Microsatellites are short, in‐tandem arranged repetitive deoxyribonucleic acid (DNA) elements which are widespread in eukaryotic and prokaryotic genomes. The basic unit lengths of microsatellites (or simple DNA sequence repeats) comprise up to six (or eight) nucleotides, and these motifs are perfectly reiterated from 5 to more than 100 times. Longer and more imperfectly reiterated periodicities border on the definitions of the so‐called minisatellites. Microsatellites have been utilised as markers for population genetic studies, forensic and relatedness testing, investigations on genetic diversity and the identification of genetic traits. However, microsatellite expansions are also involved in human diseases. Lynch syndrome, a hereditary tumour predisposition disease, is characterised by microsatellite instability due to defective mismatch repair, promoting tumourigenesis. Furthermore, microsatellite expansion diseases are rare, but interesting model diseases characterised by diverse pathogenetic pathways. Hence microsatellites exhibit a broad spectrum of biological relevance ranging from neutral or selfish to pathogenic elements.

Key Concepts

  • Microsatellites exhibit perfect tandem repetition of short nucleotide motifs.
  • Microsatellites represent most variable components throughout most genomes.
  • The biological significance of microsatellites ranges from selfishness and molecular marker for a small genome region to disease‐causing mutations when expanded, respectively.

Keywords: microsatellite; simple DNA sequences; DNA marker; repetitive DNA; genomic junk; mutations; polymorphism; hypervariability

Figure 1. CAG repeat expansion underlying Huntington disease (HD). Carriers of intermediate alleles (≥27–35 CAG repeats) usually do not develop symptoms of HD, but repeat lengths may increase during (mainly male) meiosis. The 36–39 CAG repeats are causative for HD, but show reduced penetrance, while repeat lengths of ≥40 CAG repeats lead to HD with full penetrance.


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Hoffjan, Sabine, and Epplen, Jörg T(Aug 2016) Microsatellites. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005911.pub3]