A double gene dose of mutant alleles at either the W or SI locus produces the pleiotropic effects of anemia, sterility, lack of hair pigmentation, and lack of tissue mast cells. Coincidental development of forestomach papilloma and prepyloric ulcer was observed in about 40% of nontreated (WB × C57BL/6) F1-W/Wv mice raised in our laboratory. The stomach lesions of the W/Wv mice could be detected at the 15th day after birth, and such lesions never appeared in the W/+, Wv/+, and +/+ littermates maintained under the same laboratory conditions. Since the stomach lesions were also observed in (WC × C57BL/6) F1-SI/SId mice purchased from The Jackson Laboratory, phenotypes common to both W/Wv and SI/SId mice seem to play an essential role in the spontaneous development of the forestomach papilloma and prepyloric ulcer.
Supported by Grants-in-Aid from the Japanese Ministry of Education, Science and Culture; Grants from Osaka Anti-Cancer Campaign; and Mitsuhisa Memorial Grant for Cancer Research.