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Leg Length

FGF4_retrogene_CFA18

chr18:20,697,946-20,697,946 · UU_Cfam_GSD_1.0

chondrodysplasia insertion site; not annotated as gene

Atlas-wide
Frequency
77%
dog-weighted average
Breeds with data
215
of 215
Dogs contributing
13,914
CanVAS Atlas
What the frequency means

The famous FGF4 retrogene insertion on chromosome 18 (Parker 2009).

High frequency means

breed is standard-legged - does NOT carry the chondrodystrophy retrogene insertion (the alt allele at this rep SNP marks the non-retrogene haplotype)

Low frequency means

breed carries the FGF4 chr18 retrogene insertion (Parker 2009) - causal for short legs in Dachshund/Corgi/Basset Hound. Spot-check confirms: Dachshund, Pembroke Corgi, Pekingese, Basset variants all read ~0 at this rep SNP.

Top 10 breeds, highest frequency
  1. Bedlington Terrier terrier
    100% n=11
  2. Border Terrier terrier
    100% n=59
  3. Chesapeake Bay Retriever sporting
    100% n=13
  4. Chinese Crested other
    100% n=25
  5. Chinook other
    100% n=11
  6. Collie herding
    100% n=20
  7. Curly Coated Retriever sporting
    100% n=8
  8. Dingo Bigdesert ancient_landrace
    100% n=19
  9. Dogue De Bordeaux other
    100% n=9
  10. Flat Coated Retriever sporting
    100% n=48
Bottom 10 breeds, lowest frequency
  1. Tibetan Spaniel sporting
    0% n=42
  2. Silky Terrier toy
    0% n=9
  3. Petit Basset Griffon Vendeen other
    0% n=12
  4. Pembroke Welsh Corgi herding
    0% n=24
  5. Pekingese toy
    0% n=26
  6. Norfolk Terrier terrier
    0% n=32
  7. Miniature Dachshund hound
    0% n=8
  8. Japanese Chin toy
    0% n=8
  9. Cardigan Welsh Corgi herding
    0% n=14
  10. Australian Terrier terrier
    0% n=10
Methodology

Frequency is measured at the typed-backbone 18:20697946 on chr18, 20.7 Mb (inside the gene body). Alleles T/C. Coordinates from manual position (Ensembl symbol failed). Per-breed frequencies are computed across all CanVAS dogs labelled with that breed (missing genotypes excluded). See methodology for the full pipeline.

Last updated
Sources: CanVAS (Brundage 2026) · OMIA · Dog10K (Meadows 2023)