DISTINCT GENETIC-LOCI CONTROL DEVELOPMENT OF BENIGN AND MALIGNANT SKIN TUMORS IN MICE

Genetic susceptibility to chemically induced skin cancer in mice is co ntrolled by multiple unlinked genetic loci. Mus spretus mice have domi nant resistance genes which confer resistance to interspecific F-1 hyb rids with susceptible Mus musculus strains. We have mapped three major resistance loci using a combination of Mapmaker/QTL analysis and mult iple regression analysis to mouse chromosomes 5 and 7. At least two in dependent loci on chromosome 7 exert their effects primarily during be nign tumour development and have very little influence on tumour progr ession. On the other hand, probably a single locus on chromosome 5 aff ects both early and late stages of malignancy. The results indicate th at benign and malignant tumours are largely under independent genetic control.