Dogs have at least 10 major canine coat color genes and an unknown number of minor ones. (ashgi.org)
Additionally, Gray offspring from Blue parents are considered to be purebred Gray and will never pass on the blue coat color genes. (blueriverweims.com)
A dog with two variant copies of the MLPH gene will have a blue, charcoal, Isabella (lilac) or fawn coat color depending on the other coat color genes present in the individual. (pawprintgenetics.com)