Norwich Terrier
14 Norwich Terriers in the atlas. Every number on this page has a source.
14 Norwich Terriers 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 Norwich Terrier clusters consistently as Norwich Terrier (100% of the 14 dogs here). At the trait loci, MSRB3 runs lower than average (0% here vs 80%); FGF4_retrogene_CFA18 runs lower than average (14% here vs 77%). Dogs here sit in a relatively sparse region of the atlas, fewer close neighbors than typical.
High breed predictability score (0.86), individual dogs of this breed reliably cluster together genetically. Only 14 dogs of this breed in the atlas, modestly sampled.
Closest genetic neighbors in the atlas: Scottish Terrier, West Highland White Terrier, Fox Terrier Wire, Cairn Terrier, and Norfolk Terrier.
What the genome says about Norwich Terrier
Computed from the 18,477 research dogs in the Atlas.
- Scottish Terrier7.29
- West Highland White Terrier9.26
- Fox Terrier Wire14.37
- Cairn Terrier14.90
- Norfolk Terrier21.26
Frequency of the alternate allele in this breed at each locus's representative SNP.
| IGF1 | 75% |
| HMGA2 | 0% |
| SMAD2 | 43% |
| LCORL | 75% |
| STC2 | 100% |
| ADAMTS17 | 90% |
| FGF4·CFA18 | 14% |
| FGF4·CFA12 | 96% |
| RSPO2 | 100% |
| FGF5 | 71% |
| KRT71 | 100% |
| MC1R | 100% |
| MSRB3 | 0% |
| BMP3 | 70% |
| SMOC2 | 93% |
What does the genome say about how a Norwich Terrier looks?
Norwich Terriers 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 75% 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 is at 0%, leaving most of the size signal to other loci in the panel.
SMAD2 sits at 43% at the chromosome-7 height locus.
LCORL sits at 75% at the NCAPG/LCORL height locus on chromosome 3.
STC2 is near-fixed at 100%, modulating growth-axis signaling toward the breed's body-size set point.
ADAMTS17 is at 90%, near-fixed for the size variant.
Leg length
The FGF4 retrogene on chromosome 18 is at 14%, the chromosome-18 leg-length variant, which keeps the breed short-legged like Corgis and Dachshunds.
The FGF4 retrogene on chromosome 12 is near-fixed at 96%, the chondrodystrophic variant associated with intervertebral disc disease risk in breeds that carry it.
Coat type, length, and color
RSPO2 is near-fixed at 100% for the furnishings allele, the genetic basis of the eyebrows-and-mustache pattern seen in Schnauzers and Wheaten Terriers.
FGF5 sits at 71% for the long-coat variant. Coat length is influenced by other loci as well, so intermediate FGF5 frequencies do not always correspond to intermediate visible coat lengths.
KRT71 is near-fixed at 100% 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 is at 100% at the representative SNP. MC1R controls the switch between red-to-gold and black-to-brown pigment, with the e/e homozygous genotype producing the gold-to-red spectrum by blocking eumelanin (black and brown pigment).
Ears
MSRB3 is at 0% for the drop-ear allele, keeping the breed's ears upright and prick.
Skull shape
BMP3 sits at 70%, contributing to the breed's moderate, mesaticephalic head shape rather than the extreme brachycephalic form.
SMOC2 is at 93%, the major locus contributing to the breed's brachycephalic face shape.
What genetic diseases do Norwich Terriers carry?
From a panel of 250 Mendelian-disease variants screened in 1,054,293 dogs (Donner et al. 2023), Norwich Terriers carry one 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.
We have 14 norwich terriers. We do not have yours.
Every norwich terrier added sharpens the breed's genetic neighborhood. Enrollment is free. The data stays open. The star is permanent.
- 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).