Cone Degeneration (Discovered in the German Shepherd Dog; CNGA3-related)
Cone Degeneration (Discovered in the German Shepherd Dog; CNGA3-related). Autosomal recessive. Observed in 0 of 266 breeds tested in the Sniff Atlas, with measured variant frequencies drawn from 242,665 dogs (Donner 2023). Whether a dog carrying this variant is at risk depends on the disease’s inheritance pattern; outcome also depends on penetrance, modifiers, and environment. The frequencies below describe variant prevalence, not confirmed disease incidence.
- OMIA identifier
- OMIA:001481-9615
- InheritanceInheritance patternWhat it isHow the condition is passed down: recessive (two copies needed), dominant (one copy), or more complex.For your dogRecessive means a single-copy carrier is usually healthy but can still pass it on.PreciselyThe documented mode of Mendelian transmission (autosomal recessive or dominant, X-linked, etc.) per OMIA.OMIA · documented
- Autosomal recessive
- Linked gene
- CNGA3
- Human counterpart
- In humans, this gene is CNGA3. OMIM 600053 In people, CNGA3 appears tolerant of loss-of-function variation (gnomAD v4.1 constraint, LOEUF 1.13). Constraint measures intolerance to loss-of-function only and does not indicate importance; some tolerant genes cause disease through other mechanisms. In people, variants in the CNGA3 gene have conflicting classifications in ClinVar, and none is expert-reviewed. The evidence is unsettled, not that variants here are benign.
- Source dataset
- Sniff Atlas v1.0.1 / DOI
A model of human achromatopsia 2
Dogs with this condition carry a change in CNGA3. In people, changes in the same gene cause achromatopsia 2. 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: Achromatopsia 2 is a condition that affects the color vision. Most people have complete achromatopsia which is characterized by a total absence of color vision (only able to see black, white and shades of gray). Rarely, affected people may have incomplete achromatopsia which is associated with some color discrimination. Other common signs and symptoms include reduced visual acuity, involuntary back-and-forth eye movements, increased sensitivity to light (photophobia), and hyperopia (farsightedness). Achromatopsia 2 is caused by changes (mutations) in the CNGA3 gene and is inherited in an autosomal recessive manner. Although color discrimination cannot be improved, treatments are available to address some of the other associated symptoms.
In humans it is also called: ACHM2, RMCH2, achromatopsia caused by mutation in CNGA3, achromatopsia type 2, CNGA3 achromatopsia.
Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Sniff renders this as a model-of link; the canine disease remains the subject of this page.
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.
Molecular genetics
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.
Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001481-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).
How it presents
Catalogued in the Mondo disease ontology (the cross-species disease identity used by the Monarch Initiative) as achromatopsia 2 (MONDO:0009003).
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).
Published references
The peer-reviewed papers behind this disease, curated by OMIA. Starred entries are OMIA-designated landmark papers.
- Consensus guidelines for nomenclature of companion animal inherited retinal disorders. · Vet Ophthalmol · 2024 · PMID 38334230
- 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 · 2021
- Canine CNGA3 gene mutations provide novel insights into human achromatopsia-associated channelopathies and treatment. · PLoS One · 2015 · PMID 26407004
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.
See what Cone Degeneration (Discovered in the German Shepherd Dog; CNGA3-related) looks like in your dog's breed.
Observed only in small-sample breeds
Maximum variant frequency per breed across variants in the Donner 2023 cohort, with Wilson 95% confidence intervalsWilson 95% confidence intervalWhat it isThe range the true frequency is probably in. A wide range means we are less sure, usually because few dogs were tested.For your dogTrust tight ranges; treat wide ones as rough estimates.PreciselyA binomial-proportion confidence interval (Wilson score, 95%) that stays reliable at small sample sizes.Sniff Atlas methodology · statistical. 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.
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 variant frequency is measured; phenotype outcome depends on penetrance, environment, and modifier loci. Consult a veterinarian for clinical interpretation.
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:001481-9615.
- 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
- Gene page: CNGA3, cited identity, disease associations, and the human-gene bridge.
- Sniff Atlas v1.0.1, the source dataset for these frequencies.
- Browse breeds, per-breed Mendelian profiles, including this disease in context.
- OMIA entry OMIA:001481-9615, authoritative clinical reference.
- About OMIA, the catalogue this record comes from, and how Sniff uses it.