Mice homozygous for the recessive buff (Vps33abf) mutation on a non-agouti (a/a) background have a lightened coat color that has been described as khaki. On an agouti background, Vps33bf homozygotes have dark ears, opaque eyes, and the belly is lighter in color than is the rest of the coat. Although no change in eye color is outwardly evident, electron microscopy shows fewer and smaller melanosomes than normal in the retinal pigment epithelium and choroid. These mutants have a platelet-storage pool defect evidenced by an increased bleeding time of 9.7 minutes on average, a reduction in the number of platelet dense granules, and slightly decreased collagen-mediated platelet aggregation, secretion of dense-granule ATP and secretion of seratonin. Hakansson and Lundin found increased activity of the lysosomal glycosidases beta- galactosidase, beta-glucuronidase, and N-acetyl-beta-hexosaminidase in kidney cell lysates. Suzuki et al. found no significant difference in kidney beta- galactosidase and beta-glucuronidase activity, no significant decrease in beta-glucuronidase secretion into the urine, but a 53% reduction in the secretion of beta-galactosidase into the urine. (Dickie, 1964; Davisson, 1977; Hakansson and Lundin, 1977; Suzuki et al., 2003.)
