Increased instability of human CTG repeat tracts on yeast artificial chromosomes during gametogenesis

Haim Cohen, Dorothy D. Sears, Drora Zenvirth, Philip Hieter, Giora Simchen

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Expansion of trinucleotide repeat tracts has been shown to be associated with numerous human diseases. The mechanism and timing of the expansion events are poorly understood, however, we show that CTG repeats, associated with the human DMPK gene and implanted in two homologous yeast artificial chromosomes (YACs), are very unstable. The instability is 6 to 10 times more pronounced in meiosis than during mitotic division. The influence of meiosis on instability is 4.4 times greater when the second YAC with a repeat tract is not present. Most of the changes we observed in trinucleotide repeat tracts are large contractions of 21 to 50 repeats. The orientation of the insert with the repeats has no effect on the frequency and distribution of the contractions. In our experiments, expansions were found almost exclusively during gametogenesis. Genetic analysis of segregating markers among meiotic progeny excluded unequal crossover as the mechanism for instability. These unique patterns have novel implications for possible mechanisms of repeat instability.

Original languageEnglish (US)
Pages (from-to)4153-4158
Number of pages6
JournalMolecular and cellular biology
Issue number6
StatePublished - Jun 1999
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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