THE RAT CORPULENT (CP) MUTATION MAPS TO THE SAME INTERVAL ON (PGM1-GLUT1) RAT CHROMOSOME-5 AS THE FATTY (FA) MUTATION

The autosomal recessive obesity mutations fatty (fa) and corpulent (cp ) arose in separate rat strains, 13M and Koletsky, respectively. By co mplementation analysis, the two mutations appear to be in the same gen e. The somewhat different phenotypes of fa/fa and cp/cp animals probab ly reflect the fact that the mutations are segregating on different ra t strains. The fa mutation has been mapped to the interval between Pgm 1 and Glut1 on rat Chr 5, but cp has not been mapped genetically. We m apped cp in 30 obese progeny of a LA/N-BN cp/+ intercross using micros atellite markers for these flanking genes. Cp maps to the same genetic interval as rat fa and mouse db. Cp is flanked by Glut1 and Pgm1: [GR APHICS] Thus, cp and fa map to the same similar to 8 cM interval of th e rat genome. In conjunction with the complementation studies alluded to above, these findings indicate that cp and fa are mutations in the same gene (Lepr).