Kit mice possess pleiotropic defects in pigment-forming cells, germ cells, RBC's and mast cells. In addition, they exhibit impaired resistance to parasitic infection and an intrinsic progenitor cell defect. KitW-v homozygotes resemble KitW homozygotes in color, anemia, and germ cells, but many of them survive to maturity. The lack of germ cells in mutant mice leads to the development of some ovarian tumors (mesotheliomas and granulosa cell), associated with an overproduction of pituitary gonadotropic hormone. Mutations at the Mitf locus affect eye size, pigmentation, and the capacity for secondary bone resorption. Mice homozygous for the white allele (MitfMi-wh) display an overall absence of pigment cells with the exception of the retina which expresses a few giving the eye a small amount of pigment. Homozygotes show slight microphthalmia but a normal skeleton. Heterozygotes (MitfMi-wh/+) have a diluted coat color, light ears, a white belly spot, and in rare cases a dorsal spot. In addition, they display abnormalities of both the cochlear and vestibular portions of the inner ear. Mice heterozygous for the brachyury spontaneous mutation (T) have tail defects and associated skeletal abnormalities.
