Canine Multifocal Retinopathy 2 (CMR2)

 

Gene: BEST1

Transmission: Autosomal, recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Substitution, BEST1 gene; c.482 G>A, p.(G161D)

Medical system: Eyes

Breed: Coton de Tulear, Schnauzer - Miniature

Age of onset of symptoms: Around the age of 15 weeks with an ophthalmic examination

Multifocal Retinopathy 2 (CMR2) is a disease seen in the Coton de Tulear.  Multiple regions of detachment appear in the retina around the age of 15 weeks, causing retinal swellings of varying colors and sizes.  The disease progresses slowly, until the age of 6 to 12 months in some dogs.  Over time, lesions may heal and be no longer visible.  In general, vision is not affected, although some cases of blindness have been reported.

 

References:

OMIA link: [1553-9615]

Donner J, Freyer J, Davison S, et al. (2023) Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs.  PLoS Genet. 19(2):e1010651. [pubmed/36848397]

Genetics Committee of the American College of Veterinary Opthalmologists (2021) The Blue Book: Ocular disorders presumed to be inherited in purebred dogs. 13th Edition.  [https://ofa.org/wp-content/uploads/2022/10/ACVO-Blue-Book-2021.pdf]

Guziewica KE, Zangerll B, Lindauer SJ, et al. (2007) Bestrophin gene mutations cause canine multifocal retinopathy: A novel animal model for Best disease. Investigative Ophthalmology and Visual Science 48(5):1959-1967. [pubmed/17460247]

Zangerl B, Wickström K, Slavik J, et al. (2010) Assessment of canine BEST1 variations identifies new mutations and establishes an independent bestrophinopathy model (cmr3). Mol Vis. 16:2791-804.2 [pubmed/21197113]