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. Albeit constituting elusive model disorders, microsatellite expansion diseases are rather rare entities characterised by differential pathogenetic pathways. Hence microsatellites exhibit a broad spectrum of biological relevance ranging from selfish or neutral 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 mutation when expanded, respectively.