"PLATINUM" PERSIANS (SILVER-TO-GOLD LATE COLOUR CHANGE)
While silver-and-gold has turned up in Siberians (Bimetallic Siberians), a silver-TO-gold effect has turned up in some lines of Silver Persian/Chinchilla Longhair where it has been dubbed "platinum". Thedescription of the colour change sounds simlilar to the Amber and Russet genes Amber and Russet - Late Colour Change Genes
In 1986/7, Cheryl Bennett reported in The Silver and Golden Persian Newsletter (ACFA) that one of her shaded silver females (Kelley Lane Contessa of WeANDE) had changed from pure silver to pale golden. Contessa’s parents were a shaded golden and a shaded silver; these were full siblings. At 10 – 12 months of age, Contessa began to “tarnish” i.e. show cream/reddish patches and by 3 years of age she was entirely pale golden. She produced a number of Silver Persians without tarnish, but she failed to produce any offspring when mated to a golden sire. One of Contessa’s male offspring turned from silver to golden as an adult.
An adult Silver Persian from England (Lynchard Silver Shadow) was exported to Australia as an almost snow white kitten, but later turned golden. Shadow had a few golden hairs on his paw; his whole coat turned a pale beige when he was a year old. By 3 years old he was entirely pale golden. Shadow was bred to a genetically golden female, but the pairing only produced silver offspring. However, at least one of his silver offspring later turned pale golden, againssuggesting a late colour change gene rather than genetic golden. Other descendents of Contessa also went through the late colour change. During the 1980s, several other breeders of Shaded Silver and Chinchilla Persians came forward to report that their cats had developed reddish, brownish or golden-coloured fur along their spines as they aged. Many of the cats had no golden in their ancestry. At first it was dismissed as an unavoidable genetic fault where silver was incompletely dominant and did not hide the recessive golden colour. A change of colour from black-based to reddish, starting at the spine and spreading outwards, is typical of the Amber gene.
Ana-Lan's BB, her great-grandmother and her grandsire, all turned golden by age two. Ana Lan's maternal grandsire is Platinum Beginning who traced back to Contessa. However, the idea of a new late colour change mutation was obfuscated by the fact that she also had genetic golden ancestors.
Another cat linked to the colour-changing Silver Persians was a stud cat called Kelly Lane Andromeda who shared a common ancestor with Contessa - Wicklow Donnybrook(in the UK) whose descendents were exported to the USA in the 1950s and 1960s. Some of those descendents were influential stud cats and would have spread the mutant gene far and wide.
It takes 2 carriers to produce a colour-change cat. Mary Crary Boy Tage of WeANDE appears to have been a carrier, but is not related to Wicklow's Donnybrook. He shares an ancestor with Kelley Lane Andromeda 4-5 generations back via Mary Crary Frivolous, but because all colour change cats trace back multiple times to Wicklow Donnybrook, I still think he is the origin. I wonder if there was a mis-mating and possibly Mary Crary Boy Tage is not Platinum Beginning's sire. This would not be due falsifying pedigrees, but some females have managed to tryst with another male (often one that seems sexually immature) immediately before or after their registered mating!
Like many American siver and golden lines, Kelly Lane Andromeda is connected to two early Allington imports from the UK. Firstly there is the chinchilla silver Hazeldene Felis (Fidelio of Allington x Mandy of Allington) who went to the Delphi cattery inthe USA. Secondly there was Beverly-Serrano Honey, a silver born pre-1953 to Fanfare of Allington (UK) x Lindy Lou of Beverly-Serrano. Wimauma Faustino of Allington was another English stud who contributed his genes in 1954. But all of that is a long time back and the colour change had not been observed in other lines descended from those cats. Therefore Wicklow DOnnybrook, a more immediate ancestor, is a more likely origin.
Controlled inbreeding (linebreeding) helped establish the gene, which would later double up to produce colour-changing Silver Persians. The effect of this gene on Golden Persians, if indeed it has any effect, is not known. Except for red-silvers and cream-silvers, silver cats should entirely lack phaeomelanin (red or cream pigment) and only have eumelanin (black, brown, blue etc) present. Perhaps some other gene causes the eumelanin structure to change so that it is perceived as a golden colour. Chemical analysis at the time proved that the late colour change Silver Persians did not have phaeomelanin pigment present.
From the descriptions of the colour change, the age and way it occurred and the fact that the cats did not breed as genetically golden Persians, I believe that these late colour change Persians were due to an extension gene mutation, similar to that in late colour change Norwegian Forest Cats. Genetically the cats are silver (and breed as silver) but the additional extension gene mutation turns them golden in later life.