Monday 25 July 2011

Siamese Cat Genetics

tThe bit about Siamese cat genetics that is particularly interesting is the way the pointing is created.

I'll occasionally quote Robinson's Genetics for Cat Breeders & Veterinarians if I may under fair use provisions. I am promoting the book.

"The phenotype is a form of 'Himalyan albinism'".

Production of the pigmentation that is in the hair strands depends on temperature. At a certain temperature (body temperature) the pigment is not produced while at the extremities where the skin is cooler it is.

"The albinism allele has other affects.." The visual pathway is disrupted". {see Siamese cat health}

"The seal point is a non-agouti black with the addition of the Siamese allele cs. The full genotype aaB-cscsD-. Note that Gloria Stephens in Legacy of the Cat  (page 19) says that "The genotype for a seal point shorthair is: a/a, B/-, D/-, i/i, L/-, s/s, T/-, wb/wb, w/w, cscs

Key: c=albino, cs=pointed, aa=non-agouti, B=Black, dd=dilution, D=dense pigmentation, O=red (Orange), o=non-orange. Click on this to see cat genetics symbols for more information.

The seal point is a degraded black typical of the workings of this allele.

The Blue pointed Siamese has the genotype: aaB-cscsdd.

The chocolate point Siamese has the genotype: aabbcscsD-

The lilac point has the genotype: aabbcscsdd.

The lynx point (tabby sometimes called Colorpoint Shorthair) has the genotype: A-B-cscsD-.

Blue tabby point is: A-B-cscsdd.

Blue tortie point is: aaB-cscsddOo.

Chocolate tabby point is: A-bb-cscsD-

Chocolate tortie point is: aabbcscsD-Oo.

Lilac tabby point is: A-bbcscsdd.

Lilac tortie point is: aabbcscsddOo.

Seal tortie point is: aaB-cscsD-Oo.

The seal tabby tortie is: A-B-cscsD-Oo.

All Siamese have the cscs.

The red point is: aacscsOO.

The red tabby point is: A-cscsOO.

This is not a complete list.

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