Dilute is an autosomal recessive trait that causes clumping and uneven distribution of pigment granules in the hair shaft, producing dilution of all coat colors.
Phenotype: Pigment granules in the hair shaft are clumped and unevenly distributed, producing dilution of coat colors. For example, black pigment is diluted to gray and red is diluted to cream.
Mode of Inheritance:Autosomal recessive
Alleles: D = Wild type (full color), d = Dilute
Breeds appropriate for testing: Many breeds
Explanation of Results:
Cats with D/D genotype will be full-colored and cannot transmit this dilute variant to their offspring.
Cats with D/d genotype will be full-colored and are carriers of this dilute variant. Matings between two carriers of dilute are predicted to produce 25% dilute kittens.
Cats with d/d genotype will display dilute coat color(s) and will transmit this dilute variant to all of their offspring. Matings with other d/d genotype cats are expected to produce all dilute offspring.
Note: Overall appearance of the cat's coat also depends on expression of and complex interactions with other genes.
A mutation in Melanophilin(MLPH) causes clumping and uneven distribution of pigment granules in the hair shaft, producing dilution of all coat colors. Dilute is caused by the deletion of a single base (c.83delT) resulting in disruption of the MLPH protein product. Dilute is an an autosomal dominant trait, which means that two copies of the dilute allele are needed to produce the phenotype. Black pigment is diluted to gray ("blue" is the term used by cat breeders), and red is diluted to cream. The wild type allele is non-dilute. Some cat breeds are fixed for the wild type, such as Egyptian Mau and Singapura, while others are fixed for dilute, such as Chartreux, Korat, and Russian Blue. Most other breeds have both wild type and dilute alleles.
This test for the dilute gene is useful to identify carriers of dilute and to determine the genetic type for young animals that may have yet to develop their adult coloration.
Sections reprinted with permission of Leslie A. Lyons, Ph.D.
One copy of dilute allele. Cat is a carrier of dilute.
Two copies of dilute allele. Coat color is diluted.
Ishida, Y., David, V.A., Eizirik, E., Schäffer, A.A., Neelam, B.A., Roelke, M.E., Hannah, S.S., O'brien, S.J., Menotti-Raymond, M. (2006). A homozygous single-base deletion in MLPH causes the dilute coat color phenotype in the domestic cat. Genomics,88, 698-705. doi: 10.1016/j.ygeno.2006.06.006