| Type | disease | Description | Defects in Mitf are the cause of microphthalmia (mi), a condition characterized by loss of pigmentation; reduced eye size; failure of secondary bone resorption; reduced numbers of mast cells; early onset of deafness, and which gives rise to a number of different phenotypes. Among them, microphthalmia-eyeless white (mi-ew) has a normal appearance at the heterozygous state, but shows white coat; eyes almost absent and eyelids never open at homozygosity. Microphthalmia-black and white spot (mi-bws) is normal at heterozygosity, and presents white spots and black eyes at homozygous state. Microphthalmia-white (mi-wh) has reduced coat color and eye pigmentation; spots on toes, tail and belly; inner ear defects at heterozygosity, and at homozygosity shows white coat; eyes small and inner iris slightly pigmented; spinal ganglia, adrenal medulla and dermis smaller than normal, and inner ear defects. Microphthalmia-vitiligo (mi-vi) has normal phenotype at heterozygosity, but shows gradual depigmentation of coat, skin and eyes; and retinal degeneration at homozygosity. Microphthalmia-spotted (mi-sp) shows normal phenotype; at homozygosity, however, tyrosinase activity in skin is reduced. Microphthalmia-defective irism (mi-di) has reduced retinal pigmentation at heterozygosity and shows white coat; eyes of reduced sized and possible mild osteoporosis at homozygosity. Microphthalmia-cloudy eyed (mi-ce) has a normal appearance at the heterozygous state, but shows white coat; eyes of reduced size and unpigmented at homozygosity. Microphthalmia-red-eyed white (mi-rw) has a normal appearance at the homozygous state, but shows white coat with one or more pigmented spots around the head/and or tail; eyes are small and red at heterozygosity. Microphthalmia-black-eyed white (mi-bw) shows a white coat but normal sized eyes which reamin black at homozygosity. |
