Supplementary Material Additional File 1 Table of microsatellite markers used in the construction of B6.CAST and HG.CAST speed congenic strains Click here for file Additional File 2 Table of microsatellite markers used to position the recombinant ends of each speed congenic strain Click here for file Additional File 3 Table of body weight and growth rate phenotypes of B6.CAST and HG.CAST MMU2 speed congenic strains Click here for file Additional File 4 Table of results of sequence comparisons between CAST and B6 for MMU2 hg modifier candidate genes Click here for file Additional File 5 Table of PCR primers used to sequence MMU2, 9, 11 and 17 hg modifier candidate genes Click here for file