A glimpse into the 'white spotting gene' of Scottish Folds and Shorthairs that we breed and will continue to perfect.
We have started with this topic as when we started we found it so difficult to understand anything we was reading while researching bi-colour cats...hopefully this makes it a little easier to understand.
The 'basic colours' and patterns of cat fur are determined by less than ten genes. It is believed that cats with white colour in their coats have a mutant white-spotting
gene that prevents the formation of fur colour in patches over the cat's body. This gene has been investigated in a number of species, cats included however most research has been done with mice. This gene is co-dominant to normal coat colour as it prevents
the distribution of melanocytes from developing in hair follicles. The full genetics of this pattern (bicolour) are not as well understood in cats but at least some of the genes involved in melanocyte migration and survival may play a role similar as
in other animals. The facts are, not everything is known about the white spotting gene and it is true that genetics can regularly be unpredictable.
There is however three
genotypes possible with the S (white spotting) gene, with capital 'S' standing for a wild-type copy and lower-case s standing for the mutant.
- SS (two dominant alleles) results in high grades of white spotting (sometimes resulting in a solid-looking white cat or a white cat with just a few coloured hairs) This cat however is genetically NOT a white cat and
is genetically the colour that the white spotting gene is masking. It can be likened to a BLACK CHAIR - if you got a white sheet and draped it over the chair it would look white but there is still a black chair underneath.
- Ss (one dominant, one recessive allele) results in medium grades of white spotting
- ss (two recessive alleles) results in solid color or
low grades of white spotting (sometimes as little as a few white hairs)
Bicolour cats can come in many patterns and are often given many different names: like High
Whites, Vans, Harlequins, Calicos, Tuxedos, Piebalds etc. In the Cat Fancy they are classed as 'BICOLOUR' or 'AND WHITE'. I don't necessarily agree that those terms are definitive enough when so many Grades of bicolour exist. In showing standards only bicolour
cats with less than 40% white can be shown. There are moves around the world for this to be altered and a Harlequin section be included in the standard of British Shorthairs so that medium and high Grade bicolours can be shown.