Robinow-like-Syndrome (DVL2)
With their small size, stubby faces and wide-set eyes, bulldogs, French bulldogs and Boston terriers are among the most popular of domestic dog breeds. Now researchers at the University of California, Davis, School of Veterinary Medicine have found the genetic basis for these dogs’ appearance, and linked it to a rare inherited syndrome in humans.
Genetic variants of the Dishevelled 1 (DVL1) and 3 (DVL3) genes cause the so-called Robinow syndrome in humans , which can be characterized by distinctive facial features (prominent forehead, widely spaced eyes, flat nasal bridge) as well as mesomelic limb shortening (middle parts of limbs are disproportionately short) and cardiac, oral and urogenital anomalies.
English Bulldogs, French Bulldogs and Boston Terriers
In English Bulldogs, French Bulldogs and Boston Terriers, a variant of the DVL2 gene has been found to be fixed (always homozygous for the variant DVL/DVL). This genetic variant leads to altering a protein that affects an important cell-to-cell communication system, which is crucial for tissue development.
The typical phenotype of these breeds includes a wide head, a short muzzle (brachycephaly), widely spaced eyes and a small size. Malformed, fused or lacking caudal vertebrae which leads to truncated and kinked tails, so that the breeds are also called screw tail breeds.
In these three breeds, the DVL2 variant has been found to segregate with the breed defining phenotype as well as thoracic and caudal vertebral malformations in a recessive manner, however, regarding to the thoracic vertebral malformations, the variant seems to have an incomplete and variable penetrance between different breeds. Moreover, the DVL2 variant contributes to the brachycephalic phenotype, in addition to other known genetic variants of the SMCO2 and BMP3 gene. The DVL2 variant could also be linked to other health concerns like the brachycephalic obstructive airway syndrome (BOAS) and congenital heart defects, but this is still part of ongoing research.
In other none-screw tail breeds
Beside the screw tail breeds, the DVL2 variant has also been found homo- or heterozygous in the Pit bull, Staffordshire Bull Terrier, Shih Tzu, American Staffordshire Terrier, Dogues de Bordeaux, Old English Bulldog and American Bulldog. In these breeds, the DVL2 variant seems to be associated with a brachycephalic phenotype and caudal vertebral malformations as well. However, in contrast to the screw tail breeds, the total number of the vertebrae is not reduced and the tail is not completely malformed. Furthermore, no thoracic vertebral malformations have been observed, perhaps due to the variable penetrance of this trait.
