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Comparative and Functional Genomics
Volume 2012 (2012), Article ID 947089, 7 pages
http://dx.doi.org/10.1155/2012/947089
Research Article

Transposable Elements Are a Significant Contributor to Tandem Repeats in the Human Genome

Department of Biological Sciences, Brock University, St. Catharines, ON, Canada L2S 3A1

Received 25 February 2012; Revised 10 April 2012; Accepted 11 April 2012

Academic Editor: Yasunori Aizawa

Copyright © 2012 Musaddeque Ahmed and Ping Liang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Sequence repeats are an important phenomenon in the human genome, playing important roles in genomic alteration often with phenotypic consequences. The two major types of repeat elements in the human genome are tandem repeats (TRs) including microsatellites, minisatellites, and satellites and transposable elements (TEs). So far, very little has been known about the relationship between these two types of repeats. In this study, we identified TRs that are derived from TEs either based on sequence similarity or overlapping genomic positions. We then analyzed the distribution of these TRs among TE families/subfamilies. Our study shows that at least 7,276 TRs or 23% of all minisatellites/satellites is derived from TEs, contributing ∼0.32% of the human genome. TRs seem to be generated more likely from younger/more active TEs, and once initiated they are expanded with time via local duplication of the repeat units. The currently postulated mechanisms for origin of TRs can explain only 6% of all TE-derived TRs, indicating the presence of one or more yet to be identified mechanisms for the initiation of such repeats. Our result suggests that TEs are contributing to genome expansion and alteration not only by transposition but also by generating tandem repeats.