One of the most popular colors in Siberians today is the sunshine golden tabby, also referred to as CORIN gold by some feline registries. It is not a new color, but in 2021 researchers identified a specific mutation in the CORIN gene that produced the sunshine golden color. Not long after the first CORIN variant was identified in Siberians and other breeds that hale from Russia, a second variant known as extreme sunshine or extreme CORIN was identified in Siberians, and a third coppery colored variant was found in British Shorthairs.
Even before I started my own breeding program, I noted that many golden tabby Siberians, overall, did not develop from a breed standard point of view as well as other colors. They might start out as kittens competing well, but as they aged, they didn't get as big and their heads were not as round. Their adult coats tended to be shorter. But they sure were pretty.
Because I am strictly a hobby breeder and breed so I have my own cats to show, I never pursued the the goldens. I didn't care if they were in the cat's pedigree, but I never made a thing out of it for my cattery. Color is not worth a lot of points in Siberians - the standard says "clear colors and patterns preferred." What makes a Siberian a Siberian is their unique head and body structure, three-layer coat, and a charming, intelligent disposition. There's also that hypoallergenic thing, but judges don't care about that.
However, the goldens found me. I've had golden carriers in my breeding program for a long time, and at some point I'll update my cats profiles to reflect that. Sarah, my very first breeding cat carries gold. I confirmed that recently with a genetic screen. I had screened her long ago, but the variant had not yet been identified and a test has only been commercially available for about a year at this writing. This was not a surprise, as her father, Altyn, was from the Onix Gloria cattery in Russia, often sought after by other Siberian breeders for their stunning goldens. I've also assumed that Freya, Danny, and Velma all carry sunshine gold, because they had one parent that was sunshine gold. Danny and Freya are siblings and have a golden mother from Siberian Sapphire, another well-known Ukrainian cattery that produces stunning goldens. Velma's mother, also a golden, is from the Lumikissen cattery from Finland. The
origins of her golden are a little less well known to me. Knowing both Danny and Velma had golden parents, It was not surprising that in their second litter, Velma delivered her first golden kitten, Tater. It was obvious from birth that Tater's color was quite different from his brown tabby and brown tabby and white siblings.
From day 1, Tater stood out from the pack. It wasn't just his golden color. He was also a spunky little guy. Always in the front of the pack and ready for anything. Everyone loved Tater, everyone wanted Tater. He also had surprisingly good conformation and coat compared to the other goldens I'd seen. A lot of people wanted him, but we decided to hold him back along with his brother Berry and show both of them as kittens. We also had work for them at pet product expos and wanted to groom them for future commercial work.
When Tater and Berry started their show careers at the age of four months, the judges were mixed on who they liked better. Tater's eye popping color vs. Berry's near perfect conformation gave the judges a tough call. Both had beautiful, dense coats. Berry outpointed his brother in their first shows, but only slightly. As they grew, though, Berry's overall growth and development outpaced his brothers, and when they reached the age of seven months, I retired Tater from the show ring. Berry was winning breed in nearly every ring, and Tater made it quite clear he was not a fan of these shows. They were too confining for this energetic kitten. Berry, on the other hand, embraced the show life, and quite enjoyed his quality time with me and the judges. I kept Tater, though, for both modeling work and a curiosity about how he would develop overall.
The following litter had three goldens in it - a boy and two girls, plus another surprise - a blue-golden! Freya and Caleb had produced some blue - golden mackerel tabbies, but their chances were a bit better because both parents were blue mackerel tabbies and carried golden. Velma and Danny only carried the dilution variant which produces blue in genetically brown tabbies, and cream in red tabbies, so the odds were much lower.
I found something else curious about these golden kittens. Danny had one copy of the white spotting variant. This variant is dominant, so the cats only need one copy for the trait to manifest. Velma did not have white spotting, so statistically, 50% of the kittens should have white spotting. This seemed to hold true with the brown and blue kittens - approximately half had white spotting. However, none of the golden or blue golden kittens had white spotting. Statistically, two or three of them should have had white paws, and none did.
The fourth litter had no goldens in it - three brown with white and one blue with white. The fifth litter, however, had the most mixed litter yet - one brown tabby, two brown tabby and white, one golden tabby, two blue tabby and white, and one blue-golden. Once again, the golden and the blue golden had no white. paws.
I decided to do some testing to try and figure out if the lack of white paws was just a statistical anomoly or if there was something else going on. I sent in Sarah's, the matriarch of this line, Velma, her granddaughter, and Berry, her great-grandson. This would give me a picture of Sarah's line and some insights on how the traits were being passed.
The results came back a few weeks ago. Berry didn't carry golden, which wasn't a big surprise, plus he was free of the 40 odd genetic defects they screen for. He is a blue tabby and white with a very nice fawn patina that is a desirable trait in blue tabbies, so I didn't know if that patina was enhanced by the presence of the golden variant. Apparently not. Statistically speaking, he has a 25% chance of being a non-carrier. He had one copy of the white spotting gene which was expected. There was one other interesting finding, though. He had one copy of the Birman white gloving variant.
Velma was the big surprise - she had no copies of the sunshine golden variant! The rest of the test results were consistent with what I already knew about her, so it was hard to leap to the conclusion that the lab some how messed up the test. If the test wasn't wrong, then why was I getting golden kittens? Velma and Danny have produced 25 kittens. Five have been golden, two have been blue-golden. Statistically, six should be some flavor of golden if they were both carriers, and they produced seven.
The only hypothesis I could come up with is Velma had another variant - either one of the two already identified, or another one not yet discovered. But if it was a different variant, should they even produce goldens?
Maybe not, I thought. There are four different varients of the mutation that produces long hair. As long as the cat has two of them - doesn't matter which one, they will have LH. I have three different combos in the same cat in my cattery. I have detected different coat textures based on which variant is present, but it's not a perfect predictor.
I can easily test this hypothesis by testing Danny and Tater. I already had a kit for Danny but hadn't sent it in. I had tested him back in 2020 through another lab. I swabbed Danny - as expected, he came back a carrier, likely from his mother When I sent off Danny's, I ordered another kit for Tater, and sent that off. I also ordered two more kits after I got Danny's results - one for Louie, and one for Millie.
Given Tater's rich golden color, he should test homozygous for the sunshine gold variant, i.e., one copy from each parent. If he did, the lab almost certainly errored on Velma's test and I would ask them to repeat it. If Tater comes back one copy, then we have a real mystery. It likely means that Velma's golden variant is another CORIN mutation. Drumroll, please... Tater's results came back heterozygous! One copy likely from his daddy, nothing from his mom. The plot thickens.
I contacted Velma's breeder and asked her if she had access to Velma's mother, Sadie - she didn't have access, but she knew where she was. She contacted her owner and she was pleased to help, so I ordered her a kit for her - and we wait again. I've ordered kits for two more of their offspring to gather more info...stay tuned for part 2!!!!
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