Leuzism

Leucism (from the Greek leukós, "white") refers to defective mutations in various genes in animals that are responsible for the differentiation of melanocytes and intestinal nerve cells. In early embryonic development, genes whose mutation leads to leucism cause a maldevelopment of structures of the neural crest, which results in no or very few melanoblasts migrating out of the neural crest. This means that there are no more pigment-forming cells in certain segments of the body surface. Skin and hair remain white. The disruption of melanogenesis also leads to color changes in the eyes, so that they are light brown or dark blue to orange in color, depending on how high the number of pigment cells is. In animals, most forms of piebaldness are due to attenuated forms of leucism.

Mutations in the following genes can lead to leucism:

• the endothelin receptor B gene(EDNRB)
• the paired box gene 3 (PAX3)
• SOX10, the gene for the microphthalmia-associated transcription factor (MITF)
• the gene for c-Kit and
• the Steel locus (encoding MGF).

Endothelin receptor B gene

• humans(EDNRB)
• Lethal white syndrome in horses (LWS)
• Rats (EDNRB)
• Japanese quail (Coturnix japonica) (EDNRB)

c-KIT gene

• Human (c-Kit)
• Mouse (c-Kit)
• Horses (c-Kit)
• Cattle (c-Kit)
• Pig (c-Kit)
• Cat (c-Kit)

Pax3 gene

• Human (Pax3)
• Mouse (Pax3)
• Gene for the microphthalmia-associated transcription factor (MITF)
• Human (MITF)
• fruit fly (Mitf)
• Mouse (Mitf)

SOX10 gene

• Human (Sox10)
• Mouse (Sox10)