Tibetan Mastiff
35 Tibetan Mastiffs in the atlas. Every number on this page has a source.
35 Tibetan Mastiffs in the Sniff Atlas. Population-genetic snapshot, Mendelian carrier frequencies from Donner 2023, and the data substrate's release version, sample sizes, and evidence tier on every claim.
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. At the trait loci, MSRB3 runs lower than average (45% here vs 80%); STC2 runs lower than average (43% here vs 74%).
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.
Closest genetic neighbors in the atlas: Eurasier, Tibetan Spaniel, village dog Nepal, Mongolian Dog, and Gray Wolf.
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 genome says about Tibetan Mastiff
Computed from the 18,477 research dogs in the Atlas.
- Eurasier14.98
- Tibetan Spaniel15.37
- Village Dog Nepal16.18
- Mongolian Dog16.30
- Gray Wolf16.59
Frequency of the alternate allele in this breed at each locus's representative SNP.
| IGF1 | 64% |
| HMGA2 | 46% |
| SMAD2 | 69% |
| LCORL | 93% |
| STC2 | 43% |
| ADAMTS17 | 50% |
| FGF4·CFA18 | 60% |
| FGF4·CFA12 | 83% |
| RSPO2 | 46% |
| FGF5 | 86% |
| KRT71 | 99% |
| MC1R | 69% |
| MSRB3 | 45% |
| BMP3 | 73% |
| SMOC2 | 53% |
What does the genome say about how a Tibetan Mastiff looks?
Tibetan Mastiffs look the way they do because of a small set of fixed and near-fixed morphology genes that, taken together, define the visible breed. Each translation below pairs the gene with the trait an owner actually sees, the breed's allele frequency at that locus, and a one-clause causal phrase.
Size and build
IGF1 sits at 64% for the small-body allele. IGF1 is the gene that sets dog body size from Chihuahua to Great Dane. Intermediate frequencies typically keep a breed in the mid-sized range rather than tipping toward the larger working forms.
HMGA2 sits at 46%. HMGA2 is a chromosome-10 size locus that acts together with IGF1, and intermediate frequencies reflect partial commitment to the dominant size variant.
SMAD2 sits at 69% at the chromosome-7 height locus.
LCORL is near-fixed at 93%, the NCAPG/LCORL height locus that is one of the strongest single contributors to canine body size.
STC2 sits at 43%.
ADAMTS17 sits at 50%. ADAMTS17 is a body-size locus also linked to lens disorders.
Leg length
The FGF4 retrogene on chromosome 18 sits at 60%. This is the leg-length variant. The intermediate frequency means some dogs in this breed carry the short-legged allele and some do not.
The FGF4 retrogene on chromosome 12 sits at 83%, the chondrodystrophic variant.
Coat type, length, and color
RSPO2 sits at 46% for the furnishings variant. Furnishings (the eyebrow-and-mustache pattern seen in Schnauzers and Wheaten Terriers) vary across the population at this intermediate frequency, and visible expression depends on the specific allele combination each dog carries.
FGF5 is at 86% for the long-coat variant, which is why the breed's coat sits where it does on the long end of the dog coat-length spectrum.
KRT71 is near-fixed at 99% for the wavy/curly variant. Coat curl phenotype varies across breeds at this fixation depending on modifier loci, and visible expression is not always curled even when the locus is fixed.
MC1R sits at 69% at the representative SNP. MC1R controls the switch between red-to-gold pigment and black-to-brown pigment, with the e/e homozygous genotype producing the gold-to-red spectrum. Substrate frequencies at this SNP depend on the array's polarity, so visible coat color in the breed is a more reliable indicator than this single number.
Ears
MSRB3 sits at 45% for the drop-ear allele, which is why ear set varies across the breed.
Skull shape
BMP3 sits at 73%, contributing to the breed's moderate, mesaticephalic head shape rather than the extreme brachycephalic form.
SMOC2 sits at 53%, contributing to the breed's moderate head shape.
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.
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 now in the structured data for every variant the panel covers. Mondo, OMIM, Ensembl, and HGNC cross-references on gene pages remain pending — they arrive in December 2026 alongside the imputed 9.67M-variant CanVAS dataset via the OMIA SQL dump absorption. Until then, gene IDs carry NCBI Gene and OMIA phene URLs only; the wider human-homolog and disease-ontology cross-reference set fills in with that release.
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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- Donner J, Anderson H, Davison S, et al. (2023). Frequency and distribution of 152 genetic disease variants in over 1,000,000 mixed-breed and purebred dogs. PLOS Genetics 19(2):e1010651. doi:10.1371/journal.pgen.1010651
- Brundage J, et al. (2026). CanVAS: a harmonized 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).