The Egyptian Mau
by Bonnie Wydro and Melanie Morgan
From 1999 CFA Yearbook
PREDICTING MAU COLORS
Not being a geneticist, or even of a scientific nature, we hesitate to go into too much detail regarding genetics, even with something so superficially simplistic as color predictors via genetics in what is, or was until recently essentially a four color breed (this does not include the blue which was accepted for AOV status in June of 1997)... But here goes. We'll try to put the basics into "layman's" terms. Fortunately for those of us who are not scientifically inclined, basic Mau color genetics are inherently fairly easy to understand.
There are four main genes and accompanying alleles that impact on Egyptian Mau color: The color gene, "BB (black), the tabby gene T (striped tabby). the agouti gene A/a (agouti/non-agouti),and the inhibitor gene I/i (inhibitor/non-inhibitor), Because it is a given that Maus are BB (Black cats) and they are striped tabbies (T) with a polygene effect that causes the stripes to break up into spots and make the striped tabby a spotted tabby, the two remaining genes, the Agouti (A and a) and the Inhibitor (I and i) can be used to reliably predict the probabilities of producing silver, bronze, smoke or black kittens. The Blue, which has recently been accepted on an AOV status, complicates the issue somewhat by adding another gene into the Mau color predictor pool: The color-density gene; D (dense), or d (dilute).
BASIC DESCRIPTIONS -- THE GIVENS:
BASIC BLACK IS ALWAYS EN-VOGUE!
The color gene has three alleles, black, dark brown, or light brown. All Maus are genetically BB, or, in other words, black cats. The black allele "B" is dominant and produces a black or black-and-brown tabby coat. The presence of the agouti gene affects which of the two you get. With the Maus, when you do have an agouti gene, you get a silver or a bronze, when you do not, you have a smoke or a black. For example, the smoke and black Maus inherit an "a" from each parent. Because they do not have the agouti "A", they are black cats. The Inhibitor (I) affects whether the cat is a smoke or a black; a smoke, by definition, must have at least one "I" to produce the white undercoat, but, as usual, we are ahead of ourselves here, back to the beginning...
SPOT THE TABBY!
All Maus are genetically striped or mackerel tabbies, "T", with the stripes broken into spots by multiple polygenes. The "T" produces non-agouti stripes (shudder the thought) or, where spotted tabby polygenes are present as modifiers, spots, on an agouti background. There is no actual "spotted tabby" gene. The spots are created by polygene influence that causes the stripes on a striped tabby to break into spots. The tabby gene is responsible for the coat pattern itself. Although the "T" dictates a pattern, the appearance of the pattern is generally allowed to show through clearly with the addition of the agouti gene "A". The smoke Mau, which does not have the agouti gene, gets its pattern from the T gene. Its pattern is allowed to "show through" by virtue of the Inhibitor gene which produces a white undercoat.
BASIC DESCRIPTIONS - THE VARIABLES:
RICKI TICKY TAVI! - THE TICKING FACTOR
The Agouti gene Aa:
The Agouti gene is directly responsible for ticking and has two alleles: agouti "A" and non-agouti "a". The Agouti allele "A" produces the ticked hair that produces a tabby coat (in conjunction with the Tabby gene of course). It is dominant. The agouti basically creates an on-offdepositing sequence of Melanin granules along the hair shaft. The recessive non-agouti allele "a" suppresses ticking and produces a solid black color coat. It is important to note that the agouti gene has no impact on the Mau pattern, it merely affects the presence, or absence of ticking on the individual bands of hair.
IS YOUR MAU INHIBITED?!
The Inhibitor gene Ii:
This gene's two alleles are the inhibitor "I" and the non-inhibitor "i". Neither one of these alleles affects final color or pattern. They merely determine whether the ultimate color is built upon a clear ground color or a brown one. The inhibitor gene "I" is mutant and dominant. It is the gene responsible for creating those beautiful silvers, and the white undercoat of the smoke. Basically it "inhibits" the expression of color on the hair. The "I" effectively changes the light areas on an agouti coat from brown or rufous to silver and makes the black undercoat of the non-agouti smoke white instead of black. The Inhibitor allele "I" can be variably expressed, giving modifications on the actual appearance. When the cat has two non-inhibitor "i's", it is either a bronze or a black. The non-inhibitor allele, "I", allows the color to express itself along the length of the hair. It is wild and it is recessive.
It seems to be relatively widely accepted that the Inhibitor produces an additive affect, therefore a silver Mau with relatively little (or no) tarnish would quite likely have the genotype II.
IF MAUS ARE SO SMART, WHY ARE THEY ALL DENSE?!
The color-density gene Dd (impacts on the "blue" issue)
The dense allele "D" is dominant and produces even distribution of pigment throughout the hair, ultimately producing a deep pure coat color. The dilute "d" is mutant and recessive. It causes a concentration or "clumping" of pigment in the hair shaft which results in "diluting" the black hair of the Mau to blue by causing the black hair to reflect white light. Because the dilute "d" is recessive, it stands to reason that we see less of it in our litters. All of the currently showable colors and the blacks have at least one large D in their genetic makeup. By adding the blue as an AOV, we have effectively added four registerable colors: Blue silver, Blue spotted (bronze), Blue smoke, and blue self. All blues are homozygous for dilute, "dd".
All of the Maus that are currently showable (and the black) have black paw pads and black tail tips. Blues will have blue or pink paw pads and blue tail tips. Both queen and stud must carry a dilute gene (d) in order for a cat to be a blue.
PRECIOUS METALS - THE COLORS THEMSELVES
For the purposes of this section, we will concentrate primarily on the predictors for the silver, bronze, smoke and black.
- Silver Maus must have at least one "A" and one "I".
- A silver Mau carrying a "a" is said to be carrying smoke
- A silver carrying a "i" is said to be carrying bronze
- Theoretically a silver to silver breeding can produce any of the currently recognized colors if both silvers are "universal carriers meaning they carry smoke and bronze (AaIi)
- If a silver queen has a bronze or black offspring or parent, you know that she is "Ii" (If stud was silver as well, and they have bronze or black offspring, you know that he too is "Ii")
- If a silver queen has a smoke or black offspring or parent, you know that she is "Aa.(If stud was silver as well, and they have smoke or black offspring, you know that he too is "Aa").
Genetically all silver tabbies (and indeed shaded silvers and chinchillas) are Black, Agouti, and Inhibited. The modifiers that affect those genes are what produce such different effects.
As discussed earlier, there is some speculation among Mau breeders that the presence of a non-inhibitor "i" allele in a silver would create a silver with more likelihood of "tarnish" than a silver that carries inhibitor alleles from both sides "II". Basically, the theory is that the presence of two II's increases the likelihood of penetrance for the Inhibitor effect and thus creates a clearer, silver... there are, of course, other multi-gene factors that affect how tarnished a cat is and the degree of light or dark silver for their coat. Using this theory though, it makes sense that the silvers produced from a silver to bronze breeding would have more tarnish than those produced by silver to silver breedings because all silvers produced from a silver to bronze pairing will be "Ii". These are not the only silvers who will exhibit tarnish of course. As long as one of the silvers in a match is "Ii", silver to silver breeding can still produce an "Ii" cat and those cats seem to have a less "white silver" appearance than their "II" counterparts. There is some indication, however, that the "Ii" silvers may hold onto their contrast better than the double inhibited silvers...
- A bronze must have no inhibitor (ii) and at least one agouti (A).
- If they have a smoke or a black parent, they must be Aa.
- If a bronze queen has a black offspring or parent, you know that she is "Aa" (If stud was bronze as well, and they have a black, you know that he too is "Aa")
- Bronze to bronze can only produce bronze or black kittens
- A bronze cat with Aa is said to be carrying smoke
Genetically, the bronze Mau is a brown striped tabby with polygene modifiers to make it a spotted tabby. They must be agouti and non silver. The presence, or lack thereof , of rufous polygenes impacts on the "warmth" of the coloring. Note, the rufous effect is still widely un-defined. Because rufous is a result of a polygene effect, it is not a "yes or no", "on or off" issue. Rather, it runs a spectrum of intensity and we have yet to define all the influencers.
- A smoke must be non-agouti (aa), and have at least one Inhibitor (I)
- A smoke with genotype Ii is said to be carrying bronze
- Two smokes cannot produce silver or bronze offspring, only smoke or black
- If a smoke cat has a bronze or black offspring or parent, he/she must be Ii
The smoke Mau must be non-agouti and carry the Silvergene. Because it is a non-agouti cat the smoke Mau is therefore a "solid-coated" cat. The "aa" (non-agouti) produces extra pigment in the ground coat.. Wait a minute, you say, that smoke Mau I saw the other day sure as heck looked like it had spots to me!?! The Smoke Egyptian Mau, is to my knowledge the only smoke tabby recognized by CFA (in a sense it really is kind of a misnomer). For all other smokes, it is considered a major flaw to have pattern show through! In the instance of the smoke Mau, the T impacts by producing pattern on a solid coat, but the white undercoat, caused by the Inhibitor gene, "I" creates a wider space between spots thereby making the spots more visible. By definition, the smoke Mau also has at least one inhibitor, which produces a white undercoat. Hence, the presence of the Inhibitor in conjunction with the Tabby pattern lends itself to producing the ghostly photo-negative effect of the smoke. The clarity of the spots depends on intensity of the pattern and the overall color of the cat. Smokes do tend to darken as they get older. Keep in mind, that while breeders with other breeds are breeding to minimize pattern visibility, Mau breeders are selecting for paleness so the pattern can show through....
- The self Black Mau is aaii - non-agouti, non-inhibited
A solid black Mau is a tabby where the spaces between the spots are filled in or masked. The tabby pattern is still there - there is just extra pigment that hides the spots. Many self blacks have visible patterns in the right light - especially when they are young.
Using the three "variable" genes, we can list the following genotypes for specific Mau colors
Four basic colors:
All of the above colors have either one or two dense (D) genes.
Add in the blue issue and you effectively add four colors with the following genotypes:
Once you understand the above chart, it becomes relatively easy to begin to "genotype" your own stock and once that is done, breedings can be selected to minimize unwanted colors, etc.