Parson Russell Terrier
The tested variant with the highest allele frequency is Degenerative Myelopathy, at 14% among the 181 Parson Russell Terriers tested (Donner 2023; gene copies, not dogs), then Spinocerebellar Ataxia (6.4%) and Primary Lens Luxation (6.1%).
Which disease variants turn up in Parson Russell Terriers?
From a panel of 250 Mendelian-disease variants screened in 1,054,293 dogs (Donner et al. 2023), 11 turn up in Parson Russell Terriers at observable frequency. The figure beside each is its allele frequency. Of the gene copies tested in this breed, the share that carry the variant. Every dog carries two copies, so this is not the share of dogs. It is not clinical risk. Most recessive variants require two copies for disease expression; many dominant variants show incomplete penetrance. Read this as a population fingerprint of what's in the gene pool, not a per-dog prediction.
SOD1what this gene does
SOD1 is a gene that helps protect cells from damage caused by harmful molecules called free radicals.
For your dog: If your dog is a carrier of SOD1 variants, it's worth discussing with your vet, but remember carrier status doesn't mean your dog will get the disease.
PDK4what this gene does
PDK4 helps regulate how cells use energy, especially in the heart muscle.
For your dog: If your dog is one of the breeds known to carry this gene, it’s worth discussing heart health with your vet, but being a carrier doesn’t mean your dog will develop disease.
SLC7A9what this gene does
SLC7A9 is a gene that helps transport certain amino acids in the kidneys. It plays a role in how the body handles cystine, an amino acid that can form crystals.
For your dog: If your dog is a carrier, it’s worth discussing with your vet to monitor urinary health and catch any issues early.
ADAMTS17what this gene does
ADAMTS17 is a gene that influences body size and also plays a role in certain eye conditions. It affects the structure of tissues in the eye and elsewhere in the body.
For your dog: If your dog belongs to a breed known to carry ADAMTS17 variants, it’s worth discussing genetic testing and eye exams with your vet to stay ahead of potential issues.
Full ADAMTS17 gene page →SLC2A9what this gene does
SLC2A9 is a gene that helps regulate uric acid levels in a dog's body. It plays a role in how the kidneys handle this substance.
For your dog: If your dog is one of the breeds known to carry this gene variant, it’s worth discussing with your vet to understand any potential urinary health concerns.
ENAMwhat this gene does
ENAM is a gene that helps form enamel, the hard outer layer of teeth. It plays a key role in making sure teeth develop strong and smooth.
For your dog: If your dog is from one of these breeds, it’s worth asking your vet about ENAM and dental health, especially if you notice unusual wear or discoloration on their teeth.
NHEJ1what this gene does
NHEJ1 is a gene involved in repairing breaks in DNA, helping maintain the integrity of genetic information in cells.
For your dog: If your dog belongs to one of the breeds known to carry this gene variant, it's worth discussing testing with your vet to understand any potential eye health risks.
TUBB1what this gene does
TUBB1 is a gene that helps make the building blocks of platelets, which are tiny blood cells important for clotting. It plays a key role in keeping platelet size and number normal.
For your dog: If your dog is from one of the breeds known to carry TUBB1 variants, it’s worth mentioning to your vet, especially before surgeries or if you notice unusual bleeding.
What these results mean for a Parson Russell Terrier
14.1% of Parson Russell Terriers in the Donner 2023 cohort carried it (n=181).
- DM is a loss of function in the spinal cord that begins in adulthood and progresses to paralysis of the back legs. There is no treatment that stops it.
OMIA 000263-9615
“This is an adult onset degeneration of the spinal cord that progresses to paraplegia and tetraparesis. There is no successful treatment. A genetic test is available.” OMIA 000263-9615
- Two copies of the SOD1 variant mean at risk, not affected. Some dogs with two copies never show signs.
OMIA 000263-9615
“some homozygous mutant dogs had no signs of degenerative myelopathy, which suggests incomplete penetrance or other causative loci” OMIA 000263-9615
- One copy makes a dog a carrier. In the study that found the variant, every affected dog tested had two copies.
OMIA 000263-9615
“All affected dogs tested were homozygous mutant.” OMIA 000263-9615
What to do
A DNA result is not a diagnosis. Take the result, and any change in how the dog walks, to a veterinarian.
No test, or a mix
Without a test nobody can say how many copies a dog has. A breed's allele frequency describes the breed, not this dog.
17.7% of Parson Russell Terriers in the Donner 2023 cohort carried it (n=181).
- This is a marker, not an established cause. The curated record says a test based on it is not a good indicator of heart disease risk even in Dobermans, the breed it was found in.
OMIA 000162-9615
“it is evident that any DNA test based on this marker will not be a good indicator of liability to this disorder in Dobermans” OMIA 000162-9615
What to do
A carrier result for this marker is not, on its own, a reason for heart screening. Heart screening is a conversation with your veterinarian about the breed and the dog.
No test, or a mix
What this marker means in breeds other than the Doberman is not established in the sources this page draws on.
SLC7A9 p.A217T (sold as a cystinuria test)
Marker disputed8.6% of Parson Russell Terriers in the Donner 2023 cohort carried it (n=181).
- The curated record finds no support for this variant causing cystinuria, and the researchers who studied it advise against using it as a test.
OMIA 001880-9615
“there appears to be no support for the variant to be causal” OMIA 001880-9615
“strongly recommend not to use "the variant in SLC7A9 as a test to predict the risk of developing cystinuria in male English bulldogs.” OMIA 001880-9615
What to do
A carrier result for this variant does not predict bladder stones. Straining to urinate or blood in the urine is a reason to see a veterinarian whatever a DNA test says.
No test, or a mix
The curated record gives no reason to test for this variant.
For researchers Population genetics, disease models and every recorded condition Open the research detail for the Parson Russell Terrier
Where every number on this page came from.
This page draws on one primary data source. Allele frequencies and sample sizes come from Donner et al. 2023 (CC-BY-4.0), a direct-to-consumer screening cohort, graded Limited as a study design because the dogs were tested at their owners' choice. No genotyped research dogs of this breed are in the three open releases the atlas reads, so the population-genetic sections other breed pages carry are absent here for that reason, not hidden. Conditions recorded for the breed come from OMIA.
What this page does not yet have. Inheritance modes and per-disease penetrance evidence from Donner 2023 are in the structured data for every variant the panel covers. Mondo, OMIM, Ensembl, and HGNC cross-references live on the gene and disease pages this page links to, rather than being repeated here. What is still absent from this breed page is anything not in the cited panel, and each such gap carries its cause where it appears.
How to cite this page. Cite Donner et al. 2023 (doi:10.1371/journal.pgen.1010651) for every frequency on this page, and OMIA for each condition, with the sample size shown beside the figure.
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- 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. doi:10.1371/journal.pgen.1010651
- Brundage DM (2026). CanVAS: A Harmonized and Imputed Canine Variant Atlas. bioRxiv. doi:10.64898/2026.04.13.718238
- Nicholas, F.W., Tammen, I., & Sydney Informatics Hub. (2026). Online Mendelian Inheritance in Animals (OMIA) [dataset]. The University of Sydney. https://omia.org. doi:10.25910/2AMR-PV70 (retrieved April 2026).