Siamese and Burmese patterns (Colourpoint Restriction)

The Siamese pattern is reponsible for a phenotype representing a mild form of albinism. This temperature-sensitive mutation produces normal colour pigment only at the cooler extremities of the body, causing a "mask" of the face as well as darkened paws and tail. The Siamese pattern is also called mask factor or point, since normal pigmentation occurs only at the cooler points of the body.

The Burmese pattern, the mildest form of albinism, is characterized by a normal pigmentation of the extremities and a slight shading of normal body colour.

Two mutations in the gene encoding the enzyme tyrosinase which is required for melanin production are responsible for these colour variants. This gene locus is called C-locus. The wild type allele C is dominant and causes full pigmentation, the Siamese cs allele is recessive and leads to the characteristic distribution of the dark colour on ears, mask, tail and legs when in the homozygous state. The Burmese pattern also follows a recessive inheritance and leads to the coat colour Burmese brown in the homozygous state, with varying degrees of black and dark brown.

Requirements

The tests are performed out of EDTA whole blood (0.5 ml) or cotton swabs. These cotton swabs are available upon request. Testing is performed a few times per week at Laboklin. The results are due about one week after arrival of the sample in our laboratory.