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Open Access Highly Accessed Research

Tandem repeats modify the structure of human genes hosted in segmental duplications

Anna De Grassi and Francesca D Ciccarelli*

Author Affiliations

Department of Experimental Oncology, European Institute of Oncology, IFOM-IEO Campus, Via Adamello, 20139 Milan, Italy

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Genome Biology 2009, 10:R137  doi:10.1186/gb-2009-10-12-r137

Published: 2 December 2009

Abstract

Background

Recently duplicated genes are often subject to genomic rearrangements that can lead to the development of novel gene structures. Here we specifically investigated the effect of variations in internal tandem repeats (ITRs) on the gene structure of human paralogs located in segmental duplications.

Results

We found that around 7% of the primate-specific genes located within duplicated regions of the genome contain variable tandem repeats. These genes are members of large groups of recently duplicated paralogs that are often polymorphic in the human population. Half of the identified ITRs occur within coding exons and may be either kept or spliced out from the mature transcript. When ITRs reside within exons, they encode variable amino acid repeats. When located at exon-intron boundaries, ITRs can generate alternative splicing patterns through the formation of novel introns.

Conclusions

Our study shows that variation in the number of ITRs impacts on recently duplicated genes by modifying their coding sequence, splicing pattern, and tissue expression. The resulting effect is the production of a variety of primate-specific proteins, which mostly differ in number and sequence of amino acid repeats.