SMAD2
small vs giant strong differentiation chr7
SMAD2 chr7:43.7Mb. Strong size-discriminating locus identified by Plassais 2019. Direction: SMALL vs GIANT (note: opposite sign convention from IGF1/HMGA2 at this rep SNP).
allele common in giant breeds
allele common in small breeds
Where the body size variant sits across every breed with data, by allele frequencyAllele frequencyWhat it isHow common a gene variant is across dogs, from 0% (none carry it) to 100% (all do).For your dogA high number means it's common in the breed. It does not tell you whether your own dog carries it.PreciselyThe proportion of sampled chromosomes in a population that carry the variant allele.Sniff Atlas (CanVAS) · measured · Ask about this → and grouped by AKC breed groupAKC breed groupWhat it isThe American Kennel Club's grouping of breeds by the job they were bred for: Sporting, Hound, Working, Herding, Terrier, Toy, Non-Sporting.PreciselyAKC parent-group classification. A registry convention reflecting historical use, not a genetic grouping.American Kennel Club · registry convention. Each tick is one breed; a variant fixed in one group and absent in another shows up as a gap. These come from one marker per trait, so read them as a tag, not a verdictA trait tag, not a verdictWhat it isThese frequencies come from one marker per trait. It predicts the trait for most breeds, but there are real exceptions.For your dogRead it as a tendency for the breed, never as a guarantee about your dog. One marker is not the whole story.PreciselySingle-SNP trait proxies are population tags, not deterministic genotype-to-phenotype calls. Penetrance, modifier loci, and breed-specific haplotypes cause exceptions (for example, the MSRB3 ear-type tag misreads Toy Poodles and Belgian Sheepdogs).Sniff Atlas methodology · known limitation, stated · Ask about this →: accurate for most breeds, with real exceptions.
- 100% n=182
- 100% n=37
- 100% n=22
- 100% n=20
- 100% n=20
- 99% n=532
- 98% n=141
- 97% n=381
- 95% n=20
- 93% n=22
- 0% n=31
- 0% n=38
- 2% n=228
- 3% n=32
- 4% n=26
- 6% n=25
- 8% n=25
- 14% n=28
- 15% n=62
- 15% n=26
105 breeds with fewer than 20 genotyped dogs are not ranked here. At that sample size a single dog swings the frequency, so the figure is not yet stable enough to compare.
Frequency is measured at the typed-backbone 7:43693994 on chr7, 43.7 Mb (inside the gene body). Alleles A/G. Coordinates from ensembl symbol UU Cfam GSD 1.0. Per-breed frequencies are computed across all CanVAS dogs labelled with that breed (missing genotypes excluded).
SMAD2 as it is catalogued across the genomics world. Each link is the canonical record, so this gene composes with everything those resources know.
In humans, this gene's counterpart is SMAD2. That ortholog is what connects SMAD2 to a century of human medical genetics. The dog and human proteins are 100% identical (a lower-confidence 1:1 call, shown for transparency, not hidden).
In people, SMAD2 rarely tolerates loss-of-function variation (gnomAD v4.1 constraint, LOEUF 0.25), a sign it does important, dosage-sensitive work.
In people, variants in the SMAD2 gene have conflicting classifications in ClinVar, and none is expert-reviewed. The evidence is unsettled, not that variants here are benign.
The per-breed allele frequencies on this page are derived from the open Sniff Atlas v1.0.1 (Gehring 2026, doi:10.5281/zenodo.20566358, CC-BY 4.0). The underlying genotype substrate is CanVAS (Brundage 2026, doi:10.64898/2026.04.13.718238), and disease associations are grounded in OMIA. Full citation formats including BibTeX, RIS, and CITATION.cff at sniff.world/cite.