In the crazy world of color genetics, something very interesting happens when you combine the white gene, with the colorpoint gene… But before we get to that, let's go back and take a quick referesher course about how these 2 genes actually work.
The Colorpoint Gene:
This is sometimes referred to as the "Siamese" gene, or "pointed" gene - and it is what causes the color to be restricted to only the points of the cat (the legs, tail, ears, and face).
This gene is a recessive gene, so that means a cat MUST have 2 copies of the gene in order to exhibit the trait visually. Cat's with only a single copy of the gene are knows as CPCs in the Persians - "Colorpoint Carriers" - and would be able to produce pointed kittens if bred to another cat with the colorpoint gene, but do not show the trait themselves.
The White Gene:
White is a dominant gene, and so regardless of whether the cat has one or two genes for white, the cat will always appear white. However, white is really not a separate color, but rather a MASKING color. Think of it as a winter overcoat for the cat - and know that the cat also has "regular clothes" on underneath that overcoat, which are necessary to know in order to make guesses on the color of possible offspring.
Putting Them Together
So… if you were to introduce a white cat into your Himalayan program, by breeding a white Persian to a Himalayan, you would end up with a litter of kittens that you knew carried the pointed gene - and some of those kittens would have also inherited the white gene, so you would have white CPCs.
Breeding one of those CPC kittens to a Himalayan again, statistically 50% of the kittens should have 2 copies of the pointed gene, and be Himalayans. However, some of those kittens might also inherit the white gene, and so their Himalayan color would be masked by white… Since one of the features of Himalayans from the colorpoint gene is blue eyes, these kittens will always be blue-eyed whites. So, the cat appears to be white - but underneath that "overcoat" is really a pointed cat, and because of that, the eyes are often a much more intense blue than is found in "pure Persian" blue-eyed whites. These cats are sometimes referred to as white Himalayans, or "white points".
Sound confusing? Let's look at a real world example, and see these genetics in action…
When Tanglebox cattery first started, I began with 3 Himalayan cats from Carl & Janice Shannon, of Jasea cattery. They had wonderful eye color and top heads, but needed improvement elsewhere.
Maurice Ruble of Budmar cattery allowed me to lease a Persian female name CH Katreenas Sweet Sue of Budmar.
Susan was a blue-eyed white who masked Black - but she also happened to be homozygous for the white gene, which meant she would ALWAYS produce white kittens, no matter what she was bred to.
I bred her to a seal point male, GC Jasea's Toby of Tanglebox, and she produced two kittens - both white, and both CPCs - a male, and a female.
I ended up keeping the female, an odd-eyed white, who became CH, GP Tanglebox's Pointless, DM. (Pointless is only the 2nd ever odd-eyed white to become a DM, and is the only odd-eyed white CPC DM to-date).
Since her father was a Himalayan, she was, of course, a CPC, and actually masked Black.
For one of her breedings, I bred Pointless to CH Tanglebox's Glenlivet of Kattenbach, a seal point, and had a stunning kitten born in the litter.
A lovely blue-eyed white girl, she actually masked seal point, so was a white Himalayan.
She had gorgeous dark blue Himalayan eyes, and went on to become GC, RW Tanglebox's Pipe Dreams, 10th Best Kitten in the Gulf Shore region for the 2002-03 show season.
CH Tanglebox's Glenlivet of Kattenbach
Jasea's Squint of Kattenbach
Jasea's Lexie of Tanglebox
CH, GP Tanglebox's Pointless, DM
Odd-Eyed White CPC
GC Jasea's Toby of Tanglebox
CH Katreenas Sweet Sue of Budmar