Thoughts On What May Be The Genetics Behind The Cream Color In Dachshunds
Genetic terminology used in this analysis -
1-pigment genes - the unit which instructs the DNA how to produce the particular pigment.
2-Alleles- genes in pairs (one from each parent) usually denoted by letter upper case "dominant" or lower case "recessive".
3-Locus- locus and genes are used interchangeably. Locus was used for the "location" when the gene was not known. When we say E locus, we are talking about the E gene.
4- phenotype- the genotype is the genetic makeup of the individual, but the phenotype what appears as the color on the individual.
5- Recessive or Dominant genes- in which one gene is dominant to the other in an allele, example Ee means the E allele over rules the e allele, thus in order for the effects of the e allele to be shown in the phenotype both must be e.
What are the possible genetic explanations for the cream coat color in dachshunds?
1. One possibility is that the dilute red sometimes called the "American Cream. The genetic makeup would involve the A-locus (AyAy or Ayat(which carries black and tan) coupled with the recessive "ee" allele, which would dilute the red pigment into a lighter red or cream. This is easy to recognize in the phenotype as the black nose color will have a bluish tint due the the action of the dilute allele. Unfortunately, this genotype runs the risk of some degree of hair loss (alopecia).
2. The second possibility is that the recessive "ee" allele which does not allow any other color pigment such as black and tan, chocolate or brindle to express itself. These dogs tend to have light red whiskers rather than black or chocolate.
3. The third possibility is the presence of a recessive gene "chinchilla" (cch cch) on the C-locus. Some people feel this is the English Cream. Some recent studies cannot verify the existence of any gene mutation on the C-locus, except for the recessive c gene which paired in an allele causes albinism. The dominant gene C allows for normal hair color production. To my knowledge, this gene has not been proven to exist. Obviously, there is no genetic test for this gene.
4. The fourth possibility theorizes the existence of an I-locu which acts as a red pigment modifier and can change the red pigment intensity from a very dark red to a very light red (cream). Since the locus or allele has not been proven to exist, there is no genetic test available. if it does exist, it may explain how you can get black and creams, chocolate and creams and cream brindles.
Finally, while I am not a geneticist, but a fisheries research biologist, I am inclined to believe the the I-locus may be the most logical explanation for the cream colors in dachshunds. I have noted over the years in breeding dachshunds that the red color (AyAy or Ayat) varies in intensity for very dark to a very light red. Here is what I do know, the cream coat color may appear in the phenotype without: 1) the recessive red allele "ee" and 2) without the recessive dilute allele "dd". There are reliable affordable genetic tests for both of these alleles, plus other colors and patterns. Our genetic tests are done by Paw Prints Genetics located in Spokane, WA.