Himalayan rabbita strain of rabbit in which the coat colour is white but all body extremities are black (nose tip, paws, ears and tail). The condition is controlled by a single autosomal gene with MULTIPLE ALLELISM, one for AGOUTI, one for ALBINISM and the third for Himalayan. The dominance relationship between the three alleles is: agouti > Himalayan > albino. The Himalayan allele is temperature-sensitive, coding for an enzyme that catalyses black pigment formation wherever the skin is cooler, the enzyme becoming inactive at higher temperatures.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005