Direct detection of expanded trinucleotide repeats using PCR and DNA hybridization techniques

Arturas Petronis, Henry H Q Heng, Yuriy Tatuch, Xiao Mei Shi, Timothy A. Klempan, Lap Chee Tsui, Tetsuo Ashizawa, Linda C. Surh, Jeanette J A Holden, James L. Kennedy

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Recently, unstable trinucleotide repeats have been shown to be the etiologic factor in seven neuropsychiatric diseases, and they may play a similar role in other genetic disorders which exhibit genetic anticipation. We have tested one polymerase chain reaction (PCR)-based and two hybridization-based methods for direct detection of unstable DNA expansion in genomic DNA. This technique employs a single primer (asymmetric) PCR using total genomic DNA as a template to efficiently screen for the presence of large trinucleotide repeat expansions. High-stringency Southern blot hybridization with a PCR-generated trinucleotide repeat probe allowed detection of the DNA fragment containing the expansion. Analysis of myotonic dystrophy patients containing different degrees of (CTG)n expansion demonstrated the identification of the site of trinucleotide instability in some affected individuals without any prior information regarding genetic map location. The same probe was used for fluorescent in situ hybridization and several regions of (CTG)n/(CAG)n repeats in the human genome were detected, including the myotonic dystrophy locus on chromosome 19q. Although limited at present to large trinucleotide repeat expansions, these strategies can be applied to directly clone genes involved in disorders caused by large expansions of unstable DNA.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalAmerican Journal of Medical Genetics - Seminars in Medical Genetics
Issue number1
StatePublished - Feb 16 1996


  • Methods of direct detection
  • Unstable DNA

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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