IGF1
small breeds enriched for short-allele haplotype
IGF1 is the canonical dog body-size locus (Sutter 2007). The representative SNP at chr15:41.5Mb is in the IGF1 gene body. Direction calibrated against SMALL (chihuahua, pomeranian, ...) vs GIANT (great dane, mastiff, ...) breed pools.
allele common in small body-size pool
allele common in giant body-size pool
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=228
- 100% n=62
- 100% n=38
- 100% n=31
- 100% n=28
- 100% n=26
- 99% n=67
- 97% n=26
- 97% n=26
- 97% n=102
- 3% n=192
- 6% n=381
- 10% n=21
- 16% n=31
- 18% n=20
- 18% n=22
- 20% n=117
- 20% n=34
- 21% n=32
- 21% n=20
94 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 15:41555463 on chr15, 41.6 Mb (inside the gene body). Alleles C/A. 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).
IGF1 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 IGF1. That ortholog is what connects IGF1 to a century of human medical genetics. The dog and human proteins are 88% identical.
In people, IGF1 appears tolerant of loss-of-function variation (gnomAD v4.1 constraint, LOEUF 0.68). Constraint measures intolerance to loss-of-function only and does not indicate importance; some tolerant genes cause disease through other mechanisms.
In people, variants in the IGF1 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.