Skip to main content
snıff
Canine Mendelian disease record

Progressive Retinal Atrophy (Discovered in the Basenji; SAG-related)

Progressive Retinal Atrophy (Discovered in the Basenji; SAG-related). Autosomal recessive. Observed in 1 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,664 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:001876-9615
Autosomal recessive
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human Oguchi disease-1

Dogs with this condition carry a change in SAG. In people, changes in the same gene cause Oguchi disease-1. 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: Any Oguchi disease in which the cause of the disease is a mutation in the SAG gene.

In humans it is also called: CSNBO1, Oguchi disease caused by mutation in SAG, Oguchi disease type 1, SAG Oguchi disease.

MONDO:0009775 OMIM 258100OMIM 613758

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

Disease was previously called 'Progressive retinal atrophy, Basenji'. Renamed 'Retinal atrophy, progressive, SAG-related' [13/06/2023]

Clinical features

While there are multiple types of progressive retinal atrophy (PRA), Basenjis generally obtain late onset PRA (Goldstein et al., 2013). Initially, affected individuals lose their vision in dim light and lose their peripheral visual field, resulting in tunnel vision. Many individuals can maintain forward day vision for years as disease progresses (Goldstein et al., 2013). Retinal thinning (stage I) can typically be detected at five years old, and reduced blood flow through retinal vasculature (stage II) is normally detected around seven years of age (Goldstein et al., 2013). IT thanks DVM student Maya Yaffe, who provided the basis of this contribution in May 2023.

Molecular genetics

Sequencing of the two candidate genes in this region led Goldstein et al. (2013) to the discovery of the causal mutation as a stop-loss or extensionl base substitution in the SAG gene (encoding S-antigen): a "tyrosine to cysteine transition mutation at position CFA25:47,845,680 (c.1216T>C . . .) that changed the normal stop codon to code for the amino acid arginine, which would result in a deduced addition of 25 amino acids (p.*405Rext*25) to the normal 405 amino acid protein".

Inheritance

The mating results of Goldstein et al. (2006) suggested autosomal recessive inheritance.

History

This particular form of PRA was first mentioned by Goldstein et al. (2006), who, by judicious matings, showed that even though its clinical sings are very similar to Progressive rod-cone degeneration (prcd) (OMIA 001298-9615) in a wide range of breeds, the Basenji disorder is not allelic to prcd.

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 258100 Disease · OMIM 613758 Gene · OMIM 181031

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001876-9615, 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.

  3. 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
  6. Canine progressive retinal atrophy. Occurrence by age, breed and sex. · Am J Vet Res · 1974

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 Progressive Retinal Atrophy (Discovered in the Basenji; SAG-related) 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 Progressive Retinal Atrophy (Discovered in the Basenji; SAG-related) looks like in your dog's breed.
Carrier frequency by breed

Top 1 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%
Basenji10.7% · n 131
n = 131 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 Progressive Retinal Atrophy (Discovered in the Basenji; SAG-related) is measured; phenotype outcome depends on penetrance and modifiers.
▸ Full table with Wilson 95% confidence intervals
Breed Carrier frequency n tested
Basenji 10.7% 131

265 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:001876-9615.

  • 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:001876-9615 · Donner et al. 2023