leading to further cell damage.[17] Low frataxin levels lead to insufficient biosynthesis of iron–sulfur clusters that are required for mitochondrial electron transport and assembly of functional aconitase and iron dysmetabolism of the entire cell.[18]

Diagnosis

Balance difficulty, loss of proprioception, an absence of reflexes, and signs of other neurological problems are common signs from a physical examination.[5] [19] Diagnostic tests are made to confirm a physical examination such as electromyogram, nerve conduction studies, electrocardiogram, echocardiogram, blood tests for elevated glucose levels and vitamin E levels, and scans such as X-ray radiograph for scoliosis.[20] MRI and CT scans of brain and spinal cord are done to rule out other neurological conditions.[21] Finally, a genetic test is conducted to confirm.

Other diagnoses might include Charcot-Marie-Tooth types 1 and 2, ataxia with vitamin E deficiency, ataxia-oculomotor apraxia types 1 and 2, and other early-onset ataxias.[22]

Management of Symptoms

Physicians and patients can reference the clinical management guidelines for Friedreich ataxia.[23] These Guidelines are intended to assist qualified healthcare professionals in making informed treatment decisions about the care of individuals with Friedreich ataxia.[24]

Therapeutics

Omaveloxolone

Rehabilitation

Physical therapists play a critical role in educating on correct posture, muscle use, and the identification and avoidance of features that aggravate spasticities such as tight clothing, poorly adjusted wheelchairs, pain, and infection.[25]

Physical therapy typically includes intensive motor coordination, balance, and stabilization training to preserve gains.[26] Low-intensity strengthening exercises are incorporated to maintain functional use of the upper and lower extremities. Stretching and muscle relaxation exercises can be prescribed to help manage spasticity and prevent deformities. Other physical therapy goals include increased transfer and locomotion independence, muscle strengthening, increased physical resilience, "safe fall" strategy, learning to use mobility aids, learning how to reduce the body's energy expenditure, and developing specific breathing patterns. Speech therapy can improve voice quality.[27]

Devices

Well-fitted orthoses can promote correct posture, support normal joint alignment, stabilize joints during walking, improve range of motion and gait, reduce spasticity, and prevent foot deformities and scoliosis.[28]

Functional electrical stimulation or transcutaneous nerve stimulation devices may alleviate symptoms.[28]

As progression of ataxia continues, assistive devices such as a cane, walker, or wheelchair may be required for mobility and independence. A standing frame can help reduce the secondary complications of prolonged use of a wheelchair.[29] [30]

Managing Cardiac Involvement

Cardiac abnormalities can be controlled with ACE inhibitors such as enalapril, ramipril, lisinopril, or trandolapril, sometimes used in conjunction with beta blockers. Affected people who also have symptomatic congestive heart failure may be prescribed eplerenone or digoxin to keep cardiac abnormalities under control.[28]

Surgical Intervention

Surgery may correct deformities caused by abnormal muscle tone. Titanium screws and rods inserted in the spine help prevent or slow the progression of scoliosis. Surgery to lengthen the Achilles tendon can improve independence and mobility to alleviate equinus deformity.[28] An automated implantable cardioverter-defibrillator can be implanted after a severe heart failure.[28]

Prognosis

The disease evolves differently in different people.[29] In general, those diagnosed at a younger age or with longer GAA triplet expansions tend to have more severe symptoms.[28]

Congestive heart failure and abnormal heart rhythms are the leading causes of death,[31] but people with fewer symptoms can live into their 60s or older.[21]

Epidemiology

FRDA affects Indo-European populations. It is rare in East Asians, sub-Saharan Africans, and Native Americans. FRDA is the most prevalent inherited ataxia, affecting approximately 1 in 40,000 with European descent. Males and females are affected equally. The estimated carrier prevalence is 1:100. A 1990–1996 study of Europeans calculated the incidence rate was 2.8:100,000.[32] The prevalence rate of FRDA in Japan is 1:1,000,000.[33]

FRDA follows the same pattern as haplogroup R1b. Haplogroup R1b is the most frequently occurring paternal lineage in Western Europe. FRDA and Haplogroup R1b are more common in northern Spain, Ireland, and France, rare in Russia and Scandinavia, and follow a gradient through central and eastern Europe. A population carrying the disease went through a population bottleneck in the Franco-Cantabrian region during the last ice age.[34]

History

The condition is named after the nineteenth century German pathologist and neurologist, Nikolaus Friedreich. Friedreich reported the disease in 1863 at the University of Heidelberg.[35] [36] [37] Further observations appeared in a paper in 1876.[38]

Frantz Fanon wrote his medical thesis on FRDA, in 1951.[39]

A 1984 Canadian study traced 40 cases to one common ancestral couple arriving in New France in 1634.[40]

FRDA was first linked to a GAA repeat expansion on chromosome 9 in 1996.[41]

Society and culture

The Cake Eaters is a 2007 independent drama film that stars Kristen Stewart as a young woman with FRDA.[42]

The Ataxian is a documentary that tells the story of Kyle Bryant, an athlete with FRDA who completes a long-distance bike race in an adaptive "trike" to raise money for research.[43]

Dynah Haubert spoke at the 2016 Democratic National Convention about supporting Americans with disabilities.[44]

Geraint Williams in an athlete affected by FRDA who is known for scaling Mount Kilimanjaro in an adaptive wheelchair.[45]

Shobhika Kalra is an activist with FRDA who helped build over 1000 wheelchair ramps across the United Arab Emirates in 2018 to try to make Dubai fully wheelchair-friendly by 2020.[46]

Butterflies Still Fly is a 2023 film, based on a true story, directed by Joseph Nenci. Italo is a light-hearted journalist, darkened by a personal drama that distracts him from work. He encounters with Giorgia, a young girl suffering from Friedreich's Ataxia, who will change his life.

Research

There is no cure for Friedreich's ataxia, and treatment development is directed toward slowing, stopping, or reversing disease progression.In 2019, Reata Pharmaceuticals reported positive results in a phase 2 trial of RTA 408 (Omaveloxolone or Omav) to target activation of a transcriptional factor, Nrf2.[47] Nrf2 is decreased in FRDA cells.[48] [49] [50] [51]

There are several additional therapies in trial. Patients can enroll in a registry to make clinical trial recruiting easier. The Friedreich's Ataxia Global Patient Registry is the only worldwide registry of Friedreich's ataxia patients to characterize the symptoms and establish the rate of disease progression.[52] The Friedreich's Ataxia App is the only global community app which enables novel forms of research.[53]

As of May 2021, research continues along the following paths.

Improve mitochondrial function and reduce oxidative stress

Modulation of frataxin controlled metabolic pathways

Frataxin replacements or stabilizers

Increase frataxin gene expression

External links

Notes and References

  1. 10.1093/bmb/ldx034 . Friedreich's ataxia: Clinical features, pathogenesis and management. 2017. Cook. A.. Giunti. P.. British Medical Bulletin. 124. 1. 19–30. 29053830. 5862303.
  2. McCormick. Ashley. Farmer. Jennifer. Perlman. Susan. Delatycki. Martin. Wilmot. George. Matthews. Katherine. Yoon. Grace. Hoyle. Chad. Subramony. Sub H.. Zesiewicz. Theresa. Lynch. David R.. 2017. Impact of diabetes in the Friedreich ataxia clinical outcome measures study. Annals of Clinical and Translational Neurology. 4. 9. 622–631. 10.1002/acn3.439. 5590524. 28904984. Shana E.. McCormack.
  3. Reetz. Kathrin. Dogan. Imis. Hohenfeld. Christian. Didszun. Claire. Giunti. Paola. Mariotti. Caterina. Durr. Alexandra. Boesch. Sylvia. Klopstock. Thomas. Rodríguez De Rivera Garrido. Francisco Javier. Schöls. Ludger. 2018. Nonataxia symptoms in Friedreich Ataxia. Neurology. 91. 10. e917–e930. 10.1212/WNL.0000000000006121. 30097477. Massimo. EFACTS Study Group. Jörg B.. Schulz. Giordano. Pandolfo. Katrin. Bürk. Ilaria. 51956258.
  4. Web site: Friedreich Ataxia Fact Sheet. live. https://web.archive.org/web/20190123211107/https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet. 23 January 2019. 10 February 2019.
  5. Parksinson. MH. Boesch. S. Nachbauer. W. Mariotti. C. Giunti. P. August 2013. Clinical features of Friedreich's ataxia: classical and atypical phenotypes. Journal of Neurochemistry. 126. Supplement 1. 103–17. 10.1111/jnc.12317. 23859346. free.
  6. Klockgether T . Update on degenerative ataxias . Current Opinion in Neurology . 24 . 4 . 339–45 . August 2011 . 21734495 . 10.1097/WCO.0b013e32834875ba .
  7. Role of frataxin protein deficiency and metabolic dysfunction in Friedreich ataxia, an autosomal recessive mitochondrial disease . Clark E, Johnson J, Dong YN, Mercado-Ayon, Warren N, Zhai M, McMillan E, Salovin A, Lin H, Lynch DR . Neuronal Signaling . 2 . 4 . NS20180060 . Nov 2018 . 10.1042/NS20180060 . 32714592 . 7373238 . free .
  8. Dürr A, Cossee M, Agid Y, Campuzano V, Mignard C, Penet C, Mandel JL, Brice A, Koenig M . Clinical and genetic abnormalities in patients with Friedreich's ataxia . The New England Journal of Medicine . 335 . 16 . 1169–75 . October 1996 . 8815938 . 10.1056/nejm199610173351601 . free .
  9. Montermini L, Andermann E, Labuda M, Richter A, Pandolfo M, Cavalcanti F, Pianese L, Iodice L, Farina G, Monticelli A, Turano M, Filla A, De Michele G, Cocozza S . The Friedreich ataxia GAA triplet repeat: premutation and normal alleles . Human Molecular Genetics . 6 . 8 . 1261–6 . August 1997 . 9259271 . 10.1093/hmg/6.8.1261 . free .
  10. Bürk K. 2017. Friedreich Ataxia: current status and future prospects. Cerebellum & Ataxias. 4. 4. 10.1186/s40673-017-0062-x. 5383992. 28405347 . free .
  11. 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 . 45 . 2 . 200–6 . February 1999 . 9989622 . 10.1002/1531-8249(199902)45:2<200::AID-ANA10>3.0.CO;2-U . 24885238 .
  12. Lazaropoulos M, Dong Y, Clark E, Greeley NR, Seyer LA, Brigatti KW, Christie C, Perlman SL, Wilmot GR, Gomez CM, Mathews KD, Yoon G, Zesiewicz T, Hoyle C, Subramony SH, Brocht AF, Farmer JM, Wilson RB, Deutsch EC, Lynch DR . Frataxin levels in peripheral tissue in Friedreich ataxia . Annals of Clinical and Translational Neurology . 2 . 8 . 831–42 . August 2015 . 26339677 . 4554444 . 10.1002/acn3.225 .
  13. Galea CA, Huq A, Lockhart PJ, Tai G, Corben LA, Yiu EM, Gurrin LC, Lynch DR, Gelbard S, Durr A, Pousset F, Parkinson M, Labrum R, Giunti P, Perlman SL, Delatycki MB, Evans-Galea MV . Compound heterozygous FXN mutations and clinical outcome in friedreich ataxia . Annals of Neurology . 79 . 3 . 485–95 . March 2016 . 26704351 . 10.1002/ana.24595 . 26709558 .
  14. 10.1016/j.nbd.2019.104606 . Friedreich ataxia- pathogenesis and implications for therapies. 2019. Delatycki. Martin B.. Bidichandani. Sanjay I.. Neurobiology of Disease. 132. 104606. 31494282. 201839487. free.
  15. 10.4330/wjc.v11.i1.1. 30705738. Heart disease in Friedreich's ataxia. 2019. Hanson. Emily. Sheldon. Mark. Pacheco. Brenda. Alkubeysi. Mohammed. Raizada. Veena. World Journal of Cardiology. 11. 1. 1–12. 6354072 . free .
  16. 10.1016/j.cbpa.2019.11.014 . Mammalian iron–sulfur cluster biogenesis: Recent insights into the roles of frataxin, acyl carrier protein and ATPase-mediated transfer to recipient proteins. 2020. Maio. Nunziata. Jain. Anshika. Rouault. Tracey A.. Current Opinion in Chemical Biology. 55. 34–44. 31918395. 7237328.
  17. Sahdeo S, Scott BD, McMackin MZ, Jasoliya M, Brown B, Wulff H, Perlman SL, Pook MA, Cortopassi GA . Dyclonine rescues frataxin deficiency in animal models and buccal cells of patients with Friedreich's ataxia . Human Molecular Genetics . 23 . 25 . 6848–62 . December 2014 . 25113747 . 4245046 . 10.1093/hmg/ddu408 .
  18. 10.1074/jbc.P113.525857. 3873538 . Role of Frataxin, a Protein Implicated in Friedreich Ataxia, in Making Iron-Sulfur Clusters♦. Journal of Biological Chemistry. 2013. 288. 52. 36787. 220291178. free.
  19. Corben . LA . Lynch . D . Pandolfo . M . Schulz . JB . Delatycki . MB . Clinical Management Guidelines Writing Group . Consensus clinical management guidelines for Friedreich ataxia . Orphanet Journal of Rare Diseases . November 2014 . 9 . 184 . 10.1186/s13023-014-0184-7 . 25928624 . 4280001 . free .
  20. Brigatti KW, Deutsch EC, Lynch DR, Farmer JM . Novel diagnostic paradigms for Friedreich ataxia . Journal of Child Neurology . 27 . 9 . 1146–51 . September 2012 . 22752491 . 3674546 . 10.1177/0883073812448440 .
  21. Web site: Friedreich's Ataxia Fact Sheet. National Institute of Neurological Disorders and Stroke. 26 August 2017. https://web.archive.org/web/20170826235140/https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet. 26 August 2017. live.
  22. Web site: Friedreich ataxia NIH page . NIH Rare diseases . 17 March 2019 . https://web.archive.org/web/20190331042717/https://rarediseases.info.nih.gov/diseases/6468/friedreich-ataxia . 31 March 2019 . live .
  23. Web site: FDRA Guidelines. 8 May 2023.
  24. 9652828 . 2022 . Corben . L. A. . Collins . V. . Milne . S. . Farmer . J. . Musheno . A. . Lynch . D. . Subramony . S. . Pandolfo . M. . Schulz . J. B. . Lin . K. . Delatycki . M. B. . Clinical Management Guidelines Writing Group . Clinical management guidelines for Friedreich ataxia: Best practice in rare diseases . Orphanet Journal of Rare Diseases . 17 . 1 . 415 . 10.1186/s13023-022-02568-3 . 36371255 . free .
  25. 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 . 6 . 1 . 49–65 . Feb 2016 . 26782317 . 4768799 . 10.2217/nmt.15.73 .
  26. Book: Chien H, Barsottini O . Movement Disorders Rehabilitation . 10 December 2016 . Springer, Cham . 978-3-319-46062-8 . 83–95 . 10.1007/978-3-319-46062-8 . Chien . Hsin Fen . Barsottini . Orlando Graziani Povoas .
  27. 10.1007/s12311-020-01153-3 . Feasibility and Acceptability of Lee Silverman Voice Treatment in Progressive Ataxias. 2020. Lowit. Anja. Egan. Aisling. Hadjivassiliou. Marios. The Cerebellum. 19. 5. 701–714. 32588316. 7471180.
  28. Web site: Friedreich ataxia clinical management guidelines . 2014 . Friedreich Ataxia Research Alliance (USA) . 23 October 2018 . https://web.archive.org/web/20181020163447/http://curefa.org/clinical-care-guidelines . 20 October 2018 . live .
  29. Ojoga F, Marinescu S . Physical Therapy and Rehabilitation for Ataxic Patients . Balneo Research Journal . 2013 . 4 . 2 . 81–84 . 10.12680/balneo.2013.1044 . free .
  30. Leonardi L, Aceto MG, Marcotulli C, Arcuria G, Serrao M, Pierelli F, Paone P, Filla A, Roca A, Casali C . A wearable proprioceptive stabilizer for rehabilitation of limb and gait ataxia in hereditary cerebellar ataxias: a pilot open-labeled study . Neurological Sciences . 38 . 3 . 459–463 . March 2017 . 28039539 . 10.1007/s10072-016-2800-x . 27569800 .
  31. Doğan-Aslan M, Büyükvural-Şen S, Nakipoğlu-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 . 64 . 3 . 230–238 . September 2018 . 31453516 . 6657791 . 10.5606/tftrd.2018.2213 . 29 October 2018 . live . https://web.archive.org/web/20181030090523/http://ftrdergisi.com/uploads/pdf/pdf_4066.pdf . 30 October 2018 .
  32. Dürr A, Cossee M, Agid Y, Campuzano V, Mignard C, Penet C, Mandel JL, Brice A, Koenig M . Clinical and genetic abnormalities in patients with Friedreich's ataxia . The New England Journal of Medicine . 335 . 16 . 1169–75 . October 1996 . 8815938 . 10.1056/NEJM199610173351601 . free .
  33. Kita K. December 1993. [Spinocerebellar degeneration in Japan--the feature from an epidemiological study]. Rinsho Shinkeigaku = Clinical Neurology. 33. 12. 1279–84. 8174325.
  34. Vankan P . Prevalence gradients of Friedreich's ataxia and R1b haplotype in Europe co-localize, suggesting a common Palaeolithic origin in the Franco-Cantabrian ice age refuge . Journal of Neurochemistry . 126 . 11–20 . August 2013 . Suppl 1 . 23859338 . 10.1111/jnc.12215 . 39343424 . free .
  35. Friedreich N . Ueber degenerative Atrophie der spinalen Hinterstränge . About degenerative atrophy of the spinal posterior column . de . Arch Pathol Anat Phys Klin Med . 26 . 3–4 . 391–419 . 1863 . 10.1007/BF01930976 . 42991858 .
  36. Friedreich N . Ueber degenerative Atrophie der spinalen Hinterstränge . About degenerative atrophy of the spinal posterior column . de . Arch Pathol Anat Phys Klin Med . 26 . 5–6 . 433–459 . 1863 . 10.1007/BF01878006 . 34515886 .
  37. Friedreich N . Ueber degenerative Atrophie der spinalen Hinterstränge . About degenerative atrophy of the spinal posterior column . de . Arch Pathol Anat Phys Klin Med . 27 . 1–2. 1–26 . 1863 . 10.1007/BF01938516 . 46459932 .
  38. Friedreich N . Ueber Ataxie mit besonderer Berücksichtigung der hereditären Formen . About ataxia with special reference to hereditary forms . de . Arch Pathol Anat Phys Klin Med . 68 . 2 . 145–245 . 1876 . 10.1007/BF01879049 . 42155823 .
  39. Adam Shatz, "Where Life Is Seized", London Review of Books, 19 January 2017
  40. Barbeau A, Sadibelouiz M, Roy M, Lemieux B, Bouchard JP, Geoffroy G . Origin of Friedreich's disease in Quebec . The Canadian Journal of Neurological Sciences . 11 . 4 Suppl . 506–9 . November 1984 . 6391645 . 10.1017/S0317167100034971 . free .
  41. 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 . 271 . 5254 . 1423–7 . March 1996 . 8596916 . 10.1126/science.271.5254.1423 . 1996Sci...271.1423C . 20303793 .
  42. News: Stephen . Holden . The Cake Eaters . 13 March 2009 . The New York Times . 8 July 2009 .
  43. News: Devastating Diagnosis Pushes Local Man To Live Bigger . . 30 May 2015 . 12 June 2015 . https://web.archive.org/web/20150616064832/http://sacramento.cbslocal.com/2015/05/30/devastating-diagnosis-pushes-local-man-to-live-bigger/ . 16 June 2015 . live .
  44. Web site: How the DNC Is Subtly Rebuking Donald Trump's Mockery of a Disabled Reporter . Slate . 27 July 2016 . 14 December 2018 . https://web.archive.org/web/20181215022405/https://slate.com/human-interest/2016/07/dnc-rebukes-trump-for-mocking-the-disabled.html . 15 December 2018 . live .
  45. Web site: Man with rare nerve condition climbs Mount Kilimanjaro to raise money for charity . ITV . 25 November 2018 . 14 December 2018 . https://web.archive.org/web/20181215022352/https://www.itv.com/news/wales/2018-11-25/man-with-rare-nerve-condition-climbs-mount-kilimanjaro-to-raise-money-for-charity/ . 15 December 2018 . live .
  46. Web site: Shobhika Kalra: Meet the Dubai woman in wheelchair who helped build 1,000 ramps across UAE . GULF NEWS . 30 October 2018 . 14 December 2018 . https://web.archive.org/web/20181215022330/https://gulfnews.com/world/shobhika-kalra-meet-the-dubai-woman-in-wheelchair-who-helped-build-1000-ramps-across-uae-1.2295954 . 15 December 2018 . live .
  47. Reisman SA, Lee CY, Meyer CJ, Proksch JW, Sonis ST, Ward KW . May 2014 . Topical application of the synthetic triterpenoid RTA 408 protects mice from radiation-induced dermatitis . Radiation Research . 181 . 5 . 512–20 . 2014RadR..181..512R . 10.1667/RR13578.1 . 24720753 . 23906747 . free.
  48. Shan Y, Schoenfeld RA, Hayashi G, Napoli E, Akiyama T, Iodi Carstens M, Carstens EE, Pook MA, Cortopassi GA . November 2013 . Frataxin deficiency leads to defects in expression of antioxidants and Nrf2 expression in dorsal root ganglia of the Friedreich's ataxia YG8R mouse model . Antioxidants & Redox Signaling . 19 . 13 . 1481–93 . 10.1089/ars.2012.4537 . 3797453 . 23350650. .
  49. Web site: 1 October 2020 . A Phase 2 Study of the Safety, Efficacy, and Pharmacodynamics of RTA 408 in the Treatment of Friedreich's Ataxia (MOXIe) . clinicaltrials.gov.
  50. Web site: FARA – Part 2 of the Phase II MOXIe study (RTA 408 or omaveloxolone) . www.curefa.org . 22 March 2021 . 7 March 2020 . https://web.archive.org/web/20200307034215/http://www.curefa.org/clinical-trials/clinical-trials-active-enrolling/part-2-of-the-phase-ii-moxie-study-rta-408-or-omaveloxolone . dead .
  51. Lynch DR, Farmer J, Hauser L, Blair IA, Wang QQ, Mesaros C, Snyder N, Boesch S, Chin M, Delatycki MB, Giunti P, Goldsberry A, Hoyle C, McBride MG, Nachbauer W, O'Grady M, Perlman S, Subramony SH, Wilmot GR, Zesiewicz T, Meyer C . January 2019 . Safety, pharmacodynamics, and potential benefit of omaveloxolone in Friedreich ataxia . Annals of Clinical and Translational Neurology . 6 . 1 . 15–26 . 10.1002/acn3.660 . 6331199 . 30656180.
  52. Web site: FA Global Patient Registry (FAGPR) . FA Global Patient Registry (FAGPR) . 5 October 2017 . 27 April 2021.
  53. Web site: The FA App . The FA App) . 8 July 2021.
  54. Enns GM, Kinsman SL, Perlman SL, Spicer KM, Abdenur JE, Cohen BH, Amagata A, Barnes A, Kheifets V, Shrader WD, Thoolen M, Blankenberg F, Miller G . Initial experience in the treatment of inherited mitochondrial disease with EPI-743 . Molecular Genetics and Metabolism . 105 . 1 . 91–102 . January 2012 . 22115768 . 10.1016/j.ymgme.2011.10.009 . free .
  55. Indelicato E, Bosch S. 2018. Emerging therapeutics for the treatment of Friedreich's ataxia. Expert Opinion on Orphan Drugs. 6. 57–67. 10.1080/21678707.2018.1409109. 80157839.
  56. Jasoliya M, Sacca F, Sahdeo S, Chedin F, Pane C, Brescia Morra V, Filla A, Pook M, Cortopassi G. June 2019. Dimethyl fumarate dosing in humans increases frataxin expression: A potential therapy for Friedreich's Ataxia. PLOS ONE. 14. 6. e0217776. 2019PLoSO..1417776J. 10.1371/journal.pone.0217776. 6546270. 31158268. free.
  57. Miller JL, Rai M, Frigon NL, Pandolfo M, Punnonen J, Spencer JR . Erythropoietin and small molecule agonists of the tissue-protective erythropoietin receptor increase FXN expression in neuronal cells in vitro and in Fxn-deficient KIKO mice in vivo . Neuropharmacology . 123 . 34–45 . September 2017 . 28504123 . 10.1016/j.neuropharm.2017.05.011 . 402724 .
  58. Web site: STATegics, Inc. Announces a New Grant from Friedreich's Ataxia Research Alliance.
  59. Alfedi G, Luffarelli R, Condò I, Pedini G, Mannucci L, Massaro DS, Benini M, Toschi N, Alaimo G, Panarello L, Pacini L, Fortuni S, Serio D, Malisan F, Testi R, Rufini A. March 2019. Drug repositioning screening identifies etravirine as a potential therapeutic for friedreich's ataxia. Movement Disorders. 34. 3. 323–334. 10.1002/mds.27604. 30624801. 58567610.
  60. Benini M, Fortuni S, Condò I, Alfedi G, Malisan F, Toschi N, Serio D, Massaro DS, Arcuri G, Testi R, Rufini A. February 2017. E3 Ligase RNF126 Directly Ubiquitinates Frataxin, Promoting Its Degradation: Identification of a Potential Therapeutic Target for Friedreich Ataxia. Cell Reports. 18. 8. 2007–2017. 10.1016/j.celrep.2017.01.079. 5329121. 28228265.
  61. Web site: Jupiter Orphan Therapeutics, Inc. Enters into a Global Licensing Agreement with Murdoch Childrens Research Institute.
  62. Khonsari H, Schneider M, Al-Mahdawi S, Chianea YG, Themis M, Parris C, Pook MA, Themis M. December 2016. Lentivirus-meditated frataxin gene delivery reverses genome instability in Friedreich ataxia patient and mouse model fibroblasts. Gene Therapy. 23. 12. 846–856. 10.1038/gt.2016.61. 5143368. 27518705.
  63. Web site: Melão. Alice. 19 October 2017. CRISPR Therapeutics Receives FARA Grant to Develop Gene Editing Therapies for Friedreich's Ataxia. 21 April 2019. Friedreich's Ataxia News. 21 April 2019. https://web.archive.org/web/20190421144724/https://friedreichsataxianews.com/2017/10/19/crispr-therapeutics-receives-grant-to-develop-gene-editing-therapies-for-friedreichs-ataxia/. dead.