Tibetan Mastiff
The most carried tested variant is Cystinuria Type I-A, in 3.1% of 32 Tibetan Mastiffs tested (Donner 2023). 35 dogs stand behind the atlas figures here, so treat this page as an early sketch.
Also known as Do-Khyi.
What genetic diseases do Tibetan Mastiffs carry?
From a panel of 250 Mendelian-disease variants screened in 1,054,293 dogs (Donner et al. 2023), Tibetan Mastiffs carry 2 of them at observable frequency. Carrier frequency 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.
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.
SLC3A1what this gene does
SLC3A1 is a gene that helps transport certain amino acids in the kidneys. It plays a key role in preventing the buildup of cystine, which can form stones.
For your dog: If your dog is from a breed known to carry SLC3A1 variants, it’s worth discussing cystinuria risks with your vet, especially if urinary issues arise.
What these results mean for a Tibetan Mastiff
6.3% of Tibetan Mastiffs in the Donner 2023 cohort carried it (n=32).
- 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.
3.1% of Tibetan Mastiffs in the Donner 2023 cohort carried it (n=32).
- The kidneys fail to reclaim an amino acid called cystine, which can form crystals and stones in the urine and block the urinary tract.
OMIA 000256-9615
“Cystinuria, type 1 - A is an inherited defect that causes failure of reabsorption of cystine in the proximal renal tubule, leading to cystine precipitation in the urine. Formation of crystals and calculi lead to urolithiasis and urinary tract obstruction.” OMIA 000256-9615
What to do
Straining to urinate, or passing little or no urine, needs a veterinarian the same day.
No test, or a mix
Without a test nobody can say how many copies a dog has.
Other names
The Tibetan Mastiff is also recorded as Do-Khyi.
Identified as Tibetan Mastiff (VBO:0201351) in the Vertebrate Breed Ontology (Mullen et al. 2025, CC-BY 4.0) · registry IDs FCI 230 · iDog 242 · VeNom 14432.
For researchers Population genetics, disease models and every recorded condition Open the research detail for the Tibetan Mastiff
In the atlas, the Tibetan Mastiff clusters consistently as Tibetan Mastiff (100% of the 35 dogs here). Genetic diversity is high (mean heterozygosity 0.3502), reflecting either a mixed-breed cluster or breeds with broad genetic backgrounds.
Ranks 88 of 107 on the bottleneck severity scale, in the upper quartile of genetic diversity. Mean heterozygosity is 0.350, notably high, indicates broad genetic background.
Median lifespan is 13.0 years, about 1.8 years longer than a typical dog of 48.75 kg, an unusually positive longevity for this size.
What the atlas genotypes say about Tibetan Mastiff
Computed from the 14,478 CanVAS dogs in the Atlas, on an imputed genotype backbone: 77,215 directly typed sites per dog, imputed to 9.67 million variants.
The confidence below counts dogs, not reads: it is the size of the sample, and it is separate from how the genotypes were measured.
What does genetic diversity mean?
How varied a breed's gene pool is — the share of gene spots where a typical dog of the breed carries two different versions rather than two identical ones.
How to read it: Higher = more diverse. Among well-sampled breeds it ranges roughly 0.22 (least diverse) to 0.33 (most diverse).
Diversity is a strength, not a verdict on any individual dog. Lower diversity means it's worth paying attention to recessive-risk testing — not that a dog is doomed.
What does within-breed variation mean?
How much individual dogs within the breed differ from each other genetically.
How to read it: Higher = more internal variety among individuals of the breed.
Sensitive to how many dogs of the breed we've sampled.
Tibetan Mastiffs are a natural model for human disease
Because the same genes cause the same conditions across species, the inherited conditions documented in Tibetan Mastiffs help researchers understand, and work toward treating, the human diseases they model. This is the dog advancing human medicine. The breed models the human disease; it does not have it, and this is not a prediction for your dog.
- Griscelli syndrome type 3, modeled by the breed's Coat colour, dilution, MLPH-related , the same underlying biology.
Every condition recorded in the Tibetan Mastiff
Beyond the testable carriers above, OMIA's literature catalogue records 3 genetic conditions in the Tibetan Mastiff, 1 of which have a known human equivalent. This is the documented landscape across all Tibetan Mastiffs ever studied, not a prediction for any one dog.
- Coat colour, dilution, MLPH-related Autosomal recessiveHuman equivalent: Griscelli syndrome type 3
- Osteochondritis dissecans Multifactorial
Where every number on this page came from.
This page draws on three primary data sources. Carrier frequencies for the Mendelian section come from Donner et al. 2023 (CC-BY-4.0). We grade these data at evidence Limited because the cohort is a direct-to-consumer ascertainment, which biases toward owners who chose to test their dogs. The panel also uses tag-SNP proxies for some variants rather than direct causal-variant assays. Limited is a study-design grade, not a quality grade: the Donner cohort is the largest open canine-genotype dataset in existence and we are grateful for it. We rate the confounding MEDIUM.
Population-genetic dimensions (heterozygosity, intra-breed PCA distance, nearest neighbors, trait-locus frequencies) come from CanVAS (Brundage 2026), harmonized through the Sniff Atlas. The exact release date and verification commit are pinned at the bottom of the page so a researcher can trace a number back to a specific snapshot. The disease-gene-variant graph comes from OMIA (Online Mendelian Inheritance in Animals; Nicholas, Tammen, and the Sydney Informatics Hub at the Sydney School of Veterinary Science, The University of Sydney; retrieved April 2026, DOI 10.25910/2AMR-PV70).
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. The computed dimensions on this page are derived from the open Sniff Atlas v1.0.1 (Gehring 2026, doi:10.5281/zenodo.20566358, CC-BY 4.0). Full citation formats including BibTeX, RIS, and CITATION.cff at sniff.world/cite.
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Lived experience, kept beside the science.We have 35 tibetan mastiffs. We do not have yours.
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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).