Postulated Color and Pattern Loci
There are at least five additional theoretical loci thought to be associated with coat color in dogs. DNA studies are yet to confirm the existence of these genes or alleles but their existence is theorised based on breeding data:
C (colored) locus
The alleles at the theoretical C locus are thought to determine the degree to which an animal expresses phaeomelanin, a red-brown protein related to the production of melanin, in its coat and skin. Five alleles are theorised to occur at the C locus:
- C = Full color (animal expresses phaeomelanin)
- cch = Chinchilla (partial inhibition of phaeomelanin resulting in decreased red pigment)
- ce = Extreme dilution (inhibition of phaeomelanin resulting in extremely reduced red pigment)
- cb/cp = Blue-eyed albino/Platinum (almost total inhibition of phaeomelanin resulting in near albino appearance)
- ca = Albino (complete inhibition of phaeomelanin production, resulting in complete inhibition of melanin production)
The C locus in dogs is not well understood and the theorised alleles are based on those present in other species. True albinism has not been conclusively shown to exist in dogs. It is thought that an animal that is heterozygous for the C allele with one of the other alleles will express a result somewhere between the two alleles.
F (flecking) locus
The alleles at the theoretical F locus are thought to determine whether an animal displays small, isolated regions of white in otherwise pigmented regions (not apparent on white animals). Two alleles are theorised to occur at the F locus: they cAN BE PINK
- F = Flecked
- f = Not flecked
It is thought that F is dominant to f.
G (progressive greying) locus
The alleles at the theoretical G locus are thought to determine if premature greying of the animal's coat will occur. Two alleles are theorised to occur at the G locus:
- G = Premature greying
- g = No premature greying
It is thought that G is dominant to g.
I (intensity) locus
The alleles at the theoretical I locus are thought to affect phaeomelanin expression. Two alleles are theorised to occur at the I locus:
- I = Intense red, not diluted
- i = Not intese red
It is thought that I and i are co-dominant, so that animals with i/i will be paler than animals with I/i.
T (ticking) locus
The alleles at the theoretical T locus are thought to determine whether an animal displays small, isolated regions of pigment in otherwise white regions (not apparent on non-white animals). Two alleles are theorised to occur at the T locus:
- T = Ticked
- t = Not ticked
It is thought that T is dominant to t.
Read more about this topic: Dogskin, Colors, Patterns, Lengths and Textures
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