Table 1.
Triplet repeat expansion diseases (TREDs) that have been identified in humans.
| TRED disorders | Site of pathogen | Expansion | Repeat no. |
|---|---|---|---|
| Dentatorubral-pallidoluysian atrophy (DRPLA) | Atrophin-1, exons | CAG | 49–88 |
| Fragile X syndrome (FXS) | FMR1, 5′-UTR | CGG | >200 |
| Fragile X-associated tremor ataxia syndrome (FXTAS) | FMR1, 5′-UTR | CGG | 55–200 |
| Fragile X syndrome E (FRAXE) | FMR2, 5′-UTR | CCG | 200–900 |
| Friedreich ataxia (FRDA) | Frataxin, intron | GAA | 200–1,700 |
| Myotonic dystrophy type 1 (DM1) | DMPK, 3′-UTR | CTG | 50–1,000 |
| Myotonic dystrophy type 2 (DM2) | ZNF9, intron 1 | CCTG | 75–11,000 |
| Huntington's disease (HD) | Huntingtin, exon 1 | CAG | 40–121 |
| Huntington's disease-like 2 (HDL2) | JPH3, intron, exon, or 3′-UTR | CTG | 66–78 |
| Spinobulbar muscular atrophy (SBMA) | Androgen receptor, intron | CAG | 38–62 |
| Spinal cerebellar ataxia (SCA) types 1–3, 7 | Ataxin 1–3, 7, exons | CAG | 37–300 |
| SCA type 8 (SCA8) | (ncRNA)*UD | CTG | >74 |
| SCA type 17 (SCA17) | TBP, exon | CAG | 47–63 |
*UD: undefined.