Dog legs: the genetics of short and stubby

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In recent years, the genetic mechanisms by which humans have generated massive phenotypic diversity in dogs have started to be uncovered. We now know, for example, much about the genetics of pigmentation in dogs, and a major gene controlling body size. This week, another phenotype–the short, stubby legs of some dog breeds (see right)–has been revealed to have a simple, but interesting genetic basis.

The authors mapped the short leg phenotype to a small region on chromosome 18; further analysis revealed that the probable causal mutation is the insertion of a transcriptionally-active processed (ie. intronless) retrotransposed copy of the FGF4 gene. How this change leads to the phenotype itself is unknown, but understanding the mechanism will likely lead to some interesting biology.



  1. so cute. and so evil.

  2. What would be interesting is seeing whether the same transcriptionally-active processed retrotransposed copy of the FGF4 gene, plays a part in the low cancer rate seen in dogs with short legs.

  3. Is it true that the large number of chromosomes (78) in the dog’s genome has enabled such wide diversity in Canis familiaris? I recall reading Jonah Goldberg making that claim, so I’m inclined to be skeptical.

  4. No. As for Jonah – I think everyone who has read the Aubrey/Maturin series knows what to do with a Jonah.