e. E allows normal expression of eumelanin and/or phaeomelanin according to the alleles present at the A and K loci. Em allows similar pattern expression to E except any tan (phaeomelanin) areas on the mask area are replaced with eumelanin (black/etc.) The mask can vary from the muzzle, to the face and ears, to a larger area with shading on the front and sides as in the Belgian Tervuren. The mask Em is unaffected by the greying gene G and will remain dark in a G/- animal while the rest of the dog pales, such as in Kerry Blue Terriers. Some puppies are born with a mask which fades away within a few weeks of birth: these puppies do not have the Em allele and their temporary mask is due to sabling. An animal that is homozygous for e will express a red to yellow coat regardless of most alleles at other loci. Eumelanin is inhibited, so there can be no black hairs anywhere, even the whiskers. Pigment on the nose leather can be lost at the middle (Dudley nose). In combination with a/a (phaeomelanin inhibitor), an e/e dog will be white to off-white; in combination with U/U or U/u, an e/e dog will be off-white or cream. The Grizzle allele has been studied only in Salukis and Afghan Hounds, the latter in which it is referred to as "Domino", but also occurs in the Borzoi. Its placement in the dominance hierarchy has not been solidified. Black with fawn-tan points (at/at E/-) is instead dark-sable with extended clear-tan points (at/at EG/-). Brindle affects fawn and sable areas, resulting in black with bridled-tan points (at/at E/- Kbr/-) or brindle with clear-tan points (at/at EG/- Kbr/-). Expression of EG is dependent upon the animal being homozygous for at and not possessing Em or KB. EG is theorized to have no effect on the phenotype of non-at/- nor KB dogs and to be allelic to Em and e. Little information exists regarding the Ed allele. In behavior and appearance it almost mimics the Grizzle allele found in Sighthounds, however it is not the same mutation. Domino animals of this type will either have two copies of the mutation or have a single copy paired with e. The eh sable extension allele has been studied only in English Cocker Spaniels and produces sable in the presence of dominant black KB and tan point at/at.