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Color Genetics for Ragdoll Breeders
by Dr. Solveig Pflueger
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Although many of us have heard the criticism that Ragdolls
do not breed true with respect to color, this is not
really the case. Ragdolls do indeed come in four basic
colors (seal point, blue point, chocolate point, and frost
point) with three variations with respect to white
spotting (pointed, mitted, and bicolor). However, the
colors which are possible in the offspring of a cross are
completely predictable on the basis of the parental
genotypes. Two mitted seal points can potentially produce
all twelve of the possible combinations of color patterns,
namely:
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seal point (no white)
seal mitted
seal bicolor
chocolate point
chocolate mitted
chocolate bicolor
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blue point
blue mitted
blue bicolor
frost point
frost mitted
frost bicolor
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This would require both of the seal point parents being
heterozygous for the white spotting factor, blue dilution,
and chocolate dilution.
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There are four genetic loci which are relevant to the
average Ragdoll breeder. The Siamese/Himalayan albinism
factor is a recessive gene which gives darker pigment on
the cooler parts of the body and lighter pigment on the
warmer parts. (Affected kittens are born light because
of the warm environment of their mother's womb.) Eye color
is also affected and is always blue. Since the gene is
recessive, a cat must be homozygous to exhibit the trait.
All Ragdolls are homozygous and thus breed true for this
factor.
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Blue dilution and chocolate dilution are also recessives,
which implies that a cat can be a carrier without
exhibiting the traits, which is why a mating between two
seals can produce blues, chocolates, and frosts. (The
frost is a double dilute, that
is, it is a cat which is homozygous for both blue and
chocolate dilution.)
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White spotting Is a dominant gene, which means that any cat
carrying the trait will show It. The cat which does not
carry the white spotting factor will not have any white
spotting. A cat which is heterozygous will be a mitted cat
and the homozygote will be a bicolor cat.
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Those readers who understand the above discussion will be
able to predict kitten color quite readily, but for those
who find genetics less comprehensible, the following table
should be helpful. Depending upon parental genotype, the
offspring should fall into one of the following categories:
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seal x seal
1) all seal
2) 3/4 seal, 1/4 blue
3) 3/4 seal, 1/4 chocolate
4) 9/16 seal, 3/16 blue, 3/16 chocolate, 1/16 frost
seal x blue
1) all seal
2) 1/2 seal, 1/2 blue
3) 3/4 seal, 1/4 chocolate
4) 3/8 seal, 3/8 blue, 1/6 chocolate, 1/8 frost
seal x chocolate
1) all seal
2) 1/2 seal, 1/2 chocolate
3) 3/4 seal, 1/4 blue
4) 3/8 seal, 3/8 chocolate, 1/8 blue, 1/8 frost
seal x frost
1) all seal
2) 1/2 seal, 1/2 blue
3) 1/2 seal, 1/2 chocolate
4) 1/4 seal, 1/4 blue, 1/4 chocolate, 1/4 frost
blue x blue
1) all blue
2) 3/4 blue, 1/4 frost
blue x chocolate
1) all seal
2) 1/2 seal, 1/2 blue
3) 1/2 seal, 1/2 chocolate
4) 1/4 seal, 1/4 blue, 1/4 chocolate, 1/4 frost
blue x frost
1) all blue
2) 1/2 blue, 1/2 frost
chocolate x chocolate
1) all chocolate
2) 3/4 chocolate, 1/4 frost
chocolate x frost
1) all chocolate
2) 1/2 chocolate, 1/2 frost
frost x frost
1) all frost
The white spotting factor is equally predictable:
pointed x pointed = all pointed
pointed x mitted = 1/2 pointed, 1/2 mitted
pointed x bicolor = all mitted
mitted x bicolor = 1/2 mitted, 1/2 bicolor
mitted x mitted = 1/4 pointed, 1/2 mitted, 1/4 bicolor
bicolor x bicolor = all bicolor
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Thus, the Inheritance of white spotting also follows the
usual genetic principles and even though several patterns
exist, the pattern found in the offspring can be predicted
if one knows the pattern of the parents.
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It is perhaps true that Ragdolls do not breed true with
respect to color In that the kittens need not be the same
color as the parents. However, the same is true of any
breed which is recognized In more than one color or
pattern. When one considers long established breeds such
as Persians and American Shorthairs (both of which come in
far more color combinations than the Ragdoll) one usually
doesn't question the fact that a tortie bred to a bicolor
can produce calicos, torties, bi-colors, and solids. There
is no reason to question similar Inheritance
characteristics applied to the Ragdoll. All of the color
genes found in the Ragdoll are well-known in already
established breeds where they follow the same patterns of
inheritance. The gene responsible for temperature
dependent pigmentation Is a characteristic of Siamese,
Himalayans, Balinese, and Birmans, as well as, some Rex.
Blue dilution is found In most of our breeds with the
exception of the few which do not recognize the color such
as the Bombay; even Burmese and Abysinnians have been known
to produce blue kittens. Likewise, chocolate dilution is
by no means rare. Finally, white spotting is found in the
Persian, American Shorthair, British Shorthair, Rex, Manx,
Birman, Japanese Bobtail, Maine Coon Cat and others. If
one wishes to argue that the colors of the Ragdoll do not
breed true, similar arguments can be made against many of
our other breeds as well. While some individuals may not
particularly like Ragdolls, the color pattern inheritance
cannot be used as an argument against consideration of the
Ragdoll as a breed.
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RECOMMENDED TEXTS BY SOLVEIG PFLUEGER
AT MAY 18, 1979 SEMINAR
Genetics and Animal Breeding by I. Johansson and J. Rendel
Quantitative Genetics In Sheep by Turner and Yound
Genetics for Cat Breeders by Robinson (2nd Edition 1977)
Cat Genetics by A. C. Jude
Comparative Genetics of Coat Colour In Mammals by A. G.
Searle
Genetics of Man by Paul Amos Moody
The Gene Concept by Natalie Barish
General Genetics by Adrian SRB, Ray D. Owen, Robert S.
Edgar
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