The BXD strains were derived by inbreeding the F2 progeny of B6 and D2 strains.26 Newer sets of BXDs were created by inbreeding advanced intercross progeny.27, 28 Animals were weaned at 25 days-of-age and housed in same-sex cages, 2–5 mice per cage at the University of Tennessee Health Science Center. Animals were maintained on a 12:12 light/dark cycle at room temperature that ranged from 20–24 °C and had free access to standard laboratory chow and water. All animal work was conducted according to an approved animal use protocol (UTHSC680) and in accordance with procedures approved by the Institutional Animal Care and Use Committee.
