Clinical characteristics of patients with spinocerebellar ataxias 1, 2, 3 and 6 in the US; a prospective observational study.
BACKGROUND
All spinocerebellar ataxias (SCAs) are rare diseases. SCA1, 2, 3 and 6 are the four most common SCAs, all caused by expanded polyglutamine-coding CAG repeats. Their pathomechanisms are becoming increasingly clear and well-designed clinical trials will be needed.


METHODS
To characterize the clinical manifestations of spinocerebellar ataxia (SCA) 1, 2, 3 and 6 and their natural histories in the United States (US), we conducted a prospective multicenter study utilized a protocol identical to the European consortium study, using the Scale for the Assessment and Rating of Ataxia (SARA) score as the primary outcome, with follow-ups every 6 months up to 2 years.


RESULTS
We enrolled 345 patients (60 SCA1, 75 SCA2, 138 SCA3 and 72 SCA6) at 12 US centers. SCA6 patients had a significantly later onset, and SCA2 patients showed greater upper-body ataxia than patients with the remaining SCAs. The annual increase of SARA score was greater in SCA1 patients (mean ± SE: 1.61 ± 0.41) than in SCA2 (0.71 ± 0.31), SCA3 (0.65 ± 0.24) and SCA6 (0.87 ± 0.28) patients (p = 0.049). The functional stage also worsened faster in SCA1 than in SCA2, 3 and 6 (p = 0.002).


CONCLUSIONS
The proportions of different SCA patients in US differ from those in the European consortium study, but as in the European patients, SCA1 progress faster than those with SCA2, 3 and 6. Later onset in SCA6 and greater upper body ataxia in SCA2 were noted. We conclude that progression rates of these SCAs were comparable between US and Europe cohorts, suggesting the feasibility of international collaborative clinical studies.
Department of Neurology and McKnight Brain Institute, University of Florida, 1149 S, Newell Dr,, L3-100, Gainesville, FL 32611, USA. ashizawa@ufl.edu.
Tetsuo
T
Ashizawa
Karla P
KP
Figueroa
Susan L
SL
Perlman
Christopher M
CM
Gomez
George R
GR
Wilmot
Jeremy D
JD
Schmahmann
Sarah H
SH
Ying
Theresa A
TA
Zesiewicz
Henry L
HL
Paulson
Vikram G
VG
Shakkottai
Khalaf O
KO
Bushara
Sheng-Han
SH
Kuo
Michael D
MD
Geschwind
Guangbin
G
Xia
Pietro
P
Mazzoni
Jeffrey P
JP
Krischer
David
D
Cuthbertson
Amy Roberts
AR
Holbert
John H
JH
Ferguson
Stefan M
SM
Pulst
S H
SH
Subramony
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D020754:Spinocerebellar Ataxias / Q000175:diagnosis* / Q000473:pathology