Canine Mendelian disease record

Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2)

Q: How well studied is Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2) in dogs?

OMIA curates 3 peer-reviewed references for Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2). The full, linked citation list is on this page.

Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2). Autosomal recessive. Observed in 3 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,661 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:002110-9615
Inheritance: Autosomal recessive
Variant pathogenicity: Pathogenic
Source dataset: Sniff Atlas v1.0.1 / DOI

The Pathogenic grade describes the documented variant's causality, per the Animal Variant Classification Guidelines (AVCG; Boeykens et al. 2024, Front Vet Sci), an ACMG/AMP-style framework curated in OMIA. It grades the variant, not any individual dog. See the full classification table.

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

Ataxia is characterized by uncoordinated movements and represents a relatively non-specific clinical sign. This entry describes an ataxia form that is caused by a genetic variant in the ATP1B2 gene. Phenotypically related ataxias in dogs may also be caused by variants in more than 30 other genes (Cocostîrc et al. 2023; Stee et al. 2023). Thus locus heterogeneity for this phenotype must be considered.

Clinical features

The primary clinical sign consisted of a loss of coordination and generalized ataxic gait starting at 4 weeks of age. SDCA2 affected dogs also had seizures, showed pacing and circling and developed central blindness. Due to the rapid progression of the neurological signs, most puppies were euthanized at 6 weeks of age. One affected puppy died at 6.5 weeks of age during a seizure (Mauri et al. 2017).

Molecular genetics

By whole-genome sequencing a single SDCA2 affected Belgian Shepherd, and comparing the data with genome sequences from 146 control canids, Mauri et al. (2017) identified a 227 bp SINE insertion into exon 2 of the ATP1B2 gene in the affected dog. The variant was described as XM_546597.5:ATP1B2:c.130_131insLT796559.1:g.50_276 or CanFam3.1:Chr5:32,551,064_32,551,065insLT796559.1:g.50_276. The SINE insertion was homozygous in 5 affected dogs. It did not occur in homozygous state in 258 control Belgian Shepherds. The variant was absent from 503 dogs of diverse other breeds. At the time of the canine study, there were no reports about human patients with ATP1B2 variants available. However, an Atp1b2 knockout mouse model displayed also a progressive motor impairment and spongy degeneration of the brain. Mauri et al. (2017) investigated the molecular consequences of the SINE insertion. Using skin RNA from one case, the authors detected at least three different aberrant splice isoforms. The epxressed transcripts all maintained the original reading frame. However, as several codons were altered in each of these isoforms, a loss of ATP1B2 function seems likely.

Pathology

"Histopathological changes ... were characterized by bilateral-symmetric vacuolation of the neuropil, targeting the cerebellar nuclei; the ventral horn gray matter of the spinal cord, in particular at the level of the cervical intumescence; and the brain stem. In the spinal cord, vacuolation was associated with neuronal necrosis and severe gliosis. Additionally, in the puppy MA162, neuronal necrosis and diffuse presence of hypertrophic astrocytes with vesicular nuclei, reminiscent of Alzheimer type II cells, were observed in the hippocampus, caudate nucleus, and diffusely in the cortex. Histopathological eye abnormalities were not noticed." (Mauri et al. 2017)

Human analog

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

Gene · OMIM 182331

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:002110-9615, 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.

An overview of canine inherited neurological disorders with known causal variants. · Animals (Basel) · 2023 · PMID 38003185
Phenotypic and genetic aspects of hereditary ataxia in dogs. · J Vet Intern Med · 2023 · PMID 37341581
A SINE Insertion in ATP1B2 in Belgian Shepherd Dogs Affected by Spongy Degeneration with Cerebellar Ataxia (SDCA2). · G3 (Bethesda) · 2017 · PMID 28620085

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 Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2) 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 Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2) looks like in your dog's breed.

Carrier frequency by breed

Top 3 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%5%10%

Belgian Malinois4.4% · n 1,186

4.4%n 1,186

Dutch Shepherd Dog0.78% · n 64

0.78%n 64

German Shepherd<0.1% · n 15,647

<0.1%n 15,647

n = 16,897 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 Spongy Degeneration with Cerebellar Ataxia (Discovered in the Belgian Malinois; ATP1B2-related SDCA2) is measured; phenotype outcome depends on penetrance and modifiers.

▸ Full table with Wilson 95% confidence intervals

Breed	Carrier frequency	Wilson 95% CI	n tested
Belgian Malinois	4.4%	[3.4%, 5.8%]	1,186
Dutch Shepherd Dog	0.78%	[0.1%, 7.1%]	64
German Shepherd	<0.1%	[0.0%, 0.0%]	15,647

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

Scope of this record

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

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:002110-9615.
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:002110-9615, 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:002110-9615 · Donner et al. 2023