Neuromuscular DiseasesNeuromuscular DiseasesНервно-мышечные болезни2222-87212413-0443Publishing House ABV Press67010.17650/2222-8721-2025-15-3-10-21ORIGINAL REPORTSОРИГИНАЛЬНЫЕ ИССЛЕДОВАНИЯResearch ArticleNosological structure and frequency of autosomal dominant spinocerebellar ataxias associated with nucleotide repeat expansions in RussiaНозологическая структура и частота форм аутосомно-доминантных спиноцеребеллярных атаксий, ассоциированных с экспансией нуклеотидных повторов, в Россииhttps://orcid.org/0009-0003-7386-7270VutaElizaveta V.ВутаЕлизавета Вячеславовна
Russian Federation

Scientific and Methodological Center of the Ministry of Health of Russia for Molecular Medicine

Научно-методический центр Минздрава России по молекулярной медицине

vuta.elizaveta@mail.ruhttps://orcid.org/0000-0002-9354-8790NazarovV. D.НазаровВ. Д.
Russian Federation

Scientific and Methodological Center of the Ministry of Health of Russia for Molecular Medicine

Научно-методический центр Минздрава России по молекулярной медицине

vuta.elizaveta@mail.ruhttps://orcid.org/0000-0001-8503-0759SidorenkoD. V.СидоренкоД. В.
Russian Federation

Scientific and Methodological Center of the Ministry of Health of Russia for Molecular Medicine

Научно-методический центр Минздрава России по молекулярной медицине

vuta.elizaveta@mail.ruhttps://orcid.org/0009-0001-1705-7674BaninaD. Yu.БанинаД. Ю.
Russian Federation

Scientific and Methodological Center of the Ministry of Health of Russia for Molecular Medicine

Научно-методический центр Минздрава России по молекулярной медицине

vuta.elizaveta@mail.ruhttps://orcid.org/0000-0002-4998-3699LapinS. V.ЛапинС. В.
Russian Federation

Scientific and Methodological Center of the Ministry of Health of Russia for Molecular Medicine

Научно-методический центр Минздрава России по молекулярной медицине

vuta.elizaveta@mail.ruhttps://orcid.org/0000-0002-3055-6507MazingA. V.МазингА. В.
Russian Federation

Scientific and Methodological Center of the Ministry of Health of Russia for Molecular Medicine

Научно-методический центр Минздрава России по молекулярной медицине

vuta.elizaveta@mail.ruPavlov First Saint Petersburg State Medical University, Ministry of Health of RussiaФГБОУ ВО «Первый Санкт-Петербургский государственный медицинский университет им. акад. И. П. Павлова» Минздрава России2412202515310212012202520122025Copyright ©; 2025, Vuta E.V., Nazarov V.D., Sidorenko D.V., Banina D.Y., Lapin S.V., Mazing A.V.Copyright ©; 2025, Вута Е.В., Назаров В.Д., Сидоренко Д.В., Банина Д.Ю., Лапин С.В., Мазинг А.В.2025Vuta E.V., Nazarov V.D., Sidorenko D.V., Banina D.Y., Lapin S.V., Mazing A.V.Вута Е.В., Назаров В.Д., Сидоренко Д.В., Банина Д.Ю., Лапин С.В., Мазинг А.В.https://creativecommons.org/licenses/by/4.0https://nmb.abvpress.ru/jour/article/view/670

Background. Expansion-based autosomal dominant spinocerebellar ataxias (ADSСA-E) represent a clinically and genetically heterogeneous group of inherited neurodegenerative disorders characterized by cerebellar atrophy. According to global population data, they account for approximately 61 % of all autosomal dominant spinocerebellar ataxias. The number of nucleotide repeats is a key determinant of penetrance, expressivity, and age of onset, necessitating precise molecular genetic analysis. Significant differences in the structure of ADSСA-E across populations underscore the need for regional studies.

Aim. Analysis of the molecular structure and frequency of ADSCA-E in a sample of Russian patients with cerebellar ataxias.

Materials and methods. DNA samples from 1272 patients with clinical signs of ataxia (2017–2024) were analyzed. The number of repeats in the ATXN1, ATXN2, ATXN3, CACNA1A, ATXN7, TBP, ATXN10, PPP2R2B, NOP56, and ATXN8OS genes was determined using fluorescent polymerase chain reaction and fragment analysis. The age at referral to the laboratory was considered an indirect marker of disease aggressiveness. Statistical analysis was performed using GraphPad Prism 10. Differences were considered statistically significant at p <0.05. Pearson’ correlation coefficient was used to calculate correlation.

Results. A pathological expansion was identified in 102 (8 %) patients. The most frequent form was spinocerebellar ataxia (SCA) type 1 (62.7 %), followed by SCA type 2 (17.6 %), SCA type 3 (5.9 %), and SCA type 6 (3.9 %); other types were rare. A case of combined SCA type 1 and SCA type 8 mutations was recorded in one patient. For SCA type 1 and SCA type 2, a significant negative correlation was established between the expansion size and the age at referral (p <0.0001; r = –0.6839 and –0.8838, respectively).

Conclusion. Data on the frequency and spectrum of ADSCA-E in the Russian Federation, including rare forms, were obtained. The prognostic significance of the repeat number was confirmed, and the necessity of molecular genetic testing, taking into account regional disease prevalence patterns, was emphasized.

Введение. Аутосомно-доминантные спиноцеребеллярные атаксии экспансионного типа (АДСЦА-Э) представляют собой клинически и генетически гетерогенную группу наследственных нейродегенеративных заболеваний, характеризующихся дегенерацией мозжечка либо его связей. По мировым популяционным данным, они составляют около 61 % всех аутосомно-доминантных спиноцеребеллярных атаксий. Ключевым фактором, определяющим пенетрантность, экспрессивность и возраст манифестации, является количество нуклеотидных повторов, что обусловливает необходимость точного молекулярно-генетического анализа. Существенные различия в структуре АДСЦА-Э между популяциями требуют проведения региональных исследований.

Цель исследования – анализ молекулярной структуры и частоты АДСЦА-Э в выборке российских пациентов с мозжечковыми атаксиями.

Материалы и методы. Проанализированы образцы ДНК 1272 пациентов с клиническими признаками атаксии (2017–2024 гг.). Определение числа повторов в генах ATXN1, ATXN2, ATXN3, CACNA1A, ATXN7, TBP, ATXN10, PPP2R2B, NOP56, ATXN8OS выполняли методом полимеразной цепной реакции с флуоресцентной детекцией и фрагментным анализом. Возраст обращения в лабораторию рассматривался как косвенный маркер агрессивности болезни. Статистическая обработка выполнялась с помощью GraphPad Prism 10. Различия считались статистически значимыми при p <0,05. Для расчета корреляции была использована формула корреляции Пирсона.

Результаты. Патологическая экспансия выявлена у 102 (8 %) пациентов. Наиболее частой формой была спиноцеребеллярная атаксия (СЦА) 1-го типа (62,7 %), далее – СЦА 2-го типа (17,6 %), 3-го типа (5,9 %) и 6-го типа (3,9 %); остальные типы встречались единично. Зафиксирован случай сочетания мутаций СЦА 1-го типа и СЦА 8-го типа у одного пациента. Для СЦА 1-го и 2-го типа установлена выраженная отрицательная корреляция между размером экспансии и возрастом обращения (p <0,0001; r = –0,6839 и –0,8838 соответственно).

Выводы. Получены данные о частоте и спектре АДСЦА-Э в Российской Федерации, включая редкие формы. Подтверждена прогностическая значимость числа повторов и показана необходимость молекулярно-генетического тестирования с учетом региональных особенностей распространенности заболевания.

spinocerebellar ataxiaautosomal dominant inheritancetrinucleotide repeat expansionmolecular genetic testinglaboratory diagnosisспиноцеребеллярная атаксияаутосомно-доминантный тип наследованияэкспансия тринуклеотидных повторовмолекулярно-генетическое исследованиелабораторная диагностикаIllarioshkin S.N., Ivanova-Smolenskaya I.A., Markova E.D. A new mechanism of mutation in humans: trinucleotide repeat expansion. Genetika = Genetics 1995;(11):1478–82. (In Russ.).Иллариошкин С.Н., Иванова-Смоленская И.А., Маркова Е.Д. Новый механизм мутации у человека: экспансия тринуклеотидных повторов. Генетика 1995;(11):1478–82.Cummings C.J., Mancini M.A., Antalffy B. et al. Chaperone suppression of aggregation and altered subcellular proteasome localization imply protein misfolding in SCA1. Nat Genet 1998;19(2):148–54. DOI: 10.1038/502Ruano L., Melo C., Silva M.C. et al. The global epidemiology of hereditary ataxia and spastic paraplegia: a systematic review of prevalence studies. Neuroepidemiology 2014;42(3):174–83. DOI: 10.1159/000358801Duyao M., Ambrose C., Myers R. et al. Trinucleotide repeat length instability and age of onset in Huntington’s disease. Nat Genet 1993;4(4):387–92. DOI: 10.1038/ng0893-387Mizushima K., Shibata Y., Shirai S. et al. Prevalence of repeat expansions causing autosomal dominant spinocerebellar ataxias in Hokkaido, the northernmost island of Japan. J Hum Genet 2024;69(1):27–31. DOI: 10.1038/s10038-023-01200-xMoseley M.L., Benzow K.A., Schut L.J. et al. Incidence of dominant spinocerebellar and Friedreich triplet repeats among 361 ataxia families. Neurology 1998;51(6):1666–71. DOI: 10.1212/WNL.51.6.1666Figueroa K.P., Coon H., Santos N. et al. Genetic analysis of age at onset variation in spinocerebellar ataxia type 2. Neurol Genet 2017;3(3):e155. DOI: 10.1212/NXG.0000000000000155Obayashi M., Stevanin G., Synofzik M. et al. Spinocerebellar ataxia type 36 exists in diverse populations and can be caused by a short hexanucleotide GGCCTG repeat expansion. J Neurol Neurosurg Psychiatry 2015;86(9):986–95. DOI: 10.1136/jnnp-2014-309153Klockgether T., Mariotti C., Paulson H.L. Spinocerebellar ataxia. Nat Rev Dis Primers 2019;5(1):24. DOI: 10.1038/s41572-019-0074-3Liu W., Ikeda Y., Nishizawa M. et al. Characteristic RNA foci of the abnormal hexanucleotide GGCCUG repeat expansion in spinocerebellar ataxia type 36 (Asidan). Eur J Neurol 2014;21(10):1377–86. DOI: 10.1111/ene.12497Panov A.V., Gutekunst C.A., Leavitt B.R. et al. Early mitochondrial calcium defects in Huntington’s disease are a direct effect of polyglutamines. Nat Neurosci 2002;5(8):731–6. DOI: 10.1038/nn884Vohra A., Keefe P., Puthanveetil P. Altered metabolic signaling and potential therapies in polyglutamine diseases. Metabolites 2024;14(6):320. DOI: 10.3390/metabo14060320Ashkenazi A., Bento C.F., Ricketts T. et al. Polyglutamine tracts regulate beclin 1-dependent autophagy. Nature 2017;545(7652):108–11. DOI: 10.1038/nature22078Paulson H.L., Perez M.K., Trottier Y. et al. Intranuclear inclusions of expanded polyglutamine protein in spinocerebellar ataxia type 3. Neuron 1997;19(2):333–44. DOI: 10.1016/S0896-6273(00)80942-6Chai Y., Koppenhafer S.L., Bonini N.M. et al. Evidence for proteasome involvement in polyglutamine disease: localization to nuclear inclusions in SCA3/MJD and suppression of polyglutamine aggregation in vitro. Hum Mol Genet 1999;8(4):673–82. DOI: 10.1093/hmg/8.4.673Szebenyi G., Morfini G.A., Babcock A. et al. Neuropathogenic forms of huntingtin and androgen receptor inhibit fast axonal transport. Neuron 2003;40(1):41–52. DOI: 10.1016/S0896-6273(03)00560-2Li P.P., Sun X., Xia G. et al. ATXN2-AS, a gene antisense to ATXN2, is associated with spinocerebellar ataxia type 2 and amyotrophic lateral sclerosis. Ann Neurol 2016;80(5):600–15. DOI: 10.1002/ana.24761Paul S., Dansithong W., Figueroa K.P. et al. Staufen1 links RNA stress granules and autophagy in a model of neurodegeneration. Nat Commun 2018;9:3648. DOI: 10.1038/s41467-018-06041-3. PMID: 30232329.Friedman M.J., Shah A.G., Fang Z.H. et al. Polyglutamine domain modulates the TBP–TFIIB interaction: implications for its normal function and neurodegeneration. Nat Neurosci 2007;10(12):1519–28. DOI: 10.1038/nn2011Bowman A.B., Lam Y.C., Jafar-Nejad P. et al. Duplication of Atxn1l suppresses SCA1 neuropathology by decreasing incorporation of polyglutamine-expanded ataxin-1 into native complexes. Nat Genet 2007;39(3):373–9. DOI: 10.1038/ng1985Dansithong W., Paul S., Figueroa K.P. et al. Ataxin-2 regulates RGS8 translation in a new BAC-SCA2 transgenic mouse model. PLoS Genet 2015;11(4):e1005182. DOI: 10.1371/journal.pgen.1005182Saitoh O., Masuho I., Itoh M. et al. Distribution of regulator of G protein signaling 8 (RGS8) protein in the cerebellum. Cerebellum 2003;2(2):154–60. DOI: 10.1080/14734220309409Liu J., Tang T.S., Tu H. et al. Deranged calcium signaling and neurodegeneration in spinocerebellar ataxia type 2. J Neurosci 2009;29(29):9148–62. DOI: 10.1523/JNEUROSCI.0660-09.2009Zhao Y., Tan E.K., Law H.Y. et al. Prevalence and ethnic differences of autosomal-dominant cerebellar ataxia in Singapore. Clin Genet 2002;62(6):478–81. DOI: 10.1034/j.1399-0004.2002.620610.xPulst S.M., Santos N., Wang D. et al. Spinocerebellar ataxia type 2: polyQ repeat variation in the CACNA1A calcium channel modifies age of onset. Brain 2005;128(10):2297–303. DOI: 10.1093/brain/awh590Killoran A., Biglan K.M., Jankovic J. et al. Characterization of the Huntington intermediate CAG repeat expansion phenotype in PHAROS. Neurology 2013;80(22):2022–7. DOI: 10.1212/WNL.0b013e318294b290Steffan J.S., Kazantsev A., Spasic-Boskovic O. et al. The Huntington’s disease protein interacts with p53 and CREB-binding protein and represses transcription. Proc Natl Acad Sci USA 2000;97(12):6763–8. DOI: 10.1073/pnas.100110097Yu Z.X., Li S.H., Evans J. et al. Huntingtin inclusions do not deplete polyglutamine-containing transcription factors in HD mice. Hum Mol Genet 2002;11(8):905–14. DOI: 10.1093/hmg/11.8.905Shimohata T., Nakajima T., Yamada M. et al. Expanded polyglutamine stretches interact with TAFII130, interfering with CREB-dependent transcription. Nat Genet 2000;26(1):29–36. DOI: 10.1038/79111Dunah A.W., Jeong H., Griffin A. et al. Sp1 and TAFII130 transcriptional activity disrupted in early Huntington’s disease. Science 2002;296(5576):2238–43. DOI: 10.1126/science.1072613Nucifora F.C. Jr, Ellerby L.M., Wellington C.L. et al. Polyglutamine-expanded huntingtin activates the JNK3 pathway and causes striatal degeneration in mice. J Biol Chem 2003;278(14):13047–55. DOI: 10.1074/jbc.M210307200Li S.H., Cheng A.L., Zhou H. et al. Interaction of Huntington disease protein with transcriptional activator Sp1. Mol Cell Biol 2002;22(5):1277–87. DOI: 10.1128/MCB.22.5.1277-1287.2002Gunawardena S., Her L.S., Brusch R.G. et al. Disruption of axonal transport by loss of huntingtin or expression of pathogenic polyQ proteins in Drosophila. Neuron 2003;40(1):25–40. DOI: 10.1016/S0896-6273(03)00594-8Li S.H., Li X.J. Huntingtin and its role in neuronal degeneration. Neuroscientist 2004;10(5):467–75. DOI: 10.1177/1073858404263520Gutekunst C.A., Li S.H., Yi H. et al. Nuclear and neuropil aggregates in Huntington’s disease: relationship to neuropathology. J Neurosci 1999;19(7):2522–34. DOI: 10.1523/JNEUROSCI.19-07-02522.1999Morfini G., Pigino G., Brady S.T. Polyglutamine expansion diseases: failing to deliver. Trends Mol Med 2005;11(2):64–70. DOI: 10.1016/j.molmed.2004.12.002Morfini G.A., You Y.M., Pollema S.L. et al. Pathogenic huntingtin inhibits fast axonal transport by activating JNK3 and phosphorylating kinesin. Nat Neurosci 2009;12(7):864–71. DOI: 10.1038/nn.2346Crespo-Barreto J., Fryer J.D., Shaw C.A. et al. Partial loss of Ataxin-1 function contributes to transcriptional dysregulation in spinocerebellar ataxia type 1 pathogenesis. PLoS Genet 2010;6(7):e1001021. DOI: 10.1371/journal.pgen.1001021Bennett E.J., Shaler T.A., Woodman B. et al. Global changes to the ubiquitin system in Huntington’s disease. Nature 2007;448(7154):704–8. DOI: 10.1038/nature06022Venkatraman P., Wetzel R., Tanaka M. et al. Eukaryotic proteasomes cannot digest polyglutamine sequences and release them during degradation of polyglutamine-containing proteins. Mol Cell 2004;14(1):95–104. DOI: 10.1016/S1097-2765(04)00151-0Matsuyama Z., Yanagisawa N., Yamada M. et al. Polyglutamine repeats of spinocerebellar ataxia 6 impair the cell-death-preventing effect of CaV2.1 Ca2+ channel – loss-of-function cellular model of SCA6. Neurobiol Dis 2004;17(1):198–204. DOI: 10.1016/j.nbd.2004.07.001Kumaran D., Balagopal V., Thomas M. et al. Genetic characterization of spinocerebellar ataxia 1 in a South Indian cohort. BMC Med Genet 2014;15:114. DOI: 10.1186/s12881-014-0114-4Nardacchione A., Orsi L., Brusco A. et al. Definition of the smallest pathological CAG expansion in SCA7. Clin Genet 1999;56(3): 232–4. DOI: 10.1034/j.1399-0004.1999.560310.xVan de Warrenburg B.P., Frenken C.W., Ausems M.G. et al. Striking anticipation in spinocerebellar ataxia type 7: the infantile phenotype. J Neurol 2001;248(10):911–4. DOI: 10.1007/s004150170065Michalik A., Martin J.J., Van Broeckhoven C. Spinocerebellar ataxia type 7 associated with pigmentary retinal dystrophy. Eur J Hum Genet 2004;12(1):2–15. DOI: 10.1038/sj.ejhg.5201089Choudhry S., Mukerji M., Srivastava A.K. et al. CAG repeat instability at SCA2 locus: anchoring CAA interruptions and linked single nucleotide polymorphisms. Hum Mol Genet 2001;10(23):2437–46. DOI: 10.1093/hmg/10.23.2437Chong S.S., McCall A.E., Cota J. et al. Gametic and somatic tissue-specific heterogeneity of the expanded SCA1 CAG repeat in spinocerebellar ataxia type 1. Nat Genet 1995;10(3):344–50. DOI: 10.1038/ng0795-344Chung M.Y., Ranum L.P., Duvick L.A. et al. Evidence for a mechanism predisposing to intergenerational CAG repeat instability in spinocerebellar ataxia type 1. Nat Genet 1993;5(3):254–8. DOI: 10.1038/ng1193-254Soczak K., Krzyzosiak W.J. Imperfect CAG repeats are common in human genes: implications for polyglutamine diseases. Nucleic Acids Res 2005;33(13):4425–32. DOI: 10.1093/nar/gki733Mor-Shaked H., Eiges R. Reevaluation of FMR1 hypermethylation timing in fragile X syndrome. Front Mol Neurosci 2018;11:31. DOI: 10.3389/fnmol.2018.00031Illarioshkin S.N., Ivanova-Smolenskaya I.A., Markova E.D. DNA diagnostics and medical genetic counseling in neurology. Moscow: Meditsinskoe informatsionnoe agentstvo, 2002. 591 p. (In Russ.).Иллариошкин С.Н., Иванова-Смоленская И.А., Маркова Е.Д. ДНК-диагностика и медико-генетическое консультирование в неврологии. М.: Медицинское информационное агентство, 2002. 591 с.Doyu M., Sobue G., Mukai E. et al. Severity of X-linked recessive bulbospinal neuronopathy correlates with size of the tandem CAG repeat in androgen receptor gene. Ann Neurol 1992;32(6):707–10. DOI: 10.1002/ana.410320603Kawaguchi Y., Okamoto T., Taniwaki M. et al. CAG expansions in a novel gene for Machado–Joseph disease at chromosome 14q32.1. Nat Genet 1994;8(3):221–8. DOI: 10.1038/ng1194-221Gardiner S.L., Boogaard M.W., Trompet S. et al. Prevalence of carriers of intermediate and pathological polyglutamine disease-associated alleles among large population-based cohorts. JAMA Neurol 2019;76:650–6.Perez B.A., Shorrock H.K., Banez-Coronel M. et al. CCG•CGG interruptions in high-penetrance SCA8 families increase RAN translation and protein toxicity. EMBO Mol Med 2021;13(11):e14095. DOI: 10.15252/emmm.20211409Klyushnikov S.A., Illarioshkin S.N., Abramova A.A. et al. Clinical and genetic analysis of hereditary ataxias: new disease forms in Russian families. Nevrologicheskiy zhurnal = Neurological Journal 2022;27(4):14–21. (In Russ.). DOI: 10.24412/2226-079X-2022-12443Клюшников С.А., Иллариошкин С.Н., Абрамова А.А. и др. Клинико-генетический анализ наследственных атаксий: новые формы заболеваний в российских семьях. Неврологический журнал 2022;27(4):14–21. DOI: 10.24412/2226-079X-2022-12443Fedorov A.I., Sukhomyasova A.L., Golikova P.I. et al. Prevalence of spinocerebellar ataxia type 1 in Yakutia: current state. Meditsinskaya genetika = Medical Genetics 2020;19(7):29–30. (In Russ.).Федоров А.И., Сухомясова А.Л., Голикова П.И. и др. Распространенность спиноцеребеллярной атаксии 1 типа в Якутии: современное состояние. Медицинская генетика 2020;19(7):29–30.Goldfarb L.G., Platonov F.A. Genetic identification, clinical features and distribution of spinocerebellar ataxia type 1 in the Republic of Sakha (Yakutia). Sibirskiye issledovaniya = Siberian Studies 2019;2(2):12–25. (In Russ.). DOI: 10.33384/26587270.2019.02.002rГольдфарб Л.Г., Платонов Ф.А. Генетическая идентификация, клинические особенности и распространение спиноцеребеллярной атаксии первого типа в Республике Саха (Якутия). Сибирские исследования 2019;2(2):12–25. DOI: 10.33384/26587270.2019.02.002rI D.V. Autosomal dominant spinocerebellar ataxias in Khabarovsk Krai: population, clinical-genealogical and molecular-genetic analysis. Ph. D. dissertation summary. Moscow, 2017. (In Russ.).И Д.В. Аутосомно-доминантные спиноцеребеллярные атаксии в Хабаровском крае: популяционный, клинико-генеалогический, молекулярно-генетический анализ. Автореф. дис. … канд. мед. наук. М., 2017.Nuzhnyi E.P., Abramysheva N.Yu., Chkhartishvili I.A. et al. Spinocerebellar ataxia type 8 in Russian patients. Zhurnal nevrologii i psikhiiatrii im. S.S. Korsakova = Journal of Neurology and Psychiatry named after S.S. Korsakov 2022;122(8):106–11. (In Russ.).Нужный Е.П., Абрамычева Н.Ю., Чхартишвили И.А. и др. Спиноцеребеллярная атаксия 8-го типа у российских больных. Журнал неврологии и психиатрии им. С.С. Корсакова 2022;122(8):106–11.Koob M.D., Moseley M.L., Schut L.J. et al. An untranslated CTG expansion causes a novel form of spinocerebellar ataxia (SCA8). Nat Genet 1999;21(4):379–84. DOI: 10.1038/7710Perlman S.L. Evaluation and Management of Ataxic Disorders: An Overview for Physicians. National Ataxia Foundation, 2016. Available at: https://www.ataxia.org/wp-content/uploads/2022/05/Evaluation-and-Management-2016-edition.pdf.Dos Santos Pinheiro J., Sena L.S., Donis K.C. et al. Diagnostic delay of hereditary ataxias in brazil: the case of Machado–Joseph disease. Cerebellum 2023;22(3):348–54. DOI: 10.1007/s12311-022-01404-5Chena Y.-S., Hua T.-M., Wang Y.-Y., Wu C.-L. A case of Huntington’s disease presenting with psychotic symptoms and rapid cognitive decline in the early stage. Eur J Psychiatry 2022;36(1):65, 66. DOI: 10.1016/j.ejpsy.2021.06.001Morozov I.I., Emelyanov Yu.V. A clinical case of Huntington’s disease in psychiatric practice. Zdravookhranenie Yugry: opyt i innovatsii = Health Care of Ugra: Experience and Innovations 2017;3:62–5. (In Russ.).Морозов И.И., Емельянов Ю.В. Клинический случай болезни Гентингтона в психиатрической практике. Здравоохранение Югры: опыт и инновации 2017;3:62–5Lee W.Y., Jin D.K., Oh M.R. et al. Frequency analysis and clinical characterization of spinocerebellar ataxia types 1, 2, 3, 6, and 7 in Korean patients. Arch Neurol 2003;60(6):858–63. DOI: 10.1001/archneur.60.6.858Roda R.H., Schindler A.B., Blackstone C. SCA8 should not be tested in isolation for ataxia. Neurol Genet 2017;3(3):e150. DOI: 10.1212/NXG.0000000000000150Sulek A., Hoffman-Zacharska D., Zdzienicka E., Zaremba J. SCA8 repeat expansion coexists with SCA1 – not only with SCA6. Am J Hum Genet 2003;73(4):972–4. DOI: 10.1086/378524Izumi Y., Maruyama H., Oda M. et al. SCA8 repeat expansion: large CTA/CTG repeat alleles are more common in ataxic patients, including those with SCA6. Am J Hum Genet 2003;72(3):704–9. DOI: 10.1086/367775Juvonen V., Hietala M., Päivärinta M. et al. Clinical and genetic findings in Finnish ataxia patients with the spinocerebellar ataxia 8 repeat expansion. Ann Neurol 2000;48(3):354–61.Mingazova E.Z. Clinical-epidemiological and molecular-genetic study of progressive spinocerebellar ataxias in the Republic of Bashkortostan. Ph. D. dissertation summary. Moscow, 2009. 115 p. (In Russ.).Мингазова Э.З. Клинико-эпидемиологическое и молекулярно-генетическое изучение прогрессирующих спиноцеребеллярных атаксий в Республике Башкортостан. Автореф. дис. … канд. мед. наук. М., 2009. 115 с.Durr A. Autosomal dominant cerebellar ataxias: polyglutamine expansions and beyond. Lancet Neurol 2010;9(9):885–94. DOI: 10.1016/S1474-4422(10)70183-6Bettencourt C., Santos C., Kay T. et al. Analysis of segregation patterns in Machado–Joseph disease pedigrees. J Hum Genet 2008;53(10):920–3. DOI: 10.1007/s10038-008-0330-ySchöls L., Bauer P., Schmidt T. et al. Autosomal dominant cerebellar ataxias: clinical features, genetics, and pathogenesis. Lancet Neurol 2004;3(5):291–304. DOI: 10.1016/S1474-4422(04)00737-9Hekman K.E., Gomez C.M. The autosomal dominant spinocerebellar ataxias: emerging mechanistic themes suggest pervasive Purkinje cell vulnerability. J Neurol Neurosurg Psychiatry 2015;86(5):554–61. DOI: 10.1136/jnnp-2014-308421Nethisinghe S., Pigazzini M.L., Pemble S. et al. PolyQ tract toxicity in SCA1 is length dependent in the absence of CAG repeat interruption. Front Cell Neurosci 2018;12:200. DOI: 10.3389/fncel.2018.00200Giunti P., Sabbadini G., Sweeney M.G. et al. The role of the SCA2 trinucleotide repeat expansion in 89 autosomal dominant cerebellar ataxia families: frequency, clinical and genetic correlates. Brain 1998;121(Pt 3):459–67. DOI: 10.1093/brain/121.3.459Stevanin G., Cassa E., Cancel G. et al. Characterisation of the unstable expanded CAG repeat in the MJD1 gene in four Brazilian families of Portuguese descent with Machado–Joseph disease. J Med Genet 1995;32(10):827–30. DOI: 10.1136/jmg.32.10.827González-Zaldívar Y., Vázquez-Mojena Y., Laffita-Mesa J.M. et al. Epidemiological, clinical, and molecular characterization of Cuban families with spinocerebellar ataxia type 3/Machado–Joseph disease. Cerebellum Ataxias 2015;2:1. DOI: 10.1186/s40673-015-0020-4Ranum L.P., Chung M.Y., Banfi S. et al. Molecular and clinical correlations in spinocerebellar ataxia type I: evidence for familial effects on the age at onset. Am J Hum Genet 1994;55(2):244–52.