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What is DVL2?

What is DVL2?

DVL2, IS the screwtail gene. It is a recessive gene (need 2 copies) and the reason you see no tails, or a very short screwtail, in 98% of the French bulldogs in our population today. It is responsible for BOAS, Hemivertebrae and has been linked to other health issues too such as heart issues, cleft palates/hare lips, abnormal genitalia and some types of brain cancer. All the dogs that have been bred so far with one copy have had perfect spines and breathing.


There are now several research papers about DVL2 describing the effects of this mutation and its striking similarities to Robinows Syndrome which is a genetic disease in humans resulting from both recessive and dominant mutations in DVL1, and 3. There are also several peer reviewed DVL2 research papers, but for those who find reading research papers mind boggling and difficult to decipher, Nicci @ Chaleureux French Bulldogs has produced this infogram summarising the research on DVL2 and its effects to date.


One of the most important things to understand about this mutation is that it is acts in a recessive manner, so a dog needs to carry 2 copies to manifest the effects of the mutation (just like other hereditary diseases such as HC or PRA). However, the mutated gene has incomplete penetrance which means that sometimes 2 copies can be present in a dog but the effects of the mutation are not present i.e. the spine has no hemivertebrae.


Research states that over 95% of French and British Bulldogs have hemivertebrae so we can see that it is highly heritable. Over the history of the breeds, we have been selecting for the short screwtail to achieve a particular look, we did not realise that we were indeed selecting for a mutation that has several congential health conditions associated to it and this is how from just one ancestor way back in time that carried this mutation, it has been spread through nearly the entire population of these breeds.


A common misconception is, that if by breeding 2 dogs with spines scoring 0 for hemivertebrae you will go on to produce litters that are the same. This is not AT ALL the case because any puppy that inherits a copy of DVL2 from each of its parents, has the high potential to develop hemiveretbrae no matter how good their parents spine look. It is only an inderterminant few that will be hemivertebrae free due to the effect of the incomplete penetrance. The only way to consistently GARUNTEE no congential hemivertebrae in every litter that is born, is to remove this mutant gene. Until then, unfortunately its always going to be "Russian roulette" on what the condition of the pups spine will be, even from perfect score parents we are still seeing these hemis, yet all dogs born with 1 copy dvl2, to date, have all had perfect spines. Proofs literally in the pudding.


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