Canine Mendelian disease record

Progressive Retinal Atrophy (Discovered in the Giant Schnauzer; NECAP1-related)

Q: What is the human equivalent of Progressive Retinal Atrophy (Discovered in the Giant Schnauzer; NECAP1-related)?

OMIA links Progressive Retinal Atrophy (Discovered in the Giant Schnauzer; NECAP1-related) to its human counterpart in OMIM (OMIM 615833), the bridge to the deeper human-medicine literature for the same underlying biology.

Q: How well studied is Progressive Retinal Atrophy (Discovered in the Giant Schnauzer; NECAP1-related) in dogs?

OMIA curates 4 peer-reviewed references for Progressive Retinal Atrophy (Discovered in the Giant Schnauzer; NECAP1-related). The full, linked citation list is on this page.

Progressive Retinal Atrophy (Discovered in the Giant Schnauzer; NECAP1-related). Autosomal recessive. Observed in 18 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,665 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:002198-9615
Inheritance: Autosomal recessive
Source dataset: Sniff Atlas v1.0.1 / DOI

The human connection

A model of human developmental and epileptic encephalopathy, 21

This is the canine counterpart of developmental and epileptic encephalopathy, 21 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 early infantile epileptic encephalopathy in which the cause of the disease is a mutation in the NECAP1 gene.

In humans it is also called: DEE21, EIEE21, developmental and epileptic encephalopathy 21, epileptic encephalopathy, early infantile, 21, NECAP1 early infantile epileptic encephalopathy.

MONDO:0014360 OMIM 615833

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.

Molecular genetics

"Whole genome sequencing of two PRA-affected full-siblings and both unaffected parents" followed by variant "filtering against 568 canine genomes" enabled Hitti et al. (2019) to identify "a single nucleotide variant in the gene encoding NECAP endocytosis associated 1 (NECAP1): c.544G>A (p.Gly182Arg)" as the likely causal variant of this disorder in "Giant Schnauzer (GS) littermates [that] presented with PRA around four years of age".

Prevalence

Hitti et al. (2019): "Five thousand one hundred and thirty canids of 175 breeds, 10 cross-breeds and 3 wolves were genotyped for c.544G>A. Only the three PRA-affected GS were homozygous (allele frequency in GS, excluding proband family = 0.015). In addition, we identified heterozygotes belonging to Spitz and Dachshund varieties, demonstrating c.544G>A segregates in other breeds of German origin. "

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 615833 Gene · OMIM 611623

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:002198-9615, 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.

Consensus guidelines for nomenclature of companion animal inherited retinal disorders. · Vet Ophthalmol · 2024 · PMID 38334230
Genome sequencing of 2000 canids by the Dog10K consortium advances the understanding of demography, genome function and architecture. · Genome Biol · 2023 · PMID 37582787
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
Whole genome sequencing of Giant Schnauzer dogs with progressive retinal atrophy establishes NECAP1 as a novel candidate gene for retinal degeneration. · Genes (Basel) · 2019 · PMID 31117272

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 Giant Schnauzer; NECAP1-related) and see the odds for their puppies. Single recessive variant, exact Mendelian math.

Parent A

Parent B

NNClear

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 Giant Schnauzer; NECAP1-related) looks like in your dog's breed.

Carrier frequency by breed

Top 14 well-sampled breeds (n ≥ 50)

Maximum carrier frequency per breed across variants in the Donner 2023 cohort, with Wilson 95% confidence intervals. 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%

Dachshund Miniature Shorthaired11.3% · n 585

11.3%n 585

Dachshund Miniature Longhaired10.6% · n 213

10.6%n 213

Pomeranian1.6% · n 5,294

1.6%n 5,294

Chihuahua0.30% · n 4,273

0.30%n 4,273

Pug<0.1% · n 5,154

<0.1%n 5,154

Miniature Pinscher<0.1% · n 658

<0.1%n 658

Beagle<0.1% · n 5,292

<0.1%n 5,292

Miniature American Shepherd<0.1% · n 1,476

<0.1%n 1,476

Shih Tzu<0.1% · n 7,527

<0.1%n 7,527

Schnauzer Miniature<0.1% · n 4,638

<0.1%n 4,638

Maltese<0.1% · n 2,413

<0.1%n 2,413

Yorkshire Terrier<0.1% · n 8,367

<0.1%n 8,367

Poodle Miniature<0.1% · n 3,555

<0.1%n 3,555

American Staffordshire Terrier<0.1% · n 42,793

<0.1%n 42,793

n = 92,238 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 Giant Schnauzer; NECAP1-related) is measured; phenotype outcome depends on penetrance and modifiers.

▸ Full table with Wilson 95% confidence intervals

Breed	Carrier frequency	Wilson 95% CI	n tested
Dachshund Miniature Shorthaired	11.3%	[9.0%, 14.1%]	585
Dachshund Miniature Longhaired	10.6%	[7.1%, 15.4%]	213
Pomeranian	1.6%	[1.3%, 1.9%]	5,294
Chihuahua	0.30%	[0.2%, 0.5%]	4,273
Pug	<0.1%	[0.0%, 0.2%]	5,154
Miniature Pinscher	<0.1%	[0.0%, 0.7%]	658
Beagle	<0.1%	[0.0%, 0.1%]	5,292
Miniature American Shepherd	<0.1%	[0.0%, 0.3%]	1,476
Shih Tzu	<0.1%	[0.0%, 0.1%]	7,527
Schnauzer Miniature	<0.1%	[0.0%, 0.1%]	4,638
Maltese	<0.1%	[0.0%, 0.2%]	2,413
Yorkshire Terrier	<0.1%	[0.0%, 0.1%]	8,367
Poodle Miniature	<0.1%	[0.0%, 0.1%]	3,555
American Staffordshire Terrier	<0.1%	[0.0%, 0.0%]	42,793

▸ Also observed in 4 small-sample breeds (n < 50)

Frequencies in this section are statistical estimates with wide Wilson 95% confidence intervals (typically >20 percentage points). Treat these as "carriers observed but the true population frequency is not yet measurable" rather than as comparable to the well-sampled entries above.

Breed	Estimate	Wilson 95% CI	n tested
Dachshund Shorthaired	25.0%	[6.0%, 63.5%]	6
Dachshund Wirehaired	12.5%	[1.3%, 60.4%]	4
Korean Jindo	4.2%	[0.4%, 30.1%]	12
Laika	2.8%	[0.3%, 21.9%]	18

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

Penetrance

From genotype to phenotype

Carrier status is not the same as disease status. Penetrance is the fraction of at-risk dogs that develop the phenotype. The Donner 2023 S4 table tracks this for 1 variant(s) underlying this disease in the cohort.

At-risk dogs evaluated: 3
Phenotype confirmed: 0
Penetrance range: not yet quantifiable

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

How to cite this record

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:002198-9615.
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.

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:002198-9615, authoritative clinical reference.
About OMIA, the catalogue this record comes from, and how Sniff uses it.

Last updated June 20, 2026

Sources: Sniff Atlas v1.0.1 · OMIA OMIA:002198-9615 · Donner et al. 2023