Posted on 25/01/2018

Satin (The Cream Mutation)

What is a Satin?

I can tell you what a Satin isn’t … It’s not the Hair Gene.It has nothing to do with it. In this case “Satin” is referring to a coat colour and not a coat type.

How did the name arise?

One day back in 2004, I was showing an adopter some of the mutated gerbil breeds.

The first thing she said was that they looked like Satin material. I quickly adopted that name as I thought it was quite an accurate description, and have called them that ever since.  It also made it much easier for keeping records.

What then is a Satin Gerbil?

A “Satin” gerbil is technically a phenotype mimic.  It is a soft pastel cream shade with ruby eyes and could easily be confused with other known colours such as White Bellied creams (Ivory Cream), Self Cream (a.k.a. Red-Eyed Silver Nutmeg) and Apricot by the untrained eye.  However, the big difference is in their genetics.  Even though a Satin has Ruby eyes, genetically they are P- and not pp.  This is a result of a double dose of the recessive gene that for now I shall refer to as g(x). So where the other pastel shades such as White Bellied Creams, Self Creams and Apricot are the result of a combination of diluting genes including those at the P locus, the Satin is very much a different case as it is the result of recessive genes at a single locus.  The reason for g(x) is because through breeding I believe this gene to be on the currently known G locus, and this is another mutant allele of this gene.

Gene Codes

So quite simply any combination of genes plus ‘P-’, when combined with g(x)g(x), would give us a basic Satin coat colour.  Obviously, various gene combinations plus g(x)g(x) will give slightly lighter or darker shades of Satin.

A-C-DDE-gxgxP- = Satin
aaC-DDE-gxgxP- = Satin

This was proven in very simple breeding tests when satins are bred to red-eyed gerbils and black-eyed gerbils appear in the resulting litters!

Azure Slate

What is an Azure?

Genetically an Azure coloured gerbil is a Slate gerbil which carries one recessive ‘gx’ gene and one recessive ‘g’ gene at the G locus. The new mutant gene lends a blue hue to the slate gerbil, and also the eyes are slightly more diluted than a normal slate gerbil. The Slate gerbil has a slight reddish hue to their eyes due to a very small amount of pigment dilution here being caused by ‘gg’, and with the combination of ‘gxg’ this dilution is enhanced.

When I first began to breed this coat type, I had initially thought they were normal Slates. When I bred two Azure coloured gerbils together, and these produced the Satin coloured pups mentioned above. I knew then that both parents carried a mutated gene and were not normal Slates as I had first thought.

How did the name arise?

The name Azure was chosen because of the Bluish hue this new gene lends to the normal Slate coat colour.

It was thought by some sources that I may have had the dilute gene (d) that produces the Blue coat colour on a black ‘aa’ background. This wasn’t the case because of the Satin coloured offspring being produced in breeding tests with pairs of my Azure blue gerbils.
I knew I had something very unusual happening, so my next step was to try and find out which locus this gene was on and how or if it interacted with other known mutant genes.

Nail Dilution

The nails of the Azure Slate are further diluted, being much lighter than a normal.

Gene Codes

Slate- aaC-DDE-ggP-

Azure- aaC-DDE-ggxP-

Azure X Azure (aaC-DDE-ggxP- X aaC-DDE-ggxP-) will give rise to all pups being Satin (aaC-DDE-gxgxP-), Azure (aa C-DDE-gxgP-) and Slate (aaC-DDE-ggP-)

Funky White

What is a Funky White?

Easy, it is Silver Nutmeg with gxgx. An all-white gerbil with ruby eyes.  But don’t let the eye colour fool you, they are actually dark-eyed.  Darn near impossible to tell apart from Rew’s.

How did the name arise?

I started calling them Funky Whites (FW) because they are all white and ruby-eyed, but genetically black-eyed.  Similar to our DTW’s, they are genetically P*  but have the phenotype of Ruby coloured eyes.

As with all our White gerbils, which can be quite varied genetically, so can White gerbils with a gx or gxgx combinations. The FW label is given to the Silver Nutmeg who would have two gx alleles (gxgx) instead of two g alleles (gg). Gerbils that are gxgxpp are typically our Red-eyed Silver Nutmegs and Ruby-eyed Whites. A single gx on a Silver Nutmeg has some slight changes but could also be confused with  Normal Silver Nutmeg.

Genetic Codes

Coat VarietyGenotypePhenotype
Funky WhiteaaC-D-eegxgxP-White fur, ruby eyes
Silver NutmegaaC-D-eeggP-Normal colour
Silver NutmegaaC-D-eeggxP-Slight coat dilution
R.E.Silver NutmegaaC-D-eeggppCream self
R.E.Silver NutmegaaC-D-eeggxppSlight Coat Dilution
Ruby-Eyed WhiteaaC-D—ggppWhite fur, ruby eyes

Personal Notes

I would have to say Angel was my Founder FW and her daughter Sarah came next in line. Sarah was paired with a Red Fox and she had some Nutmegs!  I knew then something really weird was going on.  But her litter colors weren’t helping me.  She had Red Fox and Nutmegs and White babies.  I bred one of her White babies when he was older, Keystone.  I paired him to Fiona another White gerbil.  All they had were Satins and Whites.  By the fourth litter, an Azure was born.  I later bred Keystone to a Lt.Deh.They had all NM, Deh and Lt.Deh.  I soon realized Keystone was the FW (SN) and Fiona was a Rew with one gx.

Genotypes for Slate & Grey Agouti

A single gx gene seems to have very little difference if any to most of the gxg coat color combinations, except for the Azure Slate coat colour which is noticeably lighter than a normal Slate coat colour. Colorpoint, Light Colorpoint, and pink-eyed dilute gxgx combinations are assumed to be White.  All gg Gerbils as we know them run a similar pattern. in some colours, for instance, the Resn, has some change in colour (dilutes further) if it is gxg.  If it is gxgx Resn it becomes an all-white gerbil with ruby eyes.

Several of these genotypes have white coats and ruby eyes, and only through test breeding with separator gerbils will you be 100% sure of what the gerbil’s actual genotype is.

Coat VarietyGenotypePhenotype
Grey AgoutiA-C-D-E-ggP-Normal, Grey colour
Grey AgoutiA-C-D-E-ggxP-Very slight dilution of colour
SlateaaC-D-E-ggP-Normal, Slate colour
Azure SlateaaC-D-E-ggxP-Dilution of Slate colour
Satin–C-D-E-gxgxP-Extreme dilution. Cream coat, ruby eyes
C.P.Grey AgoutiA-c(chm)c(chm)D-E-ggP-Normal, C.P Grey colour
C.P.Grey AgoutiA-c(chm)c(chm)D-E-ggxP-Very slight dilution of colour
C.P. Slateaac(chm)c(chm)D-E-ggP-Normal, C.P. Slate colour
C.P. Slateaac(chm)c(chm)D-E-ggxP-Very slight dilution of colour
C.P. Satin–c(chm)c(chm)D-EgxgxP-Extreme dilution. White coat, ruby eyes
Lt. C.P.Grey AgoutiA-c(chm)c(h)D-E-ggP-Normal, Lt. C.P. Grey colour
Lt. C.P.Grey AgoutiA-c(chm)c(h)D-E-ggxP-Very slight dilution of colour
Lt. C.P. Slateaac(chm)c(h)D-E-ggP-Normal, Lt. C.P. Slate colour
Lt. C.P. Slateaac(chm)c(h)D-E-ggxP-Very slight dilution of colour
Lt. C.P. Satin–c(chm)c(h)D-E-gxgxP-Extreme dilution. White coat, ruby eyes

Now let’s look at the above table again, but this time we can apply our hypothesis to the above genotypes and switch genetic notation. Below I’ve set out the allele hierarchy in order of dominance;

Hierarchy of Alleles

Uw- Full Colour.  Formerly G

uw(d)- Grey. Formerly ‘g’

uw- Cream. Formerly ‘g(x)’

Now that we understand what the (x) is in Michelle’s g(x) mutation that sits on the locus that was tentatively assigned as “Grey” by geneticists, it now becomes difficult (not to mention inaccurate) to use the old genetic notation for this allele.  We cannot continue to call it g(x), and neither can we continue to refer to this locus as being solely “grey”.  I do realise it maybe hard for people to switch, after all, we discovered way back in 2000 that Burmese gerbils were created by chinchilla medium, a similar, but different gene to that which creates the Burmese cat and changed our notation accordingly, but here we are 9 years later and people still find it hard to write c(chm) and still persist in writing it as c(b)

However, the transition shouldn’t be too painful for our gerbil geneticists out there! A few examples would be notated thus;

Golden Agouti- A-C-D-E-Uw-P-

Grey Agouti- A-C-D-E-uw(d)uw(d)P-

Black- aaC-D-E-Uw-P-

Slate- aaC-D-E-uw(d)uw(d)P-

Satin (Cream mutation)- –C-D-E-uwuwP-

Azure Slate- aaC-D-E-uwuw(d)P-

Instead of the “Grey locus” we can just as easily use the correct genetic notation for this locus which is applicable to the Underwhite series of alleles.  We certainly can’t call this locus the Grey locus anymore as test breeding has proven that this particular locus produces cream gerbil’s too, and using the same logic, we can not call it the Cream locus either!

I realise that in horses this locus is known as the Cream locus, however, the horse community only have a single allele at this locus, which is associated with

Underwhite dominant brown, but in the gerbil fancy we are in a very unique position as we not only have the recessive cream mutation on this locus but the recessive grey mutation as well. These two mutant alleles do not exist together in any fancy, not even in the mouse fancy either as far as I’m aware.  For the mouse, these rare alleles only exist in embryo in cryogenic suspension at labs such as Jackson and Harwell and are used in the ongoing research in OCA4.  In respect to previous researchers of this unique series of alleles, it is only fair that we should name the locus Underwhite.  The previous names for Grey Agouti and Slate are fine to use. Both are accurate and very descriptive, so changing their names would only invite confusion into a fancy that already has some very dubious names attached to certain colour varieties.

The New Gene in Place

As mentioned above, listing the genotypes, Colourpoint and light colourpoint uwuw gerbils run similar patterns and are presumed to be white with ruby eyes.

Below are some of the main A- and aa genotypes using the new genetic symbols for notation.

Coat VarietyGenotypePhenotype
Cream (A- type Satin)A-C-D-E-uwuwP-Cream coat, white belly, ruby eyes
Grey AgoutiA-C-D-E-uw(d)uw(d)P-Normal, formerly ‘gg’. Grey coat,white belly, black eye
Grey AgoutiA-C-D-E-uw(d)uwP-Little change with one recessive uw allele
Ruby-Eyed White (R.E. Satin)A-C-D-E-uwuwppOff-white coat, white belly, ruby eyes
White-Bellied Cream (Ivory)A-C-D-E-uw(d)uw(d)ppNormal, formerly ‘gg’. Cream coat, ruby eyes
White-Bellied Cream (Ivory)A-C-D-E-uw(d)uwpp-Assumed slight colour change with one uw allele
Ruby-Eyed White (Funky White)A-C-D-E-uwuwP-Off-white coat,white belly, ruby eyes (genetically P-)
Polar FoxA-C-D-ee-uw(d)uw(d)P-Normal, formerly ‘gg’. Cream coat with ticking, white belly, black eyes
Polar FoxA-C-D-eeuw(d)uwP-Very slight dilution of colour, less ticking.
Ruby-Eyed White (Apricot-Satin)A-C-D-eeuwuwppExtreme dilution. White coat, ruby eyes
ApricotA-C-D-eeuw(d)uw(d)ppNormal, formerly ‘gg’. Cream coat, white belly, ruby eyes.
ApricotA-C-D-ee-uw(d)uwppVery slight dilution of colour
Cream (aa type Satin)aaC-D-E-uwuwP-Cream coat, self, ruby eyes.
SlateaaC-D-E-uw(d)uw(d)P-Normal, formerly ‘gg’. Slate Grey coat, self, dark eyes slightly diluted.
Azure SlateaaC-D-E-uw(d)uwP-Diluted Slate.
Ruby-Eyed White (R.E.W.-Satin)aaC-D-E-uwuwppExtreme dilution. White coat, ruby eyes.
Ruby-Eyed WhiteaaC-D-E-uw(d)uw(d)ppNormal, formerly ‘gg’ Off-white coat, white belly, ruby eyes.
Ruby-Eyed WhiteaaC-D-E-uw(d)uwppOff-white coat,white belly, ruby eyes
Ruby-Eyed White (Funky White)aaC-D-eeuwuwP-Off-white coat, white belly, ruby eyes
Silver NutmegaaC-D-eeuw(d)uw(d)P-Normal, formerly gg. Grey coat, heavy ticking. Self.
Silver NutmegaaC-D-eeuw(d)uwP-Very slight dilution with one recessive uw allele., less ticking.
Ruby-Eyed White (R.E.S.N.-Satin)aaC-D-eeuwuwppOff-white coat, white belly, ruby eyes.
Cream Self (R.E.S.N.)


Normal, formerly ‘gg’. Cream coat, self, ruby eyes
Cream Self (R.E.S.N.)aaC-D-eeuw(d)uwppVery slight dilution with one recessive uw allele

“Wonderings & Musings”

ch, chch Theory:As in c(h) or c(h)c(h) = gx

There have been many discussions that ch or chch are involved. I have known for a very long time, This just wasn’t the case. It was one of the first things I tried checking for. Many of the Satins were CC. Many of the Slates that carried gx were Cc(chm) due to one parent being a Cp Slate or a Burmese. I have some Cch Slates with gx due to the same reason. In other words, I had placed those colourpoint genes there due to test breeding. Some Satins also have c(chm) & ch for the same reason. The colourpoints seem to make little difference.

I am currently working on and planning pure lines of Agouti and Blacks. This is done to see if the gx alone has any effect on the coat colour without interference of other recessive genes.

It seems to me it is a  simple recessive gene, not a Semi-Dominant or Dominant one. It also seems to be similar acting to several recessives genes like c(h), e, e(f) and of course p. Somewhat similar to dd as it has the ability to bleach the coat and eye colour. One g(x) gene will dilute a Slate leaving a darker tail and often facial points and/or mask. Although the feet seem to remain light.  I have noticed this “point” effect in specimens of blue gerbils.

The Satins and Whites (some) seem to have an ever so slight darkness in their tails.


Young Satins and Doves can be easily confused by the inexperienced eye. Especially if the Dove carries the e gene. So can Siamese. The Siamese tend to have a darker eye slit

More Thoughts…

Recently I began to ponder if the positioning of g(x) on the allele would make a difference in shading.

This could also explain why the Satins come in darker or lighter shades.

Given any gerbil with homozygous genes, the offspring will be guaranteed to have one of the genes.

I have toyed with the same idea with c(chm)c(h) gerbils.  Keep in mind everything at this time is based on theory. As far out as it may seem at times, It is only speculation. My expertise does have its limitations.

With a Slate x Satin pairing, you have gg, g(x)g(x), resulting in the offspring probabilities being g(x)g or gg(x). One way being near normal and the other resulting in a much lighter shade.  They would produce Slates Dilute (Azure Slate), but no Satins unless the Slate has g(x).  I suppose you could go as far as saying it’s possible it’s (x)g. g(x) makes a notable difference most Slates.

I have since then learned from Ed that polygenes may play a good part in the above statementPolygenes coupled with other hidden recessives can account for much of the shade variability that I have seen in my breeding.  Although I feel another variant of this gene may be involved, I do not have enough data to prove it at this time. Future plans will be made to test this.

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