Type
Gene
Normal/wildtype
Pathogenic
DRPLA (Dentatorubropallidoluysian atrophy
ATN1 or DRPLA
6 - 35
49 - 88
HD (Huntington's disease)
HTT (Huntingtin)
10 - 35
35+
SBMA (Spinobulbar muscular atrophy or Kennedy disease)
Androgen receptor on the X chromosome.
9 - 36
38 - 62
SCA1
ATXN1
SCA2
ATXN2
14 - 32
33 - 77
SCA3 (Machado-Joseph disease)
ATXN3
12 - 40
55 - 86
SCA6
CACNA1A
4 - 18
21 - 30
SCA7
ATXN7
7 - 17
38 - 120
SCA17
TBP
25 - 42
47 - 63
Codon
FRAXA (Fragile X syndrome)
FMR1, on the X-chromosome
CGG
6 - 53
230+
FRAXE (Fragile XE mental retardation)
AFF2 or FMR2, on the X-chromosome
GCC
200+
FRDA (Friedreich's ataxia)
FXN or X25, (frataxin)
GAA
7 - 34
100+
DM (Myotonic dystrophy)
DMPK
CTG
5 - 37
50+
SCA8 (Spinocerebellar ataxia Type 8)
OSCA or SCA8
16 - 37
110 - 250
SCA12 (Spinocerebellar ataxia Type 12)
PPP2R2B or SCA12
CAG On 5' end
7 - 28
66 - 78