Skip to main content
snıff
Canine Mendelian disease record

Progressive Retinal Atrophy (Discovered in the Swedish Vallhund; MERTK-related)

Progressive Retinal Atrophy (Discovered in the Swedish Vallhund; MERTK-related). Autosomal recessive. Observed in 7 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,651 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:001932-9615
Autosomal recessive
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human retinitis pigmentosa 38

This is the canine counterpart of retinitis pigmentosa 38 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: Any retinitis pigmentosa in which the cause of the disease is a mutation in the MERTK gene.

In humans it is also called: RP38, MERTK retinitis pigmentosa, retinitis pigmentosa caused by mutation in MERTK, retinitis pigmentosa type 38.

MONDO:0013469 OMIM 613862

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.

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.

Clinical features

As summarised by Cooper et al. (2014), "By examining 324 dogs of the Swedish vallhund breed in seven countries and across three continents, we were able to describe a new and unique form of PRA characterized by the multifocal appearance of red and brown discoloration of the tapetal fundus followed over time by thinning of the retina. We propose three stages of the disease based on the appearance of the ocular fundus and associated visual deficits. Electroretinography revealed a gradual loss of both rod and cone photoreceptor-mediated function in Stages 2 and 3 of the disease. In the few dogs that suffered from pronounced vision loss, night-blindness occurred first in late Stage 2, followed by decreased day-vision in Stage 3. Histologic examinations confirmed the loss of photoreceptor cells at Stage 3, which was associated with the accumulation of autofluorescent material in the adjacent retinal pigment epithelium."

Molecular genetics

Ahonen et al. (2015) were able to show that this disorder "is associated with overexpression of MERTK" but were not able to report a causal mutation. Everson et al. (2017) reported a likely causal variant as "a 6–8 kb insertion in intron 1 of MERTK" with the insertion "comprising a full-length intact LINE-1 retroelement".

Inheritance

A pedigree analysis "of nearly 300 Swedish vallhund dogs, including 125 affected animals" led Cooper et al. (2014) to conclude that this disorder is most likely autosomal recessive.

History

Cooper et al. (2014) were the first to provide a detailed characterisation of this type of PRA that appears to occur only in Swedish Vallhund dogs. Mention of this disorder was included in the catalogue of American College of Veterinary Ophthalmologists (2013).

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 613862 Gene · OMIM 604705

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001932-9615, 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.

  2. 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. Ocular disorders presumed to be inherited in purebred dogs. 6th ed · American College of Veterinary Ophthalmologists, Meridian ID · 2013

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 Swedish Vallhund; MERTK-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 Swedish Vallhund; MERTK-related) looks like in your dog's breed.
Carrier frequency by breed

Top 7 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%38%75%
Swedish Vallhund43.8% · n 88
Samoyed0.55% · n 549
Chinese Crested0.25% · n 204
Australian Cattle Dog0.10% · n 980
Golden Retriever<0.1% · n 12,881
German Shepherd<0.1% · n 15,648
Siberian Husky<0.1% · n 9,034
n = 39,384 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 Swedish Vallhund; MERTK-related) is measured; phenotype outcome depends on penetrance and modifiers.
▸ Full table with Wilson 95% confidence intervals
Breed Carrier frequency n tested
Swedish Vallhund 43.8% 88
Samoyed 0.55% 549
Chinese Crested 0.25% 204
Australian Cattle Dog 0.10% 980
Golden Retriever <0.1% 12,881
German Shepherd <0.1% 15,648
Siberian Husky <0.1% 9,034

259 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:001932-9615.

  • 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:001932-9615 · Donner et al. 2023