This case study is published in full, and kept current, in the Blue Eyes Directory as case study two. Read it in the Blue Eyes Directory.

Two: how refusing a trait in a breed spread it across different breeds, by creating a breed that must outcross to exist

This case study follows one variant, DBE^CEL (Roxi), and the breed built on it. Two questions run through it. Where did the variant actually come from, given that three published records disagree? And what happened when a registry, having refused the trait inside an existing breed, recognised it as a breed of its own?

The answer to the second is the finding. A breed whose standard forbids breeding it to itself cannot close its studbook, so the variant leaves the breed in every generation by the terms of the standard, and two of the three permitted partners are the British breeds in which the trait was refused. Whatever anyone intended, refusal did not contain the variant.

The history of the variant: where DBE^ALT and DBE^CEL (Roxi) came from, and how the two were confused

Two of the six variants, DBE^ALT and DBE^CEL (Roxi), arose in the same town within a few years of each other and have been mistaken for one another ever since. Setting out their origins separately is what makes the rest of this case study legible.

The cats each variant is traced to, side by side

Both variants begin in the same place: Ust-Kamenogorsk, in eastern Kazakhstan, in the late 1990s.

Fyodor and Nikita'l Seymour: two cats, one variant

Fyodor, the Russian form of Theodore, is a black self with a white tail tip, random-bred, noticed at Ust-Kamenogorsk in Kazakhstan in 1995 or 1996. He founds the Altai. Nikita'l Seymour is a black silver classic tabby with white, XSH ns 03 23 68, a domestic shorthair from Russia. He founds the British and Persian lines and stands as one of the two Topaz studs. They are separated by two facts that hold independently of one another.

The first is the coat. Silver is produced by the Inhibitor gene, which is dominant: a cat carrying it shows it, and a cat without it cannot appear silver. A black self is not silver. A self is also a cat in which the tabby pattern is suppressed, so no animal is both a self and a classic tabby. The two descriptions differ at two independent loci, which is a statement about genotype and not about how a coat was written down.

The second is the pedigree record, which places them in different countries with different parents, mates and offspring.

• Seymour has recorded parents; Fyodor has none. Two breeder-compiled genealogies, the Siberian and the Maine Coon, independently give Seymour as out of Pushok by Eliza. Fyodor enters the record as a found cat with no ancestry recorded anywhere in this survey.
• Different mates and offspring. Fyodor was mated to Deya Darlin at the Darlin cattery and sired Pani Darlin in 1999. Seymour sired Kaena, and Nikita'l Markiss out of Nikita'l Pheer-Ca.
• Different descendant breeds. The Altai descends from the first. The British, the Persian, the Ragdoll and the Topaz descend from the second.

A coat is a genotype at two loci and a pedigree is a record of parentage. Either fact alone distinguishes the two animals, and there is no reading of the record in which they are one cat. Where a source gives Fyodor as the cat known in the West as Seymour, that reading is available on neither.

The 2024 genotyping is consistent with both, listing the Altai lineage founded on Fyodor and the Seymour lineage founded on Seymour as separate rows with separate founder cats, and finding the same insertion in each. Whether the two share an ancestor is a further question, and the paper puts it no higher than likely, the origins of both being unrecorded. A third name, Nikita'l Seymour, belongs to a cat of the Nikita'l cattery on the Maine Coon genealogy and is again a separate animal.

The single most important line in that table is the one spanning both columns. The two variants appear to have been together in one breeding population from the beginning. If they were, the Topaz did not create the combination of DBE^ALT and DBE^CEL (Roxi), it inherited it, and every later programme drawing on the Darlin cats inherited it too.

The basis for it should be stated exactly, because it is not a genotyping result. The messybeast.com compilation lists Roxi Darlin among the Darlin cattery's early Altai cats, gives his variant as DBE^CEL (Roxi), traces the Altai line separately through Fyodor to Pani Darlin and Ariel Darlin, and then draws the conclusion in its own words: “This means there was a mix of Fyodor's DBE^ALT and Roxy's DBE^CEL (Roxi) genes.” That is an inference from breeder records made by the messybeast.com compilation, not a published finding, and no cat of the early Altai population has been genotyped for both insertions.

What the genealogy now traces, and what it does not

The two variants meeting in one mating is no longer an inference. It is traced, dated and named twice. Both matings were made in 2016, one in each of two countries, and in each the register holds one parent from each founder line.

Nikita'l Pheer-Ca over Nikita'l Seymour, 26 March 2016, in Ukraine. Pheer-Ca is an odd-eyed daughter of Roxi; Seymour is the DBE^ALT founder. This is the one such mating whose offspring generation has been genotyped, and the genotyping settles which allele passed: the Topaz Maine Coons return wild type for DBE^ALT and heterozygous for DBE^CEL (Roxi). Where that mating led is not this case study's subject and is followed in case study three.

Kaena over Lazuli, 18 July 2016, in France. Kaena is labelled DBE^ALT and recorded latent; Lazuli is the one animal with a laboratory result for DBE^CEL (Roxi). The litter was seven. The compiler writes DBE-CEL & DBE-ALT beside two of the seven, and those two are the two recorded deaf. Neither has been tested.

Twenty-nine cats now descend from a mating that held one variant on each side, across four named lines: the Céleste line itself, the German Longhair at the vom Leineufer cattery, the Siberian at Legende des Alpes, and the Blue Ridge Maine Coons. Each of those cats took one allele from each parent at PAX3, so each carries DBE^CEL (Roxi), or DBE^ALT, or one of each. None of the twenty-nine has been genotyped, which is what makes the list a testing list rather than a result.

None of that reaches the claim about the early population. Both matings are 2016 and both were made deliberately, from two founder lines that were by then already distinguished from one another. A traced meeting in 2016 shows the two alleles can be brought together and shows where to look for the compound heterozygote. It says nothing about whether they were together in Kazakhstan in the 1990s. That claim still rests on the messybeast.com compilation's reading of breeder records, it remains consistent with the published genotyping, which separates the two variants along exactly those two lines, and it is recorded here as corroboration rather than as proof.

One consequence of the table governs the British material below, and it depends on keeping two cats apart.

The British group carries DBE^ALT and not DBE^CEL (Roxi), by the line named for Nikita'l Seymour. It is named for him because he is the cat the pedigrees record, not because the variant is shown to have originated in him, and Fyodor does not appear in any British pedigree this survey holds. So the correct statement is that the British group carries the variant by the Seymour line, and that the variant is the same one the Altai carries.

The founding pair of the Céleste programme, one variant each

The mating of 18 July 2016 is the second of the two above and it is the one this case study follows. The two variants arrive on opposite sides of it, and the table sets out the whole of that in one place: which cat brought which variant, what the cattery called each of them, and what happened to the pair afterwards.

The Maine Coon is not part of this case study. It carries DBE^CEL (Roxi) by a route that does not pass through the Céleste at all, descending from Roxi through the Topaz, and it is followed in case study three with the other examples of a variant arriving in a breed.

The last row of the table records a difference in naming practice. The other variants take the name of the population or line they arose in; DBE^CEL (Roxi) takes the name of the Céleste. What follows from that is set out in the naming section below.

The sequence of events, 1997 to 2025

Several of the disagreements in this history are disagreements about dates, and two dates settle most of them. The account to 2014 rests on a compilation of breeding records at messybeast.com, which is not peer reviewed; the French sequence rests on the founding cattery's own account and on LOOF's published documents; the two 2024 descriptions are from the peer-reviewed literature.

Fyodor was noticed in Ust-Kamenogorsk in 1995 or 1996, and breeding for the trait began at the Darlin cattery in 1997. Fyodor was among that cattery's early cats. Blue-eyed to blue-eyed matings in the late 1990s produced cats with two copies: they survived, unlike the Ojos Azules, carried more white than their parents, and “were most often deaf”. Latent carriers were described in the same period, cats holding the variant without blue eyes which “can produce blue-eyed offspring”. Pani Darlin and then Ariel Darlin carried the Fyodor line forward between 1999 and 2001, and the Altai was established as a breed on them.

Between 2008 and 2014 Roxi founded the Topaz at the Nikita'l cattery in Ukraine, where Altai cats were also used, which is where the two lines met again. He was in Ukraine until a French cattery obtained him in 2014.

A cat named Roxi Darlin is also placed among the Darlin cattery's early animals in 1997. Whether that is the same animal is taken up in the section that follows, and one claim in this history turns on the answer.

Are there two Roxis? Roxy Darlin, an early Altai cat of the Darlin cattery at Ust-Kamenogorsk, and Roxi, founder of the Topaz at the Nikita'l cattery

One animal cannot be both. A cat breeding at Darlin in 1997 cannot have sired a kitten born in April 2015. Either they are two cats, or the 1997 date is wrong, and this survey does not choose between those two.

This is a question about identity, and as far as it can be answered it is answered by arithmetic rather than by any account. It was reported at the time of this survey that Fyodor, the random-bred black founder of the Altai, and Roxy Darlin, an early Altai cat of that same cattery, were both among the cats the programme began with in 1997. Fyodor's own record holds: he was noticed in 1995 or 1996 and sired Pani Darlin in 1999, and the line is carried forward after that by his descendants rather than by him. Roxi's does not.

The date comes from his own breeding and not from any account of him. Roxi is an experimental cat of the Nikita'l cattery in Ukraine and founder of the Topaz, the cat DBE^CEL is named for and traced to. He sired Lazuli, a Topaz male born 2 April 2015 and conceived at the end of that January, so on a breeding life of eighteen months to eight years Roxi of the Topaz was born between 2007 and 2013. A cat already breeding at the Darlin cattery in 1997 would have been eighteen at that conception and cannot be the sire of a kitten born in April 2015.

So one of exactly two things is true: either Roxy Darlin the Altai and Roxi the Topaz founder are two animals, or the 1997 date is incorrect. The arithmetic does not determine which, and the survey does not choose between them, because neither cat has a registration carrying a date of birth. Both dates come from breeder accounts, so choosing would mean preferring one account over another with no document behind either. What each would mean is worth setting out, because they do not cost the same.

If they are two animals, then Roxy Darlin is an early Altai cat of the Darlin cattery at Ust-Kamenogorsk and nothing more, and Roxi, founder of the Topaz at the Nikita'l cattery, is a separate and later animal. DBE^CEL is named for, and traced to, the Topaz founder, so Roxy Darlin carries no established variant at all and drops out of the history of DBE^CEL entirely. On that reading the variant has no documented origin before about 2007.

If instead the 1997 date is wrong, Roxy Darlin the Altai and Roxi the Topaz founder are one animal, born between 2007 and 2013, who was at the Darlin cattery later than the account places him. The line to that cattery survives, but the date of it moves forward by roughly a decade.

One claim in this history depends on which of the two holds. That both Kazakh variants were in one population before either breed existed rests on Fyodor and Roxy Darlin being at the Darlin cattery together in 1997. Fyodor's presence is not in question. Roxy Darlin's is exactly what is in question. Under the second reading the claim holds with a later date. Under the first it does not hold at all for DBE^CEL, because Roxy Darlin would not be the cat the variant is traced to. The survey therefore does not date the origin of DBE^CEL earlier than about 2007, and says so rather than resting on the 1997 figure. The 1997 date stays on the record as what was reported. It is not carried forward as the date of Roxi of the Topaz, the sire of Lazuli, because it cannot be.

What would settle it is a registration or certificate carrying a date of birth for either animal, a photograph of the 1997 cat, or the founding cattery's own records.

The spellings cannot settle it. Roxi, Roksi and Roxy are phonetic transliterations of one Russian name, and the presence or absence of the Darlin suffix does not distinguish two animals when the transliteration is itself inconsistent. Nor does the missing suffix carry any weight of its own. This survey documents in several independent places that a cat moving between programmes is re-registered under a different breed code and appears with and without a cattery prefix depending on the document: Nikita'l Seymour was a found cat who acquired his prefix on entering that programme and is entered variously as XSH, as a Siberian and as a Topaz; Krosh is HPP a 02 61 on his certificate and XSH a 02 in the database; Lazuli was bred at Nikita'l, registered experimental longhair, and carries no prefix at all; and Greg, Mishka and Pasha are drawn as bare names on the Cyrridwen genealogy while their registrations read Mio Piccolo Greg of Cyrridwen, Cyrridwen Mishka and Cyrridwen Pasha. Prefixes are gained on entering a programme and dropped on leaving it, so the absence of Darlin on the Topaz founder is not evidence of a second animal.

From Ukraine to France, 2014 to 2023

The Topaz was later discontinued, having passed DBE^CEL (Roxi) to the Maine Coon by an outcross at Nikita'l.

The French branch begins in 2014, when a British Shorthair breeder in France obtained Roxi, spelled Roxy in the French records, from a Ukrainian breeder. By June 2015 Lazuli, a Topaz male of that line bred at the Nikita'l cattery, was in France, and LOOF's official genealogy for the breed begins with him. The Topaz is the breed Roxi founded at Nikita'l, and cats of that programme were registered as experimental longhairs, as Nikita'l Markiss was in 2016. The World Cat Federation wrote its Altai standard in 2018, expressly distinguishing the Altai from the Ukrainian Topaz and from the Celestial British. At some point before 2022, on a date that has never been published, the French breed clubs refused the trait within the British Shorthair; LOOF's Conseil Scientifique minutes of 9 September 2020 were already calling it “cette mutation Altaï”, that is this Altai mutation. The Céleste was admitted as a preliminary breed in 2022 and recognised as a nouvelle race, a new breed, on 1 January 2023.

The variants themselves were separated last. DBE^CEL (Roxi) was described and named in April 2024 and DBE^ALT in June 2024, and the genotyping split them: descendants of Fyodor and Nikita'l Seymour carry DBE^ALT, and descendants of Roxi carry DBE^CEL (Roxi). The GCCF's variant tracking went live in June 2025.

Two dates carry most of the confusion. The Céleste was recognised in January 2023, and LOOF was using the word Altai for the trait by September 2020, while the variants were not separated until April and June 2024. Every statement made about these cats before April 2024 was made without the means of telling the two variants apart.

A note on two terms used below. Wild type means the ordinary, unmutated version of a stretch of DNA, so a cat genotyped wild type for a variant does not carry that variant. A latent carrier is a cat that carries a variant and does not have blue eyes. Both describe laboratory or breeding facts about a cat, and neither has anything to do with what a registry has written on a pedigree.

Three different things are called Altai

Most of the confusion in this history comes from one word doing three jobs.

• The Altai mountains, a region spanning Russia, Kazakhstan, Mongolia and China. A geographic origin.
• The Altai, a breeding population begun in Kazakhstan in 1997 and still bred today under a World Cat Federation standard drawn up in 2018. A breed.
• DBE^ALT, the variant that arose in the Altai breed population and is named after it. A stretch of DNA.

The Céleste founding cattery uses the word in the first sense, geographically, in the conditional, and flags it as unverified: “Roxy vient d'une lignée de chats de gouttières, dont les origines se situent dans les montagnes de l'Altaï... Je mets tout ceci au conditionnel car les informations qui nous ont été données n'ont pas pu être totalement vérifiées.” In English: “Roxy comes from a line of domestic cats whose origins lie in the Altai mountains... I put all of this in the conditional because the information we were given could not be fully verified.” It does not claim descent from the Altai population and it does not use the phrase Altai gene. LOOF's current breed text attributes the trait to “un gène dominant découvert au Kazakhstan dans les années 1990 chez certains chats domestiques”, that is “a dominant gene discovered in Kazakhstan in the 1990s in certain domestic cats”: Kazakhstan, with no Altai and no founder cat named.

The slippage is nonetheless traceable to the registry itself. The minutes of LOOF's Conseil Scientifique of 9 September 2020 record “Cette mutation Altaï semble autosomique dominante à expressivité variable”, in English “This Altai mutation appears to be autosomal dominant with variable expressivity”. As the timeline above shows, no variant had been described molecularly at that date. Every use of Altai before April 2024 therefore predates the distinction it is now read as making, and at that time the word was a general label for the Russian blue-eyed lines rather than the name of a particular variant.

So the breed's own account and the DNA do not in fact conflict. The cattery claims a mountain range as a place of origin and marks the claim uncertain; the DNA says Kazakhstan and a variant of its own. What conflicts with the DNA is the widely repeated claim, made by neither of them, that the Céleste carries the Altai gene. The genotyping set out next refutes it.

What the genotyping shows about the Céleste, against what the breed narrative says

Two sets of results answer the question of what the Céleste carries, Abitbol, Couronné et al., Animal Genetics 2024;55:670-675, Table 1 and Abitbol et al., Animals 2024;14:1845, Table 2.

• Fifty-two Céleste and Céleste-crossed cats carried the DBE^CEL (Roxi) insertion, and the outbred founder of the breed was heterozygous for it, meaning he carried one copy.
• Twenty-two Céleste cats, blue-eyed, white and latent, were tested for the DBE^ALT insertion and none of them had it. They were genotyped wild type at that position. This is the result of looking and finding nothing, not of failing to look.

So on the cats that have been tested, the Céleste today carries DBE^CEL (Roxi) and does not carry DBE^ALT. It holds one of the two variants, not both. On Roxi, the cat the variant is traced to, the published position is stated in terms: “Roxi transmitted a peculiar DBE variant: the DBE^CEL (Roxi) allele. He was probably not an Altai cat.” In plain terms: Roxi passed on a DBE variant of his own, DBE^CEL (Roxi), and he was probably not an Altai cat. Peculiar is used there in its older sense of belonging particularly to him, and not in the sense of strange.

What this does not tell us. Twenty-two cats are not the whole breed. Absence in twenty-two tested animals is strong evidence that DBE^ALT is not being carried forward in the Céleste, and it is not proof that no Céleste anywhere carries it. Nothing in the published work tests the founding generation, so whether DBE^ALT was ever in the breed and was bred out, or was never in it, cannot be settled from the genotyping alone.

Set against the timeline, those two results resolve the apparent conflict. The Céleste comes out of a population that held both variants, and today it holds only one. A breed descended from a mixed population, in which twenty-two cats are tested for one of the two variants and none of them has it, has not lost that variant by dilution. It was bred away from. That is a fact about selection by later breeders, not about ancestry, and it is why the breed's own history and its genotype can both be accurate at once.

None of this is recorded by the registry. LOOF, which recognised the Céleste, does not record the DBE genotype of any cat: PAX3 appears neither in its laboratory protocol test list nor on its health page. Every genotype quoted here comes from research papers and not from a studbook. So the question of whether the French register holds one variant or two has no answer, because the register holds neither.

Céleste and Celestial British are one breed at two stages of its development

Three names attach to this breed and none of them denotes a separate population. Céleste is the name in the LOOF standard, which recognises it in both coat lengths as Céleste poil court et poil long. Celestial is the name used in the peer-reviewed literature, in the title of the paper that identified the variant. Celestial British is the English form used in the messybeast.com compilation, the self-published compendium of blue-eyed lines described in the sources note. LOOF has never published the term Celestial British and there is no registry anywhere holding a breed of that name alongside the Céleste.

The genotyping is consistent with this and not with two breeds. The twenty-two wild type results mean the LOOF-registered Céleste does not carry DBE^ALT, which is what a line looks like after the second variant has been selected out.

Two things are commonly offered as evidence of two breeds and neither is. The messybeast.com compilation files its Celestial British page under the Altai and Seymour genes rather than under DBE^CEL (Roxi), which records the composition of the early programme rather than a different breed. And the World Cat Federation standard for the Altai, drawn up in 2018 to differentiate the Altai from the Ukrainian Topaz and the Celestial British, distinguishes the Altai from the Celestial. It says nothing about Céleste against Celestial British, so it cannot be read as separating them.

How both variants reached the British programme

This survey establishes how both variants reached the British, one on each side of a single mating, and that the two routes into that mating do not touch. The finding is drawn from the genealogies transcribed into this survey's register, read against the registration records and the published genotyping, and it can be followed cat by cat.

The programme meant here is the one that became the Céleste, run at the Aerlin cattery in France on British Shorthairs and British Longhairs, and it is the subject of this case study. It is not the Ermine Trace line and not the Nanotigr line, which are separate British routes and reach the breed by different animals. This programme was founded on Kaena to Lazuli, and the two variants arrive on opposite sides of that mating, as the table above sets out.

So the founding mating of the British programme put one copy of each variant into one litter. That is the mating of 18 July 2016, and it is why the early generations held two variants at once. The removal of what the cattery calls the Seymour gene is the removal of Kaena's contribution, that is of DBE^ALT, leaving DBE^CEL (Roxi) alone, which is the line LOOF recognised in 2023.

One label, two variants: why “the Altai gene” cannot be used

A naming hazard sits underneath all of this and it defeats careful readers. In the source material the phrase the Altai gene is applied to two different variants. DBE^ALT takes its name from the Altai population and traces to Fyodor and to Nikita'l Seymour, two cats carrying the same variant. The messybeast.com compilation also writes of “the Altai gene (Roxi Darlin)”, and Roxi is the founder to whom DBE^CEL (Roxi) traces. The second usage preserves an assumption the literature has since set aside: the paper describing the founding effects records that “Roxi was supposed to be an Altai cat” and concludes that “he was probably not an Altai cat”. So the phrase attaches the Altai name to a variant whose founder is not established as an Altai cat, and a sentence containing the words “the Altai gene” cannot be resolved without knowing which founder is meant.

The annotation on the breeder-compiled genealogy beside the Celestial box is exactly this problem: “The Celestial eliminated the Seymour gene and the LOOF recognised Celestial (2023) only has the Altai gene”. Read with Altai meaning DBE^ALT the sentence is wrong, because the recognised breed carries DBE^CEL (Roxi). Read with Altai meaning Roxi's variant, which is how that compilation uses it elsewhere, the sentence is right about which variant remains. The survey records the ambiguity rather than a verdict, and applies the rule it uses throughout: resolve every gene name to a named founder cat before relying on it. On this occasion the rule also disposes of the label: the founder is Roxi, and Roxi is not established as an Altai cat.

The same hazard sits in the name Celestial British, and that one is about a breed rather than a gene. The name contains a breed name, so a reader working from names rather than genotypes takes it to mean that DBE^CEL (Roxi) is established in the British Shorthair, and goes on to attribute every breed holding a blue-eyed line to DBE^CEL. The breed table records DBE^CEL (Roxi) against the British Shorthair as reported and not verified; what is genotyped in that breed is DBE^ALT. That inference is the shape of the mistaken breed lists now in circulation and the most probable origin of them. Two practices prevent it.

• Record the molecular designation, not only the nickname. PAX3 c.937C>T cannot be confused with an intron 4 insertion in the way that RE and CEL can be confused with a cattery name or a breed.
• Treat a breed name containing a variant nickname as a claim to be verified rather than as evidence of which variant the cats carry.

What the two-variant history does and does not say about the Altai breed

The two-variant history says nothing against the Altai as a breed. This survey has found no evidence of a health problem peculiar to the Altai, and none is asserted here. The harm documented in this case study is not attached to any single variant. It arises when a kitten inherits two DBE variants, whether that is two copies of the same variant, the homozygous state, or one copy each of two different variants, the compound heterozygous state. The homozygotes in the Altai programme were usually deaf. The kittens born deaf in the later literature carried one copy each of DBE^CEL (Roxi) and DBE^ALT, and the kitten that died at birth with limb contractures and an abnormal head is presumed to have carried one copy each of DBE^CEL and DBE^RE.

What the Altai's history does show is that this was understood in the founding population before any variant had a molecular name, and that a rule was written for it. That rule, and the gap left by triggering it on eye colour, is examined alongside the other registries' rules in case study one.

How the variant is named, and what the name covers

Naming belongs with the history because the name records a decision taken at one moment by one person, and the decision is now read by everyone afterwards as a statement about scope.

Each published variant is named for a population or a line: DBE^ALT for the Altai, DBE^RE for the Rociri Elvis line, DBE^AGO for the Agostino line, and DBE^CEL (Roxi) for the Céleste.

The name is the breed's, and the breed's name is the cattery's. The laboratory work was not done on a newly found founder. It was done on an existing registered cat, Lazuli, a registered descendant of Roxi, and the designation given to the result takes the name of the Céleste rather than the name of Lazuli, of Roxi, or of the population either came from. The designation was assigned by Lazuli's owner. There is no rule governing what a variant is named after, and this survey proposes none. Naming belongs to the authors who publish a variant and to the bodies that code it afterwards, and the survey follows any designation they publish.

What the name covers is a separate question from what chose it. The Céleste is one branch of Roxi's descendants and the most recent of them. Roxi founds every line in which the variant has been genotyped, including the Topaz, which used him before the Céleste existed. The Maine Coon carriers descend from the Topaz and not from the Céleste, so a reader who takes the name as a statement of scope will place those cats in the wrong population.

The finding is not about the name. It is that a breed was defined by a variant. The Céleste is constituted by carriage of DBE^CEL (Roxi), and the variant is lethal in the homozygote, so the breed cannot be bred to itself: LOOF prohibits Céleste to Céleste mating and permits only outcrossing. A breed defined by a heterozygous variant cannot become homogeneous, and its stud book can therefore never be closed. Every generation must take in cats from outside, and every generation is by construction half non-carrier. That is a structural consequence of the definition and it holds whatever the variant is called.

The founding paper genotyped 130 cats with the trait and 101 controls. Sixty-seven carried DBE^CEL (Roxi): 45 Céleste with the phenotype, one white Céleste homozygote that died at birth, one latent Céleste, seven Céleste-mixed cats, nine Maine Coons of the Topaz line and four Siberians of unrecorded origin. The variant is confirmed by genotype in the Céleste, in Céleste crosses, in the Maine Coon through the Topaz, and in the Siberian. A further twelve rows of the breed table report it without verification.

This survey writes it as DBE^CEL (Roxi) in the six variants at a glance table, in the breed table and in the table of lines in which a variant has been identified. Elsewhere the published designation stands alone, so that the material remains searchable against the sources it comes from. Nomenclature belongs to the authors who published the variant and to the bodies that have coded it since, and the survey follows any designation they publish.

The creation of a breed from a variant: how the Céleste was made

The Céleste is the breed whose name DBE^CEL (Roxi) carries. Its origins are settled above; what follows is how it was made into a breed, from the refusal of the trait in the British Shorthair to recognition by LOOF, and what the terms of that recognition did.

Step by step, from Roxi Darlin to a recognised breed

1. The line is Roxi, not Céleste. The variant traces to Roxi Darlin, the same cat written Roksi in Kazakh sources and Roxy in French ones, a tabby male with white hind feet and a white throat, bred at the Darlin cattery in Ust-Kamenogorsk. All cats carrying DBE^CEL (Roxi) descend from him. His own pedigree is not recorded, and his first use was not in France but in the Altai programme set out above, and then in the Topaz, which is described in case study one.
   Roxi and Lazuli. These have been reported as competing names for the cat the variant is traced to. They are not. Roxi is the source of the variant. Lazuli is a later male cat of the same line, acquired by the founding cattery from a Ukrainian breeder and in her house from June 2015, and it is from Lazuli that LOOF's official genealogy begins.
2. Introduction into the British Shorthair. A breeder of British Shorthairs under the Aerlin prefix mated one of her British cats to a blue-eyed cat of the Roxi line. The founding cattery, Les Célestes d'Aerlin, describes itself as élevage de British à la base, a British cattery to begin with. The programme began with a cat found in Ukraine. The cattery's own account: “j'ai continué longtemps mes recherches, qui m'ont conduite jusqu'en Ukraine, où je suis tombée un peu par hasard en 2014 sur une éleveuse ayant un chat brown tabby, presque sans blanc, aux deux yeux turquoise, venant lui même du Kazakhstan : Roxy”, that is, a search that led to Ukraine, where in 2014 she came upon a breeder with a brown tabby, almost without white, with two turquoise eyes, himself from Kazakhstan: Roxy. She then acquired Lazuli, a male kitten of that line, who was in her house from June 2015.
   Where the official record begins, and why that is not where the descent begins. LOOF accepted a working dossier and granted an official genealogy for her cats under the unrecognised-breed codes XSH and XLH, in the registre de filiation, “en partant de Lazuli”, starting from Lazuli. That is a statement about documentation and not about ancestry. The registration begins at Lazuli because an official pedigree could not be obtained for the generations before him, not because those generations are unknown: the line back to Roxy is known to the breeder and is recorded in her own material. A studbook starts where the paperwork starts.
3. The trait was refused within the British Shorthair. The founding cattery states the sequence itself: “A la base le projet était de travailler les yeux bleus chez le British. Les clubs de race en France s'y sont opposés, nous avons donc créé le Céleste, avec comme contrainte du LOOF d'en faire une race qui soit différente, et pas uniquement de par la couleur de ses yeux.” In English: “The project was originally to work blue eyes in the British. The breed clubs in France opposed it, so we created the Céleste, with the constraint from LOOF that it be a breed which is different, and not only by the colour of its eyes.” The French breed history puts the refusal in four words, cette nouvelle couleur de british est refusée par les clubs. There is no accepted British Shorthair standard for the trait.
4. LOOF imposed a condition that shaped the breed. On the cattery's account LOOF required the new breed to differ in more than eye colour, which is why the standard specifies conformation as well as the trait.
5. It was then registered as a separate breed. LOOF admitted the Céleste as a preliminary breed in 2022 and as a nouvelle race in 2023, making LOOF the only registry to have admitted a dominant blue eye breed rather than restricted one. The variant was subsequently named after that breed rather than after the Roxi line.
6. Dispersal did not occur solely through the Céleste. As the founders table shows, DBE^CEL (Roxi) in the Maine Coon came from Roxi through the Topaz and into the breed by an outcross, and the Céleste was created afterwards from a separate Roxi-sired male, so the two are parallel branches from one founder rather than a trunk and a branch. The paper describing the variant records that Roxi was heterozygous for the mutation, and that the same mutation was found in nine dominant blue eye Maine Coon cats related to Roxi and in four dominant blue eye Siberian cats of uncertain origin. The nine Maine Coons are described by their relationship to Roxi and not to any Céleste. The variant is also genotyped in the Sphynx. Further breeds have been reported without verification.

What followed from the refusal

Refusal did not remove the trait. The trait was given a breed of its own, the Céleste, that breed was recognised by a national studbook, and recognition carried rules requiring outcrossing to British Shorthairs and British Longhairs in every generation. The trait was not removed from British breeding. It moved into a breed of its own, acquired a national registry's recognition in the process, and that mating back to the British Shorthair and the British Longhair is now a requirement of that breed's standard rather than an option within it.

No intention is imputed here, and none should be read in. The purpose of the programme was to create a breed, and the founding cattery says so: the project began as an attempt to work blue eyes in the British Shorthair, and the Céleste exists because that was refused. Dispersal of the variant into other breeds is a consequence of the mating rule that recognition came with, and not an aim of anyone involved. The finding here is about what the rule does, not about what its authors wanted.

The breed did not grow and the allele did. LOOF's own breed page states the ban, “Le mariage Céleste x Céleste est interdit à ce stade”, the Céleste to Céleste mating is prohibited at this stage, and gives the permitted matings as exactly three: Céleste to British Shorthair without white, Céleste to British Longhair without white, and Céleste to domestic cat without white. Two of the three permitted partners are therefore the British breeds in which the trait was refused, and the third is not a breed at all.

The third option is different, because chat domestique means an ordinary unregistered cat. A breeder exercising it is mating a pedigree cat carrying a known dominant variant to an animal with no pedigree, no recorded ancestry, no health testing and no registry oversight of any kind. The resulting kittens are registrable.

Three things follow from that, and they are different in kind from what follows from the British options.

• The variant leaves the pedigree world entirely. An outcross to a British Shorthair puts the variant into a breed where, in principle, it can be traced. An outcross to a domestic cat puts half the litter's ancestry beyond any register, and any sibling or parent of that domestic cat is untraceable.
• The unregistered partner may itself be a carrier and nobody would know. At least nine blue-eyed lines have no identified variant and several of them run through unregistered domestic cats. A chat domestique sans blanc that carries an unmapped variant, or is a latent carrier of a known one, is indistinguishable from one that carries nothing, and no test can settle it for the unmapped lines.
• Pedigree depth is reset at every use. A breed permitted to outcross to unregistered animals in every generation, and forbidden to breed to itself, cannot accumulate recorded ancestry. The pedigree issued at the end of it is a document about one generation.

The registration figures show the result. LOOF pedigrees issued for the Céleste, from its own annual statistics:

103 pedigrees in the three years since recognition, against 4,151 British Shorthair and 24,197 Maine Coon in 2025 alone. Every one of the 103 came from an outcross, because the standard permits nothing else. That does not make all 103 carriers. A carrier bred to a non-carrier gives about half and half, and the whole litter is registered Céleste, so the figure is an upper bound on registered carriers and not a floor. One is named: Uskya d'Ysorian, registered RIEX, is described by her breeder as non porteuse du gène DBE-CEL.

What the Céleste does that no registry requires, and what LOOF still cannot do

Two facts about this breed belong together, because one is the best voluntary practice the survey has found anywhere and the other is the limit that practice runs into.

The breed hearing-tested its first five generations. The Céleste programme records that the first five generations underwent brainstem auditory evoked response testing, confirming normal hearing, with every breeding cat additionally screened for polycystic kidney disease and hypertrophic cardiomyopathy. No registry in the survey requires a hearing test of any cat. This is the strongest voluntary control found in any dominant blue eye population, it was done in the breed whose founding animal is the one genotyped cat in the line, and it was done without being asked.

Set against that, LOOF cannot yet act on a test result even when one exists. As of March 2026 the registry had no agreed protocol for DBE^ALT testing, and laboratory results accordingly “ne seront pas pris en compte par le LOOF en l'absence de protocole d'accord”, that is will not be taken into account by LOOF in the absence of an agreed protocol. A commercial test has existed since 2024 and the registry that created the breed will not receive its results.

The mating rule holds the line in the meantime. LOOF's standard permits Céleste to British Shorthair without white, to British Longhair without white, or to a domestic cat without white, and states that “le mariage Céleste x Céleste est interdit à ce stade”, the Céleste by Céleste mating is forbidden at this stage. That is a ban on the mating rather than on the cat, which is the control this survey recommends, and it is being carried by a breed standard because no test result can currently reach the registry that wrote it.

A breed defined by descent from one cat, whose own origin has three accounts

LOOF's 2019 ruling makes descent from Lazuli the definition of the Céleste: a proposed second line was refused because its founder was unrelated to him, and every Céleste must trace to him. His identity is therefore load-bearing for the breed and for every pedigree issued in it.

Three published accounts of that cat's origin do not agree.

• The founding cattery's own account. Having acquired Roxy, a brown tabby almost without white with two turquoise eyes, himself from Kazakhstan, she then acquired Lazuli as a male kitten of that line from a Ukrainian breeder, in her house from June 2015.
• A French breed reference. A male born in France in 2015 out of Roxy, brown mackerel tabby, with one blue and one green eye.
• A third French source. An ojos azules brought from Kazakhstan in 2015.

The third account is less discrepant than it looks, and the reason is a registration problem rather than a disagreement about the cat. Ojos azules was for a period the only category under which a blue-eyed cat of this kind could be entered at all, so the name records the register the cat was put into and not a claim about its breeding. The survey holds two other instances of the same thing. An Altai F2, registered name She's Got It, is recorded as “known in Russia as an Ojos Azules because that was the only classification available for registration of such cats at that time”. And a British Shorthair of the Igor line, Amur Dream, is annotated on its own genealogy “registered as Ojos Azules because Altai was not a recognised breed”, while an ARBC certificate for its descendants codes the same line BRI o 01 60.

Three cats, three countries, one mechanism. A register offers a closed list of breeds; where the animal does not fit, the record takes the nearest available label, and the label is then read by everyone afterwards as an attribution. The Ojos Azules is an extinct American breed in which no variant was ever identified, so every cat filed under its name for want of a better one now carries a breed attribution that means nothing about its genetics.

The reason the accounts can differ is stated by LOOF itself. The registration was made “en partant de Lazuli”, starting from Lazuli, because an official pedigree could not be obtained for the generations before him. So the breed is defined by descent from an animal whose own ancestry is undocumented, and the registry's own paperwork records that this is so.

Three consequences follow, and they run in different directions.

1. The variant attribution rests on the disputed part. DBE^CEL (Roxi) is traced to Roxi. If Lazuli was Roxi's son born in France, that descent is direct. If he was obtained as a kitten from a third party in Ukraine, or imported from Kazakhstan, then his variant rests on a statement about a cat from the one population known to have held both DBE^CEL (Roxi) and DBE^ALT. No contemporaneous test could have distinguished them: neither variant was described until 2024.
2. A single-founder rule places a floor under the breed's inbreeding that no generation-depth rule can lift. The coefficient of inbreeding rules examined in case study four work on generation depth and on ancestor counts. A breed in which every animal descends from one cat cannot be assessed against an ancestor-count rule at all, and its coefficient can only rise as the closed population breeds on. The obligatory British outcross is what holds it down, which makes that outcross a genetic requirement and not merely a type requirement.
3. The rule is asserted from pedigrees and could be verified by test. Descent from Lazuli is currently established by paperwork. Since April 2024 a test for DBE^CEL (Roxi) has existed, so every Céleste should carry it, and any cat registered as a Céleste that does not carry it is not descended from Lazuli through the trait. That is a check the rule makes available and nobody performs.

This survey recommends that the single-founder rule be enforced by test rather than by pedigree alone. A DBE^CEL (Roxi) result on every registered Céleste would confirm the descent the breed is defined by, at the cost of one test per cat, and would identify any animal registered on paperwork that the genetics does not support. The obstacle is the registry's own position that laboratory results will not be taken into account in the absence of an agreed protocol. A breed whose definition is a line of descent, and for which a test of that descent exists, is the clearest case in this survey for adopting a protocol.

Why a cat sold abroad cannot be a Céleste

There is a further structural point, and it does not depend on the genealogy or on anyone's intentions. The Céleste is recognised by one registry, in one country. No registry outside France recognises it.

A Céleste sold outside France therefore cannot be registered as a Céleste, because there is nowhere to register it. Whatever the seller or the buyer intends, an exported cat can only enter some other breeding programme, under some other registry, as something other than a Céleste. Export and dispersal into other breeds are the same event.

The structural point is why this survey states the effect and does not speculate about purpose. A breeder selling a cat abroad to a colleague who admires the trait, a breeder selling into a named cross-breed project, and a breeder selling with no thought about it at all produce the same outcome, because the structure permits no other. The variant is confined to the Céleste only for as long as every cat carrying it stays in France and is bred under LOOF, and the breed is simultaneously forbidden from breeding to itself.

No claim about the purpose of any sale is made here, and none should be inferred.

A second account of the dispersal, mapped from breeder records

A breeder-compiled lineage genealogy published on messybeast.com maps the same history from breeder records rather than from genotyping, and is the most complete account of the dispersal available. It traces almost all of it to one source, the Altai and Seymour genes held by Iryna Merzlenko in Ukraine, and agrees with the published account that the Topaz was founded on both. It is reported to differ on one point. An annotation states that the Céleste eliminated the Seymour gene and carries only the Altai gene. The elimination is consistent with the genotyping; the label attached to it is not. The wild type results place DBE^ALT among what was lost rather than among what remains, so what was eliminated is the gene the annotation says was kept.

The annotation is recorded here as reported and not as read. The chart is served over plain HTTP and redirects an HTTPS request back to HTTP, which this survey's retrieval tool will not follow, so the page could not be opened and no wording from it is quoted. Nothing in this section depends on it. The page is listed in the missing club list for retrieval by hand.

The chart establishes the shape of the dispersal. One source population in Ukraine reaches at least a dozen breeding programmes across France, Germany, Russia, Australia and Canada, in the British Shorthair and Longhair, Maine Coon, Persian, Ragamuffin, Munchkin, Scottish Fold, Minuet, Highlander, German Longhair and Sphynx. No registry required a test at any point on that map, and no registry holds the map.

The response, part one: two registries, one gene, and rules that point in opposite directions

DBE^CEL (Roxi) and DBE^ALT are two variants of the same gene and they behave the same way: dominant, so one copy shows; harmful when a kitten inherits two DBE variants; and invisible in a proportion of the cats that carry them. Two registries have written rules for them. The rules differ in more than detail. They are structurally opposite, and neither uses the instrument that would answer the question either is asking.

One registry has written a rule that guarantees the variant leaves the breed. The other has written a rule that guarantees it stays. Both are responses to the same problem, that two copies are harmful, and both address it by controlling which cats may be mated rather than by establishing which cats carry the variant. A commercial test exists for both variants, and neither registry requires it or records the result.

The Altai rule and its 2030 closure are examined in full in case study two.

A third position completes the picture. The GCCF neither sends the variant out of a breed nor concentrates it in one. It refuses the trait in some breeds, permits it in others and restricts it in a third group, and it is the only registry in the world that records on a cat's registration which variant that cat carries. It has never published a figure drawn from those records. Its coding has been live since June 2025, so the number of cats it has recorded under each variant is known to the GCCF and to nobody else.

Three registries have therefore taken three different approaches to a single gene. LOOF's rule moves the variant out of the breed that carries it. The World Cat Federation's rule keeps it inside a studbook that closes in 2030. The GCCF alone records which variant each cat has, and publishes none of it.

The mating rule the Altai breed standard already has, and the gap left by triggering it on eye colour

The World Cat Federation standard for the Altai, drawn up in 2018, does what this case study proposes: it prohibits the mating and not the cat. Two blue-eyed or odd-eyed Altai may not be bred together, “because it may lead to deafness and white coats in cats homozygous for this dominant gene”, and a blue-eyed or odd-eyed Altai may be bred only to a non-blue-eyed Altai, green-eyed by preference. Outcrossing to seven named breeds is permitted until 1 May 2030, after which only Altai to Altai matings are allowed, and the ban on blue to blue continues.

The World Cat Federation's Altai standard is the closest thing in the world to the control proposed at the end of this case study, and it fails at exactly one point: it is triggered on eye colour. A latent carrier is not blue-eyed or odd-eyed, so the ban does not reach it, and the same messybeast.com compilation that records the rule also records that latents exist and produce blue-eyed offspring. The rule is right in its structure and wrong in its trigger.

Why closing the studbook in 2030 makes the trigger worse, not better

The failure is not static. It gets worse on a known date, and this survey records it as a risk the standard does not appear to have considered.

Until 1 May 2030 an Altai may be outcrossed to an American or European Shorthair, a British Shorthair, a Bengal, an Abyssinian, a Somali or a Siberian. A cat brought in from one of those breeds is almost certainly not a DBE^ALT carrier, so an outcross is a reliable way of putting a non-carrier on one side of the mating whatever its eye colour. After that date only Altai to Altai matings are permitted, and the only screen retained is eye colour.

From 2030 the permitted mating is a blue-eyed or odd-eyed Altai to a non-blue-eyed Altai. If that second cat is a latent carrier, the mating is carrier to carrier and a quarter of the litter is expected to be homozygous, which in this variant means a cat that is white or nearly white and usually deaf. That is precisely the outcome the rule exists to prevent, and nothing in an eye-colour screen can detect it.

Two things follow, and neither can be resolved from anything published.

• Nobody has recorded what a carrier to latent-carrier mating produces in this breed. The founding programme observed that homozygotes were viable and usually deaf, and it observed that latent cats exist, but no study has put those two observations together and followed the matings. The frequency of latency in the Altai population is not published either, so the size of the risk cannot be estimated.
• The risk rises as the studbook closes. A closed population becomes more related over time, so the proportion of cats carrying the variant without showing it can be expected to rise rather than fall. An eye-colour screen therefore becomes less effective in the same years in which it becomes the only screen.

The remedy is available and inexpensive. DBE^ALT has a commercial test, sold as DBE3 on the five-variant panel, so a breeder can establish whether a green-eyed Altai is a latent carrier for the cost of one swab. Substituting genotype for eye colour would leave the rule's structure untouched and close the gap entirely. On the evidence available this survey treats the 2030 closure as a red flag: a mating restriction that will lose its outcross safeguard on a fixed date while continuing to screen on a trait that does not identify the carriers.

The Altai standard and the founding-programme observations are taken from Altai / Altay, messybeast.com, supplied to this survey on 10 August 2026 because the site is served over plain HTTP and redirects an HTTPS request back to HTTP, so it could not be retrieved directly. It is a self-published compilation at messybeast.com worked up from breeder records and pedigrees, and is not peer reviewed. Where it is quoted above it either agrees with the published genotyping or is marked as reported. Roxi's own pedigree is described there as unknown, so his relationship to the Altai founder line cannot be stated.

The response, part two: four registries, one trait, and four different answers

Everything above describes a decision taken in France and its consequences. Three other registries have since faced the same trait in the same breed and answered differently, and one of them arrived independently at almost exactly the French solution. This section sets the four side by side, because they began from the same point and did not end in the same place.

What the GCCF decided

The British Shorthair Breed Advisory Committee amended the British Shorthair Registration Policy, and the Council approved the revision on 27 June 2026. The operative words are these:

“Blue-eyed/odd-eyed cats of BSH appearance in any pattern other than epistatic dominant white, colourpointed or colourpointed & white shall be registered on the Reference Register with no progression as no recognised breed (XSH) and are not acceptable in the pedigrees of British Shorthairs.”

Four things follow from that wording, and each of them is a fact about the rule rather than a prediction about anyone's behaviour.

• The cat is registered, and registered as nothing. XSH is the code for an unrecognised shorthair. The cat exists on the Reference Register, cannot progress to the British Shorthair register, cannot be shown, and cannot be bred from, because unrecognised cats may not be used for breeding.
• The exemptions are three. Epistatic dominant white, colourpointed, and colourpointed and white. In those three patterns a blue eye has an established cause other than PAX3, so the rule is directed at blue eyes that cannot be otherwise explained.
• Descent is cut, not restricted. The cats are “not acceptable in the pedigrees of British Shorthairs”, so the exclusion reaches backwards through any pedigree containing one, and not only forwards from the individual animal.
• The trigger is the eye. The rule reads on “blue-eyed/odd-eyed cats of BSH appearance”. It is a phenotype rule. It names no variant and requires no test.

The same code, the same breed, two destinations

The comparison with France is exact enough to be worth stating in a table, because both registries reached for the same instrument and put it to opposite use.

The two registries began from the same refusal and the outcomes differ completely. Nothing about refusing a trait determines what happens next. What determined it was what each registry allowed the unrecognised code to lead to. France left a route from XSH to recognition open and the trait took it. The GCCF closed that route.

What the rule reaches, and what it does not

Three limits follow from the drafting, and they are the same three that run through this survey.

• A latent carrier passes through it. The rule triggers on a blue or odd eye. A cat carrying a DBE variant without blue eyes is not caught by any part of the wording, and remains registrable and breedable as a British Shorthair. The founding Kazakh programme described latent carriers before any variant had a molecular name, so this is not a hypothetical class of animal.
• The registry that could have written it on genotype did not. As set out above, the GCCF alone records a DBE variant on the cat's own registration record, through codes 162, 163 and 164. It was therefore the single organisation in a position to make this rule turn on a test result rather than on an eye colour, and the amended policy names no variant.
• The cats are removed from the register, not from breeding. The rule governs what the GCCF will register. It does not govern what exists. A cat refused British Shorthair registration by the GCCF remains eligible for registration with other organisations operating in the same country and internationally, whose British Shorthair policies differ. The effect of the rule is that the GCCF no longer records these cats, and a cat the GCCF does not record is a cat about which the GCCF holds nothing.

No outcome is asserted here. The policy took effect on 27 June 2026, it applies only to registrations submitted from that date, and what follows from it is not yet observable. The French sequence set out above is recorded as what happened in one jurisdiction and not as a forecast for another. What can be said now is what the instrument does and what it leaves untouched.

The policy has been revised three times in eight months: effective 12 November 2025, revised 29 April 2026, and revised again with Council approval on 27 June 2026. The wording quoted above is the June 2026 text.

A third answer: a new breed, with the rule this survey recommends written into its standard

A second new breed has been created for the trait, and it was created independently of the Céleste, in Germany, from British Shorthairs and Longhairs carrying the Igor line. It is called the Azul, in shorthair and longhair forms, and it is recognised as an experimental breed by the Association of Rare Breeds of Cats. The name means blue, for the eyes, and is unconnected with the American Ojos Azules.

The sequence that produced it is the Céleste's sequence, arrived at separately. The trait was refused by most clubs and British breeders did not want their breed's name attached to it. A new breed was therefore created. To register it the association required a standard differing in more than eye colour, which is the identical condition LOOF imposed on the Céleste. And the resulting standard prohibits Azul to Azul matings and permits an outcross to a British Shorthair or Longhair, which is the Céleste's mating rule in different words.

Two registries on two continents, working without reference to one another, produced the same instrument. That is worth stating plainly, because it means the structure described in this case study is not a peculiarity of French practice. It is what happens when a trait is refused inside a breed and then given a breed of its own.

The Azul standard, however, does three things the Céleste standard does not, and each appears in the prevention control set out at the end of case study one.

• It requires one variant per breed. The standard states that British Shorthairs and Longhairs with a dominant blue eye gene may not be recorded as Azul, expressly because there are different dominant blue eye genes in different British-derived breeds and Azul cats must all have the same one. That is the prevention control set out at the end of case study one, written into a breed standard by the people using it. No registry examined in the main survey has such a rule.
• It closes the return path in both directions. Azul cats and their offspring may not be recorded as British on a pedigree. The Céleste standard requires the British outcross and says nothing equivalent, so the Azul is the only instrument found that names the direction of travel and blocks it.
• It codes the trait itself. An ARBC pedigree certificate codes a cat ny 11 08 60 and glosses that on the document, in English, as “black gold, shaded, dominant blue eyes, little white spots”. So 60 is confirmed as a dominant blue eye and 08 as the accompanying white, from the issuing registry's own paper. Four cats on that one certificate carry 60, across four generations. A secondary description of the same list gives 69 for latency and 68 for mosaic eyes; neither appears on the certificate, and 68 denotes a plain blue eye at WFA and albino at FIFe, so those two codes are unverified and the mosaic reading of 68 conflicts with two other registries. Two other registries record something about latency and both can now be verified: WFA issues 68c to 68e for latent carriers, and this survey holds a WFA certificate on which an entire litter of three is coded 68e; and REFR marks the registration number of every kitten of blue-eyed parents, including those with no blue eye, because it may carry the variant. All of them record it by parentage or by appearance. None records it by genotype.

The breed's own machinery is otherwise conventional: a standard built on the British type with rounder ears and a thicker tail, minimal white or no white permitted, bicolour and orange eyes allowed only for pedigree creation, and a breeding ban recorded against any cat outside the permitted colours or produced by a forbidden mating. The founding female was acquired in 2022 and the first surviving litter was born on 27 March 2024. That litter is recorded whole on the breed's own breeder-compiled genealogy, and it is worth setting out, because it is one of the few litters anywhere in this subject for which every animal is named and coded. Five kittens: two showing a blue eye, one coded c 10 63/1 and described as “DBE odd-eyed, lilac, no visible white”, another described as odd-eyed with minimal white, and two showing no blue eye at all. On the breed's own rule those two may carry the variant, and nothing on their pedigrees currently records it.

The four answers side by side

The same trait, in the same breed, has now met four different registry responses. Setting them out together shows that the outcome was never determined by the refusal.

Read across the table. Two of the four refusals produced a new breed, one produced a dead end, and one produced a change of name on the paperwork. Three of the four leave the line able to continue, and in two of those the continuation runs through the British breeds in which the trait was refused. Only one registry records anything about the variant, and only one records the latent carrier, and they are not the same registry.

The Ojos Azules route is set out in full, with the cats named, in the line directory in case study one.

What happened in Germany before the Azul, and why it is the clearest case of latency causing harm

The Azul was created against a background the same source records, and it is the harm this survey has argued follows from an appearance-based rule, documented at the scale of a national breeding population rather than a single litter.

In Germany a large number of latent cats were bought by breeders who did not know they carried the trait. Deaf kittens followed, because those breeders mated latent to latent, or mated two blue-eyed cats without knowing what that meant. German law forbids breeding cats likely to be deaf. The law was in force throughout, and it did not prevent any of it, because nothing about a latent carrier is visible to the person buying it.

That is the whole argument of this survey in one sequence. A rule triggered on eye colour cannot reach a cat with ordinary eyes. A law prohibiting the breeding of deaf cats operates after the kitten is born deaf. The only instrument that would have worked is a test result recorded against the cat and carried with it when it was sold, and for the Igor line no such test exists to this day.

The breeders who founded the Azul responded by neutering every dominant blue eye cat they held other than the one line, in order to keep a single variant in the programme. That is the third breeding programme recorded in this survey to adopt the one-variant control voluntarily, alongside the two Maine Coon programmes named in the line directory. No registry requires it of any of them.

What no registry records: how many carriers there are, and why the number cannot be obtained

How many cats carry this variant is a simple question, and it has no answer anywhere.

The quantity the argument needs is the number of registered cats carrying DBE^CEL (Roxi) worldwide. That number does not exist, and the reason it does not exist is itself a finding about registry governance.

No registry outside the GCCF records a genetic variant on a registration record. Every other registry examined records either a colour, a breed or nothing: FIFe requires a test for the PAX3 gene rather than for a named variant, and its rule § 3.5.1 places the duty to register the result on the member, which produces a paper record in each member country and no central total. TICA, CFA and WCF record nothing genetic beyond parentage, and LOOF, as set out above, holds no genotype for the breed it recognised.

The bodies that necessarily hold the number are the laboratories, since each knows how many positive results it has issued. Three currently offer a DBE^CEL (Roxi) test, and none of them publishes any aggregate figure. A fourth has withdrawn its test on the ground that false positives cannot be excluded. That a commercial laboratory can publish such counts is demonstrated elsewhere: Wisdom's MyBreedData gives per-breed carrier counts across more than 11,000 cats, and PAX3 is not among the variants it covers. OMIA records all four published variants with their molecular descriptions and carries no frequency or carrier data.

A worldwide count of registered DBE^CEL (Roxi) carriers is therefore not obtainable at present. The published genotyping is the only verifiable floor, and 65 carriers in one paper already exceeds the 46 Céleste pedigrees LOOF issued in 2025. Four partial counts could be assembled, in ascending order of difficulty: the published floor, which is free; a cumulative LOOF count of Céleste registrations, every one of which is a carrier because Céleste to Céleste mating is prohibited; a GCCF query on code 162; and aggregate positives from the laboratories. Any count built on eye colour will undercount, because latent carriers do not show the trait.

One consequence of the missing count falls on the Maine Coon. Because the Céleste is mated to British Shorthairs and British Longhairs under the terms of its own standard, DBE^CEL (Roxi) reported in the Maine Coon is read as evidence that Maine Coons have been outcrossed to British cats. The published record does not support that. The Topaz used Roxi, an outbred domestic cat from Kazakhstan, together with Nikita'l Seymour. The British connection belongs to the Céleste's breeding rules, which are a later and separate development, and applying it to the Maine Coon attributes an outcross that did not occur.

The rules LOOF and the World Cat Federation have written for these two variants point in opposite directions, one exporting the variant and one concentrating it. That comparison belongs with the rule-design argument and is set out in case study one.

What a breed is for, when its own standard forbids breeding it to itself

Two dominant blue eye breeds have been created. Both are instructive and neither contained anything.

• The Topaz was founded deliberately on two different variants at once, Roxi carrying DBE^CEL (Roxi) and Nikita'l Seymour carrying DBE^ALT. A population holding two variants produces compound heterozygotes in every generation, and a compound heterozygote, meaning a cat with one copy each of two different variants, is the state in which deafness and neonatal death are documented. The Topaz has been discontinued, and DBE^CEL (Roxi) reached the Maine Coon through it.
• The Céleste was founded on a single variant which is reported lethal in the homozygous state, so no Céleste can inherit two copies and live. Its standard therefore forbids breeding the breed to itself and requires an outcross in every generation, which is why its 46 pedigrees in 2025 were all the product of an outcross.

The breed has stayed small and the variant has not. DBE^CEL (Roxi) is confirmed in six populations by genotyping and reported in twelve more without verification, while the breed it is named after registers fewer than fifty cats a year. The registry that recognised the breed records no genotype for any cat in it.

The question this raises is one of rule design rather than of genetics, and it is the question the first case study answers with a protocol. A trait whose harm arises only when two copies meet cannot be governed by making it the defining feature of a breed, because a breed is a closed population and this trait forbids closure. The instrument that fits the biology is a ban on the mating, recorded against the individual animal and carried with it when it is sold. That is what the Altai standard attempts, in the one respect in which it is right, and it is what breed recognition cannot do at all.

Sources for this case study are given in each section above. The founding cattery's breeder-compiled genealogy and the independently compiled lineage genealogy are primary records held outside any registry; the genotyping is from Abitbol et al., Animal Genetics 2024 and 2025, and Rudd Garcés et al., G3 2024; the LOOF registration figures are from LOOF's own published annual statistics for 2025. Declaration of interest: the author of this survey is a co-author of the 2025 paper.

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