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Canine Mendelian disease record

Canine Multifocal Retinopathy 2 (Discovered in the Coton de Tulear; CMR2)

Canine Multifocal Retinopathy 2 (Discovered in the Coton de Tulear; CMR2). Autosomal recessive. Observed in 2 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,655 dogs (Donner 2023). Per-dog phenotype outcome depends on penetrance, modifiers, and environment; the carrier frequencies below describe variant prevalence, not disease incidence.

OMIA identifier
OMIA:001553-9615
Autosomal recessive
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human autosomal recessive bestrophinopathy

This is the canine counterpart of autosomal recessive bestrophinopathy in people. That makes affected dogs a naturally-occurring model of the human disease, and it is part of why studying dogs moves medicine forward for everyone. It does not mean your dog has the human disease. It means the two share an underlying biology.

In people, the disease is described as: Autosomal recessive bestrophinopathy (ARB) is a retinal dystrophy, characterized by central visual loss in the first 2 decades of life, associated with an absent electrooculogram (EOG) light rise and a reduced electroretinogram (ERG).

In humans it is also called: ARB, bestrophinopathy, autosomal recessive, retinopathy, Burgess-Black type.

MONDO:0012733 OMIM 153700OMIM 193220

Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Closely related human conditions exist for this gene. Sniff renders this as a model-of link; the canine disease remains the subject of this page.

About this disease

From OMIA's curated record

Documented in OMIA (Online Mendelian Inheritance in Animals). This describes the disease as recorded in the published literature, not a prediction for any individual dog. As of 2026-06-03.

Summary

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 [OMIA:001444-9615], cmr2 [OMIA:001553-9615], cmr3 [OMIA:001554-9615]), all of which are very similar clinically. The form of cmr detailed in this entry (cmr2) occurs in the Coton du Tulear breed.

Clinical features

Signs of cmr 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, progressing as the dog ages, to focal areas of retinal degeneration and retinal pigment epithelial hypertrophy and pigmentation (Grahn et al., 1998).

Molecular genetics

The causative mutation for cmr2 in the Coton de Tulear is a G to A missense mutation in BEST1 (Guziewicz et al., 2007).

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.

Human analog

OMIA links this condition to its human counterpart in OMIM (Mendelian Inheritance in Man), the place to read across to the deeper human literature for the same biology.

Disease · OMIM 153700 Disease · OMIM 193220 Disease · OMIM 611809 Disease · OMIM 613194 Gene · OMIM 607854

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001553-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).

Signs & cross-references

How it presents

Catalogued in the Mondo disease ontology (the cross-species disease identity used by the Monarch Initiative) as BEST1-related recessive retinopathy (MONDO:0700239).

Phenotype terms: Human Phenotype Ontology + Mammalian Phenotype Ontology; disease terms: Mondo (Monarch Initiative). Cross-references curated by OMIA (doi:10.25910/2AMR-PV70, CC-BY 4.0).

The evidence

Published references

The peer-reviewed papers behind this disease, curated by OMIA. Starred entries are OMIA-designated landmark papers. Showing 6 of 15.

  1. Canine Best disease as a translational model. · Eye (Lond) · 2025 · PMID 39774293

References curated by OMIA (Nicholas, Tammen & the Sydney Informatics Hub), doi:10.25910/2AMR-PV70 (CC-BY 4.0). Full list at the OMIA entry.

Predict a litter

Set each parent's status for Canine Multifocal Retinopathy 2 (Discovered in the Coton de Tulear; CMR2) and see the odds for their puppies. Single recessive variant, exact Mendelian math.

Parent A
Parent B
NNClear
NmCarrier
NmCarrier
mmAffected
Clear25%
Carrier50%
Affected25%

These are the genetic odds for one known variant, not a promise: a real litter varies around them, and penetrance or other genes can change whether the condition ever appears. Use it to avoid pairing two carriers and to keep a line healthy, not to engineer a dog. Inheritance mode per OMIA.
Your breed

See what Canine Multifocal Retinopathy 2 (Discovered in the Coton de Tulear; CMR2) looks like in your dog's breed.
Carrier frequency by breed

Top 2 well-sampled breeds (n ≥ 50)

Maximum per breed across variants in the Donner 2023 cohort, with . The list below is split into well-sampled breeds (n ≥ 50 tested) and small-sample breeds (n < 50, where the Wilson CI typically spans more than 20 percentage points and frequencies should not be compared directly to the well-sampled entries). Frequencies are population-level, not per-litter or per-line.

0%10%20%
Coton De Tulear4.8% · n 104
Schnauzer Miniature<0.1% · n 4,638
n = 4,742 dogs · Donner et al. 2023 carrier-screening cohort · Sniff Atlas
Each bar is one well-sampled breed; the whisker is its Wilson 95% CI, and fainter bars have wider intervals. Frequencies are population-level, not per-litter. Carrier status for Canine Multifocal Retinopathy 2 (Discovered in the Coton de Tulear; CMR2) is measured; phenotype outcome depends on penetrance and modifiers.
▸ Full table with Wilson 95% confidence intervals
Breed Carrier frequency n tested
Coton De Tulear 4.8% 104
Schnauzer Miniature <0.1% 4,638

264 additional breeds in the Donner 2023 cohort were tested but showed no carriers.

Scope of this record

Scope

This record carries the breed-level carrier frequencies from the Donner 2023 cohort. Penetrance data (the fraction of at-risk dogs that develop the phenotype) is not yet quantified for this disease in the Sniff Atlas v1.0.1. The OMIA entry is the authoritative reference for the clinical phenotype, inheritance pattern, and gene assignment.

Predicted disease relevance at the per-dog level is UNPROVEN. The carrier frequency is measured; phenotype outcome depends on penetrance, environment, and modifier loci. Consult a veterinarian for clinical interpretation.

How to cite this record

Citations

If you use this record in published work, cite the Sniff Atlas (the published dataset that carries the breed-level carrier frequencies) and the upstream sources:

  • Sniff Atlas v1.0.1 for the per-breed carrier frequencies:

    Gehring, M. (2026). Sniff Atlas v1.0.1. Zenodo. https://doi.org/10.5281/zenodo.20566358. CC-BY 4.0.

  • OMIA for the disease definition, inheritance, and gene assignment:

    Nicholas, F. W., & Tammen, I. (2024). OMIA. Sydney Informatics Hub, The University of Sydney. https://doi.org/10.25910/2AMR-PV70. Entry: OMIA:001553-9615.

  • Donner et al. 2023 for the breed × variant carrier-frequency cohort:

    Donner, J., Freyer, J., Davison, S., Anderson, H., Blades, M., Honkanen, L., et al. (2023). Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLOS Genetics, 19(2), e1010651. https://doi.org/10.1371/journal.pgen.1010651.

Full citation formats (BibTeX, RIS, CITATION.cff) at sniff.world/cite.

Related

Related

Last updated
Sources: Sniff Atlas v1.0.1 · OMIA OMIA:001553-9615 · Donner et al. 2023