Quantitative complementation tests using SM/J and LG/J mice revealed that the Capn10 (calpain-10) gene is a QTG for Adip1, an obesity QTL identified in a set of recombinant inbred strains between SM/J and LG/J, because highly significant interaction effects between Capn10 knockout and Adip1 genotypes were obtained for body weight, weights of fat pads, liver and heart, and serum leptin level [34]. Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.