Blue and aqua-eyed cats are understandably popular. Their blue eyes lend an aura of serenity to a cat’s gaze, setting off nearly every coat color to beautiful effect. Unlike green, copper, or yellow eyes, blue eye color is not due to a blue pigment, but rather a lack of melanin production in the iris, along with Tyndale scattering — the same phenomenon that causes the sky to appear blue.

There are three main genes that are responsible for those baby blues. Some combinations of gene and allele are associated with high rates of deafness, while others come with no health concerns. Deafness is typically associated with a lack of normal pigment production in the inner ear, which for reasons unknown, is necessary for normal hearing development. Because lack of pigment in the eyes and ears is sometimes linked, there is concern among breed clubs and registries. Visual identification of respective blue-eyed variants can sometimes be impossible, rendering informed breeding for health and beauty difficult. Thankfully, many of the responsible variants are now known, and testing is increasingly available. Let’s break down the causes together.

Colorpoint Coloration

Colorpoint is the standard color pattern of the Siamese, Ragdoll, Birman, Himalayan, and seal lynx point Bengal. Colorpoint pattern can occur with or without tabby markings. This pattern is derived from variants or alleles in the TYR, or tyrosinase gene, which is involved in pigment production (melanin). Because tyrosinase is temperature-dependent, warmer areas of the body have little melanin production, including the body of the cat and their eyes. That’s why colorpoint kittens are born white, and develop their points as they age, and why as they become seniors, they tend to darken as their overall body temperature decreases. The TYR gene is designated as Locus C (Color Restriction or Colorpoint). There are 5 known alleles at this location:

• Siamese coat color pattern - c^s
• Burmese coat color pattern - c^b
• Mocha - c^m
• Albinism - c, or c^1
• Albinism - c^2

Siamese, Burmese, and Mocha alleles have semi-dominant effect, which results in intermediate colorpoint patterns. The Tonkinese or mink coloring has aqua eyes, a result of a cs/cb compound heterozygous genotype. Because the inner ear has normal melanin production, colorpoint pattern is not linked to deafness in cats. Albino cats (c1 and c2) are typically not deaf, but do have lighter blue eyes than colorpoint cats, and have photophobia, or sensitivity to light.

White Spotting and Dominant White

The second most common cause of blue eyes in cats is white spotting, which is a localized lack of pigment. White spotting can affect the coat color, eye color and inner ear, depending on where it is expressed. White spotting in cats, as well as in many other species, is primarily associated with the KIT gene, denoted as the W Locus (White Locus). Full White (also called Dominant White) and Partial White are both due to insertions in the KIT gene:

• Full white: W
• Partial white: ws
• No white spotting or wild type: w+

Partial and Full White variants can result in a partial white (bicolor) or full white appearance, depending on the length of the insertion variant inherited. If one or two copies of the full insertion are inherited, the cat will likely show bicoloration or degrees of white spotting. If at least one copy is inherited as a partial insertion, the cat will likely be full white (dominant white). White spotting that is expressed in one eye, but not the other, will result in an odd-eyed or heterochromic cat.

The Full White variant is associated with varying degrees of hearing impairment:

• Cats with two copies of the Full White variant are usually deaf or have partial hearing impairment.
• One copy of the Full White variant and one copy of Partial White variant causes deafness and hearing impairment in over 60% of cats.
• About 40% of cats with only one copy of the Full White variant and one copy of the normal variant have hearing difficulties or are deaf.

Cats with the Partial White variant alone are usually not deaf.

Dominant Blue Eyes

Dominant Blue Eyes or DBE is also called Auditory-Pigmentary Syndrome in humans. This is the newest cause of blue eyes in cats, but is becoming increasingly common, and spontaneously occurring blue-eyed domestic cats are being used to introduce new forms. The first blue-eyed cat with DBE to be used in a breeding program is thought to be the originator of the Altai breed in 1997, a natural cat out of Kazakhstan. Many of the variants discovered have been naturally occurring across Russia or neighboring countries. All currently published variants of DBE are localized to the PAX3 gene, of which there are 4, with at least another 3 yet unpublished:

• DBE^CEL (Celestial) or Variant 1
• DBE^RE (Rociri Elvis) or Variant 2
• DBE^ALT (Altai) or Variant 3
• DBE^AGO (Agostino) or Variant 4
• DBE^CDC (Chinese Domestic Cat) or Variant 5 (unpublished, proposed)
• DBE^XHW (XinHe Winnie) or Variant 6 (unpublished, proposed)

Dominant Blue Eyes cause blue eyes typically with minimal white and without colorpoint pattern, which creates a very exotic look that many breeders find desirable. DBE is rapidly being introduced into existing breeds, including the Sphynx, Maine Coon, British, Scottish, Persian, Devon Rex, Lykoi, Ragdoll, Siberian, and others. However, some variants consistently cause deafness or very high rates of it, and some variants are lethal to kittens in the womb when two copies are inherited, resulting in reduced litter sizes. The problem is that the variants cannot be visually distinguished. Many cats with combinations of these variants are not genotypically determined, and have not had appropriate hearing testing, such as BAER (Brainstem Auditory Evoked Response) testing, to ensure they have normal hearing in both ears. In addition, some cats do not show blue eyes, but carry the variant, and can pass it to offspring with potential health impacts, called “latent” cats. Additionally, some compound heterozygotes, meaning cats that inherit one copy of two alleles within the PAX3 gene — documented in combinations of Altai and Celestial variants — if inherited together in a kitten produce high rates of deafness.

Health Impacts of Dominant Blue Eyes

The following is what is currently known about deafness, latency, publications, and level of research on hearing impact:

*DBE^ALT/DBE^CEL compound heterozygotes have been found to be at high risk of deafness and are typically born white

Registry Reactions to Dominant Blue Eyes

Registries have taken very divergent approaches to this problem. The World Feline Alliance (WFA) in Russia has developed an official DBE Program, and has expanded the allowance of DBE into additional breeds. FIFe has supported member clubs in banning DBE introduction into existing breeds, such as the Maine Coon. TICA’s Maine Coon policy is to allow registration, but not championship status, which allows DBE cats to be monitored.

Until more health testing and research has taken place, and more widespread genetic testing for these variants is carried out, the general recommendations to ensure healthy, hearing cats is:

1. To not mix lines known to have more than one type of DBE variant between them (such as Altai and Celestial)
2. If blue eyes are to be introduced into an existing breed, to develop it into a separate breed, such as the Celestial, which is a British short/longhair with the Celestial variant
3. If DBE is present, to not breed to any cats with Full or Partial White, as it is presumed that this will compound the risk for hearing loss due to additional pigment inhibition.

Final Thoughts

Although blue eyes in cats are here to stay and are beautiful to behold, it’s important for the health of the cats to know the genetic cause, including the gene and the variant, as all three genes known to be involved interfere with pigment production to produce blue eyes. Some variants, such as colorpoint alleles (excluding albino), are benign. Other alleles, such as albino, Full White, or certain DBE variants, can cause vision or hearing impairment. And some combinations of variants may also reduce litter sizes. Additional DBE studies are clearly needed to identify new variants as they appear and provide science-based guidance on which alleles are appropriate to keep in breeding programs, which should be abandoned entirely, and which combinations are safe to allow with appropriate genetic testing.

References:

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. Anim Genet. 2024 Aug;55(4):670-675. doi: 10.1111/age.13433. Epub 2024 Apr 22. PMID: 38644700.

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. Anim Genet. 2025 Jun;56(3):e70020. doi: 10.1111/age.70020. PMID: 40459211.

Rudd Garces G, Farke D, Schmidt MJ, Letko A, Schirl K, Abitbol M, Leeb T, Lyons LA, Lühken G. PAX3 haploinsufficiency in Maine Coon cats with dominant blue eyes and hearing loss resembling the human Waardenburg syndrome. G3 (Bethesda). 2024 Sep 4;14(9):jkae131. doi: 10.1093/g3journal/jkae131. Erratum in: G3 (Bethesda). 2026 Jun 23:jkag156. doi: 10.1093/g3journal/jkag156. PMID: 38869246.

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 (Basel). 2024 Jun 21;14(13):1845. doi: 10.3390/ani14131845. PMID: 38997957.

Nicholas, F.W., Tammen, I., & Sydney Informatics Hub. (2025). OMIA:000202:9685 Online Mendelian Inheritance in Animals (OMIA) Coat/skin colour, oculocutaneous albinism type I (OCA1), TYR-related in Felis catus (domestic cat). https://omia.org/OMIA000202/9685/

Sarah Hartwell. DOMINANT BLUE EYE (DBE) GENETICS STUDIES. Messybeast. Publication date unknown. Accessed July 2026. http://messybeast.com/DBE-genetics-studies.htm

Arr. Sarah Hartwell. BLUE-EYED BREEDS / DOMINANT BLUE EYE (DBE). Messybeast. Publication date unknown. Accessed July 2026. http://messybeast.com/blue-eye-breeds.htm

Various authors. FIFe Health & Welfare. Fédération Internationale Féline. Publication date unknown. Accessed July 2026. https://fifeweb.org/health/