Deafness in dominant blue-eyed (DBE) cats
Dominant blue eyes (DBE) with minimal white spotting cats, are characterized by pigmentary abnormalities of the iris and skin, and in some cases, sensorineural hearing loss. This condition is caused by an abnormal distribution of melanocytes during embryonic development, leading to a lack of melanocytes in the eyes and skin. The causative genetic variant has been found in the PAX3 gene, a transcription factor that controls a wide array of developmental events, including the differentiation of melanoblasts into melanocytes.
The genetic variant, known as the DBE-RE allele, causes DBE with deafness in carrier animals. It was initially discovered in a Dutch Maine Coon lineage referred to by breeders as the "Rociri Elvis" lineage. The phenotypes of the heterozygous affected cats resembles the human Waardenburg syndrome type 1 and the Splashed white in horses.
DBE-RE homozygous mutant animals are predicted to be lethal.
Breeders have also reported ‘latent DBE cats’ in certain feline lines, which have minimal white spotting and no blue eyes but display a red-eye effect during infancy.
Symptoms
DBE cats can be recognized by the typical striking blue eyes in combination with white patches of fur, which vary in extent. Heterochromatism, in which only one eye is blue, is also possible.
Hearing loss or even complete deafness cannot be detected without complex special examination methods.
The DNA test to identify the DBE-RE variant can easily clarify whether a given DBE phenotype is associated with deafness.
Breeds affected by DBE-RE
All dominant blue-eyed feline breeds
Testinformations
The DBE-RE test identifies the substitution of 1 base pair c.937C>T in the PAX3 gene.
Application:
- Identification of the DBE-RE predisposition in cats with DBE
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Genotypes / Lab results
n/n = homozygous normal - Wild type
The tested animal does not have the PAX3: c.937C>T variant associated with DBE and deafness and cannot pass it on to offspring. The DBE trait is caused by another genetic variant in this animal.
n/DBERE = heterozygous for the mutation - DBE with deafness
The animal carries the mutant allele in one of the two copies of the PAX3 gene and will transmit it to 50% of its offspring.
The tested animal is potentially affected by deafness.
Carrier animals should not be used for breeding to prevent passing on the mutation.
DBERE/DBERE = homozygous for the mutation
Such animals are not viable
Breeding recommendations
Animals with a DBE-RE predisposition should not be used for breeding.
Literature
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 Jun 13:jkae131. doi: 10.1093/g3journal/jkae131. Epub ahead of print. PMID: 38869246.
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 Apr 22. doi: 10.1111/age.13433. Epub ahead of print. PMID: 38644700.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/age.13433
Weitere Informationen sind auf der Webseite Online Mendelian Inheritance in Animals verfügbar.