Spinocerebellar ataxia type 23 (SCA23): a review
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REVIEW
Spinocerebellar ataxia type 23 (SCA23): a review Fan Wu1 · Xu Wang1 · Xiaohan Li1 · Huidi Teng1 · Tao Tian2 · Jing Bai1 Received: 16 August 2020 / Revised: 22 October 2020 / Accepted: 26 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Spinocerebellar ataxias (SCAs), formerly known as autosomal dominant cerebellar ataxias (ADCAs), are a group of hereditary heterogeneous neurodegenerative diseases. Gait, progressive ataxia, dysarthria, and eye movement disorder are common symptoms of spinocerebellar ataxias. Other symptoms include peripheral neuropathy, cognitive impairment, psychosis, and seizures. Patients may lose their lives due to out of coordinated respiration and/or swallowing. Neurological signs cover pyramidal or extrapyramidal signs, spasm, ophthalmoplegia, hyperactive deep tendon reflexes, and so on. Different subtypes of SCAs present various clinical features. Spinocerebellar ataxia type 23 (SCA23), one subtype of the SCA family, is characterized by mutant prodynorphin (PDYN) gene. Based on literatures, this review details a series of SCA23, to improve a whole understanding of clinicians and point out the potential research direction of this dysfunction, including a history, pathophysiological mechanism, diagnosis and differential diagnosis, epigenetics, penetrance and prevalence, genetic counseling, treatment and prognosis. Keywords Spinocerebellar ataxia type 23 · Prodynorphin · Clinical symptoms · Pathophysiological mechanisms · Epigenetics · Spinocerebellar ataxias
Introduction Spinocerebellar ataxias (SCAs) are a set of degenerative and progressive diseases, and there are two major classification methods. The first one is Harding classification according to clinical manifestation, which comprises three types, ADCA I, II, III. ADCA I contains a series of syndromes, that is, ataxia with ophthalmoplegia, dementia, extrapyramidal motor signs, optic atrophy and muscular atrophy; ADCA II is a kind of progressive ataxia accompanied by retinal degeneration; ADCA III means "pure" cerebellar ataxia. Spinocerebellar ataxia type 23 (SCA23), a subtype of SCAs, belongs to ADCA III in Harding classification [1]. Helping doctors narrow the clinical scope and developing strategies for genetic and molecular detection, this classification is still playing a crucial role in clinical work. Likewise, another classification, according to the * Jing Bai [email protected] 1
Department of Neurology, The First Hospital of Jilin University, Changchun 130021, China
Department of Cardiology, The First Hospital of Jilin University, Changchun 130021, China
2
mechanism of disease, classify SCAs into three subtypes, respectively, Subtype I, II, III. Subtype I, mainly polyglutamine SCAs related to CAG repeat expansion mutations, is caused by dynamic repeat expansion mutations in the coding region of genes [2]; Subtype II refers to non-coding region SCAs encoded by repeat expansion mutations. Subtype III, which SCA23 belongs to, means SCAs for deletion, insertion, missense, nonsen
