Box 15.2The origin of a microsatellite

There is no mystery about the origins of microsatellite repeat sequences (Section 2.4.1). A dimeric microsatellite, consisting of two repeat units in tandem array, can easily arise by chance mutational events. Replication slippage (Section 14.1.1) can then increase the copy number to three, four and more.

The birth of a microsatellite within a globin pseudogene of primates has been documented by comparing the nucleotide sequences of various species (Messier et al., 1996). In the orangutan, gibbon and other species some distance from humans, the sequence 5′-ATGTGTGT-3′ occurs at the relevant position. In the gorilla, bonobo, chimpanzee and human a single point mutation has changed this sequence to 5′-ATGTATGT-3′, with subsequent expansion of the 5′-ATGT-3′ repeat motif.

Image ch15fb4.jpg

From: Chapter 15, How Genomes Evolve

Cover of Genomes
Genomes. 2nd edition.
Brown TA.
Oxford: Wiley-Liss; 2002.
Copyright © 2002, Garland Science.

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