Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 153700 , 611809 , 193220 , 613194 , 608161

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Recessive

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2007

Cross-species summary: This disorder has been renamed in OMIA on the basis of the review by Miyadera et al. (2012)

Species-specific name: Canine multifocal retinopathy

Species-specific symbol: cmr1

Species-specific description: Canine multifocal retinopathy (cmr) is an ocular disorder characterized by multiple areas of retinal degeneration. The detection of three different mutations in the one gene (BEST1) has led to the naming of three different forms of the disorder (cmr1 [OMIA001444-9615], cmr2 [OMIA001553-9615], cmr3 [OMIA001554-9615]), all of which are very similar clinically, but with the last two each occurring in only one breed. The form of cmr detailed in this entry (cmr1) occurs in several breeds (listed below).

Mapping: CFA18

Molecular basis: The causative mutation of cmr1 in the Great Pyrenees, the English mastiff and the bullmastiff is a C to T mutation that generates a premature stop codon: c.73C>T; p.Arg25Ter (Guziewicz et al., 2007).

Gornik et al. (2014) reported this same causal mutation in a Boerboel.

Clinical features: Signs of cmr1 develop around 13 weeks of age, and include multiple tan-pink subretinal patches in both the tapetal and the non-tapetal fundus along with focal areas of tapetal hyper-reflectivity. The lesions elevate the retina. They progress as the animal ages to focal areas of retinal degeneration and retinal pigment epithelial hypertrophy and pigmentation (Grahn et al., 1998).

Pathology: In retinal histology there are multiple areas of retinal pigment epithelial vacuolation, hypertrophy, apparent separation from Bruch’s membrane, and multiple serous retinal detachments (Grahn et al., 1998).

Control: Relatives of affected dogs should be tested. Breeding of affected or carrier animals is not recommended. If carriers must be bred, it should be bred only to a tested, homozygous normal dog.

Genetic testing: There are tests available to detect the known causative mutations.

Breeds: American Bulldog, Australian Shepherd, Boerboel, Bull Mastiff, Dogue de Bordeaux, English Bulldog, English Mastiff, Great Pyrenees, Italian Cane Corso, Perro de Presa Canario.

Associated gene: