Kaninchenwissen

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Some time ago I was asked from an American, if I can help him to translate a website. There had been photos from yellow/fawn/red dwarfs with red eyes.
Yes, you listened right: red eyes in a non-albino.

How can this happen? Which gene can cause such coloration? Actually, only a new, but since when is it known? Above all, if someone really have found a new gene changing the color, why nobody knows? Why is nothing to read or hear from it, even in times of Internet? \nThe few documents I found about lutino rabbits was mostly written in Danish or Norwegian. Nevertheless, I probably found pretty much everything, which could be found about it.

The History

The first fawn rabbit with red eyes was found 1985 in a litter of japanese dwarfs by the Danish breeder Gerner Rasmussen. He dont culled them, but kept them and repeated this pairing. In a 3rd litter he again found an animal with red eyes. The offspring of these animals formed the basis of a new breed. Dwarfs in the colors Lutino and Shadow were recognised in the Scandinavian standard in October 1988.

Lutino has yellow to orange coat color. Undercolor, belly and agouti markings are creamy or white, eyes red.

Shadow has creamy yellowish coat color with light blue parts. Undercolor is light blue, even lighter to the skin. Belly and agouti markings are creamy or white, eyes red with a weak blue iris.

New mutations, moreover the "usable" ones, are not so common. The most recent mutations found in rabbits was the light chinchilla factor in 1924 and the satin factor in 1930. If you consider the lutino factor was first found in rabbits more than 20 years ago, it's surprising, that he is so completely unknown.

The Lutino factor

Searching for a factor causing red eyes and heavily dilutes dark pigment inevitably leads to the factor "red eyed dilution." This factor is known for a long time in the mouse (the best investigated mammal) and other rodents. In people it causes a form of oculocutaneous albinism (OCA 2).
The factor is symbolizes with p.
Silvers wrote in "The Coat Colors of Mice" about the allele p:

The eyes of p/p mice resemble those of albinos, possessing a beautiful pink tint. However, in contrast to albino eyes, p/p eyes are not completely free of pigment; small amounts of melanin are found in the iris and retina (Durham, 1908, 1911; Little, 1913) and a few melanocytes occur in the choroid as well (Markert and Silvers, 1956).
Insofar as it concerns the pigmentation of the hair, p drastically reduces black and brown pigments, but has only a slight influence on phaeomelanin synthesis.
Thus, except for the color of the eyes, the yellow versions with and without p/p looks much alike. Agouti pink-eyed animals also superficially resemble orange or yellow animals although they possess dull or slate grey hair bases which are recognized most readily when the hair is blown.
Colors with p/p resemble the diluted colors blue and lilac, but are lighter.

In mice, there are a whole series at the locus P. Among them are alleles causing reduced growth, infertility, movement disorders and a defective tooth wear effect. The only known effect of p-mice is, except the reduction in pigmentation, a slight reduction in body size (Grueneberg, 1952).
On looking at lutinos we accordingly see, they look like normal, yellow/red agoutis with red eyes. Their gene code is ABCDee pp. The purity of color benefit from the Lutino-Faktor who heavily lighten the dark pigment and let possible smut disappear.
The Shadow (picture right) looks very similar, but is still lighter. I can't really find the "lightblue" underolor, they is just very light, almost white. The Shadow in the photo is a combination of steel/red (Es/e, this would look like solid black without pp).

Naming

The new mutation found in rabbits has received the designation Lutino. They was symbolizes with u or lu (the letter L is already being used for angora/longhair) in the european Symbole system. However, I would urgently propose the use the designation P and p, as already common in other mammals . The appearance speaks for the same gene beeing at work.
For comparison, a mouse and a guinea pig (with flash eyes) with the gene code ABCDE p.

In Norway a few breeders are working on other color varietys. There is an attempt to breed a "true" red rabbit with red eyes, the Rubino. (The name was taken over from the red birds with red eyes.)
Geir Nordvik tries to breed a black rabbit with genetically p and Roar Strand is breeding the factor to a tan rabbit. This combination looks like a lilac tan (left a 6 week old kit). However, after loosing the nestwool the animal change the coat color to nearly yellow. This shows, thats in tan rabbits the yellow pigment is not only in the tan markings but everywhere, even in the dark hair. This could be a reason for the especially intense black of tan animals. Since the new gene greatly dilute the Eumelanin, i think it is possible that it is simply no longer able to hide the yellow pigment, which is the cause for the yellow appearance of this animal.

Whether this is true, one can easily find out theoretically. One need simply to add the Chinchilla factor. Practically it is a bit difficult. Take a Shadow ABCDE p and breed him to a Silver Fox AtBcchdDE P. Now, breeding siblings together, we "only" need to get cchd, at and p together in one rabbit. With 3 factors, we have a chance of 1:64.

Colors and mice

Ok, yellow/red or lilac rabbits are not sooo special, even if they have different colored eyes. But the lutino factor could also allow color shades who not exist yet in rabbits.
Mice, for example, come, beside dove (red eyed dilution black based), in silver and champagne. These are the combinations from lutino with blue or chocolate. With lilac its named lavender and then apparently looks almost white.
Champagne looks nice, such a bright, smooth cream. But currently it looks like all pp rabbits become more or few yellowish, because the rabbits have more yellow pigment under the dark one, so this colors are, if anyhow, only able as chin variant.

http://www.rabbitcolors.info/int/en/entries/p/1.html - Images of Rabbits with lutino factor on rabbitcolors.info

Mice pics, by courtesy of [url=http://www.crazzyhmousery.homestead.com]Timiae[/url]
Lohlutinofoto, by courtesy of Sølvi Lysfjord

used literature:
http://www.dvaergkanin.dk/lutino.htm,
http://home.online.no/~geinordv ,
http://www.informatics.jax.org/wksilvers
Normal Tyrosine Transport and Abnormal Tyrosinase Routing in Pink-Eyed Dilution Melanocytes; S. Brian Potterf, Minao Furumura, Elena V. Sviderskaya,Chie Santis, Dorothy C. Bennett, and Vincent J. Hearing; EXPERIMENTAL CELL RESEARCH 244, 319-326 (1998)
The Pink-eyed Dilution Locus Controls the Biogenesis of Melanosomes and Levels of Melanosomal Proteins in the Eye, SETH J. ORLOW, and MURRAY H. BRILLIANT, Exp. Eye Res. 68, 147-154 (1999)