Table 3.
Chromosomal elements that affect FXS repeat instability
| Factors | Effect on repeat expansion (somatic) | Reference |
|---|---|---|
| Length repeat | increase or decrease expansion | (Eichler et al., 1994) |
| Number of interruptions within the repeat | increase repeat stability | (Eichler et al., 1996) |
| CGG repeatpurity of the repeat at the 3′ end | decrease stability | (Crawford et al., 2000) |
| 5′ position of the first AGG interruption | increase stability | (Eichler et al., 1995) |
| Haplotype background of the mutation | increase of decrease stability | (Kunst and Warren, 1994) |
| SNP associated with expansion (ss71651738) | increase repeat instability | (Ennis et al., 2007) |