Odd Eyed & Dominant Blue Eyed Sphynx
Important Notice: This page is continuously updated to reflect the latest research, studies, and publications. The content may change as new information and findings become available.
The "Dominant Blue Eye" (DBE) gene is a mutation that enables cats to inherit vivid deep blue or uniquely coloured eyes. This dominant gene shows incomplete penetrance. When a DBE cat mates with non-DBE cat, about half the kittens may inherit DBE, potentially resulting in blue-eyed or odd-eyed offspring.
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There's also a notable chance of producing kittens with mosaic eye colour, where the green or yellow eye has some blue colouring. This mosaic trait disqualifies cats from shows and isn't recommended for breeding.
Initially, two cat breeds showed dominant blue eyes due to a random mutation, and their genes were used in DBE Breeding Programs:
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Altai Blue-Eyed
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Ojos Azules
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Current breeding efforts focus on these breeds' genetics, involving many crossbreeds with other breeds like American Shorthair, Devon Rex, Main Coon or Domestic Shorthair. The goal is to introduce varied eye colors while reducing white coat markings.
Each mutation of DBE, can have unique traits, affecting the cat's genotype and phenotype. It's important to note that DBE gene expression varies. A kitten inheriting the DBE gene might not always have blue or odd eyes. Some kittens can be DBE latent, having orange, yellow or green eyes that may show a red glow like colour-pointed cats or have glowed when young. These cats can produce DBE blue-eyed kittens.
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Heterozygotes from a DBE Line and DBE latent or non-carrier mating can produce kittens with:
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DBE Blue eyes
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Odd eyes
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Odd eyes with sectorial colouring (mosaic eyes)
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Latent eyes (Latents with cooper eyes should be excluded from breeding)
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Normal eyes (yellow, green, or blue colour point)​​
All kittens inheriting the DBE gene will have some white in their coat. This can range from large patches to tiny spots, sometimes barely visible in overlooked areas like the mouth, scrotum, or between toes. White spots often appear on the chin or lower body, sometimes extending to a medallion or on the tip of the tail.
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Several known DBE mutations exist, potentially on different chromosomes and in various genes. Similar mutations occur in humans and other animals like mice, ferrets, dogs, and horses). Human mutations became well-known through Dutch scientist, ophthalmologist, and geneticist Petrus Johannes Waardenburg, who studied and described them between 1948 and 1951.
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In recognition of this researcher, the related human traits were dubbed "Waardenburg syndrome." It's important to note that many mutations that create breeds or colours in pets are labeled as "syndromes" and "genetic disorders" in humans. For instance, albinism or any change in normal human skin colour is automatically seen as a disease. Conditions are linked to changes in genes like:
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ASIP (causing major metabolic issues and "yellow obesity" in humans, but creates banded fur colors in cats)
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TYR (leading to oculocutaneous albinism and higher skin cancer risk in humans, but produces color point patterns in cats)
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KIT (causing the skin condition Piebaldism and playing a role in cancer in humans, but results in white patches in cats), and so on.
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WAARDENBURG Syndrome in DBE Cats
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Waardenburg Syndrome is a genetic condition commonly associated with hearing loss and pigmentation anomalies in humans. In cats with the Dominant Blue Eye (DBE) gene, certain traits linked to Waardenburg-like syndrome and some features may be observed, though the connection is not fully understood or confirmed in all cases.
The condition is often characterized by:
• Heterochromia or Dominant Blue Eyes: Cats with the DBE gene may have striking blue or odd-colored eyes, sometimes in association with other pigmentation patterns.
• White Spotting or Coat Depigmentation: Cats carrying certain variants of the DBE gene might display a white coat or areas of white spotting.
• Hearing Impairments: In some cases, DBE homozygous full white or van cats may exhibit partial or complete deafness. It is also observed in heterozygous DBERE cats.
Also Waardenburg like syndrome is more commonly seen in cats with a predominance of the white coat gene (KIT) rather than the DBE gene alone.
• Premature greying
• wider nose and shortened tail.
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Waardenburg Syndrome type 3 and 4 is not present in cats.
With the exception of the hearing loss, these are cosmetic characteristics and much less severe than, for instance, skeletal abnormalities in Scottish Folds or spinal problems in Manx.
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It’s important to differentiate between traits caused by the DBE gene and those linked to Waardenburg Syndrome. While some studies suggest that Waardenburg-like traits may occur in DBE cats, it is not definitive that the DBE gene itself causes this syndrome as DBE gene can be present together with a white gene or there could be 2 or more different DBE (re+cel / re+ alt) present in a cat DNA profile . Research is ongoing to explore the genetic mechanisms behind blue eyes, pigmentation, and their potential health implications.
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All our DBE and Odd Eyes breeding cats and their kittens undergo BAER tests to confirm they have no hearing issues. Additionally, we contribute DNA samples to various research projects and are deeply involved in studying the different variations of the dominant blue eye gene.
On the photo above - IconicSX Selina Kyle (n 09) - Odd Eyed Sphynx Cat
On the photo above - IconicSX Bruce Wayne - DBE (Blue Eyes Gene)
Mosaic Trait Example
The first historically reported blue-eyed , black cat was " Blue -Eyed -Mollie" presented on 22 July 1920 at the Croydon Cat Show .
HISTORY OF THE DBE Genes
​The term “DBE” refers to a group of genes rather than a single genetic variant, making it essential to specify which particular mutation is being discussed or worked with. Different DBE mutations should not be interbred due to potential risks.
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The Roxi DBECEL gene, Seymour DBEALT gene and Rociri Elvis DBERE gene are the best studied at present.
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DBE Alt
In 1997, Lyubov Borisovna Zikeeva from Ust-Kamenogorsk, Kazakhstan, noticed cats with blue eyes roaming the streets and decided to investigate. As the owner of Darlin cattery, she pioneered efforts to resurrect a genuine blue-eyed feline breed. The first Ust-Kamenogorsk Altai was a regular semi-long-haired house cat with white marks, a blue right eye, and a yellow-green left eye.
The cat magazine "Friend" (issue 8/9, August-September 2004) said Vera Sokolova from Ust-Kamenogorsk owned the first Altai cat. In 1995 or 1996, she had a black cat named Fyodor with blue eyes and a white-tipped tail, looking like the American Ojos Azules found in California.
Fyodor's DBE gene was dominant but not always expressed.
There is one know case of mating DBE ALT X DBE ALT with resulted with 3 homozygous kittens. 2 were bicolour and did not have hearing impaired, while the 3rd kitten was white and deaf.
There is unknown if the kittens or their parents were also a carrier of white / white spotted gene or not.
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DBE ALT come in solid, tabby, or tortie shades, with or without white patches. A unique white tail-tip, sometimes covering up to a third of the tail, is their trademark.
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DBE Cel
DBECEL gene was previously known by breeders as the DBE Altai gene . It was identified in 2024 by prof. Marie Abitbol, and from this time it was separated from DBE ALT gene . DBE CEL is an autosomal dominant trait with variable expression and incomplete penetrance. DBE-CEL cats are not linked with deafness, premature greying and do not show the hallmark dystopia canthorum, a key diagnostic feature of Waardenburg Syndrome Types 1 and 3. Homozygous DBE Cel are assumed to be white but there was no genetic verified case to confirm this theory .
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“Dystopia canthorum was not observed in adult DBE cats from Altai, Celestial, British, Sphynx, and Siberian genetic backgrounds.” (...) "The variant (DBECEL) was found in the Celestial breed, and the variant has not been associated with deafness".
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(Different Founding Effects Underlie Dominant Blue Eyes (DBE) in the Domestic Cat, Marie Abitbol et al. Animals (Basel). 2024.)​
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Read more about DBECEL Gene in Sphynx here : BLUE-EYE SPHYNX (ROXI DBECEL GENE
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DBE RE
The gene is referred to as the Rociri Elvis DBERE gene and it was considered a spontaneous mutation in Elvis ( Maine Coon), DNA found it to be a latent gene (hiding in white cats) . The gene can skips a few generations. The genetic variant known as DBERE ("Rociri Elvis" gene) causes deafness. The phenotype of the heterozygotes resembles human Waardenburg syndrome type 1 and 2A . It seems likely that homozygous DBERE is lethal. Special examination methods (BAER test) is needed to determine if there is impaired hearing. DNA testing to identify the DBERE variant can easily clarify whether a DBE phenotype cat has a gene variant that is associated with deafness.​​​
DBERE is often seen in Abyssinian, American Bobtail Shorthair, American Curl Shorthair, American Wirehair, Birman, British Shorthair, British Longhair, Burmese, German Shorthair, German Longhair, European Domestic Cat, European Shorthair , European Longhair, Maine Coon, Mongrel - Various Breeds, Norwegian Forest Cat, Persian, Ragdoll, Russian Blue, Scottish Shorthair, Siamese, Siberian Cat, Somali and in other breeds; especially if they were outcrossed with the above for the certain trait .
​​​​Under no circumstances should two different DBE lines ( for example, dbe cel + dbe re) be mated together. Also, the mating of two DBE blue-eyed cats from the same line should be avoided.
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DOG "MERLE" Gene
DBE cats and merle dogs are not the same, despite some visual resemblance. Dogs with Merle have mosaic fur and blue or odd eyes due to an autosomal, partial dominant mutation in the CFA10 region that encodes the SILV (also known as PMEL) gene. Merle dogs inherit a range of hearing and visual abnormalities similar to human Waardenburg syndrome. The size of the merle gene-DNA repeats-can vary, and the pattern and effects are related to the size of the merle gene. Different cells can have different-sized merle genes. Homozygous merle is associated with blindness or other severe eye abnormalities. Merle dogs have a high degree of white, hence the gene is also called "lethal white."
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Current Research and Developments:
Recent studies have identified specific variants in the PAX3 gene associated with the DBE trait in cats. These findings have enhanced the understanding of the genetic mechanisms underlying blue eyes in cats and have implications for breeding strategies. Recent research has identified three known variants of the DBE gene.
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The Future of DBE Breeding:
As interest in DBE Sphynx cats continues to grow, the emphasis remains on ethical practices and genetic research. Breeders are working toward a balance where these captivating cats can flourish without sacrificing health or diversity.
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Special Thanks
We are deeply grateful to Professor Marie Abitbol for her groundbreaking research on DBE genes and for inviting us to join her research project, which has advanced our understanding of these fascinating traits.
Our heartfelt thanks also go to Sarah Hartwell for her incredible dedication to classifying, describing and organising genealogical data for DNA studies, which are invaluable to the breeding and scientific communities.
At IconicSX Cattery, we celebrate the rare beauty and genetic diversity of the Dominant Blue Eye (DBE) gene while maintaining the highest standards of health and ethics.
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Reference:
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BLUE-EYED BREEDS / DOMINANT BLUE EYE (DBE) by Sarah Hartwell, http://messybeast.com/
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http://messybeast.com/blue-eyes-waardenburg.htm by Sarah Hartwell
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Different Founding Effects Underlie Dominant Blue Eyes (DBE) in the Domestic Cat by Marie Abitbol
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A PAX3 insertion in the Celestial breed and certain feline breeding lines with dominant blue eyes by Marie Abitbol
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Huang, S.; Song, J.; He, C.; Cai, X.; Yuan, K.; Mei, L.; Feng, Y. Genetic insights, disease mechanisms, and biological therapeutics for Waardenburg syndrome. Gene Ther. 2022, 29, 479–497.
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Rudd Garces, G.; Farke, D.; Schmidt, M.J.; Letko, A.; Schirl, K.; Abitbol, M.; Leeb, T.; Lyons, L.A.; Lühken, G. PAX3 haploinsufficiency in Maine Coon cats with dominant blue eyes and hearing loss resembling the human Waardenburg syndrome. G3, 2024; accepted.
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Abitbol, M.; Couronne, A.; Dufaure de Citres, C.; Gache, V. A PAX3 insertion in the Celestial breed and certain feline breeding lines with dominant blue eyes. Animal Genet. 2024; Online ahead of print.
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Moore, S.; Ribes, V.; Terriente, J.; Wilkinson, D.; Relaix, F.; Briscoe, J. Distinct regulatory mechanisms act to establish and maintain PAX3 expression in the developing neural tube. PLoS Genet. 2013
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Hauswirth, R.; Haase, B.; Blatter, M.; Brooks, S.A.; Burger, D.; Drögemüller, C.; Gerber, V.; Henke, D.; Janda, J.; Jude, R.; et al. Mutations in MITF and PAX3 cause “splashed white” and other white spotting phenotypes in horses. PLoS Genet. 2012, 8, e1002653.
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Hauswirth, R.; Jude, R.; Haase, B.; Bellone, R.R.; Archer, S.; Holl, H.; Brooks, S.A.; Tozaki, T.; Penedo, M.C.; Rieder, S.; et al. Novel variants in the KIT and PAX3 genes in horses with white-spotted coat colour phenotypes. Anim. Genet. 2013, 44, 763–765
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Epstein, D.J.; Vogan, K.J.; Trasler, D.G.; Gros, P. A mutation within intron 3 of the Pax-3 gene produces aberrantly spliced mRNA transcripts in the splotch (Sp) mouse mutant. Proc. Natl. Acad. Sci. USA 1993, 90, 532–536.
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Zlotogora, J.; Lerer, I.; Bar-David, S.; Ergaz, Z.; Abeliovich, D. Homozygosity for Waardenburg syndrome. Am. J. Hum. Genet. 1995, 56, 1173–1178
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Wollnik, B.; Tukel, T.; Uyguner, O.; Ghanbari, A.; Kayserili, H.; Emiroglu, M.; Yuksel-Apak, M. Homozygous and heterozygous inheritance of PAX3 mutations causes different types of Waardenburg syndrome. Am. J. Med. Genet. A 2003, 122A, 42–45
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Both our boys feature a white tail ends, a trait, which is typical for DBE ALT AND DBE CEL. Both were genetically excluded from having colour point blue eyes. Parents: Sophie (n 09 63) and Vincent (n 09 )
