REVIEW OF PATTERN & PREDICTION
written by Robin Pickering. May 1995
Within the Ragdoll Breed, we are fortunate to not only have 4 recognised colours, but also 3 patterns. However, though this may be a blessing to the novice breeding with 3 patterns, it can provide something of a puzzle. There are still those who think that the Mitted pattern is carried in a similar manner to that of the recessive gloving gene found in the Birmans. Perhaps the simplest way of explaining how the various patterns are inherited is to look a little more closely at the basic genotype or genetic code of the Ragdoll.
The Colourpointed pattern within the Ragdoll is due to the recessive colourpoint gene cs , probably the same gene as found in Siamese and Birmans. Its coat length is again due to a recessive gene, l, in its dominant form it gives us a short coat, and in the recessive a longer haired coat.
Finally, the Colourpointed has no dominant white spotting gene, S, and its absence in the code is written as ss, (note the lower case letters). So in summary, the Colourpointed genotype is cscs llss; this reading as a colourpointed longhair with a complete absence of white.
The key difference in the remaining patterns of Mitted and Bicolour is the presence of a dominant white spotting gene, though as both patterns differ, a slight modification between the white spotting gene probably exists. To simplify, a Mitted has again, like the Colourpointed, pairs of recessive genes for colourpointed and longer hair, but has one dominant white spotting gene, S. Though not generally recognised in genetic jargon, for our purposes it may be helpful to consider this gene as S1, representing the white spotting gene: expressing itself at Level 1. A basic genotype could be written as cscs llS1s.
In the case of the Bicolours, it has an increased distribution of white patterning on the body and to help distinguish the patterns we could call its white spotting gene S2, representing the white spotting gene expressing itself at Level 2. Again a basic genotype for a Bicolour could be written as cscs llS2s.
Now, let us suppose we mated a Colourpointed to Colourpointed, remember the genes are in ‘equal’ pairs, so when divided, (in the case of a sex cell) and reunited at conception, the genotype of the embryo will again be cscs llss, a Colourpointed Ragdoll.
In the case of Colourpointed x Mitted, a similar thing happens, but the Mitteds sex cells divide equally and 50% will have an absence of the white spotting gene and the remaining 50% will carry it. This expresses itself in the litter as 50% Colourpointed offspring and 50% Mitted offspring, the situation being the same in a Colourpointed to Bicolour mating when the litter will again be equally divided 50% Colourpointed; 50% Bicolours.
If we take a Mitted x Mitted, then we have a situation where 50% of the sex cells from each parent have the Level 1 white spotting gene, and there is a 1:4 chance that these meet up, so what will this kitten look like? Again we have recessive pairs of the colourpoint and longhair gene, but it also has a pair of Level 1 white spotting genes – cscs llS1S1. If we combine the levels of the white spotting gene together, we arrive at Level 2 expression, similar to a Bicolour in the amount of white on the body, but as this “Bicolour” has two white spotting genes it is termed as homozygous for the white spotting gene (in other words it carries the identical gene twice); whereas our more familiar Bicolour is heterozygous, (meaning it only carries a single white spotting gene). We call this a ‘High Mitted’.
If we mated this “High Mitted” Ragdoll to a Colourpointed Ragdoll, the sex cells again half, but all the cells from the “High Mitted” parent carry a white spotting gene at expression Level 1, so all the offspring will inherit this and have a cscs llS1s genotype; all the kittens are Mitted in pattern.
A similar situation occurs if two Bicolours are mated together; there is a 1:4 chance that a kitten receives an S2 gene from each parent and has a genotype cscs llS2S2. Taking the level numbers from the spotting genes and pairing them together, we arrive at Level 4 expression of the white spotting gene. The white patterning is now expressed at the highest level possible, and in appearance the cat has a ‘Van’ pattern with residual colour restricted to the extremities of the head and all of the tail. This Level 4 Bicolour we term as a “High White”. Once more the cat is homozygous for the Level 2 white spotting gene. If mated to a Colourpointed, it would produce all of its sex cells carrying a Level 2 white spotting gene. The resulting litter would all inherit an S2 gene and be perfectly normal Bicolours.
Finally, if we mated a Mitted and Bicolour together they also have a 1:4 chance of their spotting genes combining and producing a kitten homozygous for the white spotting gene, except it will receive an S1 from its Mitted parent and an S2 from its Bicolour parent; its genotype is written as cscs llS1S2. When combining the levels together we now arrive at Level 3 expression of the white spotting gene, and in appearance a Bicolour, though with more white than a usual Bicolour, but less than a “High White”. We term this Level 3 Bicolour as a ‘Mid High White’.
Therefore, it can be clearly seen, that when mating patterns together, other than Colourpointed, there is a chance that a kitten can be produced of extreme pattern. It becomes quite clear why the Ragdoll BAC recommends at least one Colourpointed parent in any Ragdoll mating. To avoid these situations from arising, and if a breeder is determined to mate other patterns together, they must be aware of the offspring’s pattern that could be produced.