KitW-44J heterozygotes have white-tipped feet and a white tail tip although the belly spot standardly found in KitW* mutations is very small in this mutant, sometimes restricted to only a few hairs. Homozygotes have a flecked pelt that is predominantly white, especially ventrally, with pigmented patches particularly at the lateral borders. The pigmentation fades with age yielding black-eyed white mice by approximately 9 months of age. While many KitW-44J homozygotes are viable, fertility is diminished. Homozygous females have greatly reduced fertility and gonads that are smaller in size with reduced activity. Homozygous males are sterile although spermatogenesis occurs. The KitW-44J allele does not produce anemia in either its heterozygous or homozygous state. The red blood cell count, white blood cell count, hematocrit, and mean cell volume are normal. However, bone marrow transplantation experiments reveal that the colony forming units in the bone marrow of KitW-44J homozygotes are much lower than normal despite the fact that the bone marrow has a normal cell count. While bone marrow transplantation from KitW-44J homozygotes can cure anemia in KitW/KitW-v hosts, it repopulates more slowly than does wild type bone marrow. Bone marrow from KitW-44J homozygotes also fails to repopulate the mast cells in the skin of KitW/KitW-v hosts. Wild type bone marrow transplanted into non-irradiated hosts out-competes the endogenous erythropoeisis in KitW-44J homozygotes but not in wild type hosts, further confirming a deficiency in erythropoeisis in these non-anemic mice. Mice doubly heterozygous for KitW-44J and KitW-39J are more mildly anemic than mice doubly heterozygous for KitW-39J and other second KitW* alleles. (Geissler et al., 1981; Geissler and Russell, 1983; Sawada et al., 1991.)
