title: The D5Mit7 locus on mouse chromosome 5 provides resistance to gamma-ray-induced but not N-methyl-N-nitrosourea-induced thymic lymphomas.
abstract: Susceptibility to gamma-ray induction of thymic lymphomas in mouse strains is controlled by low-penetrance genetic variant alleles. Our previous genome-wide scan of a mouse backcross between BALB/c and MSM strains suggested the existence of a BALB/c resistance locus near D5Mit5 on chromosome 5. To confirm this resistance, we produced congenic mice carrying a 28.4 cM region between D5Mit4 and D5Mit315 from the MSM parental strain on the BALB/c background. Lymphomas were induced in their progeny by gamma-ray irradiation or administration of N-methyl-N-nitrosourea (MNU), an alkylating agent. The incidence of radiogenic lymphomas was 87.5% in mice of the M/M genotype at D5Mit7, significantly higher than the 46% incidence in mice of the C/M genotype, indicating highly significant linkage between the locus and the resistance (P = 0.000054). In contrast, the frequencies of MNU-induced thymic lymphomas were similar between the two genotypes (P = 0.35 in chi2 test). These results confirm the presence of a resistance allele for gamma-ray induction of thymic lymphomas near the D5Mit7 locus and strongly suggest that this locus modifies carcinogenic risk from exposure to radiation but not to alkylating agents.
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D005720:Gamma Rays; D008223:Lymphoma / Q000139:chemically induced* / Q000235:genetics*; D008770:Methylnitrosourea; D051379:Mice; D008807:Mice, Inbred BALB C; D009381:Neoplasms, Radiation-Induced / Q000235:genetics*; D011836:Radiation Tolerance / Q000235:genetics*; D013045:Species Specificity; D013953:Thymus Neoplasms / Q000139:chemically induced* / Q000235:genetics*
chemical_list: D008770:Methylnitrosourea