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Triplet Repeat Diseases

Molecular Biology of Specific Diseases

  1. Stephan J. Guyenet,
  2. Albert R. La Spada

Published Online: 15 SEP 2006

DOI: 10.1002/3527600906.mcb.200500027

Reviews in Cell Biology and Molecular Medicine

Reviews in Cell Biology and Molecular Medicine

How to Cite

Guyenet, S. J. and La Spada, A. R. 2006. Triplet Repeat Diseases. Reviews in Cell Biology and Molecular Medicine. .

Author Information

  1. University of Washington, Seattle, WA 98195

Publication History

  1. Published Online: 15 SEP 2006


The repeat expansion disorders are a group of human diseases that are caused by the elongation of a DNA repeat sequence. In this chapter, we provide an overview of the discovery of repeat expansion as an important cause of human disease, and we summarize the molecular genetics and mechanistic basis of 27 microsatellite repeat disorders. Comparison of the many repeat expansion disorders reveals distinct categories of repeat diseases, allowing us to propose a classification of the repeat expansion disorders based upon mutation sequence and pathogenic mechanism. The four types of repeat expansion disorders defined by this approach are the CAG/polyglutamine repeat diseases; the loss-of-function repeat diseases; the RNA gain-of-function repeat diseases; and the polyalanine diseases. Although the genetic basis for most of these diseases was determined less than a decade or so ago, considerable advances have been made in our understanding of how “dynamic mutations” produce molecular pathology and human disease.


  • Aggregate;
  • Anticipation;
  • Gain of function;
  • Loss of function;
  • Repeat Expansion;
  • Trinucleotide