How each variant spread across breeds

Where the two Kazakh variants came from, and how all six have moved from one breeding population into another since, by date, by line and by breed

The material on this page is drawn from the Global Cat Health Survey 2026, which is where its sources and its declarations of interest are set out in full.

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.

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.

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.

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 the 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.

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 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 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 meet in one mating, and the register traces, dates and names it twice. 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 directory'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 is drawn as seven kittens on one chart and eight on another, and both readings are held: the eighth turns on whether Mavi and Mavi of Aerlin are one kitten or two, which no document settles. 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-six cats now descend from a mating that held one variant on each side, eight of them the founding litter itself and the rest below it, across four breeds: Celeste, Celeste line, German Longhair and Siberian. 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-six has been genotyped, which is what makes the list a testing list rather than a result. The Maine Coons of the Markiss line are not among them: they reach DBE^CEL by a different offspring of Roxi, not through this mating.

None of that reaches the claim about the early population. 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.

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 the survey holds.

The founding pair of the Céleste programme, one variant each

The mating of 18 July 2016 is the second of the two above and the one this directory follows. The two variants arrive on opposite sides of it.

The Maine Coon is not part of this directory. 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 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

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.

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 the survey does not choose between those two.

It was reported at the time of the 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. 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.

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 depends on which reading 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. 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. The 1997 date stays on the record as what was reported, but not as the date of Roxi of the Topaz, the sire of Lazuli.

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. 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. 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.

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.

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 dispersal, by date

Set out by date the same material makes a different point: the trait was reported for 119 years before anyone could test for it, and five registries acted within twenty-six months of the first variant being published. Rows are graded: published means the peer-reviewed literature, registry means an organisation's own document, and breeder means a breeder or breed record not verified here.

The gap is 119 years. From the first published report of permanently blue-eyed kittens in 1905 to the first identified variant in April 2024. Everything in between was managed by eye. The dispersal front-ran the science by about a decade. Between 2015 and 2022 the trait entered pedigree breeding in at least ten breeds across nine countries, and every one of those decisions was taken with no test in existence. And the regulatory response is almost entirely younger than the science. Of the registry actions above, the GCCF's variant codes, TICA's show rule, FIFe's obligatory test and the GCCF's British refusal all fall within twenty-six months of the first publication. The exceptions are the two that came first: the WCF's 2018 standard and LOOF's 2019 single-founder rule, both written before anyone knew there was more than one variant.

The lines, the variants, and which breeds hold more than one

A pedigree names catteries, not variants. This section sets out which named lines exist, which of them a variant has been identified in, and which breeds hold more than one. The animal-by-animal listing that supports it is kept separately, in the Blue Eyes Directory, which is in two parts: how it is compiled and what the numbers show, and the register itself.

Lines and cattery prefixes only here. A prefix is a trade name and appears on every pedigree the cattery issues. No individual is named here who is not already named in the published literature. Declaration of interest: the author of the survey breeds British Shorthairs carrying DBE^ALT under the Belle Ayr prefix, from the Roddifer founders of the Nanotigr line, and Maine Coons carrying DBE^RE under the same prefix. The interest is direct, and it applies to case study one of the survey rather than to the survey as a whole. Cats bred under the Belle Ayr prefix appear in its register and in its findings, both clinical series it reports were conducted on those cats, and the author stands to be affected by its conclusions. The author is a co-author of Abitbol M, Cloquell A, Kaczmarska A, Holmes K, Lühken G, Macaulay K. Dominant blue eyes in Maine Coon cats: new PAX3 variant and updated phenotypic data. Animal Genetics 2025;56:e70020, the BAER follow-on study, credited with investigation, resources and project administration. Cats of the author's own lines were among those sampled for the two 2024 papers in which the variants were identified, in which the author is acknowledged rather than an author: Abitbol M, Couronné A, Dufaure de Citres C, Gache V. A PAX3 insertion in the Celestial breed and certain feline breeding lines with dominant blue eyes. Animal Genetics 2024;55(5):670-675. doi:10.1111/age.13433; and Abitbol M, Dufaure de Citres C, Rudd Garces G, Lühken G, Lyons LA, Gache V. Different Founding Effects Underlie Dominant Blue Eyes (DBE) in the Domestic Cat. Animals 2024;14(13):1845. doi:10.3390/ani14131845. Two clinical series reported in this directory are the author's own and are not peer reviewed: the BAER hearing series in fourteen British cats of a DBE^ALT line, recorded at the University of Glasgow on 17 and 24 September 2024 and reported in a dated summary statement, Abitbol M, Cloquell A, Kaczmarska A, Holmes K, Macaulay K. BAER hearing screening in British Shorthair and British Longhair cats carrying DBE^ALT: Summary Statement. Belle Ayr Cats, 3 June 2025; and the blood pressure trial in forty-three cats of the same line, reported in a dated summary statement, Abitbol M, Macaulay K. Corin Levels vs Blood Pressure Trials in British Shorthair / Longhair Cats: Summary Statement. Belle Ayr Cats, 10 September 2024. Both form part of an ongoing research programme and are intended for publication. The registry under which those cats are registered changed during the work, because a policy change at the federation previously used closed registration to the line concerned, and the certification on which the descent claims rest was obtained from The International Cat Association thereafter. That is the author's own instance of the mechanism set out in the survey under the heading what a registry certifies, and what a ban removes. Every row carries its grade of evidence in the cell, on the same four-point scale used throughout this directory:

• Genotyped. A cat of this line has a laboratory result for the variant named.
• Wild type. Cats of this line were tested for the known variants and found to carry none of them. This is a positive finding of absence, not a failure to test.
• Pedigree. Descent traced to the founder of the line, with no genotype on the individual cat.
• Reported. A breeder account or a self-published compilation at messybeast.com, not verified here. These rows are leads for checking and not findings.

Lines in which a variant has been identified

The Selkirk Rex is recorded against the Seymour line by pedigree rather than by genotype, and appears in the breed table on that basis. Prefixes given as not established mean the survey could not trace the line to a named cattery, and not that none exists.

Lines in which no variant has been identified

These are the lines for which no test can exist until the variant is found. Two of them have been tested against every known variant and carry none, which is a stronger statement than untested and is graded accordingly.

Which variants are in which breed

What this table does not show is direction. A breed may be the origin of one variant and the recipient of another, and a mark here does not distinguish the two. The Maine Coon is the clearest case: DBE^RE and DBE^AGO both arose in it, DBE^CEL (Roxi) arrived by outcross, and DBE^ALT is reported in it as well, which is why no single test clears a cat of that breed. The breed table on the Laboratories page separates arrival from origin row by row.

The Maine Coon against DBE^ALT is the only grey tick in the table and its source is a breeder-compiled genealogy headed “blue-eye line created using Roxi and Seymour genes”: Roxi is the DBE^CEL (Roxi) founder and Nikita'l Seymour the DBE^ALT founder, so on the compiler's own account the line was founded on both.

Set against it, no genotype for DBE^ALT in a Maine Coon has been published, and the laboratory breed list for that variant runs Altai, British Shorthair and Longhair, Exotic Shorthair and Longhair, Persian, Ragdoll and Sphynx, with the Maine Coon absent from it. The cell is the strongest case in the table for a test.

If the Maine Coon blue-eye line was founded on both variants, cats of that line can carry one copy of each. A cat with one copy each of two different variants is a compound heterozygote, which is the state in which deafness and neonatal death are documented in this directory, and no test on sale reports both at once.

An empty cell means nothing has been recorded, which is not the same as nothing being present. The count on the right is what matters: a breed with two or more ticks is a breed in which two different variants can meet without leaving the breed.

A blank cell is weaker evidence than it looks. Three Sphynx carriers had no blue-eyed cat anywhere in their recorded pedigree. A breed can therefore hold a variant with nothing in its papers to suggest it, which is what latency means in practice and why absence from this table cannot be read as absence from the breed.

✓ black tick, genotyped in a cat of this breed  ·  ✓ grey tick, reported somewhere and not verified here  ·  empty cell, nothing recorded.

Six breeds and breed groups already hold two or more variants, and the four largest hold four, five, five and six. In every one of them a cross between two different variants can be made without leaving the breed and without breaking any registry rule anywhere in the world. Against that, only three breeds in the table are held to a single variant by an instrument rather than by chance: the Céleste by LOOF's rule that every cat descend from one founder, the Azul by a standard requiring one variant per breed, and the Pharaoh by a standard permitting one outcross partner.

The prefixes and the animals behind these counts

The animal-by-animal record supporting this section is held separately, in the Blue Eyes Directory, which carries one entry per cat on the same four grades of evidence used above, with views by variant, by breed, by cattery prefix and by litter. This directory argues at the level of the line and the variant; the directory enumerates animals, and it grows with every pedigree supplied. Two of its findings belong in the argument rather than in the listing.

• Forty-one of the four thousand two hundred and twenty-five cats in the whole documented record have a laboratory result of their own. The rest are attributed by descent from a named founder, or asserted with neither a test nor a traced descent. That is the state of the evidence this directory is obliged to work from. A cat whose owner holds a laboratory result that has not been supplied to the survey is graded on what the survey holds, not on what exists.
• A large part of the record cannot be keyed on a cat's name, because the cats have no name. On one breeder-compiled genealogy of a founder line, sixteen of twenty-four kittens are recorded only as "Girl 1" or "Boy 2", two of them share a label, and every animal of the second generation is unnamed. Those are the animals whose descendants cannot now be traced, and they are the reason the recommendation below is addressed to registries, which hold the only records in which such animals are individually identified.

Where the Rociri Elvis line actually begins, and why it is not a spontaneous mutation. The variant is generally described as having arisen spontaneously in Rociri's Elvis, born in the Netherlands in 2015. The pedigree record does not support that. Genotyping traced it back as a latent variant carried by white cats in which it could not be seen, to a cat recorded as Justcoons Ha Shisch, and then, after skipping several generations, to a cat recorded as JW Olmocabe's Alastor, beyond which the trail is cold. Elvis is the cat in which the trait first became visible, which is a different thing from the cat in which the variant first occurred. This is the same distinction drawn for Roxi and Lazuli in case study two of the survey, and the same one that makes a line name an unreliable guide to what a cat carries.

Two attributions circulating for this line should be treated with care. Elvis's blue eyes have been attributed to a mutation of the KIT white spotting gene, which the published genotyping does not support: the causal variant is in PAX3, and none of the fifty-eight cats sampled carried the dominant white KIT variant. And one prefix reported in this line is recorded on social media as descending from a red and white cat, while the breeder states the line descends from Joyfield cats; a third account names a stud of another prefix again. None of the three has been confirmed.

A possible explanation for the deafness disagreement. The two published series on DBE^RE disagree sharply, eight of eight hearing-tested cats abnormal in the first and none of six in the second. DBE^AGO had not been described when the first series was collected. If cats in that series carried DBE^RE and DBE^AGO together, they would have had no fully functioning copy of PAX3 at all, which would explain a severe result in one series and not the other. This is a hypothesis and not a finding: no cat has been reported genotyped for both, and it is testable on stored samples.

The Ojos Azules, and what the one closed programme actually established

The Ojos Azules is cited constantly in this subject, usually as a warning, and the citation is almost always second hand. It is set out here because it is the only dominant blue eye programme in the world that ran to a conclusion.

The line is traced to one cat. A dark tortoiseshell with a white throat locket, white toes on each hind foot and brilliant blue eyes was found in an animal shelter in New Mexico and named Cornflower. She was bred to unrelated non-blue-eyed males from 1984 and the kittens inherited the eye colour, which established the trait as dominant. TICA recognised the breed in 1991. By 1992 ten cats were registered. The breed is registration only today, held in TICA's Category VI for experimental breeds. A motion of 28 August 2014 returned it to registration only, and motions of the following day reconsidered that and reinstated its preliminary new breed status. The decision that effected the final demotion has not been located. Cats not descended from Cornflower are not of the breed, whatever they are called.

• It had a characteristic facial type, line-traced. Every descendant of Cornflower is recorded as having wide-set eyes, distinct cheekbones and plump whisker pads, with a white tail tip regardless of coat colour, and a flattened or kinked tail tip treated as an indicator of the gene. This is the only line in the survey for which a facial phenotype is traced to a single founder rather than asserted.
• Latent carriers were identified here first, and they were not harmless. Cornflower's granddaughter was a red mackerel tabby with deep amber eyes and the breed's facial type; bred to an unrelated cat she produced four kittens, three blue-eyed and one odd-eyed, proving that a cat could carry the trait without showing it. The programme's own figures then recorded that 9.5 per cent of the amber-eyed latents had birth defects. Harm was therefore not confined to the homozygote, which is a possibility no registry rule in the survey addresses.
• Homozygotes died before birth, with cranial deformities. White fur and a small curled tail are recorded with them. The deformities were described as resembling those of double merle dogs. It was never established whether the mutation itself or an adjacent linked gene caused them.

The programme ended for reasons of breeding economics rather than biology. The defects were avoidable, by never mating two carriers, and the safe mating produced roughly half non-blue-eyed kittens. Breeders left the programme because half of every litter had to be sold as pets while buyers wanted the blue-eyed cats, and because outcrossing to keep the trait safe would lose the facial type within a few generations. The instrument that prevented the harm was the same instrument that made the breed commercially unviable. That is the tension the Céleste and the Azul standards now contain, arrived at from the other direction.

The breed is treated as extinct, although cats descended from the geneticist's own animals are recorded as still being bred, with white spotting and cornflower-blue eyes and no health problem reported to date. The genetic work was never published: the only genetic study of the line was carried out in the late 1990s and early 2000s and could not be found in open sources by a later researcher, who suggests it was lost on the geneticist's death. The account above is therefore a breeder and breed record rather than published evidence, and the survey does not treat the cranial defects as established for any other line.

Two threads that lead out of it

First, a candidate gene the survey did not have. Merle in dogs is a mutation at SILV, also called PMEL, and double merle dogs show deafness, visual defects, a high degree of white and the pattern known as lethal white. The Ojos Azules homozygote defects were described as resembling double merle. Independently of that, a laboratory study for one British Shorthair line reported an approximately 100-nucleotide deletion in PMEL alongside three variant positions in PAX3. Two unconnected pointers to the same gene is not a finding, and neither has been published. It is recorded because PMEL does not appear anywhere in the four published feline variants, and because a cat carrying a PMEL variant would return a clear result on every DBE test sold today.

Second, the Ojos Azules became a registration of last resort, and this can now be dated. Because it was for many years the only recognised breed in which a blue-eyed, non-white, non-colourpointed cat could be entered, unrelated cats were registered under its name. Three instances are recorded in the survey: the founder of the Igor line, whose pedigree was registered as Ojos Azules “simply because there were no other DBE breeds at that time”; a blue-eyed tabby found in Norway and registered as Ojos Azules in 2012, at a time when that was “the only way to register blue-eyed non-white/non-colourpoint cats”; and a British Shorthair of the Igor line registered as Ojos Azules to circumvent the British registration bar.

The sequence matters. TICA reduced the breed to registration only in 2014, which removed the breed committee, the standard and any health rule, but did not remove the registration route. A cat entered under that name after 2014 therefore enters a breed with no committee to ask questions of it. Two of the three instances above post-date 2014.

The Barnaul and Aktau lines, and the one place two unidentified variants were deliberately crossed

Both were found in street cats, both were investigated by the same person, both reached pedigree breeding through the same cattery, and the two were then mated together.

Prefixes recorded in the Barnaul dispersal, in order of transfer: Slavicat to Meowrigi, then to a German breeder, to Rehaloon and Steph Mzzn in France for Minuets, to an untraced holder in Ukraine, where it founded a Scottish Fold line, to Aldmeris in Uzbekistan, to Felicious in Kazakhstan and onward to the United States, to Schastie Doma in France as a foundation cat for British chinchillas, and to Tabassum in Uzbekistan. Several of these cats carry EMS codes ending 61 or 63, the blue-eyed and odd-eyed codes, so they are registered animals with pedigrees.

A deaf stud, and the rule that would have prevented it. The deaf kitten of that litter was used for breeding and sired many kittens. The source records the contrast itself, that in Europe and the United States a deaf cat would not be bred from. European companion animal legislation provides that deaf cats must not be deliberately bred, and German law prohibits breeding animals with defective hearing. The animal in question was in Uzbekistan, where no such provision was located. A rule that binds in one jurisdiction does not bind the cat, and the cats of this line have since moved to Germany, France and the United States.

Both founders were street cats, found within a few years of each other in the same region of central Asia and noticed only because breeders in those countries had begun developing local cats into recognised breeds. The most likely explanation offered in the source is not that new variants are appearing but that they have always been present in the random-bred population and nobody was looking. That is consistent with the GCCF genetics committee's own expectation that more variants will be found, and it is the reason a test panel covering the known variants cannot be treated as clearing a cat.

A recommendation: trace the descendants, because they are the only cohort that could identify the unmapped variants

This is one of 6 recommendations about where to spend a test. The other five are test the cats whose status cannot be seen, on Findings, screen PAX3 in one cat of an unmapped line, on Findings, test the white cats, on Latent lines, a prevention control for every breed, on Health and test one cat in each cattery holding two variants in one breed group, on Variant trace. A further three recommendations, about how a registry writes the trait down, are on Recommendations.

Nobody records which pedigrees still carry descendants of these matings. No registry records the variant, and for an unmapped line there is no variant to record, so the only trace that exists anywhere is the pedigree itself. It is an opportunity that is closing.

Why the pedigree is the instrument here, and not a poor substitute for one

For a variant that has been identified, a pedigree is inferior to a test: a test reports what the cat carries and a pedigree reports only what it might have inherited. For a variant that has not been identified, the relation reverses. There is no test to be inferior to. Descent from a named founder is the only available evidence that a cat may carry the variant, and a pedigree recording that descent is therefore the primary record rather than a proxy for one.

Gene discovery needs exactly what a traced pedigree supplies. The requirement, as stated by one of the breeders working on it, is two defined groups: cats that carry the variant, and control cats in which it is certainly absent. If the carrier group turns out to hold several different variants with a similar appearance, the search for a shared difference fails, because there is no shared difference to find. A cohort assembled by pedigree from a single founder is the one way to be confident, before any sequencing is attempted, that every cat in the carrier group carries the same variant. It has nothing to do with breeding two carriers together, which is prohibited under the mating rule this directory proposes: see the proposal.

The cohorts that already exist, and what each would answer

Each is defined by named cats, and in each case the animals either exist now or existed recently enough for samples and pedigrees to be recoverable.

What a pedigree cannot answer and a genome can

The cohorts above would identify the variants that have never been mapped. A second set of questions concerns the variant that has been mapped, DBE^ALT, and none of them can be reached from pedigrees at all.

• How old is the variant. The age of a variant is estimated from the length of the chromosome segment still shared around it by unrelated carriers. Recombination shortens that segment at a known rate each generation, so a long shared segment indicates a recent origin and a short one an old origin. It requires sequence from carriers in several unrelated lines and it returns an interval with a stated error. The pedigrees give only a floor: the variant was transmitting by 1999.
• Whether it arose in a breed or arrived in it through an outcross. The question is the same for every breed on the list and the test is marker sharing. A variant that arose in a breed sits on that breed's own haplotype in a background of that breed's ancestry. A variant that arrived sits on a foreign haplotype in a background that is otherwise the receiving breed's.
  For example: if DBE^ALT arose in the British silver lines and reached the Kazakh population, cats descended from Fyodor should carry British ancestry beyond the variant itself. If it arose in the random-bred Kazakh population and entered the British, the British carriers should show the Kazakh haplotype on an otherwise British background. The same pair of predictions can be set for the Persian, the Ragdoll, the Sphynx, the Munchkin, the Lykoi, the Exotic and the Selkirk Rex.
• Did the breeds carrying it get it once or several times. DBE^ALT is genotyped in the Altai, the Topaz, the British Shorthair and Longhair, the Persian, the Ragdoll, the Sphynx, the Munchkin, the Lykoi and random-bred domestic cats, is held by descent in the Selkirk Rex, and the commercial breed list adds the Exotic Shorthair and Longhair. If every one of those carries the same haplotype, they took it from one source and the dispersal is a single event traced through pedigrees. If the haplotypes differ, the variant entered more than once, and the breed lists in circulation are describing several introductions as though they were one.

Shared ancestry across the whole genome is what separates origin from transfer. A variant carried on a foreign haplotype in an otherwise pure background arrived; a variant carried on the background's own haplotype arose there. That is the only evidence that can settle where this variant came from, and no amount of pedigree work substitutes for it, because a pedigree records what was declared and cannot exclude what was not.

All three require samples from carriers in several countries, and some of those lines are now closed to registration in the registries that hold their records. A cat a registry will not register is a cat that registry holds no record of. Nobody can then say who its parents were, which line it belongs to, or where to find its relatives, and a sample without that information cannot be used: the comparison depends on knowing which line each animal comes from. That is what the research registration class recommended elsewhere in the survey is for.

Why this is urgent rather than merely desirable

The records are being lost now, and four instances of it are documented in the survey.

• A founding cattery's records were stolen. On the invasion of Ukraine the cattery that founded the one programme deliberately built on two variants left for Poland; the computer holding its breeding records was taken, and most of its cats were required to be sterilised and homed. Cats described as that breed are still offered for sale.
• Independent lines cannot reliably be kept apart, and the reason is the trait rather than the cattery. One cattery working several DBE lines at once has recorded losing track of which cat descends from which, and the passage is set out in full below because the cause it gives is general.
• A founding cattery has closed and cannot be contacted. The line the survey's own author breeds from traces to a cattery that gave up breeding, with the note that nobody retains any connection with it and the ancestor of the line is unknown.
• A completed genetic study has already been lost. The only genetic work ever done on the Ojos Azules was carried out in the late 1990s, could not be found in open sources by a later researcher, and is believed to have been lost on the geneticist's death. That is the precedent: this has happened once already in this exact subject.

Every year that passes removes cats, closes catteries and disperses records, and the cohorts above shrink accordingly. The Aktau founder is already castrated, the Topaz lines are already sterilised, and one founding cattery is already unreachable. A cohort that can be completely ascertained today can only be sampled in five years and may not be reconstructable at all in ten.

What the survey recommends

1. Registries should be asked to run the search they alone can run. Any registry holding the pedigrees can identify every registered descendant of a named founder with a database query. None has been asked to. The request is specific and answerable: how many registered cats descend from this cat, in which breeds, and in which countries.
2. Assemble each cohort from the pedigree before sampling. A carrier group defined by descent from one founder carries a single variant by construction; one assembled by appearance does not, and appearance is what has defeated every attempt so far.
3. Prioritise the crosses over the clean lines. A cat of known pedigree carrying one of two unidentified variants is worth more than a hundred cats carrying a variant already described, because it resolves two unknowns at once.
4. Sample the deaf cat's line first. A recorded phenotype, a known pedigree, an unknown genotype and many offspring is the rarest combination in this subject, and it is the only route to distinguishing homozygous harm from compound harm in an unmapped line.
5. Record the result against the individual animal, and carry it with the cat. That is the control this directory argues for throughout, and a variant identified but not recorded on the pedigree would leave the position exactly where it is.

Every question in this directory that remains open, the deafness rate of one variant, the homozygote outcome of another, whether a facial sign is attributable, whether two variants interact, is open because no cohort was defined at the time and none has been assembled since. What has never been done is the arithmetic of joining them.

DBE^cDc and DBE^xHW are confined to China, and why their confinement is a warning rather than a reassurance

DBE^cDc and DBE^xHW have been recorded only in certain regions of China: in the domestic cat population there and, for DBE^cDc, in Abyssinians within that population. Neither has been reported outside it.

For breeders working in Europe, North America or Australasia there is at present no practical implication for a cat bred within those populations. Neither variant has been recorded in one, so testing for either is not currently indicated. That is a statement about these two variants only. An Australian breeder holding a blue-eyed cat of the Queensland line is not assisted by it, because no test exists for a variant that has not been identified, and a negative panel result on such a cat means only that the six described variants have been excluded.

The exception is an imported cat. A cat imported from China, or descended from one, is the single case in which testing for DBE^cDc is indicated now, and it is also the route by which the wider position would change. DBE^cDc can be tested for and DBE^xHW cannot, so an imported cat can be cleared of one of the two and not of the other.

The confinement of these two variants to China carries a different significance for a registry writing a rule. Both were identified within a single year, and each of the four older variants was similarly confined to one population before it dispersed: DBE^CEL (Roxi) began in one Kazakh male and is now genotyped in six populations, five of them breeds, and reported without verification in a further twelve rows of the breed table below. A requirement that names the variants it covers will therefore fall out of date, which is why the protocol proposed at the end of this section provides for annual review against the published variant list rather than a fixed schedule of tests.