The Eker rat is a promising animal model of cancer predisposition syndromes. In this study, using 129 backcross animals, we have established a new conserved linkage group on rat 10q and human 16p13.3 whereby the Eker mutation was found to be tightly linked to the tuberous sclerosis (TSC2) gene. This will be the first step toward the positional cloning and identification of the predisposing Eker mutation.