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Table 1 Microsatellite repeat expansion disorders

From: RNA biology of disease-associated microsatellite repeat expansions

Disorder

Repeating unit

Genomic location

Gene name

Normal length

Pathogenic length

Expanded repeats result in:

Repeat discovery & references

Gene silencing

xtrRNA transcription

xtrRNA proteins

xtrRNA foci

FXS/FRAXA†

CGG

5’UTR

FMR1

6-55

200+

Yes*

No

No

No

[114, 161, 230, 303]

SBMA†

CAG

Coding

AR

9-36

38-62

No

Yes

Yes*

L .D.

[167]

DM1

CTG

3’UTR

DMPK

5-37

50-10000

No

Yes*

Yes

Yes*

[193]

HD

CAG

Coding

HTT

10-35

35+

No

Yes

Yes*

L.D.

[192]

SCA1

CAG

Coding

ATXN1

6-35

49-88

No

Yes

Yes*

L.D.

[232]

FRAXE

CCG

5'UTR

AFF2

4-39

200-900

Yes*

No

No

No

[152]

DRPLA

CAG

Coding

ATN1

6-35

49-88

No

Yes

Yes*

L.D.

[155]

SCA3

CAG

Coding

ATXN3

12-40

55-86

No

Yes

Yes*

Yes

[140]

SCA2

CAG

Coding

ATXN2

14-32

33-77

No

Yes

Yes*

L.D.

[127, 253]

FRDA

GAA

Intron

FXN

8-33

90+

Yes*

Yes / No

No

No

[30]

SCA6

CAG

Coding

CACNA1A

4-18

21-30

No

Yes

Yes*

L.D.

[337]

EPM1

CCCCGC

CCCGCG

Promoter

CSTB

2-3

30-80

Yes*

Yes / No

No

No

[170]

SCA7

CAG

Coding

ATXN7

7-17

38-120

No

Yes

Yes*

L.D.

[57]

OPMD

GCG

Coding

PABPN1

6-10

12-17

No

Yes

Yes*

No

[23]

SCA8

CTG

3’UTR

ATXN8

16-34

74+

No

Yes

Yes*

Yes*

[156]

SCA12

CAG

5’UTR

PPP2R2B

7-28

66-78

No

Yes*

No

No

[121]

SCA10

ATTCT

Intron

ATXN10

10-20

500-4500

No

Yes

?

Yes*

[205]

SCA17

CAG

Coding

TBP

25-42

47-63

No

Yes

Yes*

L.D.

[224]

DM2

CCTG

Intron

CNBP

10-26

75-11000

No

Yes

?

Yes*

[184]

FXTAS/FXPOI

CGG

5’UTR

FMR1

6-55

55-200

No

Yes

Yes*

Yes*

[143, 287]

HDL2

CTG/CAG

3'UTR/antisense

JPH3

<50

50+

No

Yes

?

Yes*

[120]

SCA31

TGGAA

Intron

TK2/BEAN

0

45+

No

Yes

Yes*

Yes*

[256]

SCA36

GGCCTG

Intron

Nop56

3-14

650+

No

Yes

?

Yes*

[153]

C9FTD/ALS

GGGGCC

Intron

C9ORF72

2-25

25+

No

Yes

Yes*

Yes*

[59, 248]

FRA7A

CGG

Intron

ZFN713

5-22

85+

No

Yes* / No

No

No

[209]

FRA2A

CGG

Intron

AFF3

8-17

300+

No

Yes* / No

No

No

[210]

  1. Disorders are listed in order of the year they were discovered, with the appropriate references relating to their discovery. This table highlights known RNA biology for each disease with respect to xtrRNA transcription, translation, and formation of nuclear focal aggregates
  2. Dagger symbol (†) indicates that athough the CAG repeat for SBMA was discovered first, the CGG repeat for FXS was published first. Asterisk (*) indicates the most likely repeat-associated disease mechanism(s) for that disorder. L.D. length-dependent, SBMA Spinal-Bulbar Muscular Atrophy, EPM1 Progressive Myoclonus Epilepsy 1 (Unverricht–Lundborg Disease), FXS/FRAXA Fragile X Syndrome, DM Myotonic Dystrophy, HD Huntington’s Disease, SCA Spinocerebellar Ataxia, FRAXE Fragile X E Syndrome, DRPLA Dentatorubral-Pallidoluysian Atrophy, FRDA Friedreich Ataxia, OPMD Oculopharyngeal Muscular Dystrophy, FXTAS Fragile X–Associated Tremor/Ataxia Syndrome, FXPOI Fragile X-Associated Primary Ovarian Insufficiency, HDL2 Huntington’s Disease-Like 2, C9FTD/ALS C9ORF72-Associated Frontotemporal Dementia and Amyotrophic Lateral Sclerosis, FRA7A CGG Expansion at Fragile Site 7A, FRA2A CGG Expansion at Fragile Site 2A