Bulldogs, French bulldogs and Boston terries all miss the vertebrae that makes up the tail bone and so share a feature not found in other breeds - a short, kinked tail or “screw tail”.
The researchers analysed the genome of 100 dogs, of which 10 were screw tails. From over 12 million individual differences, the researchers identified one mutation in a gene called DISHEVELLED 2 or DVL2. The variant was present in 100 per cent of the bulldogs and French bulldogs sampled, and it was also common in Boston terriers.
In humans, mutations in the related DVL1 and DVL3 genes are linked to Robinow syndrome - a disorder that causes a short, wide “babyface”, spinal deformities and short limbs - traits also shared by screw tail breeds.
The study also identified a key biochemical step in the pathway disrupted by the mutation, suggesting that a common molecular defect is responsible for the appearances of both Robinow patients and screw tail dog breeds.
The study has been published in the journal PLOS Genetics.