Congenital sensorineural deafness in cats

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A completely deaf, solid white, blue-eyed cat A completely deaf, pure white blue-eyed cat.jpg
A completely deaf, solid white, blue-eyed cat
This engraving depicts two cats on a wall, with a dog jumping and barking below them. The white-spotted cat hisses at the dog, the solid-white deaf cat dozes unaware of the barking. Deaf White Cat.png
This engraving depicts two cats on a wall, with a dog jumping and barking below them. The white-spotted cat hisses at the dog, the solid-white deaf cat dozes unaware of the barking.

Congenital sensorineural deafness occurs commonly in domestic cats with a white coat. It is a congenital deafness caused by a degeneration of the inner ear. [1] Deafness is far more common in white cats than in those with other coat colours.

Contents

Occurrence

Domesticated cats with blue eyes and white coats are often completely deaf. [2] Charles Darwin mentions this phenomenon in his book, On the Origin of Species , to explain correlated variation. [3] Deafness can occur in white cats with yellow, green or blue irises, although it is mostly likely in white cats with blue irises. [4] In white cats with mixed-coloured eyes (odd-eyed cats), it has been found that deafness is more likely to affect the ear on the blue-eyed side. [1] Odd-eyed white cats have one blue eye and one yellow, amber, copper/orange or green coloured eye. Approximately 15–40% of the solid white cats have one or two blue eyes. [5] [ unreliable source ]

According to the ASPCA Complete Guide to Cats, "17 to 20 percent of white cats with non-blue eyes are deaf; 40 percent of "odd-eyed" white cats with one blue eye are deaf; and 65 to 85 percent of blue-eyed white cats are deaf." [6]

In one 1997 study of white cats, 72% of the animals were found to be totally deaf. The entire organ of Corti in the cochlea was found to have degenerated in the first few weeks after birth; however, even during these weeks no brain stem responses could be evoked by auditory stimuli, suggesting that these animals had never experienced any auditory sensations. It was found that some months after the organ of Corti had degenerated, the spiral ganglion of the cochlea also began to degenerate. [7]

Genetics

Although few studies have been done to link this to genes known to be involved in human Waardenburg syndrome, a syndrome of hearing loss and depigmentation caused by a genetic disruption to neural crest cell development, such a disruption would lead to this presentation in cats as well. [8] Waardenburg syndrome type 2A (caused by a mutation in MITF ) has been found in many other small mammals including dogs, minks and mice, and they all display at least patchy white depigmentation and some degeneration of the cochlea and saccule, as in deaf white cats. [9] [10]

A major gene that causes a cat to have a white coat is a dominant masking gene, an allele of KIT which suppresses pigmentation and hearing. The cat would have an underlying coat colour and pattern, but when the dominant white gene is present, that pattern will not be expressed, and the cat will be deaf. A cat that is homozygous (WW) or heterozygous (Ww) for this gene will have a white coat despite the underlying pattern/colour. A cat that lacks this dominant masking gene (ww) will exhibit a coat colour/pattern. [11] KIT mutations have also led to patchy depigmentation and different coloured irises in humans, [12] and KIT has been found to increase MITF expression, the gene involved in human Waardenburg syndrome type 2A. [13]

Non-deaf blue-eyed white cats

The established link between deafness and blue eyes is found in the link between deafness, blue eyes and solid white coats. However, it is a common misconception that all white cats with blue eyes are deaf. [14] It is possible to have a cat with a naturally white coat without this gene, as an extreme form of white spotting, although this is rare – some small non-white patch usually remains.

Furthermore, there are multiple different genes responsible for blue (incl. odd) eyes, and several of these genes are not linked to masking, white coats or deafness (e.g., "Siamese" colourpoint-gene, Ojos Azules-gene, etc.). For example, solid white blue-eyed Foreign White or Ojos Azules cats are not linked to deafness. Deafness depends on the cat's genotype (genetic make-up), and not its phenotype (physical appearance). Therefore, not all solid white cats with one or two blue eyes are deaf. It is not advisable to breed from deaf white cats, as this would pass the trait along. BAER-testing (Brainstem Auditory Evoked Response) is used to test deafness in cats. [5] [15] [ unreliable source ]

See also

Related Research Articles

<span class="mw-page-title-main">Tietz syndrome</span> Congenital disorder

Tietz syndrome, also called Tietz albinism-deafness syndrome or albinism and deafness of Tietz, is an autosomal dominant congenital disorder characterized by deafness and leucism. It is caused by a mutation in the microphthalmia-associated transcription factor (MITF) gene. Tietz syndrome was first described in 1963 by Walter Tietz (1927–2003) a German Physician working in California.

<span class="mw-page-title-main">Cat coat genetics</span> Genetics responsible for the appearance of a cats fur

Cat coat genetics determine the coloration, pattern, length, and texture of feline fur. The variations among cat coats are physical properties and should not be confused with cat breeds. A cat may display the coat of a certain breed without actually being that breed. For example, a Neva Masquerade could wear point coloration, the stereotypical coat of a Siamese.

<span class="mw-page-title-main">Heterochromia iridum</span> Difference in coloration, usually of the iris but also of hair or skin

Heterochromia is a variation in coloration most often used to describe color differences of the iris, but can also be applied to color variation of hair or skin. Heterochromia is determined by the production, delivery, and concentration of melanin. It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury. It occurs in humans and certain breeds of domesticated animals.

<span class="mw-page-title-main">Waardenburg syndrome</span> Genetic condition involving hearing loss and depigmentation

Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes, a white forelock or patches of light skin. These basic features constitute type 2 of the condition; in type 1, there is also a wider gap between the inner corners of the eyes called telecanthus, or dystopia canthorum. In type 3, which is rare, the arms and hands are also malformed, with permanent finger contractures or fused fingers, while in type 4, the person also has Hirschsprung's disease. There also exist at least two types that can result in central nervous system (CNS) symptoms such as developmental delay and muscle tone abnormalities.

<span class="mw-page-title-main">Usher syndrome</span> Recessive genetic disorder causing deafblindness

Usher syndrome, also known as Hallgren syndrome, Usher–Hallgren syndrome, retinitis pigmentosa–dysacusis syndrome or dystrophia retinae dysacusis syndrome, is a rare genetic disorder caused by a mutation in any one of at least 11 genes resulting in a combination of hearing loss and visual impairment. It is a major cause of deafblindness and is at present incurable.

<span class="mw-page-title-main">Point coloration</span> Coloration of animal coat/fur

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<span class="mw-page-title-main">Merle (dog coat)</span> Genetic pattern in a dogs coat

Merle is a genetic pattern that can be in a dog's coat and alleles of the PMEL gene. Merle results in different colors and patterns and can affect all coat colors. The merle allele creates mottled patches of color in a solid or piebald coat, blue or odd-colored eyes, and can affect skin pigment as well. There are two general types of colored patches that will appear in a merle coat: brown/liver and black. Some breeds that can be affected by this genetic trait are Carea Leonés, Australian Shepherds, and Catahoula Leopard Dogs. This genetic trait should be taken seriously when breeding merles. Health issues are more typical and more severe when two merle-patterned dogs are bred together, so it is recommended that a merle be bred with a non-merle dog of any other color.

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<span class="mw-page-title-main">Leucism</span> Partial loss of pigmentation in an animal

Leucism is a wide variety of conditions that result in the partial loss of pigmentation in an animal—causing white, pale, or patchy coloration of the skin, hair, feathers, scales, or cuticles, but not the eyes. It is occasionally spelled leukism. Some genetic conditions that result in a "leucistic" appearance include piebaldism, Waardenburg syndrome, vitiligo, Chédiak–Higashi syndrome, flavism, isabellinism, xanthochromism, axanthism, amelanism, and melanophilin mutations. Pale patches of skin, feathers, or fur can also result from injury.

Albinism-black lock-cell migration disorder is the initialism for the following terms and concepts that describe a condition affecting a person's physical appearance and physiology: (1) A – albinism, (2) B – black lock of hair, (3) C – cell migration disorder of the neurocytes of the gut, and (4) D – sensorineural deafness. The syndrome is caused by mutation in the endothelin B receptor gene (EDNRB).

<span class="mw-page-title-main">White horse</span> Horse coat color

A white horse is born predominantly white and stays white throughout its life. A white horse has mostly pink skin under its hair coat, and may have brown, blue, or hazel eyes. "True white" horses, especially those that carry one of the dominant white (W) genes, are rare. Most horses that are commonly referred to as "white" are actually "gray" horses whose hair coats are completely white. Gray horses may be born of any color and their hairs gradually turn white as time goes by and take on a white appearance. Nearly all gray horses have dark skin, except under any white markings present at birth. Skin color is the most common method for an observer to distinguish between mature white and gray horses.

<span class="mw-page-title-main">Microphthalmia-associated transcription factor</span> Mammalian protein found in Homo sapiens

Microphthalmia-associated transcription factor also known as class E basic helix-loop-helix protein 32 or bHLHe32 is a protein that in humans is encoded by the MITF gene.

<span class="mw-page-title-main">Odd-eyed cat</span> Cat with eyes of different colours

An odd-eyed cat is a cat with one blue eye and one eye either green, yellow, amber, or brown. This is a feline form of complete heterochromia, a condition that occurs in some other animals, including humans. There is also sectoral (partial) heterochromia, where two different colours occur within the same iris. The condition most commonly affects solid white cats, but may be found in cats of any coat colour.

<span class="mw-page-title-main">GJB6</span> Protein-coding gene in the species Homo sapiens

Gap junction beta-6 protein (GJB6), also known as connexin 30 (Cx30) — is a protein that in humans is encoded by the GJB6 gene. Connexin 30 (Cx30) is one of several gap junction proteins expressed in the inner ear. Mutations in gap junction genes have been found to lead to both syndromic and nonsyndromic deafness. Mutations in this gene are associated with Clouston syndrome.

<span class="mw-page-title-main">Cat genetics</span> Study of inheritance in domestic cats

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<span class="mw-page-title-main">Splashed white</span>

Splashed white or splash is a horse coat color pattern in the "overo" group of spotting patterns that produces pink-skinned, white markings. Many splashed whites have very modest markings, while others have the distinctive "dipped in white paint" pattern. Blue eyes are a hallmark of the pattern, and splash may account for otherwise "solid" blue-eyed horses. Splashed white occurs in a variety of geographically divergent breeds, from Morgans in North America to Kathiawari horses in India. The splashed white pattern is also associated with congenital deafness, though most splashed whites have normal hearing. Splashed white can be caused by multiple variants across two different genes, for which genetic testing is available.

<span class="mw-page-title-main">Dominant white</span> Horse coat color and its genetics

Dominant white (W) is a group of genetically related coat color alleles on the KIT gene of the horse, best known for producing an all-white coat, but also able to produce various forms of white spotting, as well as bold white markings. Prior to the discovery of the W allelic series, many of these patterns were described by the term sabino, which is still used by some breed registries.

<span class="mw-page-title-main">Waardenburg Syndrome Type 2D</span> Medical condition

Waardenburg Syndrome Type 2D, a subtype of the Waardenburg syndrome, is a rare congenital disorder caused by a mutation in the SLUG (SNAI2) gene. It is characterized by the lack of pigmentation in the skin, hair, and eyes as well as the abnormalities in the outer wall of the cochlea. This subtype lacks the wide distance between the eyes, known as dystopia canthorum, that is observed in most patients with Waardenburg Syndrome. Those affected, exhibit varying degrees of deafness or complete hearing loss along with heterochromia and reports of early graying. This disease is observed in the neonatal stages of early life.

<span class="mw-page-title-main">Waardenburg Syndrome Type 1</span> Congenital disorder

Waardenburg Syndrome Type 1 is a congenital disorder that caused by a mutation in the PAX3 gene that results in abnormal development in the neural crest during early development. Type 1 results in early graying and white forelock and a notable distance between the eyes, noted as dystopia canthorum. Common symptoms of the disease also includes non-progressive hearing loss in majority of patients with Type 1. Patients can display complete or partial heterochromia and hypoplastic blue irides and congenital leukemia.

Causes of hearing loss include ageing, genetics, perinatal problems, loud sounds, and diseases. For some kinds of hearing loss the cause may be classified as of unknown cause.

References

  1. 1 2 Bosher, SK; Hallpike, CS (13 April 1965). "Observations on the histological features, development and pathogenesis of the inner ear degeneration of the deaf white cat". Proceedings of the Royal Society B: Biological Sciences. 162 (987): 147–170. Bibcode:1965RSPSB.162..147B. doi:10.1098/rspb.1965.0030. PMID   14285813. S2CID   36675534.
  2. Webb, A. A.; Cullen, C. L. (June 2010). "Coat color and coat color pattern-related neurologic and neuro-ophthalmic diseases". Can. Vet. J. 51 (6): 653–7. PMC   2871368 . PMID   20808581.
  3. Darwin, Charles (1909) [1859]. On the Origins of Species. p. 13. ISBN   9788187572664.
  4. "Ask Elizabeth: White Cats and Blindness/Deafness". Cornell University College of Veterinary Medicine. Cornell University College of Veterinary Medicine Ithaca, New York. Retrieved 3 December 2016.
  5. 1 2 "White Cats, Eye Colours and Deafness". messybeast.com. Retrieved 11 September 2013.
  6. Richards, J. (1999). ASPCA Complete Guide to Cats: Everything You Need to Know About Choosing and Caring for Your Pet. Chronicle Books. p. 71. ISBN   9780811819299.
  7. Heid, S; Hartmann, R; Klinke, R (January 1998). "A model for prelingual deafness, the congenitally deaf white cat—population statistics and degenerative changes". Hearing Research. 115 (1–2): 101–12. doi:10.1016/S0378-5955(97)00182-2. PMID   9472739. S2CID   38262220.
  8. Omenn, Gilbert S.; McKusick, Victor A.; Gorlin, Robert J. (1979). "The association of Waardenburg syndrome and Hirschsprung megacolon". American Journal of Medical Genetics. 3 (3): 217–223. doi:10.1002/ajmg.1320030302. ISSN   1096-8628. PMID   484594.
  9. MARKAKIS, MARIOS N.; SOEDRING, VIBEKE E.; DANTZER, VIBEKE; CHRISTENSEN, KNUD; ANISTOROAEI, RAZVAN (1 August 2014). "Association of MITF gene with hearing and pigmentation phenotype in Hedlund white American mink (Neovison vison)". Journal of Genetics. 93 (2): 477–481. doi:10.1007/s12041-014-0370-3. hdl: 10067/1211550151162165141 . ISSN   0973-7731. PMID   25189243. S2CID   16725018.
  10. Strain, George M. (2015). "The Genetics of Deafness in Domestic Animals". Frontiers in Veterinary Science. 2: 29. doi: 10.3389/fvets.2015.00029 . ISSN   2297-1769. PMC   4672198 . PMID   26664958.
  11. David, Victor A.; Menotti-Raymond, Marilyn; Wallace, Andrea Coots; Roelke, Melody; Kehler, James; Leighty, Robert; Eizirik, Eduardo; Hannah, Steven S.; Nelson, George; Schäffer, Alejandro A.; Connelly, Catherine J. (1 October 2014). "Endogenous Retrovirus Insertion in the KIT Oncogene Determines White and White spotting in Domestic Cats". G3: Genes, Genomes, Genetics. 4 (10): 1881–1891. doi:10.1534/g3.114.013425. ISSN   2160-1836. PMC   4199695 . PMID   25085922.
  12. Hamadah, Issam; Chisti, Muzamil; Haider, Mansoor; Al Dosssari, Haya; Alhumaidan, Rawan; Meyer, Brian F.; Wakil, Salma M. (13 July 2019). "A novel KIT mutation in a family with expanded syndrome of piebaldism". JAAD Case Reports. 5 (7): 627–631. doi:10.1016/j.jdcr.2019.01.021. ISSN   2352-5126. PMC   6630042 . PMID   31341943.
  13. Lee, Youl-Nam; Brandal, Stephanie; Noel, Pierre; Wentzel, Erik; Mendell, Joshua T.; McDevitt, Michael A.; Kapur, Reuben; Carter, Melody; Metcalfe, Dean D.; Takemoto, Clifford M. (31 March 2011). "KIT signaling regulates MITF expression through miRNAs in normal and malignant mast cell proliferation". Blood. 117 (13): 3629–3640. doi:10.1182/blood-2010-07-293548. ISSN   0006-4971. PMC   3072881 . PMID   21273305.
  14. Strain, George M. (2011). Deafness in Dogs and Cats. CAB International. pp.  68. ISBN   9781845937645.
  15. Hartwell, Sarah (2023). "Blue-eyed Breeds / Dominant Blue Eye (DBE)". messybeast.com. Retrieved 11 September 2023.
  16. Hunter, Erin (17 March 2015). A Dangerous Path. Harper Children's. p. 79-81. ISBN   9780062367006.
  17. Hunter, Erin (17 March 2015). A Dangerous Path. Harper Children's. p. 94. ISBN   9780062367006.