title: CAG repeat length does not associate with the rate of cerebellar degeneration in spinocerebellar ataxia type 3.
abstract: This cross-sectional study investigated the correlation between the CAG repeat length and the degeneration of cerebellum in spinocerebellar ataxia type 3 (SCA3) patients based on neuroimaging approaches. Forty SCA3 patients were recruited and classified into two subgroups according to their CAG repeat lengths (≥ 74 and < 74). We measured each patient's Scale for the Assessment and Rating of Ataxia (SARA) score,N-acetylaspartate (NAA)/creatine (Cr) ratios based on magnetic resonance spectroscopy (MRS), and 3-dimensional fractal dimension (3D-FD) values derived from magnetic resonance imaging (MRI) results. Furthermore, the 3D-FD values were used to construct structural covariance networks based on graph theoretical analysis. The results revealed that SCA3 patients with a longer CAG repeat length demonstrated earlier disease onset. However, the CAG repeat length did not significantly correlate with their SARA scores, cerebellar NAA/Cr ratios or cerebellar 3D-FD values. Network dissociation between cerebellar regions and parietal-occipital regions was found in SCA3 patients with CAG ≥ 74, but not in those with CAG < 74. In conclusion, the CAG repeat length is uncorrelated with the change of SARA score, cerebellar function and cerebellar structure in SCA3. Nevertheless, a longer CAG repeat length may indicate early structural covariance network dissociation.
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan.
authors.forename: Shang-Ran
authors.initials: SR
authors.lastname: Huang
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan; Institute of Biophotonics, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan.
authors.forename: Yu-Te
authors.initials: YT
authors.lastname: Wu
authors.affiliation: Institute of Biophotonics, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan.
authors.forename: Chii-Wen
authors.initials: CW
authors.lastname: Jao
authors.affiliation: Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Taipei, Taiwan; School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan.
authors.forename: Bing-Wen
authors.initials: BW
authors.lastname: Soong
authors.affiliation: School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Taipei, Taiwan.
authors.forename: Jiing-Feng
authors.initials: JF
authors.lastname: Lirng
authors.affiliation: School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan; Department of Radiology, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Taipei, Taiwan.
authors.forename: Hsiu-Mei
authors.initials: HM
authors.lastname: Wu
authors.affiliation: Institute of Biophotonics, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan; Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec. 2, Shipai Rd., Taipei, Taiwan; School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong St., Taipei, Taiwan; Department of Neurology, Taipei Municipal Gan-Dau Hospital, No.12, Ln. 225, Zhixing Rd., Taipei, Taiwan.
authors.forename: Po-Shan
authors.initials: PS
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D003401:Creatine / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017827:Machado-Joseph Disease / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D018911:Trinucleotide Repeats / Q000235:genetics
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine
keywords: Brain connectivity; Fractal dimension; Magnetic resonance imaging; Magnetic resonance spectroscopy; NAA; SCA3