Breeds Affected: American Bulldog, Australian Shepherd, Bull Mastiff, Brazilian Terrier, Dogue de Bordeaux, English Bulldog, English Mastiff, Great Pyrenees, Italian Cane Corso, Perro de Presa Canario
Samples Accepted: Blood, Buccal Swabs
Disease Information: Canine Multifocal Retinopathy 1 (cmr1) is usually first noticed when pups are 10-14 weeks of age. Small light-coloured lesions develop, where the retina is separating/folding. The condition is not usually progressive, and rarely causes vision problems.
Inheritance Information: Cmr1 is autosomal recessive, meaning that animals with two copies of this allele will be affected. Animals with one copy of the gene will be clinically-normal carriers.
The possible genotypes are:
N/N The dog is normal, and cannot produce affected offspring.
N/cmr1 The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/cmr1 carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
cmr1/cmr1 The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to a N/cmr1 carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/cmr1 x N/N) without any risk of producing affected offspring. The offspring should be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/cmr1 x N/cmr1) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (cmr1/cmr1) should not be used for breeding.
Test Information: This mutation test identifies a single base change in the first coding exon of the BEST1 gene (also known as VMD2).
Donner, J., Kaukonen, M., Anderson, H., Möller, F., Kyöstilä, K., Sankari, S., Hytönen, M., Giger, U., Lohi, H. :Genetic Panel Screening of Nearly 100 Mutations Reveals New Insights into the Breed Distribution of Risk Variants for Canine Hereditary Disorders. PLoS One 11:e0161005, 2016. Pubmed reference: 27525650. DOI: 10.1371/journal.pone.0161005.
Gornik, K.R., Pirie, C.G., Duker, J.S., Boudrieau, R.J.: Canine multifocal retinopathy caused by a BEST1 mutation in a Boerboel. Vet Ophthalmol 17:368-72, 2014. Pubmed reference: 23998685. DOI: 10.1111/vop.12095.
Hoffmann, I., Guziewicz, K.E., Zangerl, B., Aguirre, G.D., Mardin, C.Y.: Canine multifocal retinopathy in the Australian Shepherd: a case report. Vet Ophthalmol 15 Suppl 2:134-8, 2012. Pubmed reference: 22432598. DOI: 10.1111/j.1463-5224.2012.01005.x.
Zangerl, B., Wickström, K., Slavik, J., Lindauer, S.J., Ahonen, S., Schelling, C., Lohi, H., Guziewicz, K.E., Aguirre, G.D.: Assessment of canine BEST1 variations identifies new mutations and establishes an independent bestrophinopathy model (cmr3). Mol Vis 16:2791-804, 2010. Pubmed reference: 21197113.
Guziewicz, KE., Zangerl, B., Lindauer, SJ., Mullins, RF., Sandmeyer, LS., Grahn, BH., Stone, EM., Acland, GM., Aguirre, GD.: Bestrophin gene mutations cause canine multifocal retinopathy: a novel animal model for best disease. Invest Ophthalmol Vis Sci 48:1959-67, 2007. Pubmed reference: 17460247. DOI: 10.1167/iovs.06-1374
Further information is available at the Online Mendelian Inheritance in Animals website.