Congenic rats reveal three independent Copenhagen alleles within the Mcs1 quantitative trait locus that confer resistance to mammary cancer.

It has previously been shown that the Copenhagen (COP) rat contains several genetic loci that contribute to its mammary tumor-resistant phenotype after 7,12-dimethylbenz(a)anthracene (DMBA) administration. One of these loci, mammary carcinoma susceptibility 1 (Mcs1), is located on the centromeric end of chromosome 2 and appears to act in a semidominant fashion. To confirm the existence and independent action of this locus and also aid in the identification of the physical location of the Mcs1 gene, congenic lines were generated by transferring the Mcs1 COP allele onto a Wistar Furth (WF) genetic background.

Physical evidence of Mcs5, a QTL controlling mammary carcinoma susceptibility, in congenic rats.

Genetic susceptibility to breast cancer is influenced by high- and low-penetrance genes. The low-penetrance genes contributing to increased and decreased risk likely exist at appreciable frequencies in the human population. To identify high-frequency, low-penetrance modifier genes, we are using a rat genetic model.