Introduction

How it is compiled, what it holds, and what the numbers show

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.

The Blue Eyes Directory traces blue eyes across breeds and along lineage. Some are identified variants of the dominant blue eye, DBE. Most are variants that have not been genotyped. A blue eye caused by colourpoint or by white is not the subject of this directory, and such a cat appears here only where a source put it forward as blue-eyed in a line. The pointing rule on the method page sets out how that exclusion is applied. The directory follows a line where breed boundaries do not: a variant carried into a British Shorthair, a Maine Coon and a Siberian is one subject, and the relationship can be seen.

What this directory does

One page for every cat, with the record as its sources give it

Each page carries the evidence grade, the sex, the eye state, the coat, the registration where one exists, and the source in full. Where a code and a description disagree both are shown and neither is reconciled to the other. Where two sources conflict the page says so and does not choose between them.

A genealogy generated from the register, not drawn by hand

Every tree on this site is generated at build time from the parentage held in the register, four generations above the cat, with the evidence grade, the sex and the eye state on each animal. Four is the pedigree convention: two parents, four grandparents, eight great-grandparents and sixteen great-great-grandparents, thirty ancestors of thirty possible. Where the register holds no parentage the page says so.

The drawing goes up and not down, and the reason is not the drawing

Upward from a cat the set of animals is closed: every cat has exactly two parents, so a four-generation drawing is complete wherever the pedigree is complete. Downward the set is open, and this register holds only the offspring somebody sent in, so descent is not drawn: a cat's recorded offspring are listed on its page, and the descent of a line is reported in the variant trace and in the findings.

Printing a genealogy

Every cat whose genealogy can be drawn carries a print link beneath the drawing. Its own print stylesheet puts the genealogy, its key and its flags onto a single A4 landscape sheet, without the record, the source or the navigation, scaled to fit where the drawing is wider.

What the survey sets out to do

In one paragraph. The register holds 1044 cats that carry a dominant eye code or are recorded blue, odd or latent, out of 4225 entered in all. Twenty-nine of them have a laboratory result of their own, and the rest are held on paper: a registry sheet, a certificate, a breeder chart or a cattery page. Six variants are named in the published work and one hundred cats sit under one of them. The rest sit under founder lines in which nothing has been sequenced. That gap is what this directory exists to measure.

Four questions, asked of the recorded genealogy rather than of any individual animal.

1. Identify the known variants in recorded genealogy, and trace them across generations in both directions. A cat is tagged where a source indicates it carries a variant, whether one of the six named in the published work or a founder line in which nothing has been sequenced, and the grade records how well founded the tag is. The downward trace, from each founder, measures how far a variant has crossed into a breed group; the upward trace, from each cat and each cattery, finds the cattery whose cats carry nothing on paper and yet descend from a line that does.
2. Confirm which breeds each variant is recorded in.
3. Confirm the first point at which two variants, known or unidentified, have met.
4. Confirm the catteries, the breeds and the named cats where two or more variants sit in one breed group. A cattery that keeps two breeds with a different variant in each is not such a case, and is not counted as one: the two variants are in two populations that do not interbreed.

What the directory currently holds

41 of the 4225 cats in this directory have a laboratory result of their own, and only 29 of those results identify a dominant blue eye variant. The other 12 were tested for the known variants and carried none of them, which is a positive finding of absence rather than an identification. Everything else in the register is descent or assertion, which is why the survey recommends that results be recorded against the individual animal and carried with the cat.

The same totals broken down by variant and by founder line are set out in the analysis at the end, with the evidence grade against each.

The counts

The evidence columns are the point of both tables: a variant with many cats and one laboratory result is attested by descent, not by measurement.

One hundred cats of 4225 carry an identified variant, and twenty-nine of those one hundred have a laboratory result identifying it. The other 1518 sit in forty-three named founder lines for which no variant has ever been identified. DBE^cDc has no named cat in this record at all, and DBE^AGO and DBE^xHW have one each, both of them the cat the variant is named after.

Read upward as well as downward. Four hundred and twenty-one cats of the 4225 hold a variant or a line in their own recorded ancestry that is not on their record, across seventy-seven cattery prefixes and seventy-nine cattery and breed group pairings. Each cat page names them, and the public export carries them in the in_ancestry column.

Inbreeding, measured over every generation the register holds

A coefficient of inbreeding is conventionally calculated over five generations, because five is as far as most registry certificates go. This register holds parent links beyond that depth on some lines, so the coefficient was calculated twice on the same cats: once over five generations, and once over every generation recorded. 1506 cats have both parents on the record, which a coefficient needs to exist at all. Over every recorded generation, one hundred and ninety-six of them return a coefficient above zero, the highest being 31.6 per cent, which is the value of a full sibling mating.

Calculating over every generation instead of five changes the answer very little here. It raises the coefficient for seventy-seven cats, and by 0.20 percentage points on average: the pedigrees are mostly too short for the deeper walk to find anything the shallow one missed. Six hundred and nine of the 1506 carry five or fewer recorded ancestors, and a coefficient of zero here means no loop of descent was found in what the survey holds, not that none exists. The full analysis, the five-generation comparison and the cats behind the figures are in the survey's case study on the coefficient of inbreeding.

The variants that have not been sequenced

The table above holds the six sequenced variants. Everything else this register treats as a variant falls into three groups, and they are not degrees of one thing. A line can be identified without being genotyped, and most below are.

1. Named in the published work, and the search for the variant is stated to be ongoing five lines

Set out in the published work as dominant blue eye lines in their own right. Cats of each were tested against the variants known at the time and carried none, which is a positive finding of absence and the reason the search continues. four hundred and eighty-four cats, seventy-six showing the trait.

2. Identified but never genotyped: foundation material for a variant already named nine lines

Founder cats and founding populations at the origin of a variant already named, under the wording of the chart or cattery they arrived on. The variant is identified; what is missing is a genotype, and these animals will never have one. Nor do they need one: what each carried is read from descendants who were tested. one hundred and eighty-one cats, fifty-six showing the trait.

3. Neither identified nor genotyped: raised by the survey from a founder cat ten lines

Each begins with a cat above whom no parent carries the trait and in whose descendants it appears. A candidate and nothing more. Some will prove to be one of the six, some the same line under another name, and some a variant nobody has described. one hundred and seventy-eight cats, eighty-five showing the trait.

Eight further lines are recorded as ancestry rather than as candidate variants, because no cat in them shows a blue or odd eye: the descent runs through them and nothing in them is unexplained. They are Altai, early population (7), Schneesternchen (5), Altai and Barnaul, both suspected (3), Altai, via the Sweet Beast cattery (2), Celeste into the German Longhair (1), Nahal (1), Roxi (1), Roxi or Nikita'l Seymour, not resolved (1).

The lines in which a variant has been sequenced, but not in these cats

The reverse case. In each of these ten lines a laboratory has sequenced the variant in some other cat of the line, so the variant is named and a test for it can be bought. The four hundred and fifty-three cats counted here are untested, and not one carries a result of its own.

A sequenced line is not a sequenced cat. It does not follow that every animal here carries the variant: the register holds cats of these same lines that were tested and found to carry none of the known variants.

Footnote on reading every table in this section. Every figure counts animals this directory holds, not animals that exist: the register is not a sample of anything, and no denominator is known. Line sizes therefore measure how thoroughly a line was charted, not how common it is. The largest, Igor at three hundred and sixty-five cats, is largest because one breeder charted its whole programme, while lines held on a single line of text elsewhere appear here with one cat. Every count here is a floor.

Aim 1: the lines, and what descends from each

Every founder this register names, and everything reached by walking down the recorded parent links from it.

Which label appears earliest, and in which breed group

Dates are the weakest column in this register. 2528 records of 4225 carry a year that can be read at all, so what follows is the earliest recorded animal and not the earliest animal. A line charted from a breeder's memory begins later on paper than it began in fact.

No founder in this table has a laboratory result of its own. A variant in this register is never named after an animal that was tested: DBE^RE is named after a cat, Rociri Elvis, who was never sequenced, and the results that identify the variant belong to his descendants. The founder column above gives the cat this register traces each line to, and the grade beside it is the grade on that cat and not on the line.

When each line reaches each breed group

The earliest recorded year for the line in each breed group, earliest first. A variant named after a breed did not necessarily begin in it. Undated records are counted in the total and cannot be placed in the order.

A year is when the line reaches those animals, not when the breed was recognised. A breed created later is applied backwards to its own foundation cats, so a cat born in 2016 can carry a breed name that did not exist then. The Celeste was made from British Shorthair stock and registered afterwards. Read the British year the same way.

Aim 1: where each line has spread

The catteries holding a cat that descends from each founder, and the breed each of those cats is registered in. A variant that reaches many prefixes has left the cattery it was found in. Where it reaches a second breed the movement has a name in genetics, introgression (a variant spread across breeds): an allele passing from one breeding population into another by outcross and persisting there.

DBE^CEL twelve catteries, eight breed groups

DBE^ALT fifteen catteries, nine breed groups

DBE^RE eleven catteries, one breed group

IGOR fourteen catteries, two breed groups

NADEYA one cattery, one breed group

SCHASTI DOMA two catteries, one breed group

Aim 2: which variants sit in which breed, and through which catteries

This table works one level above the register: it holds the catteries those animals passed through, in order of transfer where the chain is known. A row marked with two or more variants is a breed in which two different variants can meet without the mating leaving the breed, which is the situation the harm arises from.

A superscript number after a prefix is the count of cats recorded individually under it in the register below. A prefix with no number is one for which the survey holds a cattery but not a single named animal, the commoner case: ninety-nine prefixes appear here and sixty-two have any cat recorded at all.

The last rows are programmes outside any register. A variant held where no pedigree is issued cannot be traced forward or backward, and a cat sold from one into a registered breeding programme carries no record of what it holds: this is the mechanism by which a variant enters the wider cat population without leaving any trail. The columns mean less for those rows: a cattery prefix traced against a random-bred population is not the same quantity as a prefix traced against the Celeste.

Aims 3 and 4: where two variants have met

A collision is a mating and not a property of an animal: a sire tracing to one founder bred to a dam tracing to a different one. It is recorded against the offspring, in which the two descents meet.

The first point at which two variants met

Walking down the parent links from every founder this register names, fifteen matings bring two different founder descents together, in four pairings. The earliest that carries a date is Miyuki of Aerlin, given on the Celeste charts as Miyuki, 2016, in which DBE^ALT meets DBE^CEL.

Ten of the fifteen carry no recorded offspring; five do. The crossing therefore did not stop where it happened: the animals bred on carry it into Celeste, German Longhair, Maine Coon, Siberian. No recorded offspring is not the same as not bred from, only that none has been supplied to the survey.

The columns are not headed sire and dam: the register holds parents in the order the source gave them, which is not reliably sire first.

The same question asked of the lines the survey has no evidence of being sequenced

The table above counts the six founder descents, the part of the register that can be walked down a parent link. This asks the same question of the rest: every mating in which the two parents carry different attributions, an attribution being the named variant a cat carries, or, where it carries none, the founder line it is put in. twenty-four matings qualify, in three kinds, of which two are new.

• Two named variants meet. Three matings, already set out above.
• A named variant meets a line the survey has no evidence of being sequenced. Eleven matings, in four pairings. These can be resolved today, by testing the animal in which they meet: a positive result places the known variant in the line, and a negative result places a second, unsequenced variant beside it.
• Two lines the survey has no evidence of being sequenced meet. Ten matings, in four pairings. These cannot be resolved by any amount of further pedigree, because neither side can be tested. Whether the two carry the same thing stays open until one of the lines is sequenced.

What the folding assumes. Eleven lines are folded into the variant sequenced within them, so that one variant recorded two ways does not read as two meeting. That treats a whole line as carrying only the variant sequenced in part of it, which is sometimes the open question. Folded: Blue Eyed Maine Coons (Markiss); Celeste (Chatterie d'Aerlin); Celeste (de Virvarnon genealogy); Celeste into the Minuet; German Longhair (C14); Nadeya; Nanotigr; Nanotigr (Kotomodda and Cotomodda, one cattery); Rociri Elvis; Roddifer; Siberian (C7), from a DBE^ALT to DBE^CEL mating.

A named variant meets a line the survey has no evidence of being sequenced four pairings

Testing the offspring answers each of these.

Two lines the survey has no evidence of being sequenced meet four pairings

Nothing on paper can settle these.

Every variant against every other, and whether they share ancestors

The same question asked of every pairing at once. Each variant and each named line the register holds is on both axes, and a cell says whether the two meet in a common ancestor when the recorded parent links are walked upward from the cats of each. A no is a result in its own right: on the pedigrees supplied to the survey the two populations do not touch. Thirteen of the one hundred and ninety pairings share at least one ancestor.

A shared ancestor is not a shared variant: it says only that one animal stands in both pedigrees. Whether the blue eye on the two sides is one variant or two is settled by a verified genotype test on the shared animal, and the grid says where such a test would answer for two lines at once.

Reading the grid. The small figure beside each name is the number of cats the register holds for that variant or line. A figure in red is the count of ancestors the two hold in common. A figure in bold as well as red means the two have also been bred together in this register. A cell reading no means no shared ancestor was found in what has been supplied, which is not the same as none existing: most catteries have never sent a pedigree to the survey.

Two foldings are applied. A founder descent is counted with the variant traced to that founder, so Altai and Nikita'l Seymour are read as DBE^ALT. Labels that record uncertainty rather than an attribution, such as Siberian, Altai or Barnaul unconfirmed, are left out.

Which variants and lines share ancestors, whether or not they have been bred together

A crossing needs a mating. Sharing ancestors does not: two attributions can stand in one pedigree because the same cats sit above both, with no mating between them at all, which is where a crossing becomes possible next. Fifty-four pairings share at least one recorded ancestor. The last column says whether they have also been bred together.

Twenty-nine further pairings share fewer ancestors than those above.

No mating recorded here means this register holds no mating between the two, and a mating that was never written down cannot appear in any database. Both attributions are present in one pedigree, so the two can be bred together, and in a cattery that holds cats of each they may already have been.

What this table is for: a shared ancestor is where one variant could turn out to be behind both sides. If the two attributions in a row are in fact one variant, testing that one animal would answer for both lines at once, which is the cheapest test in the register. If they are two different variants, a single outcross between the two sides would put both in one cat.

The number of ancestors in common is not the strength of the case. Cats of one breed share ancestors readily. What makes a row worth acting on is a shared ancestor that is close, is untested, and stands above cats showing the trait on both sides.

Catteries in which two or more variants sit in one breed group

Not which catteries hold two variants, but which hold two in one breed group, since only there can they be bred together. An unsequenced line counts as a variant here. Thirty-four cattery and breed group pairings qualify.

The last column is the survey's own tracing: the variants and lines standing in the ancestry of the cattery's cats, found by walking the recorded parent links upward from each of them. A pedigree names ancestors, not the variants they carried, and in most of these lines no variant has ever been named to record.

The line is in the ancestry, not necessarily in the cats: a heterozygote passes an allele to half its offspring. That is why these prefixes are where a test would look first, and the same question arises in sixty-two prefixes across the register.

A prefix spelled two ways is held as two rows. Nikita'l and Nikital may be one cattery or two and nothing settles it, so they are not merged.

The rule excludes one prefix on the present record: Belle Ayr.

Latent carriers, and blue eyes that come from somewhere else

Two small groups, both bearing on a breeding rule written on eye colour, of the kind a registry imposes when it restricts or forbids matings involving a blue-eyed cat: the latent carriers, which hold the variant and do not show it, and the cats whose blue eyes come from another cause.

Latent, and latent queried 19 cats

A latent carrier has no blue eye at all. It carries the variant, cannot be found by looking, is not caught by a rule written on eye colour, and passes the variant on with nothing recorded against it. The whole prevention argument turns on it.

Nineteen cats are entered as latent because a source says so. That is the number of statements, not the number of latent carriers. Where parentage is recorded a carrier can be deduced instead, since a dominant allele cannot skip a generation. Fifty-three cats show the trait with two recorded parents and neither recorded blue or odd, so one of each pair carried it unseen; eighty-seven animals stand in those pairs. Five more show it with a single recorded parent that does not. The latent lines page carries the deduction up the pedigree.

A floor, not a count. The deduction runs only where parents are recorded, and six hundred and thirty-six of the 1008 cats showing the trait have none. Dominant white is excluded on both sides: a white coat pales an eye through KIT and masks what the animal holds at PAX3.

Latent is used where a source states the cat is a carrier without the phenotype; latent queried where the compiler wrote the word with a question mark and the survey has not resolved it. The marking is carried on each animal's own entry in the register. Three of the nineteen have a laboratory result of their own.

Blue eyes attributed to another cause, and explicit exclusions 94 cats

The Blue group above is not every blue eye in this register. These cats have a blue eye, or were considered for one, and a source attributes it to something other than a PAX3 variant: to dominant white, to white spotting, or to the colourpoint allele. They are held apart rather than dropped, because a rule that triggers on eye colour restricts them too.

Two of the exclusions are the compiler's own, written on the chart: "White spotting gene, not DBE" and "non-DBE". A compiler who records what a trait is not is doing something the survey found rare, and the exclusions are kept for that reason as much as for the animals.

What the register shows about 68 and 69

The codes 68 and 69 are written by registries as though they were two things: a dominant blue eye and a dominant odd eye. The register cannot find a line in which they behave as two things.

Litters containing both codes

10 litters in this register contain a cat coded 68 and a cat coded 69. A litter is the strongest thing a pedigree offers, because the two kittens differ in nothing that any document records except the number the registry wrote on them. They share a sire, a dam and a date.

Three of these are by one sire, Blue Ridge Urban, out of three unrelated dams, and two of those dams carry no eye code and nothing above them does either. One is by Nikita'l Markiss himself, the founder of that material, out of a dam with nothing. A single variant segregating from one parent accounts for every one of them.

Matings in which one parent is coded 68 and the other 69

A litter holding both codes shows the two separating in one generation. A mating in which one parent carries 68 and the other carries 69 is a harder fact, and a more uncomfortable one. It is a dominant blue eye animal bred to a dominant odd eye animal, which is the cross every published breeding recommendation says should not be made. The register holds nine of them, across seven matings.

The founding cross of the largest body of material in this register is one of them. Nikita'l Seymour, coded 68, bred to Nikita'l Pheer-Ca, coded 69, gives Nikita'l Markiss, coded 68, and every Maine Coon in the ALT and CEL material descends from him. Whatever the two codes are, the programme that distributed them began by putting them together. One of these matings is stated by a cattery on its own website, with all three codes printed on the page.

The litter that is not an inference

29 animals in this register have been genotyped. Three of them are full sisters of one mating, all confirmed to carry the same variant, and the registries coded them 68, 69 and nothing at all. A fourth genotyped cat of the same line carries no eye code and no white code either. That is not a reading of a pedigree. It is a laboratory result placed beside a registry code, and the two do not agree.

What follows, and what does not

An eye code is not a carrier test. The register holds an uncoded sire with three coded offspring carrying three different codes, who was placed with another cattery on the understanding that he had not inherited anything. It holds blue-eyed and odd-eyed cats, confirmed by test, on whom the registry wrote nothing. Every count in this directory drawn from eye codes is therefore a floor.

A code is also a registry's opinion rather than a measurement, and it can be revised. One cattery's published pedigree writes 61, the ordinary blue-eye code, on three consecutive generations and annotates all three with the name of a dominant variant. And one cat in this register carries both codes in sequence: 61 on his cattery's website, 68 on his registry pedigree, the website being the earlier record. Another sheet writes the same descending trait as 61, then 60, then 68, then 68, then 69 across five generations and three registries. Where a coat carries no white, a 61 in this register is a candidate 68, and the directory does not treat the two as settled categories.

None of this establishes that every 68 and every 69 in the register are one thing. It establishes that within a line traced to a single source they are not two things. Lines that were founded separately may still carry separate variants, and only a genotype can say. The register records which animal to test and why on each of the cats where it would settle something.

What the science says about dominant blue eyes

Six dominant blue eye variants have been identified, all in the PAX3 gene. Four are published. DBE^CEL (Roxi) is a retroviral insertion that arose in Kazakhstan and was used to found the Céleste breed. DBE^RE is a nonsense variant in a Maine Coon line. DBE^ALT is a second and different retroviral insertion, in the population behind the Altai breed, which is bred today under a World Cat Federation standard. DBE^AGO is a frameshift in a further Maine Coon line. Two more were identified in Chinese domestic shorthairs during 2025 and are not yet published: DBE^cDc in August 2025, since detected in the Abyssinian, and DBE^xHW in September 2025. The laboratory that identified both sells a panel covering five variants, and DBE^xHW is not among them: it is the only one of the six identified but not commercially available.

What those three terms mean. They describe three different ways of breaking the same gene, and the distinction matters because a test for one does not detect another.

• Retroviral insertion. A block of viral DNA, left in the cat genome by an infection in some distant ancestor, has copied itself into the middle of the gene. It is physically large, several hundred letters of DNA, and it interrupts the gene's instructions. DBE^CEL (Roxi) and DBE^ALT are each an insertion of this kind, at the same gene but not the same insertion.
• Nonsense variant. A single letter of DNA is changed, and the change happens to create a stop signal in the middle of the instructions. The cell stops reading there, so the protein is made only up to that point. DBE^RE is of this kind.
• Frameshift. DNA is read in groups of three letters, each group naming one building block of the protein. A frameshift is an insertion or deletion of a number of letters that is not a multiple of three, so everything after it is read in the wrong groupings and the remainder of the instruction becomes nonsense. DBE^AGO is of this kind.

All three have the same practical effect, that one of the cat's two copies of PAX3 no longer produces a working product, which is why a single copy is enough to change the eye colour. They are different events at the level of the DNA, so each needs its own laboratory assay. That is the reason no single test covers all six, and the reason a rule requiring only a PAX3 test does not specify what has actually been looked for.

All six identified variants are in PAX3, which does not mean PAX3 is the cause of every blue eye. In the nine unmapped lines no variant has been found at all, so the gene involved is unknown.

The consequence for a breeder is direct: a clear PAX3 panel on a cat from one of those lines means only that the cat does not carry the six identified variants. It does not explain why that cat has blue eyes, and it does not mean the cat will not pass the trait on.

twenty-two further lines in this register segregate variants that have not been identified: among them the Nadeya, Igor, Marusya, Malvina, Pillowtalk-Foreigner and Gosha lines, distributed across British, Scottish, Selkirk, Persian, Exotic, Siberian, Maine Coon, Devon Rex and Munchkin cats.

The six variants at a glance

The same facts are set out for each variant in the same order, so that any two can be compared directly. Green marks a variant for which a test can be bought.

Reading the table across rather than down gives three results.

• Fyodor, a black self with a white tail tip and blue eyes, is not the same animal as Nikita'l Seymour, the silver tabby of the Topaz after whom the British carriers of DBE^ALT are named as a lineage in Abitbol et al., Animals 2024;14:1845, Table 2. The two are separate cats carrying one variant. The two cats the variants are traced to, Roxi Darlin and Fyodor, were both in the Darlin cattery at Ust-Kamenogorsk in the late 1990s, which is the origin of the belief that the Céleste carries the Altai variant.
• Three of the four published variants are named after the line or population they arose in. One is not. DBE^RE takes its name from the Rociri Elvis line and DBE^AGO from the Agostino line, each being the line the variant appeared in. DBE^ALT takes its name from the Altai, the population it appeared in. The exception is DBE^CEL (Roxi), named after the Céleste, a breed begun in 2015 from the descendants of the cat the variant came from and recognised by LOOF on 1 January 2023, so named after something that did not exist when it arose. A Céleste in the pedigree cannot be inferred from a DBE^CEL (Roxi) result. Case study two of the survey sets out the consequences.
• What two copies does is known for two of the six and unknown for the other four. Four homozygotes have been genotyped, and all four were white. Three carried DBE^ALT, two Altai and one Nanotigr, viable, with more white than their parents and deafness in some of them, in Abitbol et al., Animals 2024;14:1845, Table 2. One carried DBE^CEL (Roxi), a kitten born to two Céleste parents that died at birth of cleft palate, in Abitbol, Couronné et al., Animal Genetics 2024;55:670-675, Table 1. DBE^RE is inferred embryonic lethal from the absence of homozygotes in pedigrees, and none has been observed. For DBE^AGO, DBE^cDc and DBE^xHW there is nothing at all, and DBE^AGO has been published since June 2025.

Waardenburg syndrome, and what naming a type claims

Dominant blue eyes in cats is routinely described as a feline Waardenburg syndrome. Waardenburg syndrome in humans is not one condition but a set of them, separated into numbered types by which gene is mutated and distinguished clinically by which signs are present. The type a registry names therefore carries a claim about the gene.

The rows this directory turns on are marked. Types 1 and 3 are the PAX3 types, and both carry dystopia canthorum. Type 2A is an MITF type, and it is defined by the absence of that same sign. Sources for the classification: Waardenburg Syndrome, StatPearls, NCBI Bookshelf; and the NIH Genetic Testing Registry entry for Waardenburg syndrome type 2A, which gives the condition as pigmentary abnormality of hair, skin and eyes, congenital sensorineural hearing loss, and “the absence of dystopia canthorum”.

Human Waardenburg syndrome arises from mutations in PAX3, MITF, SNAI2, SOX10, EDNRB and EDN3. The numbering is not a severity scale. It is a gene classification. Naming a type names a gene, and PAX3 accounts for types 1 and 3 and for no other type.

Waardenburg syndrome entered FIFe's material through its Maine Coon Breed Council. The Health and Welfare Commission paper Dominant Blue Eyes: A Call for Responsible Breeding, March 2025, quotes the Council's recommendation that genetic testing of blue-eyed Maine Coons is “strongly encouraged to identify potential risks early such as deafness and Waardenburg Syndrome”. A FIFe Breed Council is a FIFe body established to advise the federation on health, so this is an advisory opinion carried in a FIFe publication rather than a FIFe rule. The paper names no type, and the test it names is for PAX3. Those are two different claims and the paper does not separate them. Naming the syndrome without naming the type leaves the gene open, in the same sentence that has already fixed it.

• Wide-set inner eye corners, dystopia canthorum, have been reported in cats. Abitbol et al., Animals 2024;14:1845, record the sign in some dominant blue eye Maine Coons. It is a type 1 sign and not a 2A one. The paper does not say the variant causes it: “to date, we cannot link this defect to DBE alone or to the interaction between DBE and a specific face morphology”. The face shape has been accentuated by selection in certain Maine Coon lines, so the sign may come from the head the breed is bred for rather than from the variant. The same paper records that “dystopia canthorum was not observed in adult DBE cats from the Altai, Celestial, British, Sphynx, and Siberian genetic backgrounds”.
• A second craniofacial sign is reported in the two unmapped lines. The Igor and Marusya lines show a very small, pinched nose leather. It was reported to the survey by the breeder and is verified here from photographs. The corresponding sign in human type 1 is incomplete nostril development. One limit applies: both lines run through breeds bred for a short face, the British and the Persian and Exotic, so the nose shape may come from the breed rather than from the variant. It is recorded because these are the two lines for which no variant has been found, and a sign they share is a reason to sequence them.

One caution, from the paper that identified the first feline variant. Rudd Garcés et al., G3 2024, record that the mouse model of PAX3 loss of function does not reproduce the human picture: “Unlike WS1 human patients, Sp+/− mice do not show alterations in auditory function and ear morphology when compared with wild-type animals”. A cat resembling a human subtype therefore need not carry a mutation in the gene that causes that subtype in people, and the human numbering may not transfer to cats at all.

The conclusion is the one this directory reaches about breed names and line names: a name is not a genotype. For the four described feline variants the accurate description is the variant itself, and for the Igor and Marusya lines no type can be claimed at all, because no variant has been found in them.

A related point of law, if the resemblance is pressed. Type 2A in humans is described as carrying no deleterious effect other than deafness, and deafness alone is enough to engage a ban: European companion animal legislation provides that deaf cats must not be deliberately bred. Sources for the human classification: Pingault et al., Human Mutation 2010;31:391–406; Tachibana et al., Pigment Cell Research 2003;16:448–454; and for the equivalent equine work, Hauswirth et al., PLoS Genetics 2012;8(4):e1002653.

Sources

Grouped by the kind of source, because the kind is what fixes the grade.

1. Peer-reviewed genetics

The only sources in this directory that establish a variant in a named animal. Author names are omitted here as they are throughout the survey.

• Animals 2024, 14(13):1845. The founding-effects study: 177 cats, 117 of them blue-eyed, across fourteen lineages. The source for DBE^ALT in the Nanotigr line, for the Igor line carrying none of the known variants, and for the line-by-line deafness counts. PubMed 38997957. mdpi.com/2076-2615/14/13/1845
• G3 2024, 14(9):jkae131. The Maine Coon BAER series and the Waardenburg comparison. academic.oup.com
• Animal Genetics 2025, 56:e70020, "New PAX3 variant and updated phenotypic data", and 2024, 55:e13433. Both returned 403 to the survey and have not been read in full. The 2025 paper is the outstanding source for the craniofacial question.
• OMIA 001688-9685, the four PAX3 alleles with their nomenclature. The phene is now titled "Auditory-pigmentary syndrome, PAX3-related". omia.org/OMIA001688/9685

2. Registry documents and issued pedigree certificates

Thirteen certificates, P1 to P13, supplied to the survey and read from the documents. These are what settled the coding question, and they are the only sources that give a cat a registration number.

• WFA, Ukrainian Felinological Alliance "LenCat": the Wabisabi certificate, the 68 series including 68e for a carrier, and a litter of three all coded 68e (P1). Coding rules at wfall.ru, whose eye table did not render for the survey.
• ARBC, Association of Rare Breeds of Cats, Nizhyn: the certificate that glosses code 60 as "dominant blue eyes" in English (P13); and the breed pages for the British Ice, Pharaoh and Chinese Tank, which carry the "BE" registration marking. rareexoticfelineregistry.com
• WCF: certificates from the Astra centre (P6) and the Kotofey club RU-0197 (P8), the latter with sixteen ancestor cells reading "not registered". EMS list at wcf.de, where 69 sits under non-recognised eye colours.
• TICA: does not record eye colour. Its Individual Registration carries no eye code and no eye field (P7), and the Winter 2025 Maine Coon standard ballot, passed 331 to 40, never mentions this trait. The consequence is that descent certified by TICA is certified without any record of the eye, so a breeder whose cats are registered there cannot evidence the trait from the certificate whatever they observe. tica.org
• Felidae e.V.: a certificate carrying four registries at once, ARBC, Felidae, ITAVC and WFA (P12).
• FIFe EMS list, where 68 is albino. fifeweb.org
• LOOF: the Céleste recognised as a new breed from 1 January 2023, with Céleste to Céleste matings forbidden. loof.asso.fr
• GCCF: Maine Coon breeding policy, October 2025, refusing registration and import of affected cats from 28 June 2025. gccfcats.org
• TopCat and the Felinological Federation of Russia: the Altai Blue-Eyed standard, the breed raised to Fundamental status 3 November 2025, carrying the 68 series with 68c to 68e for latent carriers. ru.top-cat.org and en.top-cat.org
• PawPeds: the record showing a genotyped founder with no eye code and no ancestry (P2). pawpeds.com

3. Breeder charts supplied to the survey

Fifteen pedigree and dispersal charts, C1 to C15. They are the richest source held and the weakest graded, because a chart records what its compiler could see. One states its own provenance: "Not on pedigree databases, derived from publicly available information on breeder websites and social media sources."

• Ermine Trace (C1); Marusja, Cyrridwen cattery (C2, superseded by C8); DBE Siberians (C3); Celestial and German Longhair (C4, C14); DBE-CEL Sphynx (C5), which states that names have been withheld deliberately; Topaz Foundation (C6); Blue-Eyed Siberians (C7); the Cyrridwen spread (C8); Mink Ragdoll (C9); Blue Eyed Maine Coons (C10); DBE Highlander, Olynx (C11); DBE British from the Igor gene (C12); Nanotigr and its link to Ermine Trace (C13); Azul Shorthair and Longhair (C15).

4. Breeders' own web pages

Found by the survey's own search rather than taken from another compilation. Every one is graded reported unless it publishes a laboratory result. They matter for three reasons: they name catteries no other source names, they show what buyers are told, and several of them state breeding rules no registry requires.

• Publishing a test or a hearing protocol. IconicSX, Sphynx, DBE^CEL (Roxi) heterozygous with the laboratory named and every cat BAER-tested. Celeste's Legacy, whose first five generations were BAER-tested with PKD and HCM screening throughout: the strongest voluntary control the survey has found anywhere. Aerlin, the Céleste founding cattery.
• Naming a line. Ermine Trace, the breeder's own account of the Nadeya line with EMS-coded pedigrees. Chonky Bears, Germany, the only live site naming the Igor line, and recording "deaf and even dead kittens" before the genetics were understood. Belle Ayr, United Kingdom, to which the survey's declaration of interest refers.
• Stating a rule no registry imposes. Eremitage Palace, Germany, never two blue or odd-eyed cats paired. Vlastar Lux, Ukraine, warning of white or deaf neonates from cross-line matings and recommending PAX3 testing with BAER.
• Breeding it without naming a variant. Blue Eyed British, United States. Chatterie Carbin, France. Sweet Beast, Ukraine, whose cats appear on a British certificate in this register. ThatsMe2, Germany. New Wave Kitty, Hungary, whose claim that no cat has ever shown deafness is recorded and not accepted. Tassel Castle and Think Sphynx, United States.
• Publishing against the trait. A position worth recording, because it shows the fancy is divided rather than unaware. Macadamia, Netherlands, the source of the 68 and 69 reading the survey could not reconcile with the certificates. King Size, Russia. Greek Garden and LMCoonCat, United States. Blue Obsidian, China, which records that it cannot obtain BAER testing locally.

5. Laboratories

Which variants can be tested for, and by whom.

• CombiBreed and VHLGenetics, DBE^ALT and DBE^CEL (Roxi). Generatio and Labogen, DBE^RE. Antagene, DBE^CEL (Roxi) and DBE^ALT. Vetlab and Shans Bio, Russia. PetGeno. Felome from February 2026 and Genindexe from March 2026.
• No laboratory offers a test for the Igor, Nadeya, Marusya, Karagaisky, King's Way or Pillowtalk lines, because no variant has been identified to test for. Six of the lines in this directory are therefore untestable by anyone at any price.

6. Historical record, compilations, advertisements and social media

• London Daily News, 23 July 1920, a prize-winning blue-eyed shorthair of "mysterious pedigree" shown at Croydon. The earliest record the survey holds.
• Cattery social media: a post of 21 May 2020 recording two Munchkin sisters, one blue-eyed and one odd-eyed, published nowhere else. Several of the breeder charts state that they were themselves assembled this way.
• messybeast.com, the largest existing compilation of this subject and the starting point for part of this directory. Its pages could not be fetched here, as HTTPS redirects back to HTTP in a loop, so the material was supplied to the survey as text and is cited to the site. Ten lines and breeds rest on it alone, searched in Russian without a second source: Malvina, Barnaul, Caspian, Aktau, Karagaisky, Gosha, Azul, Azure Dream, Pantherina and Heavenly Eyes. Four of the ten are named in the source and are not in this register. Caspian and Aktau are described by the survey and no cat has been entered for either; Pantherina is named in the source material only; and Heavenly Eyes is a cattery suffix rather than a line, carried by one cat.
• General classified advertisements: four blue-eyed British cats offered in Moscow and Vladivostok with no pedigree, no code, no cattery and no registry. Recorded because that is where the chain ends.

What is not here. No Ragdoll cattery anywhere could be found breeding this trait on any source other than messybeast, though DBE^ALT is published in an American Ragdoll lineage and no Ragdoll body has a position on it. No EMS code or date of birth could be found for any dominant blue eye Maine Coon or Ragdoll from any public source. No origin details exist for the cat DBE^AGO is named after. And no independent source for the cat Igor exists at all: every search in English, Russian and German returned one compilation and the peer-reviewed paper, and nothing else.

Declaration of interest

The compiler 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 compiler is also a co-author of published genetics research on this trait, and cats of both lines have contributed to that research and inform part of the current published literature. Both lines appear in this directory on the same terms as every other, and the entries touching them are held to a higher standard of sourcing rather than a lower one.

The cattery and its published work on this trait are at belleayr.com.