Coat trait caused by mutations in the TYR gene (C locus) that produce temperature-sensitive pigmentation, with pigment restricted to the extremities. The genotypes are cs/cs (Siamese or pointed pattern, with blue eyes), cb/cb (Burmese or sepia pattern) and cb/cs (intermediate or mink). It is not a disease. Complementary, not substitutive, to the clinical examination.

Trait widespread in Asian breeds and in lines with colorpoint ancestry; limited frequency data. No breed exclusion is warranted.

- Pigment restricted to the ears, tail, legs and face
- Siamese (cs/cs): almost white torso and blue eyes
- Burmese (cb/cb): more extensive pigment, darker points and yellowish or greenish eyes
- Mink (cb/cs): intermediate phenotype
- No systemic manifestations

The Siamese and Burmese patterns were attributed to the C locus based on breeding data (allelic series C > cb > cs, Robinson 1991). Lyons et al. (2005) identified the causal mutations in TYR and Schmidt-Küntzel et al. (2005) independently confirmed them.

- Genotype the TYR (C, cb, cs) of breeding animals before mating
- C/C does not transmit the pattern; a carrier mated with a clear animal produces 0 % colorpoint and 50 % carriers
- cs/cs or cb/cb fix their phenotype
- cb/cs x cb/cs produces the three forms in an approximate ratio of 1 sepia : 2 mink : 1 lynx point
- Inform the buyer that the exact phenotype depends on the genotype

Genotyping is more reliable than the phenotype. Watch for confusion with dilution or with the complete c allele (albinism) and cm (mocha), which are not detected if the panel does not include them.

1. Lyons LA et al. 2005, Tyrosinase mutations associated with Siamese and Burmese patterns in the domestic cat (Felis catus). Anim Genet. PMID: 15771720. 2. Imes DL et al. 2006, Albinism in the domestic cat (Felis catus) is associated with a tyrosinase (TYR) mutation. Anim Genet. PMID: 16573534. 3. Lyons LA 2015, DNA mutations of the cat: the good, the bad and the ugly. J Feline Med Surg. PMID: 25701860. OMIA:000202-9685.