Variations in the human genome commonly found within the population may predispose affected individuals to frequently occurring disease conditions. The existence of these DNA sequence variations, called single nucleotide polymorphisms or SNPs, has sparked intense interest within the scientific community to identify and characterize them for epidemiological study. However, the functional significance of SNP variants in DNA repair genes in relation to environmental toxins and carcinogens is largely unknown. The objective of the Seattle Comparative Mouse Genomics Center is to develop genetically engineered mouse models for studying SNP variant-environment interactions, using the resources and expertise found at the University of Washington and Fred Hutchinson Cancer Research Center.