GENETIC-MAP OF RAT CHROMOSOME-5 INCLUDING THE FATTY (FA) LOCUS

Thirteen loci, including the obesity gene fatty (fa), were incorporate d into a linkage map of rat Chromosome (Chr) 5. These loci were mapped in obese (fa/fa) progeny of a cross between BN x 13M-fal+ F-1 animals . Obese rats were scored for BN and 13M alleles at four loci (Ifna, D1 S85h, C8b, and Lck1) by restriction fragment length polymorphisms and at eight additional loci (Glut1, Sv4j2, R251, R735, R980, R252, R371, and R1138) by simple sequence length polymorphisms (SSLP). The resulti ng map spans 67.3 cM of Chr 5, presenting nine previously unmapped loc i and one locus (Lck1) previously assigned to Chr 5 by use of somatic cell hybrid lines. Seven of the eight SSLP loci are newly identified; the SSLP linkage group alone spans 56.8 cM. The order of the loci is 8 0-R1138-Ifna-fa-D1S85h-C8b(Glut1-R252-R371)-Lck1. One locus, D1S85h, w as found to lie only 0.4 cM from fa, close enough to serve as a reliab le marker for the prediction of phenotype from genotype, and will be u seful also for studies on the development of obesity in the fatty rat.