Definition of the repeat, as originally published for the main SCA loci

(modifed from Table 1 of Sequeiros J, Seneca S and Martindale J: Consensus and controversies in best practices for
molecular genetic testing of the spinocerebellar ataxias. Eur J Hum Genet 18:1173-6, 2010)

SCA1 ATXN1 (CAG)n(CAT)n(CAG)n2 (Orr et al, 1993; Chung et al, 1993; Sobczak et al, 2004)
DRPLA ATN1 (CAG)n (Koide et al, 1994; Nagafuchi et al, 1994)
SCA2 ATXN2 [(CAG)n CAA (CAG)n]n 3 (Pulst et al, 1996; Sobczak et al, 2004)
MJD/SCA3 ATXN3 (CAG)2 CAA AAG CAG CAA (CAG)n (Kawaguchi et al, 1994; Maciel et al, 1995)
SCA6 CACNA1A (CAG)n (Zhuchenko et al, 1997)
SCA7 ATXN7 (CAG)n (David et al, 1997)
SCA8 ATXN8 (CAG/TAG)n (Koob et al, 1999)
SCA10 ATXN10 (ATTCT)n 4 (Matsuura et al, 2000)
SCA12 PPP2R2B (CAG)n (Holmes et al, 1999)
SCA17 TBP [ (CAG)n (CAA)n (CAG)n ]n (Koide et al, 1999)

1 Full references are available at:
2 May be interrupted by 1 to 3, or exceptionally 4, CATs.
3 The CAG repeat may be pure or have 1 to 4 CAA interruptions.
4 Interruptions with multiple pentarepeats (ATGCT, ATTGT or TTTCT) or septarepeats (ATTCTAT, ATTTTCT and ATATTCT) or complex ATTGT-TTTCT repeats may be found.