Ghost QTL and hotspots in experimental crosses: novel approach for modeling polygenic effects

Jonas Wallin, Małgorzata Bogdan, Piotr A. Szulc, R. W. Doerge, David O. Siegmund

Research output: Contribution to journalArticlepeer-review


Ghost quantitative trait loci (QTL) are the false discoveries in QTL mapping, that arise due to the "accumulation" of the polygenic effects, uniformly distributed over the genome. The locations on the chromosome that are strongly correlated with the total of the polygenic effects depend on a specific sample correlation structure determined by the genotypes at all loci. The problem is particularly severe when the same genotypes are used to study multiple QTL, e.g. using recombinant inbred lines or studying the expression QTL. In this case, the ghost QTL phenomenon can lead to false hotspots, where multiple QTL show apparent linkage to the same locus. We illustrate the problem using the classic backcross design and suggest that it can be solved by the application of the extended mixed effect model, where the random effects are allowed to have a nonzero mean. We provide formulas for estimating the thresholds for the corresponding t-test statistics and use them in the stepwise selection strategy, which allows for a simultaneous detection of several QTL. Extensive simulation studies illustrate that our approach eliminates ghost QTL/false hotspots, while preserving a high power of true QTL detection.

Original languageEnglish
Issue number3
Publication statusPublished - 2021

Subject classification (UKÄ)

  • Genetics

Free keywords

  • expression quantitative trait loci (e-QTL) mapping
  • ghost QTL
  • hotspots
  • mixed effect model
  • polygenes
  • QTL mapping


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