This recessive coat color mutation arose in the DBA/2J inbred strain. Homozygotes on the DBA/2J background are easily identifiable at 6 days of age by coat color dilution, pale ears, feet and tail. Eye color is not affected. Homozygotes are not deaf. Adult homozygotes may develop coat color mosaicism and in two instances the entire coat color reverted to nearly full color. Homozygotes are viable, fertile, produce all ge/ge offspring, and on an agouti (C3HeB/FeJ) background are extremely difficult to identify. There may be a barely discernable lightening of agouti hair on the belly or a fleck of white on the dorsum. Homozygotes on the C57BL/6J background are slightly dilute and closely resemble sepia. Coat color may be considerably lighter than normal on the belly with variable flecking on the dorsum. Occasionally the nose appears grizzled. Matings between homozygotes on either of these two backgrounds may produce some phenotypically normal appearing progeny
This recessive coat color mutation arose in the DBA/2J inbred strain in 1988 and has been located on Chromosome 1.