MOLECULAR AND PHENOTYPIC CHARACTERIZATION OF A NEW MOUSE INSERTIONAL MUTATION THAT CAUSES A DEFECT IN THE DISTAL VERTEBRAE OF THE SPINE

We have identified and characterized the phenotype of a new insertiona l mutation in one line of transgenic mice. Mice carrying this mutation , which we have designated TgN(Imusd)370Rpw, display undulations of th e vertebrae giving rise to a novel kinky-tail phenotype. Molecular cha racterization of the insertion site indicates that the transgene integ ration has occurred without any substantial alterations in the structu re of the host sequences. Using probes that flank the insertion site, we have mapped the mutation to chromosome 5 near the semidominant muta tion, thick tail (Tht). Thick tail does not complement the TgN(Imusd)3 70Rpw mutation; compound mutants containing one copy of each mutation display a more severe phenotype than either mutation individually.