Before we get into the particulars of color inheritance, a brief overview of the terms geneticists used to describe colors in dogs is in order. As well as an overview of all color genes present in Miniature Schnauzers.
This discussion for the most part will be confined to White Mini Schnauzers.
Each series of genes involved in creating different aspects of creating the coat color we see, is represented by a letter of the alphabet. Each series is called a locus. Each gene within a series is called an allele. Every dog carries two (2) alleles at each locus.
Series
The A Series--A stands for AREAS of dark pigment. Sometimes referred to as "pattern" genes. As=solid (in our breed, generally black**, sometimes brown); Aw=Agouti, or "wild color"commonly referred to in this breed as S/P; ay = red-sable (not applicable in this breed) and At=tan-points, expressed as black/silver
The B Series--B=Black; b=brown
The C Series--This series is one of the two factors that are involved in producing the white miniature schnauzer. They will be discussed in detail below.
The E Series--This is the second of the two series involved in creating the white miniature schnauzer. It will also be discussed in great detail below. Other e series members (generally considered to belong to this string) but not noted in this breed are Em (masking gene -- as in fawn pugs) and Ebr (brindle -- as in Bouviers, Bullmastiffs, etc.) However, these may indeed be at the "new" K series.
The G Series--G=Progressive fading from birth; g=coat remains at full color strenth for the life of the animal.
The K Series -- A NEW THEORY see LINKS at the bottom of this page for Sue Bowling's article
The S Series--S stands for Spotting. All dogs not parti-color carry S the highest allele. The other alleles are, in order, si=Irish spotting; sp=parti color spotting; swh=extreme white piebald.
The T series--T is for Ticking. T=ticked; t=non-ticked.
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How the Series are expressed in a full genetic formula for a dog
The typical, homozygous salt and pepper mini carrying no recessives for white, brown, or parti-color would be as follows:
aw aw B B cch ce E E G g S S t t
The C and the E series and how they create the white miniature schnauzer
We are going to start with the E series as it is easier to understand and lays the basis for forming the white miniature schnauzer.
E stands for Extension of dark pigment. E is the dominant allele; present in all miniature schnauzers not white, cream, red (more on this later in C series.) E is carried by all Salt/Peppers, Black/Silvers, Blacks, partis, & browns. If a "colored" mini is carrying white factors, he is Ee at that locus. If he meets in breeding another Ee, the two will produce whites. The e is recessive. The double ee recessive restricts the dark pigment to eyes, nose, & pads. What color is left when the dark pigment is restricted to those areas? That is determined by the C series.
C is Color Strength determiners. The most important thing to remember about the C series is that IT HAS NO EFFECT ON BLACK ("dark"--black or brown) pigmentation. It ONLY affects what geneticists refer to as "blonde" pigment. (for our purposes in this discusson-- the light areas on S/P and B/S; (including both the 'furnishings' as well as the light part of the banded hairs of s/p) and whether an ee mini is going to be red, reddish/cream, cream, or ice-white.
C--Dominant to all other alleles. Allows full pigment to be distributed throughout the coat. (As the pattern gene allows) In ee minis, it produces red. THESE are BANDED hairs with red to cream to white just as a s/p banded hair is black to grey to white/cream. In s/p Minis, we get the reddish-looking pepper which was common in the early days of the breed.
Cch--"Chinchilla"--pales the ee to a cream or just off-white color. This is the gene that was selected for by early Mini breeders to create what they then called a "clear salt/pepper".
Ce--Extreme paling of red/yellow pigment. All ice white minis are ce ce at this locus.
Intermediate types of allele pairings cause intermediate types of color, i.e. C cch would be lighter than red but not as light as cream; a cch ce would be just off ice-white towards the cream color.
Creams/reds tend sometimes to have darker (reddish) stripe down the middle of the spine, just as s/p minis sometimes have the black or darker stripe down their spines. The exact cause of this in both cases is unknown.
The "white" we see today can trace its origins back to the RED miniature pinschers used to bring the size down on the Standard Schnauzers in creating the Miniaturized version. Possibly more of these genes could have been added later, as there are references in history to possible crosses to poodles or pomeranians, both which carry this same genetic formula.
However it got here, it is here, and here to stay, and as much a part of our breed as the black/silvers, who of course, trace their at genes back to the black/tan miniature pinschers. It is the cch and ce that pale the "tan" points to cream and off-white and give us that flash dog we call a black/silver!! Of course, in countries where the white mini is banned from conformation showing, the gene e has been selected against for many generations in show stock.
Therefore, the genetic formula for an ice white miniature schnauzer which came from, for the purposes of this example, Black and black/silver stock originally, would be:
(Example #1) As at B B ce ce e e G g S S t t
If he were from many generation of pure black stock he would be:
(Example #2) As As B B ce ce e e G G S S t t
A cream colored mini from salt/pepper stock would be:
(Example #3) Aw aw B B cch cch e e g g S S t t
These "hidden" pattern genes (meaning whites carrying two alleles at the A locus; and will produce, when bred to a self-colored dog, (not carrying for white) in the ratio according to the A series alleles he carries,) of the white miniature schnauzer, is why a white is able to be bred to a Salt/pepper, and produce black, as could the dog in example #2 above, certainly could!
The subject of "mismarks"
The genes that cause the white miniature schnauzer, are not, in themselves, the cause of any mismarks. The causes are: Minus modifiers of the S series (even in dogs that are not, or do not carry for white or parti) and/or the actual presence of one of the lower alleles of the S series. Self-colored dogs carrying for parti are often "mismarked," meaning white chest spot, white on toes and/or legs, and sometimes a small white "spot" on underside of chin. Again, these mismarks are created by the lower alleles of the S series, (or simply minus modiers of S)and are not actually caused by the crossing of a white mini to a self-colored mini.
