Genes affecting color
This locus controls the changes between black and yellow pigments within individual hairs. In other species the A locus can control the distribution of color on the back and belly.
Gerbils have three color bands on the hairs. The tip of the hair is called ticking, this is black. The undercoat of a gerbil refers to the middle and base layer of the hair. The middle of the hair on an Agouti is yellow. The base is gray.
In gerbils there are two alleles at the A locus. A is dominant agouti, and a is recessive non-agouti. Homozygous recessive aa affects the extension of eumelanin in the agouti hair. and causes the coat to become solid black. It primarily affects the undercoat.
It is unikely that the gene we currently denote as d, dilute at all, There are a few better candidates, slaty and
P- Pink eye
Pink eye dilution in mice is largely caused by a reduction in the size of the pigment granules inside the cells. (sources). In general the affect is more dramatic on the black pigment, and hardly effects the yellow pigment. Black becomes gray.
Genes affecting fur