Feline Brown (Chocolate and Cinnamon)
Feline coat color is determined by the same biochemical pathways as those found in dogs and other mammals. The colors and patterns may not be identical, but the genes that are responsible are the same as those which have been identified in the dog.
Researchers have now identified a number of mutations responsible for specific color variations in cats. Two different mutations have been identified in the TyrpI gene (B locus), which are responsible for chocolate and cinnamon. Unlike dogs where there does not appear to be any correlation between different shades of brown and different "b" alleles, in cats each of the "b" alleles is associated with a distinct color, either chocolate or cinnamon. These are both recessive.
Vetgen offers results for both when testing for "b".