The mutant mouse is easily distinguished from heterozygous or wild type controls. The hair is slightly lighter in coloration. Eye color varies from ruby to almost black. The shade of color may vary on different genetic backgrounds depending on alleles at other coat color loci that may be carried by the strain. The decrease or dilution of the coloration of hair and other pigmented tissues is due to the reduced number, enlargement, and clumping of melanin granules.
All tissues containing cells with various types of cytoplasmic granules have giant lysosomes.
A variety of immunological deficiencies or abnormalities associated with the granular defects are well known for the beige mutation. Skin lesions include alopecia that occurs around the time of weaning followed by regrowth of hair, adult onset alopecia, papular dermatitis, and chronic ulcerative dermatitis as the mice age. A variety of ophthalmic anomalies occur that are associated with malformations of the lens in utero. Hydrocephalus occurs with low incidence. Since the beige mutation causes specific types of immunodeficiencies, it is not surprising that these mice are more susceptible to infectious diseases.