Dear Markus, We have not made a BSgenome object for mouse. Your versions of R and Repitools are outdated. Currently, it is possible to directly import the output of the GEM Mappability program. Also, in the development version of Repitools, I have added the ability to use the bigWig mappability tracks that are hosted on the UCSC Genome Browser. Please update to either the release or development version of Repitools, depending on the input file type you want to use. -------------------------------------- Dario Strbenac PhD Student University of Sydney Camperdown NSW 2050 Australia