A couple of definitions and a brief discussion:
Allele: An allele is a different version of a gene. These are caused by mutations and sometimes (not always) change the function of the gene. In this context, the mutations we will be discussing, affect how the genes produce pigment (ie rabbit color). The original color (ie allele) is called the “wild-type” allele.
Locus: This is the gene where the alleles occur.
Dominant: Takes precedent over another allele. “Strongest”
Researchers have recently located a frame-shift mutation on MLPH that corresponds to the dilution phenotype in 100% of the rabbits studied.
The Dilute Color in Rabbits
In rabbits there is a distinctive phenotype known as dilute that reduces the intensity (dilutes) both black and yellow/red pigment. Black pigment (eumelanin) is diluted to a blue or gray color and yellow/red pigment (pheomelanin) is diluted to a fawn. This results (in the absence of other modifiers and dilutions) in a rabbit that would otherwise be back being blue or gray while a chestnut rabbit is diluted to opal. Although, by studying inheritance, rabbit breeders have long known that dilution is inherited as a recessive, the causative mutation had never been located. Similar mutations occurring in dogs, cats, and mice however, had been located. These known mutations gave researchers a starting point in the search for dilution in rabbits.
Characterization of the rabbit agouti signaling protein (ASIP) gene: Transcripts and phylogenetic analyses and identification of the causative mutation of the nonagouti bla