Question
my cat
Hello!
I would like to ask a seriously "scientific" question :)
I'm a proud owner of a gorgeous traditional Siamese male, and I'm at university learning biotechnology, meaning I'm super interested in genetics. What I would like to know is:
My boy is the son of two seal point Siamese, but his colour differs pretty much from his parents'. And by different I don't mean blue, I mean he's rather chocolate.
No matter how much I searched, I just couldn't find out if seal or chocolate point is the recessive phenotype. What I know is, Siamese colour depends on four genes, and the second one (bb or BB) decides if he's seal, or chocolate.
Please help me out with a little information, I'm eagerly looking for an answer for half year :)
Thank you in advance, and happy new year!
Livia
AnswerLivia,
Happy new year back at ya'!!!!!!!!!
The best source of feline coat color genetics is the latest edition of Roy Robinson's "Genetics for Cat Breeders".
I do know one of the authors and have much faith in the accuracy of this text, based on what we know currently.
To get back to your question: The so-called brown gene has three alleles. The B is the wild gene and will give you seal point, if no other modifier is in place (e.g. the density gene [Dd]. or the sex linked orange gene [Oo], etc.).
To get chocolate, both parents must be carrying the b (chocolate) allele and the progeny may be homozygous for bb. So, BB, Bb, bB will give you seal, and bb will give you chocolate. There is one other allele of the brown gene, called cinnamon allele, denoted b1. Cinnamon is recessive to chocolate which is recessive to the wild allele. Cinnamon rarely occurs in Siamese, so I would not worry about it, but here is the full breakdown:
BB, Bb, bB, Bb1, b1B all give you seal. bb, bb1, b1b would give you chocolate, and b1b1 would give you cinnamon. The archetypal cinnamon cat is the so called red or sorrel Abyssinian.
I hope this helps.
Seasonal regards... Norm.