Cis-acting DNA sequence at a replication origin promotes repeat expansion to fragile X full mutation Academic Article uri icon


MeSH Major

  • Fragile X Syndrome
  • Replication Origin
  • Trinucleotide Repeat Expansion


  • Fragile X syndrome (FXS) is caused by CGG repeat expansion that leads to FMR1 silencing. Women with a premutation allele are at risk of having a full mutation child with FXS. To investigate the mechanism of repeat expansion, we examined the relationship between a single-nucleotide polymorphism (SNP) variant that is linked to repeat expansion in haplogroup D and a replication origin located ∼53 kb upstream of the repeats. This origin is absent in FXS human embryonic stem cells (hESCs), which have the SNP variant C, but present in the nonaffected hESCs, which have a T variant. The SNP maps directly within the replication origin. Interestingly, premutation hESCs have a replication origin and the T variant similar to nonaffected hESCs. These results suggest that a T/C SNP located at a replication origin could contribute to the inactivation of this replication origin in FXS hESCs, leading to altered replication fork progression through the repeats, which could result in repeat expansion to the FXS full mutation.

publication date

  • January 2014



  • Academic Article



  • eng

PubMed Central ID

  • PMC4151148

Digital Object Identifier (DOI)

  • 10.1083/jcb.201404157

PubMed ID

  • 25179629

Additional Document Info

start page

  • 599

end page

  • 607


  • 206


  • 5