Comparative assessment of methods for aligning multiple genome sequences

Abstract

Multiple sequence alignment is a difficult computational problem. There have been compelling pleas for methods to assess whole-genome multiple sequence alignments and compare the alignments produced by different tools. We assess the four ENCODE alignments, each of which aligns 28 vertebrates on 554 Mbp of total input sequence. We measure the level of agreement among the alignments and compare their coverage and accuracy. We find a disturbing lack of agreement among the alignments not only in species distant from human, but even in mouse, a well-studied model organism. Overall, the assessment shows that Pecan produces the most accurate or nearly most accurate alignment in all species and genomic location categories, while still providing coverage comparable to or better than that of the other alignments in the placental mammals. Our assessment reveals that constructing accurate whole-genome multiple sequence alignments remains a significant challenge, particularly for noncoding regions and distantly related species.

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Figure 1: Comparison of coverage of the alignments.
Figure 2: Comparison percentages agree%, unique% and disagree% for TBA, MAVID and MLAGAN.
Figure 3: Comparison of accuracy of the alignments, as measured by suspicious%.
Figure 4: Pairwise alignment scores of suspicious regions versus those for alternative alignments of the same human region.
Figure 5: Summary plot of suspicious% vs. coverage, aggregated over all four location categories.

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Acknowledgements

We thank P. Green, W. Noble, W.L. Ruzzo and especially A. Prakash for helpful discussions and technical advice. We thank the US National Institutes of Health and the Natural Sciences and Engineering Research Council of Canada for financial support.

Author information

X.C., design, implementation, experimentation, analysis; M.T., design, analysis.

Correspondence to Martin Tompa.

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The authors declare no competing financial interests.

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Chen, X., Tompa, M. Comparative assessment of methods for aligning multiple genome sequences. Nat Biotechnol 28, 567–572 (2010). https://doi.org/10.1038/nbt.1637

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