Reference work entry
A Siamese cat displays darker fur color at its extremities because during slow blood circulation, more pigment develops at specific locations of the body. This is due to the presence of a temperature-sensitive gene, similar to Himalayan rabbits and other animals. The pattern distribution is due to a transition mutation from G→A in the 2nd exon of a tyrosinase gene, resulting in replacement of glycine by arginine (Lyons LA et al 2005 Anim Genet 36(2):119). The mutant allele produces pigment at the lower temperature of the extremities; it is thus a modification of albinism when pigment formation is absent in the entire body. Normal function of tyrosinase is required for the production of melanin, a pigment of fur color. pigmentation of animals, Himalayan rabbit, temperature-sensitive mutation, see Fig. S54.
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