FRA10B structure reveals common elements in repeat expansion and chromosomal fragile site genesis

Duncan R. Hewett, Oliva Handt, Lynne Hobson, Marie Mangelsdorf, Helen J. Eyre, Elizabeth Baker, Grant R. Sutherland, Simone Schuffenhauer, Jen I. Mao, Robert I. Richards

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77 Citations (Scopus)


A common mechanism for chromosomal fragile site genesis is not yet apparent. Folate-sensitive fragile sites are expanded p(CCG)n repeats that arise from longer normal alleles. Distamycin A or bromodeoxyuridine-inducible fragile site FRA16B is an expanded AT-rich ∼33 bp repeat; however, the relationship between normal and fragile site alleles is not known. Here, we report that bromodeoxyuridine-inducible, distamycin A-insensitive fragile site FRA10B is composed of expanded ∼42 bp repeats. Differences in repeat motif length or composition between different FRA10B families indicate multiple independent expansion events. Some FRA10B alleles comprise a mixture of different expanded repeat motifs. FRA10B fragile site and long normal alleles share flanking polymorphisms. Somatic and intergenerational FRA10B repeat instability analogous to that found in expanded trinucleotide repeats supports dynamic mutation as a common mechanism for repeat expansion.

Original languageEnglish
Pages (from-to)773-781
Number of pages9
JournalMolecular Cell
Issue number6
Publication statusPublished or Issued - May 1998

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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