Abstract
Many traits are defined as ratios of two quantitative traits. Methods of QTL mapping for regular quantitative traits are not optimal when applied to ratios due to lack of normality for traits defined as ratios. We develop a new method of QTL mapping for traits defined as ratios. The new method uses a special linear combination of the two component traits, and thus takes advantage of the normal property of the new variable. Simulation study shows that the new method can substantially increase the statistical power of QTL detection relative to the method which treats ratios as regular quantitative traits. The new method also outperforms the method that uses Box-Cox transformed ratio as the phenotype. A real example of QTL mapping for relative growth rate in soybean demonstrates that the new method can detect more QTL than existing methods of QTL mapping for traits defined as ratios.
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Acknowledgements
The research was supported by the National Institute of Health Grant R01-GM55321 and the National Science Foundation Grant DBI-0345205 to SX, and the Chinese National Natural Science Foundation Grant 30471236 to RY.
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Yang, R., Li, J. & Xu, S. Mapping quantitative trait loci for traits defined as ratios. Genetica 132, 323–329 (2008). https://doi.org/10.1007/s10709-007-9175-0
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DOI: https://doi.org/10.1007/s10709-007-9175-0