Genetics

Genetics are a big challenge and yet in a perfect world would be easy.  Today, it's really challenging through mixed breeding, hidden (recessive) genes that are in you rabbits profile that could be expressed either in all or part of a litter, even if the rabbit shows no signs of the gene present.  Pedigrees often times are a good source to help track the genetics of each rabbit, however, recessive genes may still be hidden over many generations and at times the pedigrees themself's may hold inaccuracies, such as misclassifications of color type that can bring surprises.  This is a guide to help you understand how the genetics are layed out.  This by no means will predict what you will get but give you an idea of what you can expect.  Only through test breeding will you be able to determine what a pairing will create.  For the serious breeder, it makes it all to important to have good quality stock with strong and well known blood lines.  This in turn will allow better predictability to an end result.   This page is meant to be a source of learning for basic genetics and how the known modifiers and allele's work in tandem in producing your rabbits color.  The information provided by no means will account for unknown modifiers or co-dependencies, nor get into the very deep anomalies we see within some rabbits or certain breeds.


Big Thanks to help of Sherita Hogan for making this page possible!

The Genetic Code

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A_B_C_D_E_En_Si_Du_P_W_V

 So there is your code! Get after it right? Theres a lot to it, but the basic first 6 will be the most common.  I will start at the beginning and work through each locus point and update as I get time. But to begin, I will cover each locus point and describe it broadly and we will focus on the details of each locus point as we go down the list.


A- The A locus point controls pattern (not color).  First (A) is the most dominate and reflects Agouti.  Next is (at) which reflects tan, and lastly is (a) which reflects the most recessive trait and produces self.


B- This locus point controls whether your rabbit is black (B) or chocolate (b).


C- The C locus point has several additional genes.  C- meaning full color, cchd will reflect chinchilla color removal (orange/tan) , cchl meaning shaded, ch will provide himalayen, and finally (c) if two copies present will provide ruby eyed white. (c) is the most recessive so it can always be present if in the blood line but is generally trumped by a higher up more dominate gene therefore not expressed in the color pattern.


D- This locus point controls dilution not dispersion.  Dilution being black dilutes to blue or chocolate diluted to lilac.


E- This locus point provides extension of color as a modifier.  EsE being steel, E as full extension, ej as harlequin, and e being the non-extension recessive.


En- The En locus point is also a modifier that controls broken color and also known as the English Spotting Gene.  En being the dominate will create broken color, whereas the recessive "en" will retain full color if both genes present are "en".


Si- also known as the silvering gene. This locus point only has 2 genes. The dominant Si produces normal color.  However, the (si) recessive if found in both rabbits. It is most prevalent in champaign d'argent rabbits.


Du- This particular locus point produces the dutch pattern.  Du being dominate actually doesn't change the rabbit pattern. However, two (du) genes would produce the dutch pattern you see in many dutch rabbits whether black or chocolate derivatives.


P-  P gene is called "Pink" It's responsible for lutino coloration, as well as what is called "shadow" gene. This locus point is relative to a mutation gene.  The P being the most dominate. It affects coat color and eye color and can also effect the E modifier gene.  Rabbits recieving to (p) the recessive version would have pink eyes.  It's common to see this with rabbits also with regards to the coloration around the eyes, back of the neck, and further.  This one wont come up as much as you think, however it is possible but it is a mutation that both rabbits would have to carry at least one recessive to pass on.


W- This stands for the wideband.  The banding width in the hair shaft is wider generallly.  Again, you would need both recessives (w) in the locus to create double wide banding of those two colors.  Wideband also is common in rufus color on some breeds.  It's responsible for the larger area of intense red (rufus) on rabbits such as Tan rabbits, or Tan otters, and can be somewhat breed specific.


V- This is the vienna gene.  The vienna gene is either V, the dominant, or "v" the recessive.  VV is present in normal colored rabbits.  Vv will produce the banding similar to in dutch rabbits, but usually incomplete, and not necessarily around the neck.  The most important however is "vv" which is presented in blue eyed whites where it overrides all color with white and gives the blue eyes.  This gene should be used in caution and only within a BEW program.  Mixing vienna into other non vienna rabbits will create problems in eye color, and can lead to a real mess in your other blood lines.

"A" Locus Point

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All about Agouti, Tan, and Self

The A locus point is in charge of pattern. The locus point is comprised of 3 variables of which a rabbit can only possess 2 of any variable, listed below in order of dominance:

A- Agouti

at- Tan

a- Self


A- Agouti pattern is easily identifiable by blowing into your rabbits fur and visually seeing the bands of the hairs. Generally 3 or more bands to be considered agouti. One exception however would be steel which is considered agouti, but due to later script modifications the banding is turned off. An example of an agouti would be a chestnut (pictured at left).


at- The tan pattern is the more recessive than Agouti, but dominant over selfs. These are solid colored rabbits with silvery white belly, under chest, under tail, under the jaw, inside the ears, and even a spot behind the ears.  An example being otters or martens. This can occur in brokens with white through modifiers later in the genetic string.


a- Self is pretty simple. There are only 4 self colors of Black, Blue, Chocolate, Lilac.  The self colors must cover entire body with no other colors, and with no banding or shading. However, it can occur in conjection with white in brokens.


One thing to note regarding any locus point is that only 2 variables can be placed in each.  So in this case either AA, Aa, A(at), aa, at(a).  This is the case for all locus points.  The most dominate of the two variables is what will present in your rabbit.  The recessive will remain with the rabbit, but not be visible.  A more dominant variable will ALWAYS trump a lower one, but not in reverse.  Modifiers further down the genetic color string will change, modify, or eliminate color depending on the type of modifier to produce additional colors in the self category the same as in Agouti's and the tan patterns.

"B" Locus Point

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The derivative of black and chocolate.

 The B locus point is the first determination of color.  All colors are derived from this point of the genetic string.  There are only two colors to which this point begins, black and chocolate.  There are only 3 combinations of variables:


BB- black rabbit

Bb - black rabbit

bb- chocolate rabbit


B is the dominant gene, therefore if you have a B in either position of the locus point, you will get a black rabbit.  However if both parents possess at least one "b", then a % of the kits will recieve both "b" and be chocolate.  The rest would be black.


Variations to the black and chocolate will be made further down the genetic string such as C-color modification, D-dilution, and breaking of color via the "En" locus point.  The variations will change color black or chocolate to it's new variation as we continue down the string.


The colors that are based on black, and the colors that are based on chocolate are below.  The list provides the base color, then provides it's dilution.  Will add more as time allows to this list of the most common


Black base colors and dilutions:


Black - Blue

Siamese Sable - Siamese Smoke Pearl

Sable Point - Blue Point

Chestnut - Opal

Chinchilla - Squirrel

Black Tan - Blue Tan

Black Otter - Blue Otter

Black Silver Marten - Blue Silver Marten

Sable Marten - Smoke Pearl Marten

Black Himalayen - Blue Himalayen

Orange - Fawn/cream

Black Tortoise Shell - Blue Tortoise Shell (Blue Tort)


Chocolate Based Colors and Dilutions:


Chocolate - Lilac

Cinnamon/Chocolate Agouti - Lynx (lilac agouti)

Chocolate Tan - Lilac Tan

Chocolate Otter- Lilac Otter

Chocolate Silver Marten - Lilac Silver Marten

Chocolate Himalayen - Lilac Himalayen

Chocolate Tort - Lilac Tort

The Illustrious "C" Locus

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Color, Chinchilla, and REW

So....you made it this far! Good job!  The C locus is comprised of 5 variables.  As we discussed at the end of the A locus discussion, a kit can only recieve one variable from each parent at any locus point.  So therefore, there are more combinations based on the number of variables.  The following are the variables in order of dominance:


C - Full color

cchd - chinchilla that remove orange color.

cchl - chinchilla that turns solid into a shaded rabbit

ch - himalayen which removes all color except from the points and is temperature sensitive.

c - most recessive and creates REW with cc at the locus point no matter what the string is prior.


C is the most dominate.  This will allow the rabbit to contain full color. Such as in a chestnut. 


cchd - this variable will remove all the orange shading from your rabbit. An example being a black otter that has it's orange removed by this gene to produce silver marten with no orange.


cchl - will take a solid rabbit and introduce banding.  The banding of the color coat or ticking of the hairs is the best example of this.


ch -  If you own a pointed type rabbit, this is the type of gene that causes this. It removes color from the body of the rabbit and leaves it at the points such as ears, nose, feet.  It is also temperature sensitive.  For example a really cold winter when the fur came in, would present differently than if the color came in during the summer. However, this will eventually correct after a molt of the fur coat.


c - this is the most recessive gene or variable in the locus point.  Everything above will trump c and so therefore your rabbit may carry c with any of the above variables as a second gene in the locus.  However, it is recessive and it is not expressed.  However, if you were to pair with another rabbit that carries the c in it's locus, the result would be a chance at a ruby eyed white (REW).  REW can only present if both alleles inherited are cc. Any genetic string that is cc, no matter what came before it in the genetic string will be REW. 



Diluting the "D" Locus Point

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Dilution (not dispersion) of color

Dilution is what we refer to when we talk about the D locus point.  There are only 2 variables that take place at this point.  D is the dominant, and d is the recessive.  This means the only combinations you can have is DD, Dd, or dd.  That simplifies this locus point by saying that if D is dominant, you only truly have 2 choices.  Either the rabbit is diluted or it is not since D trumps d.  However a Dd at the locus point of the rabbit means, that the recessive gene if paired with another rabbit that is Dd or dd, then dilution would be possible in the litter in some kits, and not in others.  It all depends on what is passed to each individual kit from the parents.  Any dilute color will represent in the genotype as "dd".


Examples of dilution are under the B locus point as affiliated with their base colors. Black dilutes to Blue, as Chocolate dilutes to Lilac.   


This is pretty simple when it comes to this locus point.  It is where you will also find fawn and cream. Harliquin can also be dilute so recognizing how dilute affects color is half the battle.

Extension and "E" Locus Point

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Extension and non-extension and everything in between!

So we have gotten through the first 4 points. On to the E locus!  This spot of the genetic string is where we find interesting modifications. The following variables are at play in the E locus:


EsE

E

ej

e


Those are the 4 we have to work with.


EsE is interesting as it is a steel colored rabbit.  The gene is responsible for taking an agouti rabbit and removing the rings on the hair shaft and yet all the while leaves the tipping or ticking at the end of the hair.  This produces steel color in rabbits.  A condition called "supersteel" exists when a kit recieves a steel allele "Es" twice at the E locus.  This result in the loss of the ticking on hairs in addition to the agouti rings.  Supersteel rabbits may in fact look like a self black.  Breed testing a self black to another rabbit that carries no steel allele's will result in a full litter of steel rabbits possessing only 1 copy of the steel gene.  It's dominance over whatever the non-steel rabbit transmitted results in ticking but still no agouti rings as in regular steel rabbits.  Steel rabbits can present in LOTS of ways...so many in fact, that there are still things misunderstood still.  The main steel colors are Supersteel, Gold Tipped Steel, Silver Tipped Steel, and self black steel to name the most common.


E is rather the full extension of color.  The rabbits full color expression is extended past this locus and could be enhanced by later points on the genetic string.  With this the dominate variable over ej and e, this locus will make no change to the rabbits color or markings as we continue to next locus point as long as E is the dominate variable of the two.


ej is fully responsible for harlequin rabbits.  This variable is what produces the patchy marks we see visibly as harlequin, and is only dominate over "e".   This gene is also related to producing tri color rabbits, as we will discuss further when we reach the En locus.   There are situations known as incomplete dominance between "ej" and "e".  These situations can present in many different ways, also depending on the pattern type of the rabbit.  Incomplete dominance we will not go into much til later on in the YouTube video lessons.  The result of incomplete dominance tends to be a brindled harlequin vs the proper harlequin patchwork that is desired.


The non-extension gene variable of "e" is responsible for restricting the extension of black pigment in the hair shaft but leaving the yellow and orange pigment but can appear tan/cream.  It is also responsible for turning a black rabbit into tortoise shell. black agouti into orange, siamese sable into sable point.  All 4 colors of tort (black, blue, chocolate, and lilac) can be acted on by the "e" variable.


By genetics we know that a harlequin cannot be a tort harlequin. For any tort, there must be 2 non-extension "e" genes present as they are the most recessive.  If harlequin is ej, it takes one place, the other inherited "e" is overruled by the ej by dominance, producing harlequin.  So torted harlequin is not a color that's possible.  With that said, there is still cases of incomplete dominance as described previously under the "ej" allele.

"En"veloping the En Gene

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The Broken Gene

So, this gene is responsible for it's broken pattern.  If your rabbit is broken (not literally) then it is responsible for the patches of color.  Also known as the English Spotting Gene.  There are only 2 genes at work.  


En

en


EnEn will result in "charlie" pattern. This pattern is (double broken) meaning it may only have color on hears, around the nose, but no markings on the body itself.


Enen is what will give your rabbit it's true broken pattern.


enen is most recessive and allows the solid pattern with no broken markings.


This gene is quite useful as we have discussed in previous locus points about tri-color and harlequin.  Harlequin is necessary to break into the patches created by this gene.  Therefore charlie's and broken put together with a harlequin will result in tri-color.  You may get 3 colors by other means, but, it will not be the proper patchwork that would be needed for true tri-color which is defined as broken harlequin with white.  A magpie is also technically a harlequin, the only difference in a magpie harlequin is that the orange has been removed by the chin allele at the C locus such as in the genotype of A_B_cchd_D_ej_.  Magpie's are a great example of how one allele at a particular locus point as long as it is the dominant allele can affect the color of the entire rabbit.



The "Si"lvering Gene

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Silvering and common uses

 This gene is only seen in a very few breeds. Primarily the Argent breeds, Champagne de Argent, Argent Brun, Creme de Argent.  These rabbits are born a solid, dark color. Their silvering appears  over time as they mature. This gene causes white tipped hairs to be  deposited throughout the coat, resulting in a coat that appears to have a  silver overlay. The 2 allele's are:


SI - no effect
si - silvered


 Very few of you will ever encounter this gene. The Si gene has been  introduced to the Netherland Dwarf rabbit, but they have not managed to  get it passed yet.

"Du"tchin

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Dutch Rabbits

This is not only a breed of it's own, but it gets it's very own locus point, "Du".  Dutch rabbits work very simply.  They can be blue, chocolate, blue, and lilac.  By using combinations of the genetic string prior to it.  This means that rabbits may be black or chocolate based with dilute.  The banding is around the neck, and the white on the nose is all dictacted by the 2 alleles at this locus point.  Dutch gene is represented by the following 2 alleles.


Du - does not advance the dutch banding

du - creates dutch banding


For the banding to be created, the dutch markings require both allele's to present as "dudu".  The dutch gene does not have the banding affect that is sometimes associated with vienna gene in vienna based rabbits.  It is not the cause of banding in those genotypes.  

Lutino, the "P" gene

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Lutino also known as the Pink gene

These are somewhat rare rabbits.  They require what is known as the P gene. This particular gene again has 2 alleles. This is the gene that is responsible for the Lutino coloration, it  lightens the brown pigmentation to a light brown, and produces pink  eyes. Right now, the Lutino color is mostly being seen, and produced, in  the Netherland Dwarf. As of right now, this color is not recognized in  the USA. The dilute of the Lutino gene is called "Shadow". 


The two alleles available is:


P - no affect presented in the rabbit

p - lutino is presented


As in other gene loci points, a rabbit must recieve 2 "p" alleles for the lutino to be presented.

Wideband

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Wideband and Rufus

Wideband gene is concentrated on 2 main things.  One being the wider banding of generally the middle band in agouti's, and again at enhancing rufus color in certain rabbits.  So a rabbit with standard banding in chinchilla would be normal at WW for each allele.  A rabbit also therefore with Ww would also represent the same way.  "W" is more domininant than "w".  


In a "ww" situation, the banding is double the width than what is normal.  This is particularly found in chinchilla type coloring schemes.  


Wideband is also responsible for the deep and intense rufus color of Tan rabbits, as well as Tan Otter.  The red is very vibrant and rich in color.  This can be found also in some mini rex such as castor.  One thing to note in this case, is that there will be no shading present in the rabbit.  For wideband to be present, it would be very bright, unshaded,  in the rufus areas.  As in castor, it would envelop the entire rabbit.

Vienna and the V Locus

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BEW and the vienna....

Vienna gene is solely responsible for the BEW rabbit.  In fact, vienna doesn't eliminate the color, but overrides it with white.  It's basically a colored rabbit that turns a rabbit all white and gives the blues eyes as seen in BEW.


There are 3 combinations you could see in the allele's at this locus point. 


VV - No vienna present 

Vv -  Vienna present as in vienna carriers (VC) or in vienna marked (VM).

vv - gets you blue eyed white (BEW)


So as you can see, there are 3 different outcomes.  "VV" is a rabbit that carries no vienna.  That means that it doesn't carry a "v" in either alleles, so therefore cannot produce BEW.


"Vv" however is a bit more tough to deal with.  Vv is responsible for mismarked rabbits in situations where a rabbit with no vienna or a vienna carrier rabbit is bred to a another vienna carrier.  What happens is you may get no markings as at all of white.  This type of rabbit is know as vienna carrier as one of the alleles could be "v".  It's unknown because the rabbit will exhibit NO markings or blue eyes, but still carry the vienna.


Another possibility is that the rabbit is a vienna marked.  IF the rabbits you have bred carry vienna or are marked or is a BEW, then a small patch of white behind the head, on the face, even looking like a mismarked dutch is possible.  I have even seen it marked on one foot.  


This is what makes vienna rather a dangerous gene.  Vienna should ONLY be used within a BEW program.  Breeding vienna into rabbits that don't carry it, is not only irresponsible, but will mess up every blood line you have quickly.  The vienna is known to skip 1, 2, 3, up to even 7 generations before showing up again visually.  That's why it's important for breeders to be cautious with the gene and not allow BEW stock to go with other colored stock.  BEW with other stock will only produce problems that you cannot fix. 


"vv" is the signature of a BEW rabbit.  It must be full white all over, no other markings, and have blue eyes.  The blue eyes are much brighter blue than in other blue eyes that you may see in some chinchilla's.  BEW can be a tough lesson, hence why we are doing this segment on them!  


Main thing to remember is, breed BEW to BEW as much as possible.   It's not a good idea to breed anything that is not vienna into your BEW program or vice versa.  It's also a good idea that if you are breeding rabbits outside of vienna, that purchasing a rabbit you look at not only the pedigree for signs of vienna, but also look at kits that have been produced by the rabbit.  If you happen to get a litter of kits that show vienna markings, such as blue eyes and a white spot....it's always a good idea to assume that the entire litter is potentially vienna carrier.  It just may not be expressed in the color of the rabbit.