GENETIC-MAPPING OF TUMOR SUSCEPTIBILITY GENES INVOLVED IN MOUSE PLASMACYTOMAGENESIS

Plasmacytomas (PCTs) were induced in 47% of BALB/cAnPt mice by the int raperitoneal injection of pristane, in 2% of (BALB/c x DBA/2N)F1, and in 11% of 773 BALB/cAnPt x (BALB/cAnPt x DBA/2N)F1 N2 backcross mice. This result indicates a multigenic mode of inheritance for PCT suscept ibility. To locate genes controlling this complex genetic trait, tumor susceptibility in backcross progeny generated from BALB/c and DBA/2N (resistant) mice was correlated with alleles of 83 marker loci. The ge notypes of the PCT-susceptible progeny displayed an excess homozygosit y for BALB/c alleles within a 32-centimorgan stretch of mouse chromoso me 4 (>95% probability of linkage) with minimal recombination (12%) ne ar Gt10. Another susceptibility gene on mouse chromosome 1 may be link ed to Fcgr2 (90% probability of linkage); there were excess heterozygo tes for Fcgr2 among the susceptible progeny and excess homozygotes amo ng the resistant progeny. Regions of mouse chromosomes 4 and 1 that ar e correlated with PCT susceptibility share extensive linkage homology with regions of human chromosome 1 that have been associated with cyto genetic abnormalities in multiple myeloma and lymphoid, breast, and en docrine tumors.