The locus D or dilution refers to a mutation in the MLPH gene that causes a diluted coat colour. This mutation dilutes black to blue, chocolate to lilac and yellow to champagne. The mutation tested is the d^2 mutation and is specific to the Chow Chow, Sloughi and Thai Ridgeback breeds. For the other breeds, the test to be performed is the DOG-LOCUS-D test.
