Expert: Norman Auspitz - 1/10/2010

Question
hello, i have recently breed my siamese for the first time, and we are waiting to find out if she is pregnant, i was hoping you may be able to tell me what color kittens we would be likely to get? my girl is a seal point and the boy is a blue point, i don't know which color is more dominant? or if that is how it even works? i know the kittens would be born white but i would love to know what to expect as they begin to get there color.

Answer
Hayley,

Seal point is the original wild color of the Siamese and is dominant over most other colors.  The blue point is determined by what is called the density or the dilution gene.  In the wild state the density gene (denoted "D") has no effect on the pigment. There is an allele (denoted "d" and called the dilution allele) which can affect the pigment so that it is less densely distributed in the hair shaft, making the cat appear as a blue point.

The way it all works is that each kitten will get a copy of the density gene from each parent. For a cat to be a blue point, both copies of the density gene (i.e. from each parent) have to be "d" (this is denoted dd).  If you have both copies as DD or as Dd or dD, you will have not dilution. So, since the blue point is dd, each kitten will have a d on one side of the density gene. If the seal point is DD (i.e. does not carry the dilution allele), all the kittens will be Dd or dD, which in either case all will be seal points.  If the seal carries the dilution allele, then one could expect some of the kittens to be Dd or dD (these will be seal points) and some to be dd (these will be blue points). This type of allele is called recessive as it is dominated by the wild allele.

One way to tell the color early on is to look at the paw pads.  The seal points, generally, have black or sepia paw pad color and the blur points have slate blue to mauve paw pad color.

Of course, I am assuming neither parent carries chocolate which would introduce a whole other complicating factor.

Best regards... Norm.