If you've ever wondered why your Boston terrier, French bulldog or bulldog have tails that look like screws, you have only yourself to blame.
A new study published in the scientific journal PLOS theorizes that the aforementioned breeds have their distinct tails linked to the genetic mutation known as DISHEVELLED 2 or DVL2.
"Mutations in the related DVL1 and DVL3 genes are known to cause Robinow syndrome, a rare inherited disorder in humans characterized by strikingly similar anatomical changes—a short, wide 'babyface,' short limbs and spinal deformities," a statement accompanying the study reads.
UC Davis School of Veterinary Medicine professor Danika Bannasch noted that there may be a link between the disease, which is rare in humans but common in dogs because of the mutation.
"It's a very rare human disease but very common in dogs, so that could be a model for the human syndrome," Bannasch said in the statement.
Only a few hundred cases have been documented since the syndrome was identified in 1969.
This type of genome comparison is relatively new, Bannasch added. "Normally, we would have first had to identify a region DNA and work from there," she said. "We could look at breed-specific traits, but not as well as we can now."
In addition, humans with Robinow syndrome and dogs with screw tails also are more likely to have traits such as cleft palates. Peter Dickinson, professor of surgical and radiological sciences at the School of Veterinary Medicine, said that DVL genes "are part of a signaling pathway called WNT involved in development of the skeleton and nervous system, among other things."
Boston terriers, French bulldogs and bulldogs are among the most popular breeds in the U.S. according to data compiled by the American Kennel Club. Retrievers (Labradors) were the most popular breed in 2017, while French bulldogs, bulldogs and Boston Terriers ranked 4th, 5th and 21st, respectively.
The study analyzed "the genome sequences of 100 dogs, including 10 screw tail dogs, and identified all the genetic differences between those dogs." They found that the screw tail, which has specific DNA sequences and the affected gene identified, "are very similar to the types of mutations that have been shown to be responsible for a rare human disorder with similar clinical abnormalities, called Robinow syndrome."
Researchers added that "the dog mutation makes an altered protein that affects an important cell-cell communication system crucial for tissue development."
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